nr. 1

HOW HOW INNOVATIVE HYDROLOGICAL MONITORINGINNOVATIVE HYDROLOGICAL MONITORING AND MODELLING ARE NEEDED TO UNDERSTAND AND MODELLING ARE NEEDED TO UNDERSTAND

WETLAND FUNCTIONING AND FUNCTIONS:WETLAND FUNCTIONING AND FUNCTIONS:

RECENT EXPERIENCES IN RECENT EXPERIENCES IN DIFFERENT TYPES OF DIFFERENT TYPES OF WETLANDSWETLANDS

Aljosja HooijerAljosja Hooijer

WL | Delft HydraulicsWL | Delft Hydraulics

nr. 2

BETTER TITLE: BETTER TITLE: THE VALUE OF THE VALUE OF WATER LEVEL INFORMATIONWATER LEVEL INFORMATION IN IN

QUANTIFYING WETLAND HYDROLOGY QUANTIFYING WETLAND HYDROLOGY FOR FOR WATER RESOURCES MANAGEMENTWATER RESOURCES MANAGEMENT

Topics:Topics:

22 … type of data needed needed in order to … type of data needed needed in order to address the problems in wetlandsaddress the problems in wetlands

44 … advances in robust/accurate measurement … advances in robust/accurate measurement techniquestechniques

55 problems of data acquisition ...problems of data acquisition ...

nr. 3

Why is wetland hydrology Why is wetland hydrology important?important?

• Conservation aim: it determines the ‘internal’ Conservation aim: it determines the ‘internal’ functioningfunctioning of the ecosystem, and of the ecosystem, and

• Water Resources Management aim: it determines the Water Resources Management aim: it determines the ‘external’ ‘external’ functionsfunctions that wetlands can have within the river that wetlands can have within the river basin (flood peak reduction, storage of pollutants and basin (flood peak reduction, storage of pollutants and sediments, baseflow maintenance).sediments, baseflow maintenance).

In many cases, conservation aims are not considered In many cases, conservation aims are not considered important by decision makers, but WRM aims are…important by decision makers, but WRM aims are…

Claims on hydrological functions of wetlands only Claims on hydrological functions of wetlands only valid in WRM if well-proven == valid in WRM if well-proven == quantifiedquantified!!

nr. 4

Some relevant studiesSome relevant studies

Presented:Presented:

• Sarawak peatswamps (Indonesia, 1995-1997)Sarawak peatswamps (Indonesia, 1995-1997)

• Sumatra peatswamps (Indonesia, 2003-2004)Sumatra peatswamps (Indonesia, 2003-2004)

• Danube Delta (Romania, 1997-2002)Danube Delta (Romania, 1997-2002)

Similar:Similar:

• Shannon floodplains (Ireland, 1990-1995)Shannon floodplains (Ireland, 1990-1995)

• Madagascar coastal wetlands (1997-1998)Madagascar coastal wetlands (1997-1998)

• Doňana National Park (Spain, 2003-2004)Doňana National Park (Spain, 2003-2004)

(partly with WL | Delft Hydraulics)(partly with WL | Delft Hydraulics)

nr. 5

What do these wetlands have What do these wetlands have in common?in common?

‘‘Disadvantages’Disadvantages’

• Flat: (sub-)basins can not be delineated from topography.Flat: (sub-)basins can not be delineated from topography.

• Wet, water tables near soil surface, often flooded: diffuse flow.Wet, water tables near soil surface, often flooded: diffuse flow.

• Tidal/backwatered: no rating curves, discharges very hard to Tidal/backwatered: no rating curves, discharges very hard to measure.measure.

• Inaccessible: only periodic visits possible, automatic monitoring Inaccessible: only periodic visits possible, automatic monitoring required.required.

basin area and discharge can not be determined ‘as usually’; basin area and discharge can not be determined ‘as usually’; (as in dryland).(as in dryland).

S = P - E - S = P - E - QQ

nr. 6

What do these wetlands have What do these wetlands have in common?in common?

‘‘Advantages’Advantages’

• High water tables (<40 cm) and soil types (organic, silt) keep High water tables (<40 cm) and soil types (organic, silt) keep unsaturated zone at field capacity; any change in storage is unsaturated zone at field capacity; any change in storage is directly expressed in water level change.directly expressed in water level change.

• Water levels can be recorded permanently and cheaply, at many Water levels can be recorded permanently and cheaply, at many points: with ‘diver’ dataloggers or by local inhabitants.points: with ‘diver’ dataloggers or by local inhabitants.

