Simplified RainfallRunoff model

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Simplified Rainfall-Runoff model using PCRaster
Karin Rebel
Css 620
Tuesday, March 27th
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Goal of the talk To give some exposure to other
packages that are out there
Why PCRaster PCRaster is especially useful when
you are interested in spatial dynamic modeling.
Introduction to the dynamic Modeling
Language core of the PCRaster package.
Simplified hydrological runoff model is used to
illustrated the concepts of the
language (Karssenberg, http//www.geog.uu.nl/pcras
ter/runoff/).
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Dem.map Digital elevation map of the study area,
in meters above sea-level
Rainstat.map Map with the location of three
rainfall measurement stations
Dem.map
Rainstat.map
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Soil.map map with the different soils of the
study area.
Soil.map
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Rainfall data available for one week on a 2 hour
basis.
Model simulates the spatial pattern of
superficial runoff during this week, taking into
account different infiltration parameters for the
different soil types.

• Needed
• Rainfall estimate for each cell based on
  measured data
• of rain stations.
• Assign infiltration values to different soils,
  creating a new
• map with infiltration capacity.
• Determine actual infiltration of rain water.
• Redistribute excessive rain downstream over
  study area
• to estimate runoff.

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The rainfall data for the three rain stations are
stored in the ascii formatted timeseries file
rain.tss
Rain.tss each timestep represents 2 hours
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Interpolate three rain measurements.
Assumption For each location the nearest rain
measurement is the most characteristic.
Used Spread and Spreadzone
Pcrcalc raindist.map spread (rainstat.map,0,1)
This function calculates the smallest cost
(distance) to reach one of the non zero points
on the map.
Pcrcalc rainzone.map spreadzone
(rainstat.map,0,1)
This function applies the same function as the
spread operator, but assigns the unique cell
value of the rain station that is nearest.
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Raindist.map
Rainzone.map
Rainstat.map
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model for simulation of rainfall 84 timesteps
of 2 hours gt modeling time one week
Binding Rainstations rainstat.map RainTimeSerie
s rain.tss RainZones rainzone.map SurfaceWat
er rainfall
Areamap Mask.map
Timer 1 84 1
Initial Report RainZones spreadzone
(RainStations,0,1)
Dynamic Report SurfaceWater timeinputscalar
(RainTimeSeries, Rainzones)
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A part of the rainfall and runoff will infiltrate
in the soil.
Infiltration capacity (maximum amount of water
that can infiltrate during one timestep of 2
hours, mm/2hours) is different for each soil type.
 

• Lookup table
• 2.1
• 8.3
• 19.0

First column soil type 1 clay 2 loam 3 sand
Second column associated infiltration capacity
Infilcap.map
Pcrcalc infilcap.map lookupscalar
(infilcap.tbl, soil.map)
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Excessive rain must be redistributed downstream
over the catchments.
Make local drain direction map, using the DEM.
The local drain direction map contains for each
cell a pointer to its lowest downstream neighbour
on the DEM
Ldd.map
Pcrcalc ldd.map lddcreate (dem.map, 1e31, 1e31,
1e31, 1e31)
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Water transported downstream Amount water from
upstream cells and rainfall infiltration
capacity value of infilcap.map.
Runoff.map
Logrunof.map
Pcrcalc runoff.map accutresholdflux (ldd.map,
rainfall.054, infilcap.map)
Pcrcalc logrunof.map log10 (runoff.map
0.0001)
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The dynamic modeling language also allows to
sample the cell value at certain location on a
map for each time step and report these values
in a time series.
The three sampling location samples.map
Through timeoutput statement, runoff values at
the sampling locations are stored in the
database.
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Binding Raisnstations rainstat.map RainTimeSeri
es rain.tss RainZones rainzone.map SurfaceWa
ter rainfall SoilInfiltrationTable
infilcap.tbl SoiYpe soil.map InfiltrationCapac
ity infilcap.map Dem dem.map Ldd
ldd.map ConvConst 720000 LogRunOff
logrunof SamplePlaces samples.map RunoffTimeSe
ries runoff.tss Areamap Mask.map Timer 1 84
1 Initial Report RainZones spreadzone
(RainStations,0,1) Report InfiltrationCapacity
lookupscalar (SoilInfiltrationTable,
SoilType) Report Ldd lddcreate (Dem, 1e31,
1e31, 1e31, 1e31) Dynamic Report SurfaceWater
timeinputscalar (RainTimeSeries,
Rainzones) Runoff, Infiltration
accuthresholdflux, accuthresholdstate (Ldd,
SurfaceWater, InfiltrationCapacity) Report
LogRunOff log10 (Runoff/ConvConst
0.0001) Report RunoffTimeSeries timeoutput
(SamplePlaces, Runoff/ConvConst)