watershed

1July 2003

watershed

• what is a watershed?

--- major watershed

The land area that water moves across or under, while flowing to a stream, spring, pond, lake or river The area of land where all of the water that is under it or drains off of it goes into the same place

--- smaller watershed

2July 2003

importance of watershed understanding

watershed human body

medium

3July 2003



health problems

pollution/catastrophe

diseases/injury

4July 2003



investigation

examination

fieldstudy

5July 2003



tests

medical analysis

chemical,biological,…

tests

6July 2003



medication/surgery

diagnostic and action

remediation,law enforcement,

better management,…

7July 2003

watershed

raingroundwater

water input input increasesthe amount ofwater in thewatershed

watershed outlet, domestic, agriculture,and industrial use

transpiration, evaporation…

water output

output decreasesthe amount ofwater in thewatershed


amount of water available today=

amount of water available yesterday

+water input between today and

yesterday-

water output between today a yesterday

WATER BALANCE

equilibrium means

OUTPUT=INPUT

WATER BALANCE:

make sure that the mount of water available tomorrow will

not be too low

allows a good management of the watershed and long term

water supply

8July 2003

watershed


Why? Where is thepollution source?

Understanding the watershed also means:

understanding where the water is, how the different water bodies are inter-connected,

in which direction water flows in the watershed

Important to help identify pollution sources

9July 2003

wateshed

• what is a river?

runoff

groundwate

rwater table

a river is surface water, it is where the water table is higher than the ground. It then follows

gravity

recharge

infiltration

tributary

main river

source

discharge

runoff

10July 2003

watershed

• what is a lake?

a lake is surface water that accumulates in a low point

11July 2003

measuring discharge

river

distance

duration (hours)

surface velocity of water = distance / duration

mean velocity of water ~ 0.8 x velocity

12July 2003

measuring discharge

cross-section

area = number of x area of

discharge = area x mean water velocity

accurate discharge measure is trickyalso, discharge changes with…

position along the river… why?time… why?

13July 2003

measuring volume

1

A1

2

A2

3

A3

4

A4

5

A5L 1-2 L 2-3 L 3-4 L 4-5

L 4-5L 3-4L 2-3

L 1-2

...2

AAL

2

AAL

2

AAL Volume 43

4332

3221

21

...

3at discharge4at discharge4 and 3between recharge



14July 2003

watershed

• what is a watershed? we all live in a watershed!• where is yours?

• what is its size?• where is your water (rivers, streams, lakes) ?• how does it flow?

draw a map of your watershed

• find maps and use them• look at mountains, sea

• look at the topography• where will you find the maps?

15July 2003

water source team

• where are the rivers and streams in your area?

– what names do your rivers have?

– how large are they?

– where do they come from?

– how would you measure their stream-discharge?

– how much water do they have at any time?

complete your map

16July 2003

water source team

• is there a lake in your area?

– what type of water?

– what size, how deep?

– which rivers are connected to the lake?

– how old is it? how has it been created?

– how much water does it have? When?

name the lake on your map

17July 2003

groundwater and runoff

• what is groundwater and runoff?

impervious rock

permeableunderground

ground water=aquiferrunoff soil surface

18July 2003

underground structures

soillayer 1

layer 2

impervious rock (granite, clay)bedro

ck

19July 2003


Permeability measures how fast water flowsin the rock. The flow-rate is proportionalto the permeability

L

P

μ

AKQ L

h

A=r2

pressureP = g h

permeability

water viscosity

water density

gravity

20July 2003


L

ρgh

μ

AK

dt

dhA

L

P

μ

AKQ

L

h0

A=r2

P

ρg

μL

h(0)

h(t)ln

t

1K

L

ρg

μ

K

dt

dln(h)

L

ρg

μ

K

dt

dh

h

1

h(0)

h(t)lnt

L

ρg

μ

Kln(h(0))ln(h(t))

h(t)

- +

-

-

-

-

1 Darcy = 10-12 m2

-

21July 2003


water tank

rock sample

water saturates

Permeability measures how fast

water flowsin the rock.

The flow-rate is proportional

to the permeability

porosity=volume of water in the sample

volume of the sample

22July 2003

K

permeability

enter initial volume of water in ml

enter volume of soil sample in ml

enter time at which measure is made in secondsenter volume of water at measurement in ml

absolute permeability in Darcy (1Darcy=1E-12m2)permeability coefficient in Darcy cm/hpermeability coefficient in Darcy cm/s

μ

kρρK,

L

Dp

μ

AkQ

K is the velocity of waterunder gravity

analysis of experimental (falling head) data

23July 2003

groundwater

soillayer 1

layer 2

bedro

ck

impervious rock (granite, clay)

water-table depthdepth of

aquifer bottom

unconfined aquifer

24July 2003

groundwater

soillayer 1

layer 2

bedro

ck

impervious rock (granite, clay)

water-table depthdepth of

aquifer bottom

confined aquifer

25July 2003

groundwater and stream

surface water

water table

soil

grains making up the rock

water-tablepore space saturated

pore space partially saturated

saturated zone

unsaturated zone

impervious rock

26July 2003

aquifer-stream connections

aquifer gaining

perched aquifer

aquifer loosing

27July 2003

runoff

plants roots hold soil in position

plants are obstacles: slow down water

plants limit water impact

28July 2003


soil erodes

sediment transported tonearby stream

desertification: plant cannot grow back

deforestation can trigger soil erosion,sediment pollution and desertification

29July 2003

runoff

lower runoff higher runoff

the larger the angle, the faster the runoffthe fast the runoff, the larger the erosion force

velocity is proportional to sin(angle)force is proportional to velocity

angleangle

runoffrunoff

30July 2003

water source team

• what is groundwater and runoff?– what parameters affects surface runoff?– how important is runoff in your area?– where can you measure the water-table?– when should you measure it?– how deep is your aquifer?– how could estimate its volume?

