Hydrology, Environment and Water Resources 2015 / · PDF fileAssignment 1 Watershed characterization Hydrology, Environment and Water Resources 2015 / 2016

Assignment 1

Watershed characterization

Hydrology, Environment and Water

Resources

2015 / 2016

Work Plan

• Week1:

– Group organization.

– Georeference the map;

– Select the watershed

• Week 2 – Part 1

– Delineate the watershed limit;

– Digitize the river network.

– Compute the watershed area and

perimeter;

– Compute Gravelius compactness indicator;

• Week.3 – Part 1

– Compute the hypsometric curve, as well as

the min, avg and max watershed altitude

and average watershed height;

– Draw the main river profiles and compute

their average and equivalent river slopes;

– Classify the river network;

– Compute drainage density and the average

overland flow distance;

– Compute bifurcation ratio.

Hidrologia, Ambiente e Recursos Hídricos, 2015/16: @Rodrigo Proença de Oliveira 2014/15 2 06-10-2015

• Week.4: Part 1 / Part 2

– Characterize watershed geology, soil

and soil use.

– Estimate annual average

precipitation and evapotranspiration

from the Climate Atlas maps;

– Check the annual water balance;

• Week.5: Part 2

– Get the annual precipitation time

series from SNIRH and estimate the

basic statistics of these time series;

– Get the average annual temperature

time series from SNIRH and compute

their basic statistics

• Week.6: Part 2

– Estimate the annual average

precipitation using the Thiessen and

the isohyets method;

– Estimate the average annual runoff

using the Turc method and the

Quintela equation.

Recommendations for the report

• Submit the report in paper form;

• The report cover shoud indicate the students name and number, the

map number and the watershed name;

• The form summarizing the results should be presented after the index.

• The text should be well organized, clear, complete and concise;

• Results and computations should be presented whenever possible in

tables and graphs; All tables and graphs should be referenced in the

text

• Results should be discussed when appropriate;

• Maps, graphs and tables must be clear and easy to read;

• Maps should have a title and include a scale, a legend and the north

indication;

• Graphs must have a title and axis titles, indicating the plotted variable

and its units;

• All numeric values should be presented with units; the number of

decimals should be adequate.


Map georeferencing

Watershed selection

• Each group will work with a map at a 1:50’000 scale.

• Each map is define by 4 files that can be obtained at

\\alicerce\aulas\hrh\50k

• Files for each map (Série IGOE M7810: 50:000)

– Image: *.tif

– Metadata: *.met

– Coordinates from the 4 corners: *.tab

– Coordinates from UL corner: *.tfw

• Copy the map files to your pen/folder.

• Use Windows Paint to view the map.

• Select a river cross section that defines a watershed with around 50 - 80 km2

– Each blue grid: 1 km x 1km

• Steps to select the watershed

– Identify possible cross-section;

– Roughly draw the limit;

– Estimate area and confim that its between 50-80 km2;


Watershed limits


Watershed limits


Map loading and georeferencing

Hidrologia, Ambiente e Recursos Hídricos, 2015/16: @Rodrigo Proença de Oliveira 2014/15 8

Check folder \\alicerce\aulas\hrh\50k

• Files for each map (Série IGOE M7810: 50:000)

– Image: *.tif

– Metadata: *.met

– Coordinates from the 4 corners: *.tab

– Coordinates from UL corner: *.tfw

UL

Xa,Yb

LL

Xa,Ya

LR

Xb,Ya

UR

Xb,Yb

The tab file:

06-10-2015

ArcGIS project setup

• Open ArcGIS > ArcMap

• Save your project file (*mxd) in the folder

– File > Save as > ***.mxd (e.g. HARH201415.mxd)

• Create a geodatabase in the folder to store your data

– Catalog: Create folder connection

– Catalog: Right click in the folder > New > Personal geodatabase

• Make the geodatabase the default geodatabase

– File > Map doc properties > Default geodatabase

• Set up projection:

– Right-click on Layers > Properties > Coordinate systems > Projected Coord. System:

• IGOE 50000: National > Europe > Lisboa- Hayf. Gauss - IGeoE

• IGOE 25000: National > Europe > Lisboa- Hayf. Gauss - IGeoE

• Add map to the database

– Catalog: Right click in the gdb > Import > Raster dataset > select map

• Assign a projection to the map

– Toolbox > Data Management tools > Projections and transformations > Define projection

– Select map from the gdb

– Coordinate system > Select > Projected > see above

• Add map to the project

– Press +

– Select map from gdb

• Check corner coordinates << IMPORTANT !!!


Watershed delineation

• Create new dataset (feature class)

– Catalog: Right click in the gdb > New > Feature class > Polygon

– Projection: Import > Select the projection of the map

• Change color scheme of the dataset

• Define the watershed limit with rigour;

– Click on Customize > Toolbars > Editor

– Editor: Start > Select the new dataset > Construction >

Polygon

– Select <straight segment> and digitize watershed limit

– Editor: Stop

• Check the area of the watershed

– Right click on the limit dataset > Open attribute table


Useful tips

• While digitizing:

– Use the mouse rod to zoom in /

Zoom out

– Use the arrows to move the map

• You can correct the watershed

boundary by: Editor: Start > Select the new dataset >

Construction > Polygon

Select Reshape feature tool on the Editor menu

Editor: Stop

• Instead of using Windows Paint you

can use ArcMap to roughly draw the

watershed limit and then use the

above tools to correct it.

• To check the area and perimeter of

the watershed: Right click on the limit dataset > Open attribute

table


Symbology

Open attribute table Reshape feature

tool

Editor menu

Additional datasets to be digitized

• Additional datasets to be digitized

– River network (complete network)

– How to do it:

Catalog: Right click in the gdb > New > Feature class > Line

Projection: Import > Select the projection of the map

Editor: Start > Select the new dataset

Create Features > Organize template > Select the new dataset >

New template

Create Features > Select the new dataset > Construction > Line

Select <straight segment> and digitize the line

Editor: Stop

• Add meaningful atributes:

– River network (river classification)

– How to do it: Right click on the limit dataset > Open attribute table

Table options > Add field


Organize

templates Create features box

Watershed characterization

Part 1

Shape characterization

There are many indicators:

• Gravelius compactness index: Ratio between the watershed perimeter and the

perimeter of a fictitious circular watershed with the same area.

– Circular watershed: Kc = 1

– Squared watershed:

• Equivalent rectangle

• Elongation ratio:

– Rounded watershed: Kc < 1.128

– Long watershed: KL > 2


A

P

P

PKc

2'

A A

AP 2'P

128,12

2

4

LL

LKc

bLA

bLP 2

L

b

2

128.111

128.1

c

c

K

AKL

2

128.111

128.1

c

c

K

AKb

b

LKL

Perimeter length

• What is the length of an irregular line? :

– It depends on the resolution/accuracy adopted in the

analysis.

– It may be infinite !!


Hypsometry

• Maximum altitude

• Minimum altitude

• Median altitude = corresponds to 50% of the area.

• Average altitude= Vol. under the terrain / Watershed area

• Average height= Average altitude – minimum altitude

• Hypsometric curve


Área (km2)

Altitude (m)

Altitude média

Altitude

máxima

Altitude

mínima

Área da

bacia

Altura média

06-10-2015

Hypsometry

• Maximum altitude: Z5

• Minimum altitude: Z0

• Average altitude = Vol. abaixo da superficie do

terreno / Área da bacia

• Median altitude = Altitude corresponding to 50%

of the área.