• Soils and topography highly uniform: point measurements of water Soils and topography highly uniform: point measurements of water level representative for large areas.level representative for large areas.

• Little underground leakage across watershed boundary. Little underground leakage across watershed boundary.

• Relatively low rainfall variability in these flat lands.Relatively low rainfall variability in these flat lands.

changes in basin storage, actual evapotranspiration and rainfall changes in basin storage, actual evapotranspiration and rainfall can be monitored wellcan be monitored well

SS = = PP - - EEactact - - QQ

nr. 7

SarawakSarawakPeatswampPeatswampStudyStudy

0 100 km

S a ra w a k

Sibu

6 m

0 5km

A uge rho le w ith w e l lIns t rum e n t s ite :A : ra in fa l l, c lim a te , m od era te f low s .B : low f low s .C : w a te r leve ls , th rough fa ll.D : ra in fa ll.

A

B C

D

T ra ns ec t 6C on tou r lin es ,m e tres a bo vem ea n s ea le ve l.

M a t u

T h a i l a n d

V i e t n a mP h i l ip p i n e s

M a la y s ia

B r u n e i

S i n g a p o r e

In d o n e s ia

BBBBB ooooorrrrrnnnnneeeeeoooooStudy

area

0 300km

South China Sea

Je m o re n gca tc hm e n t

NNWS a p r ic pe a t

H e m ic p e a t

M a r in e c la y

S a n d & c lay S

CS S C

CSSCC S CC

0 1 0 0

6

J e m o r e n gs t r e a m m

k m

P ea tsw am p s u rfa ce a lon g t rans ec t 6

• Goal: Water Supply Goal: Water Supply Study (for Malaysian Study (for Malaysian Government)Government)

• Question: how much Question: how much discharge during discharge during 1:25y droughts? 1:25y droughts? Worth conservation?Worth conservation?

• Approach: discharge, Approach: discharge, water level, water level, monitoring studies in monitoring studies in 10 catchments.10 catchments.

nr. 8

SE AsianSE AsianPeatswampsPeatswamps(>25 Mha)(>25 Mha)

nr. 9

What do we want to study?What do we want to study?

The ‘natural’ The ‘natural’

peatswamppeatswamp

hydrology,hydrology,

undisturbedundisturbed

by drainageby drainage

P

P n

SW

SDS S

S G

Q D

Q S

Q G

c lay

sa n d

p e a t

ca n o p y

E i E t Q W

flo o d eda re a

Q B P

C an op y

G ro u n d w a ters to ra g e

SG

QD

QS

QW

Q

QG

Ei

SD S u rfa c ed e p re s s io ns to ra g e

SS S ubs u r fac es to rage

SW O pen w a te rs to rage

QBP

Et

PE

nr. 10

Sarawak peatswamp studiesSarawak peatswamp studies- it started with Q …- it started with Q …

nr. 11

Sarawak peatswamp studiesSarawak peatswamp studies- and ended with P, L …- and ended with P, L …

nr. 12

Basin-wide water table studiesBasin-wide water table studies

• Peat dome and Peat dome and water table ‘in water table ‘in balance’balance’

• Water level Water level fluctuations fluctuations uniformuniform

2-weekly water 2-weekly water table monitoring table monitoring for changes in for changes in basin storage (40 basin storage (40 wells per basin)wells per basin)

2.5

3.5

4.5

5.5

-7.5 -5 -2.5 0 2.5 5 7.5

Distance from Jemoreng stream (km)

Wa

ter

leve

l (m

ab

ove

da

tum

)

23-05-96

20-06-96

04-07-96

01-08-96

15-08-96

26-09-96

N S

Stream

-0.2

-0.1

0

0.1

25/04/96 9/05/96 23/05/96 25/05/96 6/06/96 20/06/96 22/6/96 29/6/96 4/07/96 8/01/96 15/08/96 29/8/96

Date

Ave

rag

e w

ate

r ta

ble

de

pth

(m

)

Average for Rentis 6 (13 wells)

Station levels, corrected

nr. 13

Diurnal water table studiesDiurnal water table studiesFor:For:

• actual evapotranspiration rates actual evapotranspiration rates

• recharge rates, recharge rates,

• (peat characteristics, for above)(peat characteristics, for above)

-0.35

-0.25

-0.15

-0.05

0.05

0.15

1996 06 14 18 1996 07 05 14 1996 07 26 10 1996 08 16 06 1996 09 06 02

Date

Wate

r ta

ble

depth

(m

above p

eat surf

ace)

