Automated updating of land cover maps used in hydrological modelling

Abstract

Urbanization and rapid growth in population are leading to development in flood plains. Natural absorbent lands are substituted by confined ones. As a result, hydrology changes in such catchments, and flood risk increases. In the regions of urban spread out, the changes in land cover need to be frequently updated, as input to hydrological models for better estimations of the discharges (i.e. run-offs). Data processing and model building are processes generally done manually through multiple software packages. These are often laborious and time consuming activities. An automated method was developed to incorporate updated land cover maps in a hydrological model. The procedure involves calculations of new model parameters (e.g. curve numbers) as per new land cover maps and further use them in the hydrological model in order to simulate catchment run-off resulted due to the change in land cover. Present paper presents the developed method of automating the ArcGIS geoprocessing by using the Python programing language and the ArcPy libraries of ArcGIS. The connection with the hydrological model was done using MATLAB, which has specialized API that can change the input files for the HEC-HMS model. