REPORT ON

CONSULTANCY SERVICES ON GIS –

BASED MAPPING OF EROSION AND

WATERSHED SITES IN KANO STATE

SUBMITTED

TO

KANO STATE NIGERIA EROSION AND

WATERSHED MANAGEMENT PROJECT

(NEWMAP)

WORLD BANK ASSISTED

Project ID: P124905

Credit No IDA 51050

REFERENCE NO:

KNSPMU/CQS/17/2.3

BY

PREPRA NIGERIA LIMITED

222A JIGIRYA, YANKABA, KANO

www.prepraconsult.com

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1. CHAPTER ONE: INTRODUCTION

1.1 Background

The Government of Nigeria initiated the preparation of the erosion and

watershed management project [NEWMAP]. The Project is supported with

financing from the World Bank to the tune of $500 million. The Agency

responsible for the management of the project at the Federal level is the

Federal Ministry Environment (FME), Department of Erosion, Flood and Coastal

Zone Management. In addition, States, local governments, local communities

and CSO‟s are involved in the project, given that the Project is a multi-sector

operation involving MDAs concerned with water resources management,

public works, agriculture, regional and town planning, Earth and natural

resources information, and disaster risk management.

NEWMAP activities currently involve nineteen states, namely: Anambra, Abia,

Cross-River, Edo, Enugu, Ebonyi, Imo, Delta, Kogi, Akwa Ibom, Nasarawa,

Niger, Plateau, Gombe, Borno, Oyo, Kano and Sokoto. NEWMAP is designed

to support participating states and local governments to reduce vulnerability

to erosion and development of watersheds. The overall objective of NEWMAP

is “to restore degraded lands and reduce longer-term erosion vulnerability in

targeted areas. „‟The Project includes four components, namely:

a. Component 1: Investment in Targeted Areas to support on the ground

interventions that address, prevent and reverse land degradation.

b. Component 2: Institutional development and information Systems for

Erosion Management and Watershed planning to address longer term

sustainability by strengthening the enabling Federal and states MDAs

on the environment with a view to addressing erosion and watershed

degradation problems in a comprehensive manner across sectors and

states.

c. Component 3: Climate Change Agenda Support Outcomes focus on

providing tools and approaches for government to become better

equipped to respond to climate change; and on supporting

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demonstration projects on the ground to test the viability and scaling-

up potential of low-carbon development options.

d. Component 4: Project management to support at federal and state

levels to implement this project including (a) procurement and

financial management; (b) social and environmental safeguards issues;

(c) strategic project communications and outreach; (d) project M&E,

including two Mid-Term Reviews; and (e) an impact evaluation fully

integrated into M&E arrangements that will help build replicable

intervention models during implementation.

Against this background, the Project Management Unit of Kano State

NEWMAP commissioned various studies aimed at effectuating successful

implementation of the NEWMAP in the state. One of the assignments is the

Mapping of Gully Erosion/flood Sites and the generation of Land Resource

Inventory data within a geographic information system (GIS) framework. This

will aid in knowing the status of gully erosion sites and land resources in the

State and also underpin project presentation and reporting on key status of

erosion sites especially the sites for the NEWMAP GRASS component.

The scope of work includes the following:

Identification of the sites affected by flood and erosion in the State through

proper ground „truthing‟ and/or field visits which involve appraisals,

observations and measurements (sample/specimen collection).

I. Generation of geological maps for erosion and watershed

management

II. Generate Land Resource Inventory (LRI) data such as soil/land

suitability maps, for erosion and watershed/ catchment management.

III. Mapping of land use land cover including the acquisition of necessary

spatially referenced data of both primary source (such as attributes of

selected sites, comprising of soil types, vegetation types and geo-

ecological characteristics of the area in the state).

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IV. Hydrological analysis for erosion and watershed management in the

state

V. Acquisition of spatial data of secondary origin, such as topographic

sheets and satellite images with 0.5m spatial resolution and other

records for the whole state.

VI. Development of spatial database that can be updated from time to

time and subsequently, build a GIS for erosion and flood information

management from the acquired primary and secondary data arising in

(1-3) above.

VII. Conduct series of spatial analysis and modeling to produce map

documents that can guide key policy and management decision

making.

VIII. Derivation of geo-database on the priority erosion and flood sites in the

State

IX. Identification and delineation of major and minor watersheds in the

State

X. Identification of other potential areas prone to gully erosion and

flooding in the State and the classification of the degree of

vulnerability/risk potentials

XI. Assessment of the socio-economic impact of gully erosion and flood

hazards on the people

XII. Present in easy to read maps:

i. Spatial extent of erosion in the selected area

ii. Spatial extent of flood affected area

iii. Spatial analysis of socio-economic impacts

iv. Predictive models of erosion and flood risk hazard based on

anthropogenic, climatic and environmental factors

v. Land Resource Inventory Map

vi. GIS Catchment Management Plan

vii. Soil Maps

viii. Land use Land cover maps

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ix. Soil Suitability Map

x. Geology maps

xi. Map of a high-resolution satellite image 0.5m covering the

state

1. Proffer best management practices that could mitigate the current

problems and prevent future erosion and flood hazards in the state.

1.2 Location and characteristics of Kano state

Kano state lies within the Sudan Savannah region of Nigeria. It is located on

latitude 110.30N and longitude 80.30E on ( Fig.1) and has a total land area of

20,680 km2 which represents 2.07% of the land mass of Nigeria.

Figure1: Map of Kano state

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1.3 Location of selected sites for intervention

Table 1: location of the Nine selected sites

RARIN - DAWAKIN TOFA

N 12006‟29.80 E 008.19‟ 26.3‟‟

This site is made up of gully heads developed on the

Rarin river . It has encroached and destroyed l

properties and infrastructures. The gullies are l

expanding and will divide Dawakin tofa town into

two sectio. This is a to the socio – economic and

administration of the area being the headquarters of

the local government headquarters, thus disrupting the

livelihood of hundreds of thousands of people. The

existing intervention through concrete stabilization has

only succeeded in pushing the problem to another

location in the town

KAMANDA KIRU

N 110 38‟19.2 E 0080.05‟11.8‟‟

Kamanda river is a 3rd order stream that contributes

water into the Challawa gorge dam. Over he years

human activities along the river and elsewhere

particularly sand mining has increased lateral erosion

that has widened the channel making it increasingly

difficult to cross thereby disrupting the livelihood of

several rural communities. Abridge across will make it

possible the transportation of valuable agricultural

commodities that is abundant in the area, and

movement of people. That is not possible now with

disastrous consequences

YAN SABO - TOFA LGA

N 12003‟18.4 E 0080 18‟41.0‟‟

This is a medium earth dam that potentially can

change the lively hood of several communities. The

dam collapsed as a result of disrepair. Once

rehabilitated the dam can serve as a source of

domestic water supply, fishing, irrigation and recreation

to the many communities in the area. In addition to the

repairs to the dam, there is also the need for access

road and channelization of the water to the field for

irrigation.

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YAR TITI - SHANONO

N 120 03‟53.1 E 0080 00‟25.7‟‟

This is a conservation project to harness the huge

water in the area through impoundment. There are

several communities in the area that currently use the

water during the rainy season. It has rich soil that is used

for rice, sugarcane and vegetable. In addition there is

a need for access road and channelization of the

proposed dam in order for the water to reach the

farmlands

TUDUN FULANI BACHIRAWA - UNGOGO

N 12002‟39.6 E 008028‟06.8

This is a major gully that stretches over several km within

a densely low income area of Kano metropolis.

Already thousands of houses and roads and other

infrastructures have been destroyed. Many families

have been displaced with all their life saving lost. This

project will not only save the remaining properties and

infrastructure in the area, but also help to stem the

growing menace as at the moment the gully is fast

expanding west wards towards Bayero University new

campus.

BULBULA GAYAWA- NASSARAWA LGA

N 12002‟32.5 E 008033‟40.8

This is a major gully within a densely low income area of

Kano metropolis. Already several families have been

displayed with hundreds of houses and roads and

other infrastructures destroyed. This project will not only

save the remaining property and infrastructure in the

area, but also help to stem the growing menace.

KAUYEN ALU - TARAUNI LGA

N11057‟26.60 E 008034‟38.7

This is a major gully within a densely populated area of

Kano metropolis. Already thousands of houses and

roads and other infrastructures have been destroyed.

Intervention already carried out by the state

government and ecological fund is beginning to give

way threatening the community. This project will not

only save the remaining property and infrastructure in

the area, but also help to stem the growing menace as

at the moment the gully is fast expanding southward.

FAJEWA TAKAI LGA

N 110 26‟19.8 E 009012‟00.8

This is a project that will involve the harnessing and

conservation of the huge water in the area through

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impoundment. There are several communities in the

area that currently use the water during the rainy

season. It has rich soil that is used for rice, sugarcane

and vegetable. In addition there is a need for access

road and channelization of the proposed dam in order

for the water to reach the farmlands

DAWAN KAYA - MAKODA LGA

N 12017‟56.0 E 0080 32‟16.8

This is a project that will involve the harnessing and

conservation of the huge water from the Dawon Kaya

stream. The catchment area in Dawon Kaya forest in

which over 20sqkm is a semi virgin land that can

accommodate the reservoir. There are several

communities in the area that can benefit from this

project. It has rich soil that is used for rice, sugarcane

and vegetable. In addition there is a need for access

road and channelization of the proposed dam in order

for the water to reach the farmlands

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CHAPTER TWO: MATERIALS AND METHODS

2.1 Preparing a work plan

In order to accomplish the assignment, a systematic approach was adopted

as illustrated in Fig.2

Figure 2: Schema of work plan

2.2 Mapping of Erosion and watershed sites in the state

The job involves a number of step by step tasks as follows:

2.2.1 Bibliographic Data Review

This involves the following tasks:

Identifying the various data required for the study.