QG=dL(G)*Sf

Et=dL(Et)*Sf

0 6 24 h

CQD=(L(t)-L(t-1))/L(t)

Sf=dL(P)/P

nr. 14

Data collection methodsData collection methodsWater table studiesWater table studies

• Diurnal Diurnal water table water table studies for studies for actual actual evapotranevapotranspiration spiration ratesrates

0

1

2

3

4

5

0 1 2 3 4 5

A c t u a l e v a p o t r a n s p i r a t i o n o n r a in le s s d a y s ( m m / d )

Penm

an p

oten

tial e

vapo

trans

pira

tion

(mm

/d)

L = - 0 . 1 t o - 0 . 2 m

L < - 0 . 2 m

nr. 15

Data collection methodsData collection methodsWater table studiesWater table studies

• Diurnal Diurnal water table water table studies for studies for recharge recharge ratesrates

0

2

4

6

8

10

0 0.1 0.2 0.3 0.4 0.5

Depth below peat surface (m)

Gro

undw

ater

see

page

rate

(mm

/d) Jemoreng (maximum depth is 0.31 m)

Dalat (maximum depth is 0.5 m)

Daro (maximum depth is 0.38 m)

nr. 16

Data collection methodsData collection methodsWater table studiesWater table studies

• Model Model schematisation schematisation with Sf, Qr and ET with Sf, Qr and ET from diurnal WT from diurnal WT record. record.

• Model calibration Model calibration with storage with storage changes from water changes from water table record (and table record (and with measured Q).with measured Q).

• Catchment area Catchment area optimimisation optimimisation through calibration.through calibration.

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

Wa

ter

leve

l (m

)

L observed

L modelled

0

10

20

30

40

50

Jan-96 Mar-96 Jun-96 Sep-96 Dec-96 Mar-97

Dis

cha

rge

(m

m/d

)

Q observed

Q modelled

nr. 17

Sumatra: next stepSumatra: next stepIntact and impacted peatswampsIntact and impacted peatswamps

• Goal: Management plan Goal: Management plan Air Hitam Laut river Air Hitam Laut river basin. basin.

• Question: Entire peat Question: Entire peat dome needs dome needs protection?protection?

• Approach: water table Approach: water table studies along 2*5 studies along 2*5 transects:transects:

Batang ??

Batang ??

Air

Hita

m D

alam

Air Hita

m D

alam

Batang HariBatang Hari

Air Hita

m Laut

Air Hita

m Laut1 intact peatswamp2 drained for agriculture3 drained for plantation4 logged5 burnt

nr. 18

SumatraSumatra What do we want to study?What do we want to study?

Effects of Effects of changeschanges

to the natural to the natural

hydrology, on:hydrology, on:

• Water levelsWater levels

• Peat SubsidencePeat Subsidence• Watershed area Watershed area

• Lowest flowsLowest flows

• Peak flowsPeak flows

• Water qualityWater quality

Air Hitam Dalan

Air Hitam Laut

Air ?

BasinBoundary

BasinBoundary

Peat dome Peat dome

Drains Drains

nr. 19

Danube deltaDanube deltalakes and reedlandslakes and reedlands

• Highly complex Highly complex system of system of lakes, streams, lakes, streams, artificial artificial channels, channels, reedlands, reedlands, floating floating reedlandsreedlands

nr. 20

Danube deltaDanube delta What do we want to study?What do we want to study?• Goal: accurate hydraulic/WQ Goal: accurate hydraulic/WQ

model for WQ management model for WQ management (with DDNI)(with DDNI)

• Question: connectivity Question: connectivity between lakes? how much between lakes? how much flow under floating reedbeds, flow under floating reedbeds, and how much through and how much through channels?channels?

• Approach: collect calibration Approach: collect calibration data for existing model.data for existing model.

nr. 21

Danube deltaDanube deltamonitoring & measurementsmonitoring & measurements

• Flows in Flows in channels channels measured measured daily daily (shown: (shown: Lake Isac Lake Isac system).system).

nr. 22

Danube deltaDanube deltamonitoring & measurementsmonitoring & measurements

• Water levels Water levels monitored in monitored in lakes (‘divers’, lakes (‘divers’, gauges).gauges).

• Ideal ‘Water Ideal ‘Water balance’ period: balance’ period: high water, no high water, no ‘net’ water level ‘net’ water level change in lakes.change in lakes.

