The rational method toolbox

Dr. Huidae Cho
Institute for Environmental and Spatial Analysis...University of North Georgia

1   The rational method

The rational method

2   Homework: Algorithm for finding the largest complete watershed

Submit your idea for delineating the largest complete watershed within the extent of a DEM. Flow directions should have only one cell that crosses the boundary of this watershed at the outlet. Again, I don’t know of any efficient non-brute-force solution either. I want to see how you expand your idea into an algorithm. I’ll grade your effort by checking how closer I believe you have approached a yet unknown solution. Yes, I can still grade your report without any keys. How? I’ll try to defeat your logic and find counter examples showing that your approach won’t work for specific cases. You don’t necessarily have to use existing geoprocessing tools if you can explain your logic very clearly and programmatically.

Please don’t submit an algorithm that has to try all possible watersheds across all the cells as pour points (a very inefficient brute-force method).

3   Homework: The rational method toolbox using kriging

We want to improve the Rational Method toolbox because its current output raster has discontinuous runoff discharges. Use the kriging tool instead of Thiessen polygons to create the rainfall intensity raster without the discontinuity issue. Please use the linear semivariogram model with the default properties for lagSize, majorRange, partialSill, and nugget. That is, you don’t have to specify these properties as long as you set the semivariogramType to LINEAR. Remember, the kriging tool directly creates a surface raster. Use for testing and validation.

Please submit your FirstLastname_RationalMethod.pyt to D2L.