• Altura média = Altitude média - Altitude mínima


1

0

'

12

11 n

i

iii

t

med AzzA

Z

Cota (m) Área acima da cota (km2)

Z5 0

Z4 A4 = A’4

Z3 A3 = A’4+A’3

Z2 A2 = A’4+A’3+A’2

Z1 A1 = A’4+A’3+A’2+A’1

Z0 A0 = A’4+A’3+A’2+A’1+A’0=Abacia

minZZh medmed

06-10-2015

Zo = Zmin

Z1

Z2

Z3

Z4

Z5

X’2

X’3

X’4

X’5

X’1

Zmax

Hypsometric curve

IST: Hydrology, environment and water resources © Rodrigo Proença de Oliveira, 2015 18

Área acima da

cota (km2)

Altitude/Cota (m)

Altitude média

Z5 = Altitude

máxima

Z0 = Altitude

mínima

Área da

bacia

Altura média

50% da área

da bacia

Altitude mediana

Z1

Z2

Z3

Z4

A1A2A3A4

Area above a

given altitude

Altitude (m)

Median altitude (m) Average altitude (m)

Average height (m)

Watershed

area

Z5 – Max

altitude

Z0 – Max

altitude

06-10-2015

Dimensionless hypsometric curve

IST: Hydrology, environment and water resources © Rodrigo Proença de Oliveira, 2015 19 06-10-2015

A/Abacia x 100

(%)

Cota (m)

Curvas Hipsométricas

adimensionais

Jovem

Antiga

Intermédia

100

Vale fluvial jovem

Vale fluvial antigo

Young

Old

Young

Old

Hypsometric curve: How to proceed

• Get the digital terrain model from \\alicerce\aulas\HRH. The model

projection is Hayford-Gauss, Datum 73 (GCS_73) and has a resolution of

30 m x 30 m.

• Add the digital terrain model to the Geodatabase

• Add the digital terrain model to the ArcGIS project. You need to

transform the projection from GCS_Datum 73 to GCS_Lisboa_Hayford

• Extract the area within the watershed:

– Toobox > Spatial analyst > Extraction > Extraction by mask

– Define the raster (mdt), the mask (watershed limit) and the output

• Get the elevation statistics (remember each cell has 900 m2)

– Right click on the watershed dtm > Properties > Source > Statistics

– Tools > Spatial Analyst > Zonal > Zonal Statistics by table

– Open and export the watershed dtm atribute table to XLS

• Convert cell numbers to m2 and build the hypsometric table.


River profile


Cota (m) Distancia à secção (km)

Z5 X4 = X’5+X’4+X’3+X’2+X’1

Z4 X4 = X’4+X’3+X’2+X’1

Z3 X3 = X’3+X’2+X’1

Z2 X2 = X’2+X’1

Z1 X1 = X’1

Z0 X0 = 0

06-10-2015

River profile


A

B

C

D

Linha de água 1

Linha de água 2

Linha de água 3

LB

ZB=ZF

ZC=ZE

E

F

Altitude

(m)

Desenvolvimento

(m)

Linha de água 1

Linha de água 2Linha de água 3

ZA

LA

ZC=ZE

LB LC

ZB=ZF

ZD

LDLELF

06-10-2015

River profile: How to proceed

1. Show 3D Analyst Tool: Customize > Toolbar > 3D Analyst

2. Select the dtm

3. Select folder to store profile

4. Identify profile by digitizing over each main river

5. Plot profile

6. Get file from specified folder and open in Excel


2 3 4 5

River slope indicators

• Average slope

• Equivalent slope

• Slope 10, 85


Altitude

(m)

Desenvolvimento

(m)

Altitude

(m)

Desenvolvimento

(m)

Altitude

(m)

Desenvolvimento

(m)

A

A

O,1L O,85L L

L

ZZimed

minmax

LZZXZZ eqi

n

i

ii )(2

1)(

2

1min

'

1

1

0

1

min

1

0

'

11)(1

ZXZZL

Zn

i

iiieq

L

ZZi

eq

eq

min

L

ZZi

75.0

108585;10

06-10-2015

Equivalent slope


Zo = Zmin

Z1

Z2

Z3

Z4

Z5 = Zmax

X’1

X’2

X’3

X’4

X’0

06-10-2015

Drainage networks classification

• Dentritic

• Radial

• Angular

• Paralel


Drainage density

• Drainage density = Sum of the lenth of all water courses/

Watershed area:

• Dd depends on the detail or scale of the map that is being used:

– Esc ?? : Global values: 1 a 100 km/km2

– Esc 1:25’000: Values from PT: 3 a 5 km/km2

– Esc 1:1’000’000: PT national average: 0,3 km/km2

– Low values: areas with steep slopes and low erodible soils.