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The sources are of the data

A review of all the available materials in terms of their relevance,

suitability in terms of date/year

The format of the data

Thereafter it is proposed that the project execution shall be carried out

under the following taks:

2.2.2 Survey of the Project sites

The location, alignment of the gully/watershed was traversed to

determine the cross-section and also determine the actual area of the

project. Chain pegs and pillars were used as reference points during the

delineation of drainage location. Appropriate ground controls were

provided for selecting the image of the areas.

Acquisition of coordinates of prominent features and landmarks

In order to carry out delineation of features on land correctly, a high

precision instrument Germain XP Differential Global Positioning System

(DGPS) was used to obtain coordinates of prominent features. A total

Station and Trimble Mobile Mapper was alos used as supplement for the

DGPS. A minimum of twenty field referencing locations would be required

for the study.

2.3 Data acquisition and processing

2.3.1 Process of data acquisition

Figure 3: Shows the step by step tasks that was used in the acquisition.

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Figure 3: Schema of satellite and secondary data acquisition

2.3.2 Data acquired

On the basis of the bibliographic review and field measurements, data the

following were deemed to be the imagery/data for the project.

Quick bird 2016 0.5 m resolution imagery was acquired

SRTM or Aster data to create a digital terrain model for the study area.

Modis dataset was downloaded from Earth explorer USGS which is

used to create Normalised Differential Vegetation Index (NDVI),

Normalised Differential Water Indices (NDWI) and Land Use Land Cover

(LULC) map.

Topographical map sheets of the selected areas at the scale of 1:

25,000.

Cadastre maps, foot prints of the building captured from the geo-

referenced satellite

Geological Maps

GeoNetcast Climate data and In –situ records

Population data of Kano state

Socio – economic impact of gully erosion in the affected sites

2.3.3 Field Verification of acquired imagery

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This was done through acquisition of coordinates of prominent features and

landmarks and Collection of randomly selected spot height by field visits to

the sites. The data obtained from the field verification exercise, such as

coordinates of prominent features was used to further geo-reference the

acquired imagery during image registration process. Both distance and

direction measured on the satellite imagery was confirmed to be accurate.

2.4 Data processing

Figures 4 and 5 show the schematic flow of the processes involved in the

processing of the data acquired.

2.4.1 Digital Elevation Model (DEM)

The Advanced Space borne Thermal Emission and Reflection Radiometer

(ASTER) Global Digital Elevation Model was utilized for various analyses. Six

tiles of AsterDEM that covers the Kano region were mosaic using ENVI

software. The DEM within the boundary of the study area was extracted for

the analysis. This analysis include: generation of drainages, slope and

elevation.

2.4.1.1 Drainage generation

The drainage analysis was carried out using the Arc Hydro extension tool in

ArcGIS.

The DEM was first fill to remove minor artifact. The fill DEM was used create

flow direction grid (fdr) and the flow direction is then as an input to create

the flow accumulation (fac). The fdr and fac were used as input for Stream

definition analysis (str). Finally the stream raster is been convert to drainage

feature.

2.4.1.2 Drainage density

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Drainage density map was created from using Kernel density tool and was

classified into four classes.

Extracted DEM Fill DEM Flow direction Flow Accumulation Stream

definition

Stream features

Drainage

density

2.4.1.3 Identification of flood risk zones

In order to identify disaster risk areas, zones of influence were created around

the erosion sites. This was overlaid on the cadastre map of the study areas.

Flood plains were identified and delineated and a buffer zone of about 45

meters is created around them so as to identify vulnerability zones

2.4.1.4 Elevation

The DEM was used to generate relief map which is categorized into five

classes according to elevation.

2.4.1.5 .Slope

The slope was generated from the DEM which is been reclassified into five

classes based the percentage rise.

2.5 MODIS Dataset

NDVI extracted from Modis data was used to create vegetation map. The

vegetation was been categorized into five classes according to density.

2.5.1 Normalized Differential Water Index (NDVI)

The NDVI indices have been used to generate soil wetness. The Modis Bands

used are: band 1 (RED), band 2 (NIR) and band 7 (SWIR). The soil wetness was

reclassified into four class base on the degree of wetness.

2.5.2 Land Use Land Cover (LULC)

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Land Use Land Cover map was created using Mahalanobis distance

supervised classification using ENVI software. Five classes of land covers were

created which include water bodies, vegetation, built up, sediments and

hard rock.

2.6 SPOT 4 Data

Small water bodies were extracted from the SPOT 4 dataset.

2.6.1 Distance from water bodies

Proximity analysis was carried on the small water bodies using Buffer tool in

ArcMap. Multiple ring buffers of 1000 to 5000meters were performed.

2.7 Rainfall

Rainfall dataset obtained from GEONETcast (EUMESAT) was validated using

In-situ rainfall data.

2.8 Geology

The Lithology of Kano was obtained from Nigeria Geological Survey Agency

(NGSA).

2.9 Weighted overly

The classes of each layer was compared and weights are been assign to

each class according to the degree of preference. Each layer is then ranked

according to the degree of influence. Finally weights sum was used to

produce the final Risk Map.

2.10 Socio- economic survey of the study communities

Focus Group Discussion was undertaken to identify different communities in

each site – tribal, religious, cultural, social and economic as well as to

determine the historical evolution of erosion and the perceived

environmental and socio – economic impact of erosion as well and

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potentials of the intervention from the perspectives of the communities. One

Focus Group Discussion (FGD) was conducted in each of the sites and 86

participants took part in the FGD, which consisted of 47 participants from

communities around gully erosion sites and 39 participants from communities

around watershed conservation sites. The participants involved were heads

of associations and traditional institutions including ward and district heads,

farmers associations, women association, self-help community associations,

religious leaders, traders associations among others. The participants were

selected because both gully erosion and watershed conservation failure

affect their livelihood directly.

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Slope

Drainage

NDVI

AsterDEM MODIS

NDWI

SPOT 4

Small Water

BodiesDEM

Drainage

Density

Distance from

Water Bodies

Geometric &

Radiometric Corr

Elevation

FLOOD RISK POTENTIAL MAP FOR KANO STATE

In-situ

Rainfall

(EUMETSAT)G

GEONETcast

Rainfall Map

Rainfall

Estimate

(RFE)

Validation

Distance from

Drainage

FLOOD RISK POTENTIAL MAP

Weighted Overlay

Figure 4: Flood risk index in Kano state

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LULC

Drainage

NDVI

AsterDEM MODIS

NDWI

SPOT 4

Small Water

BodiesDEM

Weighted Overlay

Drainage

Density

Distance from

Water Bodies

Geometric &

Radiometric Corr

Elevation

Soil

EROSION POTENTIAL MAP FOR KANO STATE

Slope Soil Type

EROSION POTENTIAL MAP

NGSA

Lithology

Figure 5 Erosion potential index in Kano state

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2.11 Delineation of erosion maps

Soil samples based on standard methods was collected from the sites of the

study and laboratory analysis was conducted for erodibility, which was used

to produce a map through spatial interpolation of geo-statistical analysis

function of ArcGIS. This was incorporated in the Revised Universal Soil Loss

Equation (RUSLE)illustrated in figure 6 into GIS for modeling erosion prediction

and control, and to generate erosion risk hazard map.

Figure 6: RULSE Model for soil erosion assessment

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2.12 watershed management

Recently, the use of watershed modeling system (WMS) in combination with

the output of the hydrological models have been used with Digital Terrain

Model (DTM) successfully as illustrated in figure 7.

Figure 7: Model for flood risk assessment and catchment management

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3.0 CHAPTER THREE: PRESENTATION OF DERIVABLES

3.1 Elevation

The elevation of the state is shown in figure 8. Five principal zones of

elevations are found. These are: the south and southeast highlands, the

middle and western high plains and the northeastern low Chad Plains. Table 2

shows the calculated area covered by the five different elevations indicating

clearly the dominance of the plains in the state

Table 2: Calculated area of Elevation in Kano state

S/N Class Area (SqKm) Percent

1 79739 – 1207.927 8,04.7817 3.902915448

2 624.47 – 797.39 2,959.179 14.35100404

3 534.035 – 624.47 5,596.717 27.14215946

4 460.449 – 534.035 5.982.74 29.01423872

5 224.1 – 460.449` 5,276.596 25.58968232

TOTAL 20,620.0137 100

The Highlands occupy a relatively small area to the south (3.9%) and

constitute part of the foot slopes of the Jos Plateau. The elevation is generally

above 650 m and reaches well over 1000 m in the Rishi Hills. Most of the rocky

outcrops in this zone are of Younger Granites.

The High Plains occupy more than 50% of the surface area of the state and lie

on elevations ranging between 450 m and 650 m. The plains are developed

on rocks of the Basement Complex and outcrops of these rocks constitute

most of the hills, both grouped and ungrouped.

The Low Chad Plains occupy a small section of the state to the east of the

Hydro-Geological Divide. The elevation of this zone is about 420 m, with a

local relief of about 20 m. The beds of the alluvial channels which are

prominent in this zone lie at elevations 10 to 20 meters lower than the

average given above.

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Figure 8: Elevation of Kano state

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3.2 Slope of Kano state

The slope is a major factor in land use, flood occurrences and erosion as well

as flood hazard identification. Figure 9 shows the slope characteristics of

Kano state. Kano state occupies the southwestern rim of the Chad

depression and shares physiographic divides with the Niger and Benue River

Systems to the south and southeast, and with the Niger System to the

southwest and west, including the Chad-Sokoto Divide. The elevation of the

area above mean sea level ranges from about 400 meters (m) at the

northeast margin to the over 1000 m at the highest southern tip. The state,

except for the section east of the Hydro-Geological Divide, is part of the

popular High Plains of Hausaland. Six landform types are identified in the

state as follows: dissected hilly highlands, high plains with grouped hills,

pediplains, sandy plains, dune fields and alluvial channel complexes.

1. The Dissected Hilly Highlands consist of the Rishi Hills and constitute the most

rugged topography in the state. The mean foothill elevation is between 700

and 800m. The maximum elevation is put at 1230m, with a dominant slope

angle of about 20 degrees.

2. The most distinct ones are: the Dadi and the Dakwat Plains. The mean

elevation is about 700 m. The dominant slope angle is put at 13 degrees and

hill slopes are steeper than 30 degrees.

3.The Garanga Plains occupy an extensive area, starting from Rano in the

north and extending to the south-centra1 boundaries of the state where they

merge with the Ningi Piedmont (outside the state). The mean elevation is

about 550 m, but rocky hills (Older Granites). The dominant slope angle is

between 3 and 5 degrees but hill slopes steeper than 20 degrees are quite

common.

4. The Dakwat Plains are found north of the Gari Plains. The mean elevation of

the flattish plains is about 47Om, but the quartzite ridges, which trend NNE-

SSW, rise up to 120 m above the plains. Hill slopes are steeper than 20

degrees, but the plains slope at a mean angle of 2 degrees.

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5. The Pediplains are developed over the rocks of the Basement Complex.

The Kano Plains are made up of many distinct sections, prominent among

which are: the Gari, the Jakara, the Chalawa, the Kamanda and the Basara

Plains. Most of these pediplains has been covered by a layer of wind drift

material which could be up to 2.5 m thick. The residual hills, usually located

on the upland plain, are of three types:

a) Granitic outcrop which can occur anywhere in the landscape (e.g. the

Tamburawa rock) and a regolith hill, usually capped by laterites, which

occurs usually at the interfluves (e.g. Goron Dutse and Dala Hill. Hill slopes are

generally steeper than 20 degrees.

b) Sandy Plains are great sand sheets occupying the north and central parts

of the low Chad Plains. They are characterized by very gentle slopes and low

relief (usually less than 15 m) and disappearing stream channels.

c) The Dune Fields occupy the rest of the low Chad Plains not utilized by

rivers. They lie to the south of the sandy plains and are traceable to Latitude

11o N where they are believed to mark the southern margin of an extensive

desert during the time of their formation. They are a combination of

longitudinal (ridge-like along wind direction) dunes and transverse (across

wind direction) ones at different stages of conversion into longitudinal types.

Satellite images show them to be multi-linear and aligned NNE-SSW. The

Latenwa Dune fields in the border area of Kano and Jigawa state, on the

Chad Plains. Table 3 shows the calculated area of the state occupied by the

different slope characteristics. More than 71% are plains that are liable to

flooding.

Table 3: Slope characteristics of Kano state

S/N Class Area (SqKm) Percent

1 37.6139 – 259.2310 54.8991 0.266246743

2 17.28207 – 37.6139 277.6324 1.346446887

3 7.1161 – 17.28207 2999.139 14.54506524

4 2.033 – 7.1161 2643.002 12.81789091

5 0 – 2.033 14644.96 71.02435022

TOTAL 20,619.6325 100

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Figure 9 slope of Kano state

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3.3 General Climatic Characteristics

The climate of Kano state is the tropical dry-and-wet type. The seasonal

migration of the Inter-Tropical Convergence zone (ITCz), gives rise to two

seasons, one dry and the other wet. The wet season lasts from June to

September although May is sometimes humid. The dry season extends

properly from mid-October of one calendar-year to mid-May of the next.

Figure 10 shows the rainfall pattern in the state. Clearly five distinct ecological

zone can be identified on the basis of rainfall amount and duration of the

rainy season. Table shows the calculated areas of the five rainfall zones in the

state.

The annual mean rainfall in the state is between 800 mm and 900 mm as

shown in table 4 Variations about the annual mean value are up to ± 30 per

cent. More than 300 mm of the rainfall is received in August alone, while the

truly wet season lasts from June to September. However, it is usual to regard

mid-May to mid-October as the wet season.

Table 4: Long-Term Mean Climate Conditions of Kano

(http://www.worldclim.org/)

Month Temperature oC Rainfall

(mm)

Evaporation

(mm)

Sunshine

(hr/day)

Relative

Humidity

(%) Mean Range

Jan 21.2 17.8 0.0 133.3 9.0 28

Feb 23.7 20.9 0.3 141.1 9.0 25

Mar 27.7 18.5 1.8 182.8 8.6 23

Apr 30.5 16.4 8.9 195.5 8.4 36

May 30.4 13.6 70.2 187.9 8.8 51

Jun 2S.1 13.0 132.7 156.3 8.7 65

Jul 25.7 10.7 210.9 126.4 7.5 7S

Aug 24.9 9.0 314.0 112.7 6.0 S3

Sep 25.9 10.9 132.8 126.5 7.9 79

Oct 26.8 16.5 12.8 144.0 9.5 58

Nov 24.6 19.7 0.0 139.9 9.8 37

Dec 21.7 18.7 0.0 127.4 9.2 32

Year 25.9 15.5 884.4 1771.8 8.5 49.6

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The highlights of the climatic parameters include: the occurrence of peak

rainfall, peak runoff and peak discharge from the last decade of August to

the first decade of September as shown in table 5 which represents the

average conditions for the state. Table 5 shows the calculated area of layers

of rainfall in Kano state

Table 5 Calculated areas of layers of rainfall in Kano state

S/N Value Area (SqKm) Percent

1 667.04 – 757.16 807.4 3.915653886

2 614.04 – 667.44 4,304.6 20.87605117

3 578.80 – 614.04 1,998.4 9.691655593

4 547.82 – 578.80 5,991.3 29.05605292

5 484.81 – 547.82 7,538.1 36.55758058

TOTAL 20,619.80 100

Rainfall intensity is in the range of 40-60 mm hr-1 but it is particularly at the

beginning and end of the wet season when rainfall is characterized by heavy

storms whose average intensity is about 80 mm hr-1. There is the occurrence

of squalls and thunderstorms from April through to August. During the early

part of this period (April and May) squall winds at speeds of up to 100 km hr-1

occur

Apart from the normal (seasonal) variations, there are periodic variations

which are greater than the ±30% stated. These include short-term periodic

cycles (5 to 10 years) and the longer cycles. Major droughts have occurred

in the state this century in 1913-1915, 1940/41, 1948/49 and 1972/73, with

minor ones in 1963, 1967/68, 1977 and in 1983/84. During the most recent

major drought in 1972/73, Kano received only 414 mm of rainfall per year (i.e.

in 1972/73) which is about 48% of the mean value for the station.

Climatic changes are believed to have occurred in the past. There were

pluvial period when climatic conditions were much wetter than the current

ones and large rivers occupied the region, alternating with arid phases when

conditions were very much drier than the current conditions.

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Figure 10: Rainfall pattern in Kano state

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3.4 Population of Kano state

Kano state is the most populous state in Nigeria and accounts for 6.5% of

Nigeria‟s population as shown in table 6. The population of Kano in 1963 was

2,177,467. At present time the estimated population of the state has risen to

14,455,420 in 2016

Table 6: Numerical and Percentage of Nigeria‟s Population by State.

State Population % of Nigeria‟s

population

Abia 2,338.487 2.6

Adamawa 2,1 02,053 2.4

Akwa ibom 2,409,613 2.7

Anambra 2,796,475 3.1

Bauchi 4,351,007 4.9

Benue 2,753,007 3.1

Borno 2,536,003 2.8

Cross Rivers 1,911,297 2.1

Delta 2,590,491 2.9

Edo 2,172,005 2.4

Enugu 3,154,380 3.5

Imo 2,489,635 2.8

Jigawa 2,875,525 3.2

Kaduna 3,935,618 4.4

Kano 5,810,470 6.5

Katsina 3,753,133 4.2

Kebbi 2,068,490 2.3

Kogi 2,147,750 2.4

Kwara 1,548,412 1.7

Lagos 5,725,116 6.4

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Niger 2,421,581 2.7

Ogun 2,333,726 2.6

Ondo 3,452,720 3.9

Oshun 2,452,143 2.4

Oyo 3,452,720 3.9

Plateau 3,312,412 3.7

Rivers 4,309,557 4.8

Sokoto 4,470,179 5.0

Total 73,398,555 100

Source: NPC, 1991.

