Transcript Predicting streamflow from the soil map in the Weatherley

MODELING
HILLSLOPE WATER
Hydropedology dialogue
Pretoria
2014
J. J. van Tol, S.A. Lorentz & P. A. L. Le Roux
INTRODUCTION
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Catchments are ideal management units
Hillslope determine hydrological response
Fundamental landscape unit
Common form of organization and symmetry
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Interaction between:
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Topography
Climate
Vegetation
Geology
Soils
Ideal scale for understanding and simulating
hydrological process
Basic building block for some hydrological models
HILLSLOPE HYDROLOGY
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Progress in hillslope hydrology declined
modellers
experimentalists
 Modellers:
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Small scale physical descriptors
Don’t incorporate the experimentalist’s knowledge into model
structure
Hydrological modeling problem
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Dominant paradigm in hydrological modelling
a
priori set of small scale theories and process
descriptions
 splitting the catchment into small enough uniform
elements for these theories to work
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Models require mapping of heterogeneities and
process complexities
Impossible!!
Hydrological modeling problem
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Models rely on calibration
Models ‘work’ but for wrong process reasons
Overparameterized
Equifinality
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Large degree of modeling uncertainty
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Unsuitable for PUB’s!!
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HILLSLOPE HYDROLOGY
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Progress in hillslope hydrology declined
modellers
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Modellers:
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experimentalists
Small scale physical descriptors
Don’t incorporate the experimentalist’s knowledge into model
structure
Experimentalists
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Unconventional behaviour of new hillslopes
No intercomparison
Extrapolation value is low
No minimum set of measurements to characterize a single hillslope!!
Hydrological modeling problem
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Paradigm shift required
 Accept
landscape heterogeneity and process
complexity
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Find common threads, patterns, concepts and laws
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Identify, classify and quantify
Hydrological soil type
Recharge
Interflow (A/B)
Interflow (soil/bedrock)
Responsive (shallow)
Responsive (saturated)
Symbol
Letaba:
4 hillslopes
Craigieburn:
3 hillslopes
Mokolo:
5 hillslopes
Newcastle:
3 hillslopes
PAP:
1 hillslope
Skukuza:
4 hillslopes
Two Streams:
3 hillslopes
Noord Kaap:
2 hillslopes
Thaba Nchu:
2 hillslopes
Taylors Halt:
1 hillslope
Schmitsdrift:
2 hillslopes
Cathedral Peak:
2 hillslopes
Bozrah:
2 hillslopes
Bloemfontein:
5 hillslopes
Weatherley:
5 hillslopes
Hogsback:
2 hillslopes
Loeriesfontein:
2 hillslopes
Riversdale:
1 hillslope
Bedford:
2 hillslopes
Baviaans:
2 hillslopes
Observations and measurements
Catchment
Craigieburn
Letaba
Skukuza
Mokolo
New Castle
Two Streams
Taylor’s Halt
Noord Kaap
Taba Nchu
Schmitsdrift
Bloemfontein
Cathedral Peak
Weatherley
Loeriesfontein
Hogsback
Fort Hare
Bedford
Riversdale
Baviaans kloof
PAP
Hillslope
3
4
4
5
3
3
1
2
2
2
5
2
5
2
2
2
2
1
2
1
Pedology
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Soil physics
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x
x
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x
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Hydrometrics
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x
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x
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x
x
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Geology
Granite
Granite
Granite
Aeolian
Sandstone/dolerite
Sandstone
Sandstone
Aeolian
Sandstone/mudstone
Alluvium
Shales/dolerite
Basalt
Mudstone/dolerite
Shales
Shales/dolerite
Shales
Shales
Sandstone
Conglomerate
Granite
AI
0.28
0.2
0.25
0.2
0.35
0.4
0.45
<0.1
0.28
0.15
0.25
>0.6
0.5
0.2
>0.6
0.26
0.2
0.5
0.2
0.3
Framework of hillslope classification
Application – distributed modelling
Application – wetlands (Hogsback)
Class 4
Class 1
Conclusions
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We can:
 Indentify
 Classify
 Dominant
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hydrological responses
We need to:
 Quantify!
THANK YOU!!
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WRC