– High values: areas with gentle slopes and high erodible soils.


A

L

D

n

i

i

d

1

Average overland flow length

Assumes a fictitious square watershed with a single

watercourse that crosses it through the middle:


L

L

Área = L2

Length of the drainage network: L

Drainage density, Dd = L/L2 = 1/L

Average slope length = L/2 = 1/(2 Dd)

Average overland flow length = L/4 = 1/(4 Dd)

Drainage network classification

• Bifurcation ratio:

• Average bifurcarion ratio:


1

1

1

1

1

1

1

1

1

2

3 22

2

1

2

33

4

Strahler classification (1957) (or Horton-Strahler)

11

1

1

1 1

nn

n

u u

ub N

N

NR

1

1,

u

uuub

N

NR

Ordem, u Nu Rel.Bifurc

1 10 2.5

2 4 2.0

3 2 2.0

4 1

Média Geom 2.2

2,2100,20,25,2 1414 bR

Varies between 2 and 4

Exemple:

06-10-2015

STRAHLER

Drainage network classification


1

1

1

1

1

1

2

2

3

4

4

4

4

4

3

3

2

2

Horton classification (1945)

• How to identify the main

water course:

– Sub-basin area

– Length of the tributary

– Confluence angle

06-10-2015

HORTON



06-10-2015 33 Hidrologia, Ambiente e Recursos Hídricos, 2015/16: @Rodrigo Proença de Oliveira 2014/15 06-10-2015




Soil, pedosphere and lithosphere

• Rock >> regolith >> soil

• Solo: Superficial layear (1-2 m) of the geologic substract

(pedosphere), holding:

– Minerals: Sand, silt and clay - mineral nutrients

– Humus: provides nutrients, as well as the soil structure and its

ability to hold water and nutrients;

– Air: source of oxygen and CO2 requited by micro organisms

– Water: provides the environment where the chemical reactions

that hold life can occur


desagregation + water

+ organic matter

Solo

Lito

sfe

ra

Pe

do

sfe

ra

~2

00

m

~2 m

06-10-2015

Regolith


<Earth

Moon> 06-10-2015

Soil


Elements that condition soil production

• Parent rock

• Time – allows for the parent rock desegregation and for the adding and mixing of

water, organic matter, and for the degradation of organic matter:

– More time leads to thicker soils with distinctive characteristics from the parent rock

• Climate – determines the physical and chemical processes that act over the

primary rock, its reaction times, as well as the types of plants and animals that

interact with the soil:

– Precipitation enables parent rock desegregation and provide conditions for the movement

of oils particles by percolation. Excessive precipitation may carry all minerals to inferiors

layers, leaving only insoluble material in the upper layers.

– High temperatures facilitates chemical desegregation of the parent rock and provides

conditions for a faster degradation of the organic matter.

• Plants and animals – provides the organic matter to the soil (mainly

plants) and the microorganisms required for its degradation. Topography

– determines the erosion and conditions the amount of water and solar energy

available to the soil:

– Steep slopes lead the thinner and less developed soils

– Gentle slopes lead to humid soils with a high percentage of organic matter


Soil profile


Soils taxonomy

• World Soil Classification (UNFAO, 1974)

– 12 classes e 106 unidades

– Substituído pelo WRB

• USDA/NCRS ()

– Ordem (12), subordem, grupo, subgrupo, família e série

• World Reference Base for Soil Resources (WRB) (1998)

– Baseado no WSC e na taxonomia da USDA

– Patrocinado pela FAO e pela IUSS (International Union of Soil Sciences)