complete your map

31July 2003

rain

evaporation

windprecipitation

runoff

runofftranspirationrunoff

infiltration

infiltration discharge

discharge

32July 2003

rain

it varies with season

March August September

runoff varies with seasonsfiltration varies seasonriver level and discharge vary with season

33July 2003

amount (mm)

duration (hours)

rule

rrain

• measuring rainintensity =

rainfall amountrainfall duration

34July 2003

water source team

• how is rain on your watershed?– rainfall amount– rainfall intensity– rainfall duration– rainfall distribution– rainfall frequencycomplete your map

35July 2003

water source team

• what would you measure to perform a water balance?

• rain amount?• consumption?• aquifer volumes?• river volumes?• …?

36July 2003

pollution transport and dispersionpoint source pollution

initial extent of pollution

final extent of pollution

dispersion

point source pollution initial extent of pollution

final extent of pollution

dispersiontransport

transport

37July 2003

pollution transport and dispersion

non-point source pollution

runoff

38July 2003

use and pollution

• how does your community use your watershed!• where are the houses?

• how can they affect water quality?

• where are the farms?• how can they affect water quality?

• where are the industries?• how can they affect water quality?

• where are the embankments?• how can they affect water quality?

• where are the wells?

complete the map of your watershed

39July 2003

example

Nongboanoi village, Nam Phong river,Khon Kaen province

500,000 fishes dead,enormous numbers of dead shellfishes and aquatic fauna

December 5th 1997

Hg j gj g jg jg kihik ho u kh kg uf jh loh kg kg iy I gbkjgbjgfj tgj gj gj gt hk hg kh kh k hk y kg kjy kh hi yk h ,jh lk h hk hk hk h kj ;l ;p I;p oi; I [ppo ‘;k ;k k; k; k ;l ;k ;ip uipuilkhk h hk hk h hkhkhk kj khkh kjh kj hkjhkh iu gtf re t jlk jp; kuhjyghfdtyd lk kg jyfgj b li lj lj Hg j gj g jg jg kihik ho u kh kg uf jh loh kg kg iy I gbkjgbjgfj tgj gj gj gt hk hg kh kh k hk y kg kjy kh k hi yk h ,jh lk h hk hk hk h kj ;l ;p I;p oi; I I [ppo ‘;k ;k k; k; k ;l ;k hk hk h kj ;l ;p I;p oi; I I [ppo ‘;k ;k k; k; k ;lkg iy I gbkjgbjgfj tgj gj gj gt hk hg kh kh k hk y kg kjy kh hi yk h ,jh lk h hk hk hk h kj ;l ;p I;p oi; I [ppo ‘;k ;k k; k; k ;l ;k ;ip uipuilkhk h hk hk h hkhkhk kj khkh kjh kj hkjhkh iu gtf re t jlk jp; kuhjyghfdtyd lk kg jyfgj b li lj lj Hg j gj g jg jg kihik ho u kh kg uf jh loh kg kg iy I gbkjgbjgfj tgj gj gj gt hk hg kh kh k hk y kg kjy kh k hi yk h ,jh lk h hk hk hk h kj ;l ;p I;p oi; I I [ppo ‘;k ;k k; k; k ;l ;k hk hk h kj ;l ;p I;p oi; I I [ppo ‘;k ;k k; k; k ;l

Thailand News

why?

40July 2003

1st step

• where is it? find a map, locate village and riverKhon Kaen province

Upper Mae Nam Chin basin

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

41July 2003

2nd step

• ask the locals: what do you think, what do you know?

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

Pulp and paper factory!

wood, bamboo

pulp, paper, organic wastes

42July 2003

3rd step

• prepare testing strategy: what to measure and where?

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

choose sampling stations

4 4upstream suspected source

3 3downstream suspected source2

2downstream suspected stream1

1 upstream suspected stream

43July 2003

3rd step

• prepare testing strategy: what to measure and where?

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

choose what to measure

4

32

1

organic material

bacterialactivity

decay(tannin/lignin)

BOD, DO tannin

COD

oxidised

44July 2003

4th step

• analysing the result?

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

results (mg/l)

4

32

1

4

3

2

1

0.19

O.77-15.95

0.57

?

tannin

72

140-664

424

51

COD

?

?

3.55-3.75

4

DO

45July 2003

5th step

• conclusion?

Nam Phong river

Chot

strea

m

Nongboanoivillage

Ubolr

ata

na d

am

4

32

1

Where does pollution come from?

How to improve the investigation?

What could make the investigationmore difficult?

Documents

watershed