3.4.1Population growth in Kano state

With the persistently high level of fertility accompanied by declining mortality

in the state, the rate of the natural population increase has risen from an

estimated 2.51 per annum in the 1960s to about 3.3% per annum in the 1980s

and 2.9% currently. Table 7 shows projected population growth in Kano state

from 1963 to 2020. All available evidences indicate that the level of

reproduction has been persistently high in Kano state for the last three or four

decades and still remain the same at present. If the present trend in fertility

and mortality condition continue in the future, the rate of growth of

population due to natural increase alone will continue to increase while the

doubling time will be shorter. Urban growth rate is about 5.5% per annum at

present due to internal and external migration. Internal migration within the

state takes the form of rural to rural as well as rural to urban movement.

However, rural to urban migration is the most significant. It is usually

dominated by the young generation in search of empowerment and other

opportunities in especially Kano metropolis and other urban areas.

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Table 7: Projected population growth in Kano state 1963 – 2021

S.No.

LGA

1991

2006

2011

1963

1968

1973 1978 1983 1988 1993 1998 2003 2006 2011 2016 2021

1 Ajingi

172,610 203,580 39,979 45,690 52,217 59,677 71,139 84,803 101,091 120,508 143,655 172,610 211,447 259,023 317,303

2 Albasu 116,603 187,639 221,300 43,460 49,668 56,764 64,873 77,333 92,187 109,893 131,001 156,163 187,639 229,858 281,576 344,930

3 Bagwai 106,645 161,533 190,510 37,413 42,758 48,866 55,847 66,574 79,361 94,604 112,775 134,436 161,533 197,878 242,400 296,941

4 Bebeji 118,833 191,916 226,340 44,450 50,800 58,058 66,352 79,096 94,288 112,398 133,987 159,722 191,916 235,097 287,994 352,793

5 Bichi 182,674 278,309 328,240 64,460 73,669 84,193 96,220 114,702 136,733 162,995 194,302 231,623 278,309 340,929 417,637 511,606

6 Bunkure 122,856 174,467 205,770 40,409 46,182 52,779 60,319 71,905 85,715 102,179 121,805 145,200 174,467 213,722 261,810 320,717

7 Dala

418,759 493,880 96,990 110,846 126,681 144,779 172,587 205,736 245,252 292,358 348,512 418,759 512,980 628,400 769,790

8 Dambatta

210,474 248,230 48,749 55,713 63,672 72,768 86,744 103,406 123,267 146,943 175,167 210,474 257,831 315,843 386,907

9 Dawakin Kudu 163,668 225,497 265,950 52,228 59,689 68,216 77,962 92,936 110,786 132,065 157,432 187,670 225,497 276,234 338,386 414,523

10 Dawakin Tofa 156,443 246,197 290,360 57,023 65,169 74,478 85,118 101,467 120,956 144,189 171,883 204,897 246,197 301,591 369,449 452,575

11 Doguwa 83,365 150,645 177,670 34,891 39,876 45,572 52,083 62,087 74,012 88,227 105,173 125,374 150,645 184,540 226,062 276,926

12 Fagge

200,095 235,990 46,345 52,965 60,532 69,179 82,467 98,306 117,188 139,697 166,529 200,095 245,116 300,268 367,828

13 Gabasawa 152,899 211,204 249,090 48,918 55,906 63,893 73,020 87,045 103,764 123,695 147,453 175,775 211,204 258,725 316,938 388,249

14 Garko

161,966 191,020 37,514 42,873 48,997 55,997 66,752 79,574 94,858 113,077 134,796 161,966 198,408 243,050 297,737

15 Garum Mallam

118,622 139,900 27,474 31,399 35,885 41,011 48,889 58,279 69,473 82,816 98,723 118,622 145,312 178,007 218,059

16 Gaya

207,419 244,630 48,041 54,904 62,748 71,711 85,485 101,905 121,478 144,810 172,624 207,419 254,088 311,258 381,291

17 Gezawa 154,629 282,328 332,980 65,391 74,733 85,409 97,610 116,358 138,707 165,349 197,108 234,967 282,328 345,852 423,668 518,994

18 Gwale

357,827 422,020 82,878 94,717 108,248 123,712 147,474 175,800 209,566 249,818 297,802 357,827 438,338 536,964 657,781

19 Gwarzo 118,778 183,624 216,570 42,530 48,606 55,549 63,485 75,678 90,214 107,542 128,198 152,821 183,624 224,939 275,551 337,550

20 Kabo 90,158 153,158 180,630 35,473 40,541 46,333 52,952 63,122 75,246 89,699 106,928 127,466 153,158 187,619 229,833 281,545

21 Kano Municipal 371,243 437,840

85,985 98,269 112,307 153,003 182,391 217,424 259,185 308,967 371,243 454,773 557,097

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22 Karaye

144,045 169,890 33,363 38,129 43,576 49,801 59,366 70,769 84,362 100,566 119,881 144,045 176,455 216,158 264,793

23 Kibiya

138,618 163,490 32,106 36,692 41,934 47,925 57,130 68,103 81,184 96,777 115,365 138,618 169,807 208,014 254,817

24 Kiru 156,584 267,168 315,100 61,880 70,720 80,823 92,369 110,110 131,259 156,471 186,524 222,351 267,168 327,281 400,919 491,126

25 Kumbotso 166,558 294,391 347,200 68,185 77,926 89,058 101,781 121,330 144,634 172,414 205,530 245,007 294,391 360,629 441,770 541,169

26 Kunchi

110,170 129,930 25,517 29,162 33,328 38,089 45,405 54,126 64,523 76,916 91,689 110,170 134,958 165,324 202,522

27 Kura

143,094 168,760 33,143 37,877 43,288 49,472 58,974 70,302 83,805 99,902 119,090 143,094 175,290 214,730 263,045

28 Madobi 78,924 137,685 162,390 31,890 36,445 41,652 47,602 56,745 67,644 80,637 96,125 114,588 137,685 168,664 206,614 253,102

29 Makoda

220,094 259,580 50,977 58,259 66,582 76,094 90,709 108,132 128,901 153,659 183,173 220,094 269,615 330,279 404,591

30 Minjibir 139,750 219,611 259,010 50,865 58,131 66,436 75,927 90,510 107,895 128,618 153,322 182,771 219,611 269,023 329,554 403,703

31 Nasarawa

596,411 703,400 138,137 157,871 180,424 206,199 245,804 293,016 349,296 416,387 496,363 596,411 730,603 894,989 1,096,362

32 Rano

148,276 174,880 34,343 39,249 44,856 51,264 61,110 72,848 86,840 103,519 123,403 148,276 181,638 222,507 272,571

33 Rimin Gado 60,622 103,371 121,920 23,942 27,362 31,271 35,739 42,603 50,786 60,541 72,169 86,031 103,371 126,629 155,121 190,023

34 Rogo

227,607 268,440 52,717 60,248 68,855 78,691 93,806 111,823 133,301 158,905 189,426 227,607 278,819 341,553 418,402

35 Shanono 84,861 139,128 164,090 32,224 36,827 42,088 48,101 57,340 68,353 81,482 97,133 115,789 139,128 170,432 208,779 255,754

36 Sumaila 164,242 250,379 295,300 57,991 66,276 75,744 86,564 103,191 123,011 146,638 174,803 208,378 250,379 306,714 375,725 460,263

37 Takai 130,007 202,639 238,990 46,934 53,639 61,302 70,059 83,515 99,556 118,678 141,473 168,646 202,639 248,233 304,085 372,504

38 Tarauni

221,844 261,640 51,382 58,722 67,111 76,699 91,430 108,992 129,926 154,881 184,630 221,844 271,759 332,905 407,808

39 Tofa 64,796 98,603 116,290 22,838 26,100 29,829 34,090 40,638 48,444 57,748 68,840 82,062 98,603 120,789 147,966 181,259

40 Tsanyawa

157,730 186,030 36,532 41,751 47,716 54,532 65,007 77,493 92,377 110,120 131,271 157,730 193,219 236,694 289,950

41 Tudun Wada 141,288 228,658 269,680 52,960 60,526 69,173 79,054 94,239 112,339 133,917 159,638 190,301 228,658 280,106 343,130 420,334

42 Ungogo 168,373 365,737 431,350 84,710 96,811 110,641 126,447 150,734 179,686 214,199 255,341 304,385 365,737 448,028 548,834 672,322

43 Warawa 81,666 131,858 155,510 30,540 34,903 39,889 45,588 54,344 64,782 77,224 92,057 109,739 131,858 161,526 197,869 242,390

44 Wudil

188,639 222,480 43,691 49,933 57,066 65,219 77,745 92,678 110,479 131,699 156,995 188,639 231,083 283,076 346,769

9,401,288

2,177,467

2,488,534

2,844,039 3,250,330 3,874,629 4,618,840 5,505,993 6,563,544 7,824,222 9,401,288 11,516,578 14,107,808 17,282,065

3.5 Land use/ land cover maps

Figure 11 shows the vegetation map of Kano state. The typical natural

vegetation of the Kano state is the savanna vegetation, three varieties of

which are identifiable from the south to the north. In the southern fringes from

Tudun Wada is the dry Guinea Savanna. From there up to Ungoogo and

Bichi, is the Sudan savanna while the Sahel thorn bush occupies the

northernmost tips. Indeed, the Sahel incursion is a recent phenomenon in the

Kano state. The normal vegetation has always been the dry Guinea in the

southern fringes and the Sudan in the remaining larger part of the state.

