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Prevention and Managing the Prevention and Managing the Occurrence and Impact of Flood Occurrence and Impact of Flood

in the City of Ibadanin the City of Ibadan

Adelere Ezekiel Adeniran, Ph.D, FNSE

August 2012

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Introduction I am not sure if I have ever met Mr. Kunle

Akinyele whose memory we are honouring today. I am sure that as a Christian who would want to

save other souls he would like to do anything like Paul that ... he may be able to safe others even after his death.

This lecture series will surely raise both technical, social, emotional and economic awareness that may possibly prompt our Governments and our people into taking positive action.

.

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Why Me?Why Me? I am not sure while I was chosen to deliver the first in the series of

this memorial lecture.

Is it because I was born and raised in Ibadan and lived with the dirty waters of Ibadan streams (onipasan, oluyoro, beyerunka, agbadagbudu, gege olorun, ogunpa, kudeti, tabi elege, ogbere, omi, odo ona etc) for the first 21 years of my life?

Or because I have studies rivers, hydraulics, hydrology, river modelling and waste and storm water disposal for almost 37years of my life?

What ever the reason for my choice, I am humbled and wish to thank the organisers for this most undeserved honour. The Lord that we serve will surely reward you.

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Mathematics without Equations!Mathematics without Equations! The organisers have put me in a very difficult

position. I am faced with delivering a lecture on a highly

technical subject to a mixed audience some of whom may not understand the language of hydrology or hydraulics or (mathematics) of floods

I have the task of speaking in plain language to benefit generality of the audience without trivialising the subject and.

I will try my best to strike a balance. May God help me

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Ibadan City and Its Rivers

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Ibadan Land

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Ogunpa River: Statistics

The Ogunpa River river system is a third-order stream i.e. it falls into the 3rd category on a scale of 12. In order word Ogunpa is a small stream in order of ranking!

Channel length of 21.5 km and area 73.3 km2 draining the densely populated eastern part of Ibadan Nigeria

The city of Ibadan in south western Nigeria (7º23’ N, 3º5’ E) is the largest urban centre in Africa south of the Sahara

Ogunpa River is known to be highly polluted receiving untreated storm waters, domestic sewage and solid waste.

Ogunpa river is septic.

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Ogunpa and Ogbere Streams Ogunpa and Ogbere Streams CatchmentsCatchments

Ogbere

Ogunpa

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Disaster Records of Ibadan Floods1960 More than 1,000 residents became homeless

1963 • More than 500 houses were damaged

1978 • 32 bodies retrieved; 100 houses destroyed.

1980 • "Ogunpa" became notorious internationally• More than 100 bodies were retrieved from the debris of several

collapsed houses and• Many vehicles washed away by the flood

1999 Several properties and houses were lost to yet another Ogunpa flood

August 26, 2011

• Ogunpa struck again Claiming the life of our dear Mr. Kunle Akinyele

• Destroying houses, roads, culverts and bridges• Creating emotional trauma• Leaving behind colossal economic woes• It was a National disaster of monumental dimension• 26,000 houses have been marked for demolition

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Floods:Hydrology and Hydraulics of Floods

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Floods

A form of natural disaster when there is more water than the lakes, rivers, oceans, or ground can hold.

Many different types of floods named for how

often they occur There're 10 years floods, 100 years floods, 500 years floods, Floods can be seasonal or sudden.

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Causes of Flood Natural Causes

– Excesive rains.– Overflowing of rivers, lagoons, lakes,etc

Human Causes– Bad agricultural practice– Bad infrastructures location– Obstruction of Stream paths – Solid Waste Disposal– Deforestation (Removal of Igbo Agala)– Urban population increase

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Causes of Flood Continued…. Reduction in Carrying Capacity of the river

– Encroachment in river and tributaries banks draining into the rivers

– Disposal of Debris and solid wastes including plastics

Lack of Remote Rain Gauging and Telemetric Early Warning System

Rapid and unco-ordinated Urban growth due to rural to urban migration (lack of rural development)

Refuse Disposed into Ibadan Streams

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Constructions on River Constructions on River Banks in IbadanBanks in Ibadan

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Encroachment of Flood Plain of Kudeti Stream

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Spatial Growth of Ibadan

2010201020102010

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Direct EffectsI. Displacement of Families in the river banks

II. Destruction of private property on the river banks

III. Destruction of Biodiversity on the river banks

IV. Disruption of Transport and communication systems

V. Destruction of drainage and sewage system

VI. Eroding of river banks

VII. Adverse effect on Public Health

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Flood Damages Injuries and loss of life

Social disruption

Income loss and Emergency costs

Physical damage– Structures, utilities, autos,

crops, etc.

