1. What is BTOPMC?
BTOPMC = Blockwise application of TOPMODEL, using Muskingham-Cunge Routing.
BTOPMC allows representation of spatial variability and heterogeneity for a majority of hydrological fluxes and catchment property representation - including precipitation and potential evaporation, local recharge and runoff generation behaviour, and soil and vegetation properties. Based upon the assumption of the dominant role played by topography in the generation of discharge at the catchment scale, BTOPMC employs a TOPMODEL-style lumped representation of the catchment water table, including the spatial variability in water table depth/thickness, and net fluxes to and from the lumped water table. BTOPMC incorporates sub-division of large catchments into many smaller hydrological "blocks", each with an independently-behaving lumped water table, in order to overcome the identified limitation of lumping the water table behaviour over large catchments. BTOPMC may therefore be described as a semi-lumped, semi-distributed modelling approach. A website describing BTOPMC, the underlying theory, results of previous and ongoing applications, and details of model execution is under development.
2. What are the data requirements I need for simulating the hydrology of my local application using BTOPMC?
The Virtual Academy will provide instructions for obtaining the following data from public-access GIS databases on the internet:
- A digital elevation map (DEM) - available for download.
- Soil/landform map - available for download.
- Vegetation map - available for download.
Of course, you are welcome to use any alternative GIS data you may have access to - this is recommended if you are able to obtain data at a finer resolution than the default resolution offered by the databases used in the Virtual Academy.
In addition, you must have access to the following data to successfully apply BTOPMC:
- Discharge data - essential for calibration and validation of the model.
- Precipitation data - preferably from multiple locations
- Potential evapotranspiration data/estimate - from measurement or energy balance modelling (note: an energy balance method for estimating potential evapotranspiration, which has it's own specific data requirements, will be detailed in Lesson 5 of the Virtual Academy).
As a distributed model, estimation of spatially-distributed precipitation and potential evaporation from point measurement datasets has a large potential impact upon the predictive accuracy of BTOPMC. Model users are therefore encouraged to use data from as many locations as possible to derive spatially-distributed input datasets.
Finally, the length of the precipitation, evaporation, and discharge data records should be sufficient to permit calibration and validation - a minimum length of 8 years of data record is advised.