– 98 grupos de solo

• SROA (Serviço de Reconhecimento e Ordenamento Agrário)

– Predominantemente FAO


World soils


Soil Map of Europe (FAO)

Europe’s soils


Classificação dos solos (SROA)

Portuguese soil classification


Portugal’s soils (included in the European Soil Map)

46 06-10-2015

Cambissolos – thin soils

with a high percentage

of minerals

Litossolos – thin

and with a high

percentage of

rocks

Podzois– typical from

conifer forests; ácids

Luvissolos

constituted by

minerals, with clay

in the B horizon

IST: Hydrology, environment and water resources © Rodrigo Proença de Oliveira, 2015

FAO vs SROA


FAO SROA

Afloramentos rochosos

Fluvissolos Aluviossolos

Luvissolos Argiluviados

Vertissolos Barros

Cambissolos Calcários

Litossolos Litossolos

Luvissolos Mediterraneos Pardos

Luvissolos Mediterraneos Vermelhos

Planossolos Planossolos

Podzois (Po, Pg) Podzois

Podzois (U) Rankers

Regossolos Regossolos

Solochacks Salinos

06-10-2015

Geology, Soil and Landuse datasets

• Themes:

– Geology >> Geologia

– Soils >> Solos

– Soil use (land cover) >> Uso do solo

• Online resources: – http://sniamb.apambiente.pt/Home/Default.htm

– http://www.portugal.veraki.pt/

– http://www.igeo.pt/gdr/index.php?princ=PROJECTOS/CLC2006&sessao=m_projectos#cartografia

• Check the Environment Atlas maps;

– http://sniamb.apambiente.pt/Home/Default.htm

– Select Pesquisa por metadados

– Specify the theme you are looking for (in portuguese) and press Pesquisar

– Select the Map and press Aceder

– Get the rar file;

• Soil Use is also available in shp format. – http://www.igeo.pt/gdr/index.php?princ=PROJECTOS/CLC2006&sessao=m_projectos


Make no mistake:

Soil type;

Soil capacity;

Soil use.

http://sniamb.apambiente.pt/Home/Default.htm



Climatic and hydrological

charaterization

Part 2

Annual water balance

Hidrologia, Ambiente e Recursos Hídricos, 2015/16: @Rodrigo Proença de Oliveira 2014/15

Precipitação

Precipitation Evapotranspiração real

Real evapotranspiration

Escoamento

Runoff

50

Gerês: P = 2500 mm; ETR = 800 mm; H = 2500-800 = 1700 mm

Alentejo interior: P = 500 mm; ETR = 400 mm; H = 500-400 = 100 mm 06-10-2015

Average annual runoff


Atlas do Ambiente Check the Environment Atlas maps;


Search for escoamento



Access to SNIRH

• http://snirh.pt

• Select

– Dados de base

– Monitorização

– Redes

– Rede meteorológica

– Aplicar filtro

• Use the search functions ny

watershed (bacia) and municipality

(concelho); check coordinates.

• Obtain the time series.


How to describe a sample of values

• Average

• Variance

• Standard deviation

• Variation coefficient

• Skewness

• Kurtosis


n

P

P

n

i

i 1

11

2

2

n

PP

S

n

i

i

P

11

2

2

n

PP

SS

n

i

i

PP

P

SCV

p

P

3

1

3

21 P

n

i

i

PSnn

PPn

G

21

13

321

12

1

4

nn

n

S

PP

nnn

nnK

n

i P

iP

06-10-2015

Main statistical descriptors


P

SP

GP < 0

P

SP

GP > 0

Average

Variance,

Standard deviation

Skewness

06-10-2015

Useful MS Excel functions

• Para distribuir os valor inseridos numa unica coluna por várias

colunas usar Data > Text to columns;

• Para resolver problemas com os separadores decimais, investigar

Change and Replace.


Descritor Inglês Português

Média AVERAGE ?

Variância VAR ?

Desvio Padrão STDEV ?

Coeficiente de assimetria SKEW ?

Kurtosis KURT ?