Lost value of public services– Police & power poles, water

mains, hospitals, etc

Damaged PHCN and Water at Apete, Ibadan

Bridge Washed away: Emergency Foot Bridge improvised

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Homelessness and Losses

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Colossal Lost of Properties

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Discomfort and Fear

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Hydrology Genesis 1:6-7: “Then God said, Let there be a firmament in

the midst of the waters, and let it divide the waters from the waters. Then God made the firmament and divided the waters which were under the firmament from the waters which were above the firmaments”

Ecclesiastes 1:7 “All the rivers run into the sea, yet the sea is not full; to the place from which the rivers come, there they return again”

I submit to the Almighty and Omniscience God, before continuing, that to Him belong all the knowledge.

Indeed He designed the hydrology of the world and we humans have made a mess of it.

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Hydrologic Cycle

Excessive Runoff, FLOOD

Precipitation, P(t)

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Stream flow and Flood Hydrograph

Peak

Ris

ing

Lim

b

Recession Lim

b

Time

Dis

char

ge, Q

Beginning of Direct Runoff

BaseflowRecession

BaseflowRecession

Centroid of Precipitation

Basin Lag

Time of Rise

End of Direct Runoff

InflectionPoint

Baseflow

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Flood: Excessive Storm Runoff

Rainfall – Divided

1. Direct runoff (Pe) (Flood)

2. Initial loss (before DRO, Ia)

3. Continuing loss (after DRO, Fa)

Time

Pre

cipi

tatio

n

pt

aI aF

eP

aae FIPP

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Ibadan Flood - 2011

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Time (hr)

Ru

no

ff (

cfs)

0

1

2

3

Pre

cip

(in

)

Precipitation

Streamflow

Flood High Point

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Hydraulics: Channel Capacity

Q = VA (Carry Capacity) More water than the

channel can carry will result in flood

Reduction in the area of the channel will increase the velocity and thus result in channel overflow or flood

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Flood Hydraulics

Debris

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Flood Management

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Stages of Flood Management

Mitigation

Preparedness

Response

Recovery

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Phases of Emergency Management

Prevention-Mitigation Preparedness

ResponseRecovery

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EmergencyOperation Plan

PrecipitationPrediction(nowcasting)

Threatrecognitionsystem

Informationdisseminationsystem

Data acquisition and transmission system

Forecastmodeling system(forecasting uncertaintyestimate)

?EmergencyOperation Plan

PrecipitationPrediction)

Threatrecognitionsystem

Threatrecognitionsystem

Informationdisseminationsystem

Informationdisseminationsystem

Data acquisition and transmission system

Forecastmodeling system(forecasting uncertaintyestimate)

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A Model for Flood Disaster Management

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Flood-Damage Reduction MeasuresMeasures that reduce damage by reducing discharge

Measures that reduce damage by reducing stage

Measures that reduce damage by reducing existing damage susceptibility

Measures that reduce damage by reducing future damage susceptibility

Reservoir Channel improvement

Levee or floodwall

Land-use and construction regulation

Diversion Flood proofing Acquisition

Watershed management

Relocation

Flood warning and preparedness planning

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Effect of Flood Management Measures

Impacted Relationship

Stage - Discharge

Stage - Damage

Discharge - Damage

Discharge - Frequency

Damage -Frequency

Reservoir ✓ ✓Levee ✓ ✓ ✓ ✓ ✓Channel improvement

✓ ✓ ✓ ✓Diversion ✓ ✓Flood Forecasting

✓ ✓Flood Proofing ✓ ✓ ✓Relocation ✓ ✓ ✓Flood warning ✓ ✓ ✓Land use control ✓ ✓ ✓ ✓

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Response and Preparedness

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Engineering Measures for Disaster Management

Increase in River carrying capacity by

– Dredging to remove silt

– Excavated Debris can be reused eg sand for construction

Protection

– Construction of protection wall to protect major flood prone areas

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ACTION PLAN FOR FLOOD FORECASTING & DISASTER

MANAGEMENT

1. Installation of Remote Rain Gauging, level gauging and telemetry system for early warning to control peak discharge

2. Prevent encroachment of the river and streams by declaration of Biodiversity Restoration Zones along the banks

3. Creation of Green belts on river banks for stabilisation and allow percolation of water

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Mapping and Delineation of the flood-prone area by use a probability-based analysis wherein systematic records and historical information on past flooding are used to develop a relation of probability of occurrence versus magnitude.