Clumps of woodland are common in the guinea savanna zone, while fringing

or gallery forests develop along the banks of most rivers in the state.

The dry Guinea Savanna is a mixture of trees and tall grasses (1.5 to 2 meters

tall). Some of the trees include tropical hardwoods, cotton wool trees which

may be over 20 meters tall, while the grasses include elephant grasses. A few

species of acacias are also found as well as the Baobab tree in areas with

light vegetation. The Sudan Savanna consists of expanse of shorter grasses,

usually 1.0 to 1.5 meters tall and scattered low trees with wide canopies. The

trees hardly rise above ten meters. Several species of acacias and the

baobab dominates the vegetation. A few thorny trees are encountered on

an increasing occurrence as one move northwards. Table 8 shows the

calculated area of the different types of vegetation in Kano state

Table 8 calculated area of Vegetation Cover

S/N Density Area (SqKm) Percent

1 High 2,986.5 14.48372188

2 Moderate 5,945.5 28.83407615

3 Low 6,885.2 33.39136845

4 No Vegetation 4,802.5 23.29083352

TOTAL 20,619.70 100.00

In Kano state, particularly in the zone where continuous cultivation has been

in practice for centuries, natural vegetation does not exist in reality anymore.

Thus, the vegetation has given way to man-made vegetation consisting of his

cropped land, reserved forests, planted forests, shelterbelts and other such

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establishments. Instead of the savanna vegetation with expanse of grasses

and scattered trees, there are the staple crops and scattered tree, some of

them planted, in the rain-supported crop lands during the wet season and a

park-like scenario of bare ground and scattered trees during the dry season,

giving what is known as the “orchard parkland” of scattered trees and

scanty, shrubs or bare ground. Elsewhere, there is the expanse of staple crops

and hardly any tree in the irrigated fields in both the wet and dry seasons.

Where trees have been planted, most of them are exotic ones such as neem,

teak and eucalyptus.

3.6 Soil of Kano state

Soil is an important environmental resource that affects agriculture, civil

engineering, water resources, erosion and flooding among others. Table 9

shows the main soil type in Kano state

Table 9 Soil Type in Kano state

S/N Type Area (SqKm) Percent

1 Lixisols 671.912 3.258603798

2 Gully 442.176 2.144442119

3 Fluviosols 11,09.61 5.381328746

4 Lake 194.678 0.944139218

5 Lixisols/arenosols 31.5609 0.153062408

6 Lixisols/cambiosols 3.9608 0.019208881

7 Arenosols 4,712.21 22.85303046

8 Luvisols/arenosols 46.0906 0.22352779

9 Luvisols 1,335.03 6.474558913

10 Arenosols/cambisols 302.234 1.465758701

11 Luvisols/cambiosols 29.728 0.144173305

12 Arenosols /gleysols 302.907 1.469022581

13 Cambiosols/luvisols 961.677 4.663890992

14 Cambisols 9,668.01 46.887411

15 Cambiosols/rock 270.99 1.314233178

16 Rock 181.741 0.88139803

17 Arenosol/lixisols 356.779 1.730288199

TOTAL 20,619.62858 100

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Figure 11 Vegetation of Kano state

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Most soils in Kano state are developed on the deeply weathered

metamorphic rocks of Basement complex. These, according to CCTA legend

belong to the leached ferruginious tropical soils (FAO; Ferric Luvisols). A few

occupying valley botton positions (hausa, Fadama) are hydromorphic (FAO;

Gleysols), while those around the base of inselbergs and other residual hills

one weakey developed and are lithosols. The characteristics of these soils in

terms of their morphological and analytical properties and agricultural

potentials are largely clayed and loamy to some extent. Figure 12 shows the

distinct soils of Kano state.

3.6.1 Physical Conditions

The color ranges from dark brown in the topsoil to reddish black in the subsoil.

Many soils have faint to prominent reddish mottles at the depth when mottles

will sufficiently high concentration of iron have the capable of irreversible

handering repeating wetting and drying, they form plinthine (US Soil

Taxonomy and when hardened ironstone.

The top horizons are sandy loams with clay content generally between 15 -20

percent. The subsoil is less sandy often sandy clay loams or sandy clays, with

clay loams or sandy clays with clay content between 25 and 40 percent. A

large proportion of the soils are gravelly within 40cm of the surface. The

gravel content, especially at the soil surface, tends to be greater on steep

slopes and at the bluff lines, and also on the locality of settlements where

land is more or less under permanent cultivation.

In terms of consistency, the upper few centimeters of soil are loose even

when slightly moist. They are friable when moist and non-sticky and non-

plastic when wet. Moist sub soils are generally friable but may be firm if they

have high clay content or lose if they have high gravel content. When dry

lower horizons became slightly hand to slightly sticky and moderately plastic.

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Figure 12 soil type in Kano state..

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The top soils develops a weak crumb structure, and the lower horizons are

weak or moderate sub angular blocky structure where Aeolian

contamination is less, the soils are highly porous with common to many, fine

to coarse pores in the upper horizons, these extending down into the subsoil,

the soils are well drained over most of the year, although the presence of

reddish mottles and iron segregation, especially in the middle and lower

slope positions suggests that many do became saturated at depth for at

least brief periods.

3.6.2 Chemical Characteristics

The soils are moderately acid, with pH (in H2O) between and an exception to

this pattern includes the localized slightly calcareous soils. Soils organic

carbon content is highly variable, but generally low, often less than 1.5

percent at the surface and 0.5 percent at the subsoil. Total nitrogen and

available phosphorous are low, less than 0.1 percent and 15ppm,

respectively and slow strong correlation with organic matter contents. The

cation exchange capacity are low to very low, often lss than 15me/100g,

and so the exchangeable cations (Ca2+, Mg2+, K2+, Na+, Al3+.). The clay

mineralogy is dominated by Kolinite type.

3.6.3 FADAMA Soils

These occupy the flood plains of the major rivers. The surface horizons are

dark grey and faintly mottled, becoming well mottled lower down the profile

where the color is dark grey brown to grey brown and were soft iron

concretion are many. The parent materials of these soils are characterized by

a great heterogeneity, as reflected by the satisfactions of the profiles. Some

variations in soil texture are therefore to be expected. Quite often clay loam

top soil overlay clayey or silty clay sub soil, with clay content more than 40

percent. The soils have well developed sub angular blocky to prismatic

structure in the surface horizons but usually massive and permanently moist at

lower horizons. During the dry period, the surface layer often shows weak

polygonal cracking. The soils have poor to very poor drained. The reaction is

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ostly slightly acidic and the clay mineralogy mostly kaolinite, but often with

small amount of 2:1 lattice clay.

3.6.4 Weakly developed Soils

These occur principally near the base of inselbergs and crests of ridges, but

may also close to rock out crops in any topographical position. They are poor

in horizon development and are mainly less than 50cm deep. Color ranges

from pale brown to light yellowish brown in the surface layer to yellowish red

at the lower layer. Some prominent mottles, often associated with weathering

rock fragments, may occur at depth, structure are moderate sub-angular

blocking throughout, while texture range from sandy loam in the top layer to

sandy clay loam at lower layer. The soils contain many angular quartz and

feld spar grains, and a few stones. There is usually an irregular boundary to

the underlying granitic rocks and occasional pockets up to 1m. The soils are

moderately acid, with pH of less than 6.0 the level of all exchangeable

cations and CEC are low and so also organic matter content.

3.6.5 Soil wetness index

The emergence of new digital tools and techniques has aided in the

prediction of the behavior of soils and their attributes and has contributed to

a better understanding of the soil-landscape relationships. From digital

elevation models (DEM) it has been possible to create the so-called terrain

attributes, which are environmental variables representative of the relief, such

as slope, curvature and wetness index, information regarding moisture levels

are extremely important in planning the use and management of the area,

because water is a major factor of production. Soil moisture is a key variable

to be initialized in meteorological

models since the partition between sensible and latent heat fluxes depends

on the quantity of water in the soil available in the root zone. The

characterization of soil moisture in deep layers is more important than the

surface soil moisture since the superficial reservoir has a small capacity and

almost no memory features. As the near-surface soil moisture (wg) is

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reasonably well correlated with the profile soil moisture content under

specific circumstances, the retrieval of root-zone soil moisture (w2) using

surface observations is possible (Calvet and Noilhan, 2000).

Figure 13 Wetness index of soil in Kano state

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3.7 Geology

Figure 14 shows the geology of Kano state. Generally the state has two

geological regions, the south and central parts of the state are underlain by

crystalline rocks of the basement complex but in the southern part

cretaceous sediments overlap the crystalline rocks.

