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46 lines
5.0 KiB
HTML
46 lines
5.0 KiB
HTML
<html>
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<head><link rel="stylesheet" type="text/css" href="help.css" /></head>
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<body>
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<h1 class='module'>TOPMODEL</h1>
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<div class='author'>(c) 2003 by O.Conrad</div>
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<div class='description'>Simple Subcatchment Version of TOPMODEL<br/>
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<br/>
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Based on the 'TOPMODEL demonstration program v95.02' by Keith Beven (Centre for Research on Environmental Systems and Statistics, Institute of Environmental and Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK) and the C translation of the Fortran source codes implementated in GRASS.<br/>
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<br/>
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This program allows single or multiple subcatchment calculations but with single average rainfall and potential evapotranspiration inputs to the whole catchment. Subcatchment discharges are routed to the catchment outlet using a linear routing algorithm with constant main channel velocity and internal subcatchment routing velocity. The program requires ln(a/tanB) distributions for each subcatchment. These may be calculated using the GRIDATB program which requires raster elevation data as input. It is recommended that those data should be 50 m resolution or better.<br/>
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<br/>
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NOTE that TOPMODEL is not intended to be a traditional model package but is more a collection of concepts that can be used **** where appropriate ****. It is up to the user to verify that the assumptions are appropriate (see discussion in Beven et al.(1994). This version of the model will be best suited to catchments with shallow soils and moderate topography which do not suffer from excessively long dry periods. Ideally predicted contributing areas should be checked against what actually happens in the catchment.<br/>
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<br/>
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It includes infiltration excess calculations and parameters based on the exponential conductivity Green-Ampt model of Beven (HSJ, 1984) but if infiltration excess does occur it does so over whole area of a subcatchment. Spatial variability in conductivities can however be handled by specifying Ko parameter values for different subcatchments, even if they have the same ln(a/tanB) and routing parameters, ie. to represent different parts of the area.<br/>
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<br/>
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Note that time step calculations are explicit ie. SBAR at start of time step is used to determine contributing area. Thus with long (daily) time steps contributing area depends on initial value together with any volume filling effect of daily inputs. Also baseflow at start of time step is used to update SBAR at end of time step.<br/>
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<br/>
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References<br/>
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- Beven, K., Kirkby, M.J., Schofield, N., Tagg, A.F. (1984): Testing a physically-based flood forecasting model (TOPMODEL) for threee U.K. catchments, Journal of Hydrology, H.69, S.119-143.<br/>
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<br/>
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- Beven, K. (1997): TOPMODEL - a critique, Hydrological Processes, Vol.11, pp.1069-1085.<br/>
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</div>
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<h2>Parameters</h2>
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<dl class='parameters'>
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<dt>Grid system <div class='type'>Grid system</div></dt><dd>Grid system <div class='constraints'></div></dd>
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<dt>A / tan(Ã) <div class='type'>Input Grid</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Soil Moisture Deficit <div class='type'>Output Grid</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Climate Data (P, EP) <div class='type'>Input Table</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Simulation Output <div class='type'>Output Table</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Time Step [h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Number of Classes <div class='type'>Integer</div></dt><dd> <div class='constraints'>Minimum: 1.0</div></dd>
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<dt>Initial subsurface flow per unit area [m/h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Areal average of ln(T0) = ln(Te) [ln(m^2/h)] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Model parameter [m] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Initial root zone storage deficit [m] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Maximum root zone storage deficit [m] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Unsaturated zone time delay per unit storage deficit [h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Main channel routing velocity [m/h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Internal subcatchment routing velocity [m/h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Surface hydraulic conductivity [m/h] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Wetting front suction [m] <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Water content change across the wetting front <div class='type'>Floating point</div></dt><dd> <div class='constraints'></div></dd>
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<dt>Green-Ampt Infiltration <div class='type'>Boolean</div></dt><dd> <div class='constraints'></div></dd>
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</dl>
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</body></html>
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