Designation of Floodway (River Channel) and High Flood Level Components

High Flood Level

Floodway

Development Zone

Submersible ZoneDevelopment Zone

Submer

sible

Zone

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Flood Forecasting Methodologies hydro-meteorological data acquisition and

transmission system

forecasting modeling system

precipitation prediction

forecasting uncertainty estimate

threat-recognition and information dissemination system

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Comprehensive Non Structural Flood Management System

The proposed system can be divided into three important sub systems viz.

Telemetry System

Management Information System

Decision Support System

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Telemetry System gathers hydrological and meteorological data such as

Rain fall data from rain-gauge stations in the catchment

Water level data from river gauge stations

Reservoir level data from level sensors installed at the reservoirs

Data is gathered without any human intervention

Collected data is then presented to the Management Information System and the Decision Support System

Based on the received data and the pre-fed conditions/parameters/rules the system computes information required for controlling discharge of water

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Future Directions Encourage and consolidate knowledge networks

Mobilize and train disaster volunteers for more effective preparedness, mitigation and response

Increased capacity building leads to faster vulnerability reduction.

Learn from best practices in disaster preparedness, mitigation and disaster response

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Boys Scout: Be Prepared Be Prepared : Preparedness and Mitigation is

bound to yield more effective returns than distributing relief after a disaster.

Create a Culture of Preparedness and Prevention.

Evolve a code of conduct for all stake-holders

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Invest in Preparedness Investments in Preparedness and Prevention

(Mitigation) will yield sustainable results, rather than spending money on relief after a disaster.

Most disasters are predictable, especially in their seasonality and the disaster-prone areas which are vulnerable.

Communities must be involved in disaster preparedness.

RecoveryRecovery

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Recovery StrategiesRecovery Strategies

Relief/Support schemes for flood victimsRelief/Support schemes for flood victims Reconstruction of damagesReconstruction of damages Recovery Strategies must lead to actions Recovery Strategies must lead to actions

leading to prevention and/or minimization leading to prevention and/or minimization of effect of future floodsof effect of future floods

» General flood mitigation Master PlanGeneral flood mitigation Master Plan

» Action Plan StrategiesAction Plan Strategies

» Research and Development of actions and Research and Development of actions and regulationregulation

» Enforcement of RegulationsEnforcement of Regulations 48

Re-Construction of Bridge Re-Construction of Bridge over Ogunpa at Agodiover Ogunpa at Agodi

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Installation of Remote Rain Gauging, level gauging and telemetry system for early warning to control peak discharge from the streams in Ibadan

Prevent encroachment of the river and streams by declaration of Biodiversity Restoration Zones along the banks

It is necessary to create a regional (SW) centre for Regional Warning Management for Flood

A National Data Bank for collection and dissemination of stream flow data should focus more on design and modeling and simulation.

Recommendations

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Conclusions• In view of the general global warming and the

general terrains of Ibadan, we will always have the tendency for Ibadan streams to overflow their banks, but to reduce the impact of the effect of the flood, we must put in place:

• Mitigation policies

• Preparedness attitude

• Response Mechanism

• Recovery Techniques

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Thank Thank YouYou

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Brief Resume Brief Resume Dr. Adelere Ezekiel Adeniran, FNSE, Ph.DDr. Adelere Ezekiel Adeniran, FNSE, Ph.D..

• Dr. A. E. Adeniran, the current Director of Works & Physical Planning of the University of Lagos, Nigeria, also lectures and supervises research works in the Department of Civil and Environmental Engineering of the University as a Senior Research Fellow.

• A UNESCO scholar in alternative water and wastewater options, Dr. Adeniran holds a B.Sc.(Hons.) degree in Civil Engineering from the University of Lagos, Nigeria; a M.Sc. degree in Water & Wastewater Engineering from Loughborough University, UK and a Ph.D. degree in System Dynamics Modeling with specialization in Water Supply Systems from the University of Ibadan, Nigeria.

• He is a visiting scholar to the Capella University, USA.

• He has presented peer-reviewed papers in many local and international academic and professional conferences. He has also authored and co-authored academic and professional articles in learned local and international journals. He is an editorial member of the International System Dynamic Journal based in MIT, USA.

• He received the 2010 World Federation of Engineering Institutions for the Best Innovative Research award in Water Resources for a paper in presented in Rio De Janeiro, Argentina.

• He has served and still serving as consultant to UNDP on sustainable water projects and the World Bank as Analyst for Procurement of Water supply projects.

• Dr. Adeniran, who was a former Chairman of Ibadan Branch of the Nigerian Society of Engineers, is a member of American Waterworks Association, American Water Resources Association, International Water Association, Fellow of the Nigerian Institute of Civil Engineers and a Fellow of the Nigerian Society of Engineers.

• He was born in Ibadan and married to Olayinka Adeniran. He is blessed wit four children who are all University graduates.