06-10-2015

Tabela com as principais estatísticas

Table with main statistics


Parameter Gage A Gage B Gage C Gage D Gage E

N (years)

Pannual

Avg

Stdev

Skewness

Average

monthly

precipitat

ion

Oct

Nov

...

Parameter Gage T

N (years)

Annual

average

temperature

Avg

Stdev

Skewness

Monthly

average

temperature

Oct

Nov

...

How to import the gage locations to ArcMap

• Get the gage coordinates from “Caracteristicas das estações”

• Prepare an xls file with the following format

• Option 1: In Catalog

– Rightclick on the geodatabase

– Create Feature Class >> From XY data

– Select the xls file and the xls specific worksheet

– Select the columns which have the X and Y coordinates

• Option 2: In ArcMap:

– Go to File >> Add data >> Add XY data

– Select the xls file and the xls specific worksheet

– Select the columns which have the X and Y coordinates


Gage id Gage Name Xcoord Ycoord

1 A 100 100

2 B 100 200

3 C 400 200

Delaunay triangles

• Triangles formed by points which define a circle that do

not include other points (Boris Delaunay, 1934);

• Delauny triangles are the set of triangles that is closest

to a set of equilateral triangles; they maximize the

minimum angle between any 2 triangles sides.


Delaunay triangles verification


Delaunay triangles: Example of ERRORS


Erro 1 Erro 2

06-10-2015

Thiessen polygons

• Thiessen polygon: Given a set of

points, each polygon defines the area

closest to a given point.

• Method

– Marcar os pontos médios das arestas de cada

triângulo;

– Os lados de cada polígono cruzam

perpendicularmente os lados de cada

triangulo pelo seu ponto médio;

– Os lados encontram-se em pontos comuns de

intersecção.


Watershed precipitation average estimation using

Thiessen polygons


Gauge Área of

influence (km2)

Ai

Weigth

wi

Precipitation

(mm)

Pi

Contribuition

(mm)

wi x Pi

1 A1 w1 = A1 / Ab P1 w1 x P1

2 A2 w2 = A2 / Ab P2 w2 x P2

3 A3 w3 = A3 / Ab P3 w3 x P3

… …. …. …. …

n An wn = An / Ab Pn wn x Pn

Control

sum

Ab - Área da bacia

(km2)

1 - Average precipitation

over the basin

Isohyets

• Isohyet – Line of equal

precipitation value

• Method to determine an

isohyet map: – Using linear interpolation mark on

the sides of each triangle the

precipitation values of the isoyet to

be drawn / Por interpolação, assinalar

nas arestas dos triângulos de Delaunay

os valores da isoietas a desenhar;

– Connect the points (you can take

into account the hypsometry) / Unir

os pontos por rectas (opcionalmente

pode-se adoçar as linhas tendo em conta

a hipsometria).


Watershed precipitation average estimation using

isohyets


Isoyets Area between

isoyet (km2)

Ai

Weigth

wi

Precipitation

(mm)

Pi

Contribution

(mm)

wi x Pi

1 – 2 A1 w1 = A1 / Ab P1,2 = (P1+P2) / 2 w1 x P1,2

2 – 3 A2 w2 = A2 / Ab P2,3 = (P2+P3) / 2 w2 x P2,3

3 - 4 A3 w3 = A3 / Ab P3,4 = (P2+P4) / 2 w3 x P3,4

… …. …. …. …

(n-1) – n An wn = An / Ab Pn-1,n = (Pn-1+Pn) / 2 wn x Pn-1,n

Control sum An- Basin area

(km2)

1 - Average

precipitation over

the basin

Turc formula

Turc (1951; 1954/55)

Data from Europe, América, África e Java


2L

2P

0,9

2P

D

0,1

2L

2P

3T0,05T25300L

LDPlim

06-10-2015

Regional curves


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Hydrology, Environment and Water Resources 2015 / · PDF fileAssignment 1 Watershed characterization Hydrology, Environment and Water Resources 2015 / 2016