GenRiver 1.0

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GenRiver 1.0 Distributed process-based model
spatial scale 1-1000 ha,temporal scale daily
Can be used as a tool to explore our
understanding of historical changes in river flow
due to land use change
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cloud interception
Hydrological functions of forest
rainfall
canopy water evaporation
Forest
transpiration
surface evaporation
Trees
through-fall
surface run-on
stem-flow

Quick flow
infiltration
surface run-off
recharge
sub-surfacelateral inflow
Soil
lateral outflow
uptake
base flow
percolation
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poverty
Adequate supply of clean water, no flooding
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Watershedfunctions
Site cha- racteristics
Relevant for

• 1. Transmit water
• 2. Buffer peak rain events
• 3. Release gradually
• 4. Maintain quality
• 5. Reduce mass wasting

• Rainfall
• Land form
• Soil type
• Rooting depth (natural vegetation)

• Downstream water users,
• esp. living in floodplains river beds,
• esp. without storage
• or purification
• at foot of slope

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GenRiver 1.0 a simple model that translates a
plot-level water balance to landscape level river
flow
Land cover influences evapotranspiration -gt
water yield (immediate) infiltration (medium
term soil type)
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The core of the model Patch level represent
daily water balance, driven by local rain
rainfall and modified by land cover and soil
properties of the patch
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• The patch can contribute to three types of stream
  flow
• Surface quick flow on the day of rain event
• Soil quick flow on the next day after rain
  event
• Base flow via gradual release of groundwater

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Step 1 canopy interception
1. Interception evaporation from wet surfaces
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Current LAI Waterfilm thickness
Cap(1-EXP(-Rain/Cap))
Will evaporate within a day
Calder (2004) HYLUC
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Step 2 Lack of Infiltration gt overland flow
1. Interception evaporation from wet surfaces
2. Overland flow into streams quickflow
PotInfRate
Rain duration, Can.Interc.Delay Surface staorage,
Slope
SoilSat - Actual
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Step 3 Soil quickflow drain towards field
capacity
1. Interception evaporation from wet surfaces
2. Overland flow into streams quickflow
3. Subsurface flow into streams interflow or
soilquickflow
Two-tank model
RootZone store
Saturation
FC
SoilQuickFlow Max(0,Soil- FieldCap)
Percolation Fraction
GW store
Saturation
GW release Fraction
Baseflow
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Step 4 Plant uptake and transpitation
1. Interception evaporation from wet surfaces
2. Overland flow into streams quickflow
3. Subsurface flow into streams interflow or
soilquickflow
4. Uptake by plants for transpiration ( soil
evaporation)
(Epot IntercEff Einterc) W_avail
Evaporation of intercepted water reduces transp.
demand
Energy driven, e.g.Penman
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Step 5 Percolation to streams as slow flow
1. Interception evaporation from wet surfaces
2. Overland flow into streams quickflow
3. Subsurface flow into streams interflow or
soilquickflow
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4. Uptake by plants for trans-piration ( soil
evaporation)
5. Gradual release to streams through deep soil
pathways
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RootZone store
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Percolation Fraction
GW store
Saturation
GW release Fraction
Baseflow
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Topology of stream network distances to array
of observation points
A
Obs point 1 2 3 4 5
B
SubA 15 -1 -1 7 . SubB
16 -1 -1 8 . SubC 14
8 2 -1 . SubD 8 1 -1
-1 . ..
C
D
3
4
E
2
F
G
1
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Array dimensions in the model
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Model implementation in Excel

• GenRiver.xls
• Rain Debit data (daily)
• Land cover
• Subcatchment info

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Model implementation in Stella
GenRiver.stm Model sector
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Model implementation in Stella
GenRiver.stm
GenRiver.stm
Input section
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Model implementation in Stella
GenRiver.stm
GenRiver.stm
Patch level water balance
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Model implementation in Stella
GenRiver.stm
GenRiver.stm
River flow
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Default run of GenRiver 1.0
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When seen over a long time series, both under-
and over-estimates occur in dry periods, but the
model tends to exaggerate peaks
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The model is in the right range but
underestimates flows in dry periods and
exaggerates peaks
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Model implementation in Stella
GenRiver.stm
GenRiver.stm
Output sector
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GenRiver application in Sumberjaya - Indonesia
Explore the effect of land cover spatial
pattern for rainfall on river flow
Using 2 time series of land cover fractions
Year 3()
Year 20() Forest 58
14 Cropland
22 11 Coffee
12 70
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Cumulative water balance
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River flow using Pathcy Homogenous rain
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Simulation results current MixedLU situation
not much different from forest, but for a
Degraded soil buffering would be much less