Underlying rocks are overlain by sandy drift deposits laid down the last arid

phase about twelve thousand years ago. In the southern part of the state,

covering material largely clayed soil, about five meters in depth and very fine

texture. The soils are different to work, tending to became waterlogged with

heavy rains and to dry out and crack during the dry season. The exact

character of the leached ferruginous soils is dependent on such factors as

nature of parent rock topographical relatives anthropogenic. The properties

point to some of the characteristics soil forming processes that take place in

the area

3.8 Drainage and hydrology of Kano state

The drainage of the Kano state is mainly part of the inland drainage system of

the Chad Basin, except for some pockets in the south and northwest as well

as a small portion in the southeast (all together less than 5% of the surface

area) which drain to the Niger and Benue respectively. The main drainage

consists of the headstreams of the river system known as the Yobe in Borno

State, particularly the Kano, Chalawa and Gaya Rivers as shown in figures 15

16, 17, 18 and 19. Both the drainage and the hydrology of the region are

influenced by the climate, rock and human activities .

The state drains essentially northeastwards to the Lake Chad, although the

headstreams rise from the southeast, south, southwest and west. Two types of

surface drainage can be identified. The principal type is the through-flow

which consists of the Hadejia (know as River Wudil in Wudil) and Jama'are

River Systems and drains the southeast, south and southwest sections of the

region towards the northeast.

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Figure 14; Geology of Kano state

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The important headstreams include the Kano, the Chalawa and the Gaya

(headstreams of the Hadejia River) as well as, the Bunga, the Katagum and

the Fakate (headstreams of the Jama'are).

The second type of surface drainage consists of the disappearing flow. This

type is made up of individual streams such as the Gari, the Tomas and the

Jakara which drain the northwest -and north of the region eastwards. These

streams rise and flow freely over the Basement Complex section only to lose

their channels, at a short distance east of the Hydro-Geological into the

unconsolidated sediments of the Chad Formation.

The climate of the region controls the amount of water that is available both

on the surface and at sub-surface at any given time within a water-year. The

climate also controls the regimen and other characteristics of the rivers. For

example, water is abundantly available during the wet months both on the

surface and at sub-surface. The more humid the micro-climatic zone, the

more water is had. Thus River Kano which rises from a fairly humid zone has a

mean discharge of 39 cubic meters per second (m3/s) over a similar land

area as the River Chalawa which rises from a drier area and has a mean

discharge of 22 m3/s. The streams in the area are characterized by flashy

flows, storm discharges and seasonality. Surface water is not available during

the dry season, except in a few deep ponds and lakes, even on the

Basement Complex structure, while groundwater level falls rapidly through

seepage, extraction by man and high evapo-transpiration. Table 9 shows the

calculated drainage density of Kano state

Table 10: Drainage Density in Kano state

S/N Density Area (SqKm) Percent

1 Very high 5745.571781 27.86352133

2 High 5845.376561 28.34753105

3 Moderate 3004.383598 14.56995224

4 Low 4183.867631 20.28993622

5 Very low 1841.208429 8.929059157

TOTAL 20620.408 100

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The construction of dams which started about 1969 ( Figure 18 and table 11)

marked the beginning of the modification of drainage and hydrology in the

state. More than thirty earth-dams are in existence across the state. The

reservoirs of the dams and the intricate networks of main distribution and field

canals in numerous irrigated sites have created a different type of surface

drainage.The modification is great on the Basement Complex section where

the dams, reservoirs and canals have been concentrated. Minor, but

significant, changes (e.g. perennial flow, flood control) in drainage and

hydrology have occurred in parts of the Chad Formation.

In general, the forms of the channels have been affected and the flashy

flows and storm discharges have been controlled where dams and reservoirs

exist. Water is now available on the surface throughout the year, storm

channels are decreasing in width while the Kano River, in particular, has

become perennial in regime, regulated to a mean discharge of 9.6 m3/s

downstream of the Tiga Dam.

Groundwater retention has been improved in the Basement Complex zone in

the neighborhoods of the reservoirs. Conversely, groundwater depletion is on

the increase in the Chad Formation zone through increased extraction by

boreholes and a lower rate of recharge owing to the impoundments

upstream.

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Figure 15 Minor and Major rivers of Kano state

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Figure 16 Major Rivers of Kano state

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Figure 17 Elevation and drainage pattern in Kano state

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Figure 18: Drainage distance in Kano state

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Figure 19 Drainage density of Kano state

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Table 11: An Inventory of Man-Made Lakes in the Kano Region S/No Location Surface Area of

Reservoir at

Capacity (Km2)

Total

Storage

Capacity

(x 106 m3)

Rank in

ascending

magnitude

Catchment Area (Km2)

1 Brinin Kudu* 0.61 1.19 21 40

2 Bagauda 3.76 22.14 9 207

3 Karaye 1.98 17.22 12 80

4 Kaffin Gana* 1.80 NA 19 NA

5 Tiga 178.10 1,968.00 1 6,641

6 Ibrahim Adamu* 2.63 7.99 16 NA

7 Ruwan Kanya@ 2.50 NA 17 NA

8 Tomir (Tomas) 14.97 60.30 6 585

9 Muhammadu

Ayuba*

1.16 5.54 20 NA

10 Jakara 16.59 65.19 5 559

11 Gari 33.16 214.00 3 1,185

12 Kafin Chiri 8.42 31.12 7 225

13 Warwade* 5.26 12.30 13 106

14 Tudun Wada 3.50 20.79 10 185

15 Watari 19.59 104.55 4 653

16 Guzuguzu 6.35 24.60 8 106

17 Magaga 3.72 19.68 11 119

18 Pada 4.09 12.00 14 62

19 Marashi 2.18 6.77 18 43

20 Kango 2.55 8.73 15 41

21 Rimin Gado 0.10 0.26 22 5

22 Chalawa Gorge 101.17 969.00 2 3,859

TOTAL 415.08 3,571.37+ Variable

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3.9 Flood Risks

Figure 21 shows flood disaster risk areas (vulnerability zones) in Kano state

Flooding phenomenon is a major environmental problem prevalent in Kano

state. It causes ecological havocs: destroying lives and property as well as

agricultural land and social infrastructure. The phenomenon arises as a result

of the following: when rain falls on unsaturated soil, it infiltrates, increasing the

moisture content until the soil becomes saturated, after which additional

rainfall becomes surface runoff. The runoff accumulates into a big flood as it

flows down slopes and erodes the soil. It uses the heavy particles and other

objects it gathers to erode the bed and walls of the flood path causing big

gullies to be created. The gullies continue to grow bigger and multiply, if

adequate measures are not taken to control them. With the increasing value

and high demand for land, due to rapid urbanization and population growth,

there is a compelling need to halt the occurrence of flooding and erosion.

Table 12 shows the calculated extent of areas affected by flooding in Kano

state.

Table 12: Calculated areas for flood risk in Kano state

S/N Class Area (SqKm) Percent

1 Low 6391.99 30.99931231

2 Moderate 9046.72 43.87398896

3 high 5181.07 25.12669873

TOTAL 20619.78 100

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Figure 21 Flood risk areas (vulnerability zones)

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3.10 Soil erosion in Kano

Figure 22 shows the pattern of soil erosion in Kano state. Nowadays one of the

major problems on global scale is the rapidly increasing demand to the food.

This demand is of course totally parallel to the population growth. Even more

land is used for agricultural purposes day by day. Cultivation without using

specific control techniques, unplanned land use, such as establishing

industrial facilities or constructing summer houses on the agriculture land,

uncontrolled urban development and also destroying forests are

fundamental factors of soil erosion. Soil erosion is the systematic removal of

soil particles including nutrients from the land surface by the various agents

and occurs in several parts of Kano state under different local geological,

relief and management conditions. However, the degree of occurrence of

soil erosion varies considerably from one part of the state to the other. Thus,

while soil erosion is one of the most serious on the land surface of Kano state,

only rare occurrences of the phenomenon are recorded in some parts of the

state. Equally varied are the factors responsible for the inception and

development as well as the types that exist in parts of the state. Table shows

the calculated area of the extent of soil erosion over Kano state

Also its severity and frequency, where and when erosion occurs is also

strongly influenced by social, economic, political and institutional factors.

Conventional wisdom favors explaining erosion as a response to increasing

pressure on land brought about by a growing population and the

abandonment of large areas of formerly productive land as a result of

erosion, salinization or alkalization

The "on-site" impacts of soil erosion in Kano state are commonly associated

with shortages of arable land that is capable of supporting agricultural

production. The short and medium term consequences for Kano state are

evidenced by the widespread prevalence of food shortages and

abandonment of agriculture for menial job in the urban centres. In the last

forty years, the combined effects of soil erosion and rapid populations growth

of 3% per anum has meant that a little over a quarter of the arable land per

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capita deemed necessary to ensure people diverse diets, is available in Kano

state.