0

0.5

1

1.5

2

2.5

03/0

8/20

02

10/0

8/20

02

17/0

8/20

02

24/0

8/20

02

31/0

8/20

02

07/0

9/20

02

Wa

ter

lev

el (

m)

Sf Gheorge BranchSulina BranchLake Isac

nr. 23

Danube deltaDanube deltaclosed w. balance per lake systemclosed w. balance per lake system

• Using flow- Using flow- and water level and water level measure-measure-mentsments

Flow under Flow under reed very reed very limited, even limited, even during during high high waterwater

4-sep 5-sep 6-sep 7-sep 8-sep 9-sep 10-sep 11-sep Average Average

Inputs 5-11 Sep June

Inflows through channels (not Isac 3)*

Channel Isac 1 to Isac 3.64 3.3 2.93 3.3 3.7 4.01 4 4.02 3.61 4

Channel Isac 1 to Isacel 1.75 2 2.71 2.7 2.6 2.5 2.5 2.48 2.50 0.9****

Uzlina Channel 2.79 4.46 4.42 4 3.5 2.92 2.5 2.05 3.41 1.3

Total m3/s 8.18 9.76 10.06 10 9.8 9.43 9 8.55 9.51 6.2

Total m3/d 706752 843264 869184 864000 846720 814752 777600 738720 822034 535680

Rainfall (mm/d) 0 0 0 0 0 0 0 0 0 ?*****

Outputs

Outflows through channels

Isac 2 3 3.75 4.12 5.25 5.5 5.87 5.02 6.18 5.10 2.5

Isac 3 (sometimes inflow)* -2.21 0.37 -1.9 2.11 1.7 1.36 3 4.66 1.61 1.7

Total m3/s 0.79 4.12 2.22 7.36 7.2 7.23 8.02 10.84 6.71 4.2

Total m3/d 68256 355968 191808 635904 622080 624672 692928 936576 579991 362880

Loss to evapotranspiration

mm/d 3 3 3 3 3 3 3 3 3 4

m3/d** 126000 126000 126000 126000 126000 126000 126000 126000 126000 168000

equivalent m3/s 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.9

Change in storage, inferred from water level change2

Water level in Isac (m) 1.84 1.861 1.878 1.88 1.87 1.864 1.855 1.84W. l. change in Isac (m) 0.022 0.02 0.017 0.002 -0.01 -0.006 -0.009 -0.015

Storage change, m3/d** 924000 840000 714000 84000 -4E+05 -3E+05 -4E+05 -6E+05 -6000 ?*****

Storage change m3/s 10.7 9.7 8.3 1.0 -4.9 -2.9 -4.4 -7.3 -0.07

Result: Outflow outside main channels (partly through reed) from Isac to Perivolovka channel to east

. -4.8 -5.5 -1.9 0.2 6.0 3.7 3.9 3.5 1.4 0.1

% of total outflow 17.4 1.3flow velocity (m/s)*** -0.0019 -0.0022 -0.0008 0.0001 0.0024 0.0015 0.0016 0.0014 0.00057 0.00002

nr. 24

Danube deltaDanube deltahydrological system definitionhydrological system definition

• ‘‘Discharge Discharge points’ points’ outside of outside of channels channels identifiedidentified

Isac

Isacel

Uzlina

Gerasimova

Litcov Channel

Per

ivo

lovk

a C

han

nel

Definition of the Isac Lake System(including Isacel and Gerasimova) A. Hooijer, Delft Hydraulics / DDNI / RIZA

Closed system boundary‘Open’ boundaryChannel flowFlow through reedland

?

nr. 25

Danube deltaDanube deltaanalysis analysis modelling modelling management management

• Comparison of measured and modelled Comparison of measured and modelled flows and flows and water levelswater levels, as basis for further calibration., as basis for further calibration.

nr. 26

Summary conclusion…Summary conclusion…

In all cases, In all cases, water level datawater level data and specific ‘wetland’ water level and specific ‘wetland’ water level record analyses methods help(ed) improve understanding and record analyses methods help(ed) improve understanding and modelling of wetland hydrology:modelling of wetland hydrology:

• Actual evapotranspiration determinedActual evapotranspiration determined

• Soil characteristics determined (storage coefficient)Soil characteristics determined (storage coefficient)

• Water balance ‘closed’ with storage informationWater balance ‘closed’ with storage information

• Hydrological models calibrated with water levelsHydrological models calibrated with water levels

• Catchment areas refined/determinedCatchment areas refined/determined

Water level monitoring & analysis will improve hydrological Water level monitoring & analysis will improve hydrological studies in wetlandsstudies in wetlands