Presenter/Author Information

David Maréchal
Ian P. Holman

Keywords

model, rainfall-runoff models, catchment scale, soil

Start Date

1-7-2002 12:00 AM

Description

A conceptual rainfall-runoff model, the Catchment Resources and Soil Hydrology (CRASH) model, designed for catchment management purposes, has been developed to compute continuous river flow at the catchment or river basin scale. Its input data requirements are limited to data normally existing in any catchment of potential interest. The mechanistic model is driven by soil, land use and weather data, and is parameterised according to the soil series types within the catchment. One model parameter related to runoff is derived from computed coefficients from the soil hydrological classification of the Hydrology Of Soil Types (HOST) system. HOST is a conceptual representation of the hydrological processes in the soil for which calibrated values of Base Flow Index and Standard Percentage Runoff have previously been computed. The three other parameters are calibrated for each HOST class. Due to the specification of the HOST system CRASH has been evaluated at first in the United Kingdom. It has initially been independently applied to medium size catchments with acceptable results. As a second step, the model has been tested with a common set of parameter values in two catchments of similar size and soil characteristics but with contrasting climate condition. The results are reasonable through the range of the flow duration curve and would tend to confirm that it is possible to derive unique model parameters for soils with similar hydrological behaviour. It is however necessary to test the model more widely to obtain a robust set of parameters that would allow the use of the model in ungauged catchments without catchment-specific calibration.

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Jul 1st, 12:00 AM

A Soil Hydrology-Based Catchment Water Resources Model

A conceptual rainfall-runoff model, the Catchment Resources and Soil Hydrology (CRASH) model, designed for catchment management purposes, has been developed to compute continuous river flow at the catchment or river basin scale. Its input data requirements are limited to data normally existing in any catchment of potential interest. The mechanistic model is driven by soil, land use and weather data, and is parameterised according to the soil series types within the catchment. One model parameter related to runoff is derived from computed coefficients from the soil hydrological classification of the Hydrology Of Soil Types (HOST) system. HOST is a conceptual representation of the hydrological processes in the soil for which calibrated values of Base Flow Index and Standard Percentage Runoff have previously been computed. The three other parameters are calibrated for each HOST class. Due to the specification of the HOST system CRASH has been evaluated at first in the United Kingdom. It has initially been independently applied to medium size catchments with acceptable results. As a second step, the model has been tested with a common set of parameter values in two catchments of similar size and soil characteristics but with contrasting climate condition. The results are reasonable through the range of the flow duration curve and would tend to confirm that it is possible to derive unique model parameters for soils with similar hydrological behaviour. It is however necessary to test the model more widely to obtain a robust set of parameters that would allow the use of the model in ungauged catchments without catchment-specific calibration.