The "off-site" or downstream impacts of soil erosion are associated with for

instance, eroded sediment that are deposited in reservoirs, which caused

reduction in the flow of water supplies for irrigation and residential uses. Also,

the use of large amounts of fertilisers, pesticides and irrigation to help off-set

the deleterious effects of soil erosion have the potential to create pollution

and health problems, as well as destroying natural habitats, and contribute

high energy consumption and unsustainable agricultural system

The "off-site" or downstream impacts of soil erosion are associated with for

instance, eroded sediment that are deposited in reservoirs, which caused

reduction in the flow of water supplies for irrigation and residential uses. Also,

the use of large amounts of fertilisers, pesticides and irrigation to help off-set

the deleterious effects of soil erosion have the potential to create pollution

and health problems, as well as destroying natural habitats, and contribute

high energy consumption and unsustainable agricultural system

3.10.1 Causes of soil erosion in Kano state

Many processes have been found to exert an influence on soil erosion. In

Kano state, there appear to be four possible causes of erosion. First, the

removal of vegetation cover by overgrazing has been observed to be the

primary factor which initiates soil erosion in Kano state. We found many

erosion hotspots that develop where the vegetation cover has been

disturbed by livestock. Other causative factors include cultivation and

grazing practices as a principal cause of erosion. The removal of vegetation

by fire has been shown to reduce infiltration and increase surface erosion

especially in the southern part of the state.

Second, land use changes particularly in urban areas and construction which

has led to excavation of earth as a cause of accelerated erosion in Kano

state. Many local people had said trucks from Kano that had started

extracting sand from a site adjacent to the village as the initiator of erosion

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Indeed, as the demand for building materials in Kano has steadily grown in

recent years, this has become a more common practice.

Third, climate fluctuations have also been cited as cause of accelerated

erosion. A shift to either drier or wetter conditions may trigger episodes of

erosion. A shift to drier conditions can lead to a reduction in vegetation

cover. A decrease in vegetation cover may reduce infiltration and increase

surface runoff which may produce incision in channels.

Conversely, a shift to wetter conditions may lead to an increase in vegetation

cover and infiltration. However, this increase in infiltration may not

adequately compensate for the volume of runoff produced by the increase

in precipitation. Therefore, an increase in surface runoff due to either an

increase or decrease in precipitation may cause increased erosion

Fourth, increased erosion may result from natural adjustments within a

geomorphic system. In most parts of Kano state alternating cycles of erosion

and deposition have occurred in the past and this episodic erosion may be a

normal part of the erosional evolution in areas of high relief and high

sediment production

In Kano state surface and subsurface flows are dominant hydrological

processes but other factors such as material and morphological

characteristics also influence the activity of processes. Different mass failure

processes have been found in the gully channels observed suggesting mass

failure as the main source of sediment in erosion . Mass failure processes

could be grouped into three categories of slumping, block failure, tensile

failure and spalling, and desiccation debris avalanches, based on the factors

controlling speed of movement and the shape of failure.

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Figure 22 Soil erosion risk hazard zone

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3.1 1 Maps of the study sites showing impact to houses and infrastructures

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3.12 Assessment of the socio-economic impact of gully erosion and flood

hazards on the people

Table 13 Erosion sites

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S/N

EROSION SITES

KAMANDA KAUYEN ALU RARUN BULBULA GAYAWA

TUDUN FULANI

1 Historical Background

a. Kamanda erosion started over sixty years ago

a. For the past fifty years KauyenAlu had no erosion, but had a stream used by the community for both watering of animals and domestic uses.

a. Erosion in Rarun started more than thirty five years ago with a stream used for farming activities in the community

a. Erosion started in the last ten years in the area.

a. For the past twenty five years ago, had no Erosion, but started with a narrow pass like gutter for draining wastewater.

2 Causes a. Erosion was caused by increase in water volume during rainy season b. Sand mining for Chalawa gorge dam’s construction c. Deforestation along the stream

a. Construction of drainage system in 1978 by NNPC depot facilitated erosion process at KauyenAlu, Walawai and eastern bypass in Kano metropolis

a. Gully Erosion at Rarun was caused by sand mining

b. Change in the stream course

c. Lack of adequate drainage systems

d. Failure of embankment made at the upstream locations of Rarun.

a. Erosion was caused by lack of drainages

b. Indiscriminate waste disposal by the people in the limited available drainages

c. Sand mining in the area

d. Looseness of the soil in the area

a. Sand mining activities

b. Erosion was facilitated by looseness of the soil in the area

c. Being a water collection point where water from different locations converged facilitated the erosion also.

d. Human activities along water channels and drainages such as local fishing also accelerated the erosion in the area.

3 Social Effects

a. Loss of lives

b. Displacement of people

c. Physical injuries, Trauma and illness

d. Effects on social activiti

a. Loss of lives of many children and causes physical injuries to people among others

b. Effects

a. Loss of lives of children

b. Affects social interaction

c. Affects social relation such as frequency of visits to friends

a. Loss of lives of both children and adults

b. Destruction of cemetery by exposing some buried human bodies.

a. Erosion affects accessibility to nearby schools, and led to transfer of some pupils and students to other schools

b. It affects access to cemetery for burial of dead people

c. It led to the loss lives of people and animals.

d. Many people sustained injuries as

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es e. Occurr

ence of thief and criminal activities

f. Effects on school attendance

on frequency of visits and social interactions among people .

and relatives

d. It causes trauma and psychological stress among people

c. Destruction of social interaction between people and among others inneighbouring communities

d. Erosion sites harvoured thieves and other criminals.

e. It also affects school attendance by pupils and students during rainy season

f. The erosion resulted in serious trauma and psychological disturbance among inhabitants

g. It affected access to mosques, hospital, and other social institutions.

a result of the erosion.

e. Erosion sites became hiding places for thieves and criminals.

4 Economic Effects

a. Loss of public

a. Loss of propert

a. Loss of farmlan

a. Loss houses,

1. The erosion

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facilities such as electricity poles and utility cables, bridges and roads

b. Loss of houses, farmlands, crops and trees

d.Isolation of villages and towns e. Displacement of villages f. High transportation costs.

ies such as farmlands, plots of land and houses

b. Destruction of some water wells and water pipes

c. Collapse of bridges and roads

d. Loss of a famous Gangara market

ds,

b. Loss of properties such as roads, houses, and plots of lands in the area

roads, shops and plots of land.

b. Loss of properties including electrical poles, and cable wires, bridges and drainages

affects trading activities.

2. Loss of public facilities such as bridges, roads, schools

3. Loss of properties such as houses, farmlands, and farm produce

4. The erosion also affects transportation and its costs.

5 Livelihood Changesafter Erosion

a. Practiced Farm activities including irrigation and rainy season cultivation of sorghum, rice, maize, cowpea, cotton, and cassava before erosion

b. Presently, changed to non-farm activities such as trading and marketing of farm produce in addition to only rainy season crop farming

a. Residents were farmers before the gullies, but changed to non-farm activities such as brick laying, plumbing, house painting, carpentry, local land and house valuation after the erosion

a. The participants cultivatedcrops such as sugar cane, mango, guava, lemon, and banana in the past.

b. Presently, their farmlands were washed away by erosion and the soil became barren.

a. Livelihood of the people changed.

b. In the past, the inhabitants were traders having shops.

c. Presently, most of them lost their shops to the gullies.

a. Erosion changed the livelihood of the people from farming and trading to purely non-farm activities such as petty trading activities and housing and land valuation.

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.

6 Erosion Threat

a. Became threat since 1990 to 1992 following sand mining for dam construction

a. Became threat immediately after the construction of drainage systems BY NNPC’s Deport in 1978.

a. The erosion became a threat to the community for about twenty five to thirty years ago.

a. The erosion became threat to the community over six years ago.

a. The erosion effect became a threat for the last twenty years.

7 Community Efforts

a. Construction of temporary bridges

a. Used sand to fill the affected areas through community participation

b. Construction of local bridges made up of wood and rock materials

c. Construction

if drainages and bridges by local authority and federal Government

a. Community to fill erosion affected areas with sand

b. Community constructs drainage systems and concrete barriers to prevent erosion

c. Local authority also constructed some drainages

a. Community use to fill some sections of the erosion sites with sand and waste materials.

b. Also, they constructed drainages and local bridges to link up many areas.

a. The community constructed many bridges and drainages in the area

b. Community bought sand to fill some erosion sites

c. Community also participated in filling the erosion sites weekly using solid waste materials.

d. Local authority also constructed a bridge at the site to ease hardship faced by the community.

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8 Expected Intervention Benefit

a. Will boost agricultural production and marketing of farm produce

b. Boost Trading

c. Improves transportation services,

d. Increases communication and linkages between towns and villages

e. Provision of public facilities such as electricity poles and utility cables

f. Creation of job opportunities

a. Intervention would boost their livelihood by providing bridges

b. It will reduce the effects of the erosion on their lives and valuable properties.

a. Intervention would boost livelihood of the community through revival of agricultural activities,

b. Expansion of the villages by coming to together of different communities

c. It will also strengthen relationship and accessibility among people.

a. The intervention would enhance their livelihood, and reduce loss of lives.

b. It will also allow for improving accessibility of the people to various places such as mosques and schools.

c. Intervention will overcome the erosion in the cemetery and other important places like schools, and

d. It will also reduce further effects on lives and valuable properties.

a. The intervention would boost their income level and ease accessibility to school and cemetery

b. It will reduce illness caused by mosquitoes.

c. It will also reduce pollution caused by waste materials used for filling the gully sites

d. The intervention will also boost trading and save lives as well as properties communities

9 Suggestions a. Need

for quality projects especially on bridges and roads

a. Appealed for quality work in the constructions of bridges and culverts

a. The community appealed for the control of the gully erosion

b. Advised for

the use of quality materials in

a. Community advised that quality work should be done on the constructions of bridges and culverts b. Appealed

for incorporating

a. The participants appealed for the use of quality materials in the construction of bridges and culverts.

b. They also emphasized on the involvement of

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constructions

b. Need for employing professionals from the communities such as brick layers, plumbers and carpenters.

the projects that will be sustainable

local community members who are professionals such as bricklayers, plumbers, and carpenters in the project

professional local people in the project.

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Table 14 : Watershed Conservation sites

S/N

WATERSHED SITE

YAR TITI YAN SABO FAJEWA DAWAN KAYA

1 Historical Background

1. a.Constructed more thirty two years ago, but for the past sixteen years (1999 or 2000) ago the conservation site ceased to retain water because of its failure in 1999 to 2000 as a result of erosion.

a. Yan Sabo stream was more than one hundred years ago.

b. The stream was dammed five to six years ago

c. Erosion led to its collapse a year after damming because of serious flooding

a.Fajewa watershed conservation was constructed more fifty years ago along a small water stream

a.Dawan Kaya watershed was more than forty years ago, presently affected by erosion

2 Causes/Purposes

a. Need for domestic uses, irrigation and animal watering in the communities

b. It was affected by gully erosion

a. Yan Sabo was dammed at one section of the stream for conserving the water for farming activities, animal watering, and fishing

a. The purpose of the watershed conservation was for irrigation and watering animals such as cattle, sheep, goats, and camels.

a. Commercial sand mining activity facilitated erosion at Dawan Kaya watershed

3 Social benefit of watershed

a. Maintenance of good

a. The watershed led good

b. a. The social benefit included

a. In the past, the site

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relationship between the people and visitors who used the water in the past

b. Presently, there is loss of the good relationship between the community and the visitors because of failure of the watershed conservation.

relationship between the people of the area and users of the watershed from other communities.

strengthening of relationship with neighbouring villages and other people coming to water,fishing, domestic uses and feed their cattle.

allowed for good relationships and interaction between people and neighbouring villages

b. Presently, after the erosion at the site, there was loss of such relationships enjoyed before and communication linkages were lost between villages due failure of roads and bridges.

4 Economic benefit of watershed

a. Communities around YarTitiplanted some orchard trees and crops such as maize,

a. The watershed was used for irrigation and fishing, but its failure affects the

b. Community used the site for domestic uses, farming, watering of animals, washing

a. Growing of economic trees and crops such as maize, sorghum,cowpea, and raised animals

b. After the erosion, their economicactivities changed

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sorghum, rice and vegetables with grazing land in the past

b. Presently, the participants believed that presently economic trees such as orchard trees and crops are affected and removed from the watershed site

farming and fishing potentials of the site

of clothes and body.

c. It reduced migration of people especially youth to the cities for economic reasons

to commercial cutting for firewood and petty trading.

5 Changes in the land use Patterns

a. In the past, the site boosted the income level of the community because of irrigation farming and rearing of animals before the failure,

a. The land was used for farming activities such as crop farming and watering of animals, but after the conservation the expectation on the stream

a. In the past, the watershed was used for watering of animals, fishing, and domestic uses and conservation of tree species,

b. Presently, the land use had changed because the water could not remain in the dam for long time during dry season for

a. The land was used for irrigation farming, sand mining and fishing before the erosion, Presently, it is no longer

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b. Presently, farming and rearing of animals are affected, consequently the level of income fall, thus change in landuse. .

was not realised because of the failure of the embankment.

b. There was no change on land use pattern before and after the watershed conservation.

irrigation

used as before

6 Erosion Threat of Watershed

a. Erosionbecame at the site became a threat to the community for the past sixteen years (1999). Since then, the conservation site has not been fully utilised.

a. Erosionat the site became a threat to the community a year after its construction five to six years ago because of its failure

b. Visits to relatives and friends and going to the mosques became difficult

a. Watershed conservation failure becomes a threat to the community after two year of its utilization.

b. And after the drying off of the watershed during dry season

a. Erosion at the watershed became a threat to the community for the past thirty five years.

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after the failure of the dam.

c. Loss of lives among members of the community, especially among guest and strangers

d. Destruction of roads and bridges because of erosion.

7 Community Efforts on Conserving and Maintaining Watershed

a.Bags of sand were used as barriers to block the failed section of the watershed to prevent further erosion effects and for continuous utilisation in the area.

a. Community made efforts in blocking affected section of the dam with big rocks and bags of sand to block the failed section of the dam, though became eroded

b. Community raised some funds to dredge reservoir of the watershed and physical efforts were by the members of the community to do the work

a. Bags of sand were used to fill erosion affected section by the community

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again

8 Expected Intervention Benefit

a. Intervention will reduce emigration young people for economic reasons to other places.

b. The Fulani shedsmen that used the watershed for watering their animals such as cattle, sheeps and goats that left the watershed for watering and feeding and will return back.

c. Intervention would boost economic status of the communities.

d. In addition to rain fed agricultur

a. The expected benefit of watershed conservation intervention would discourage emigration of young people to other areas job seeking.

b. The Fulani shedsmen in the community and neighbouring villages will utilised the dam for watering.

c. Irrigation farming and fishing activities will be boosted, if the interven

a. Intervention would improve the livelihoods of the people using the watershed

b. Intervention on the watershed will prevent young people from migrating to the cities for economic reasons.

a. Intervention would in merging some villages near the watershed.

b. Economic status of the community and neighbouring areas will rise

c. Relationship between people in the community and neighbouring areas will be increased

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e, irrigation activities, and fishing also would be boosted.

e. The livelihood of the people in the neighbouring villages and communities also will improve, when the interventions come.

tion is done.

9 Suggestions a. Participants suggested for quality construction at the site to conserve the watershed in a sustainable manner.

b. The participants also appealed for provision of adequate channels

a. Participants appealed for high quality materials and construction of conservation measures

b. Appealed for better dredging of the floor of stream for

a. Participants appealed for the rehabilitation and expansion of the existing dam so that their lives will be renewed

b. Participants also appealed to the authority concern for better

a. Channels need to be constructed for irrigation purposes

b. Appealed for quality construction of Watershed conservation project

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for irrigation farming.

collection of more water for irrigation farming purposes

c. They appealed foradequate compensation for the farm owners to be affected by the project

way of conserving the watershed.

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Plates showing interaction with communities during focus group discussions

Plate 1: Discussion at Fajewa

Plate 2 Group picture with participants in D/tofa

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Plate 3 Discussion at Dawan Kaya

Plate 4: Discussion at Kauyen Alu

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Plate 5 : Discussion at Kamanda

Plate 6: Group photograph with participants at Kamanda

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Plate 7 Group photographs with participants at D/tofa

Plate 8: Group photographs with participants at Fajewa

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3.13 Information System for Integrated Watershed Management

Soil, water and vegetation are the most vital natural resources for sustainable

development and management of any watershed, and hence should be

handled and managed effectively, collectively and simultaneously. A

watershed has been taken as the smallest planning unit, as it conveniently

and efficiently represents continuum of three vital natural resources i.e. soil,

water and vegetation. Managing the natural resource with sustainable

approach is a rational phenomenon and is proposed in this project. In this

approach, the natural watershed are conceptualized in terms of the flow of

water, which influences almost all fields of the environment.

Figure 32 Information system for watershed management

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3.14 Information system for soil erosion management

Figure 32 Model of information system for soil erosion management

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3.15 Information system for soil erosion assessment

Figure 33 Model of information system for soil erosion assessment

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3.16 Information system for flood assessment and management

Figure 34 Model of information system for soil erosion assessment

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Conclusion

There is considerable concern worldwide about the impacts of

environmental change induced by human activity. Hydrological issues

include the effects of large scale deforestation and climate change on soil

erosion and flow regime and the dispersal of contaminants from agricultural

and industrial activities. Increasingly, therefore, it is accepted that the

development of river basins for economic purposes should be tempered by

the maintenance of an acceptable environmental quality. Establishing the

necessary trade-off between economic development and environmental

quality is a decision-making process involving many elements, one of which is

an appreciation of how environmental systems respond to imposed change.

In particular, there is a need to assess the impacts of different levels of

development on basin hydrology, soil erosion and contaminant

concentrations, in advance of any development taking place. Environmental

impact and economic return can then be weighed against each other for

different levels of development, providing a rational basis for selecting an

optimum development strategy.

Efforts to balance economic development with environmental protection

have increased the demand for simulation tools which enable predictions of

the human impact on the landscape. In order to prevent irreversible changes

and avoid costly, ineffective solutions, the simulation tools should provide

detailed spatial and temporal distributions of modeled phenomena.

Statistical averages for entire study areas or predictions only for a certain

point, such as a watershed outlet, are often insufficient. Effectiveness of land

management decisions aimed at preventing negative impacts of soil erosion

in complex landscapes can be significantly improved by detailed predictions

of erosion and deposition patterns for proposed land use alternatives.

Development of improved soil erosion prediction technology is required to

provide conservationists, farmers and other land users with the tools they

need to examine the impact of various management strategies on soil loss

and sediment yield and plan for the optimal use of the land. Additionally, soil

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erosion prediction technology allows policymakers to assess the current status

of the land resource and the potential need for enhanced or new policies to

protect soil and water resources. Erosion prediction is most needed by

conservationists at the field level who work directly with farmers and other

land users, which has large implications for development and adoption of this

technology.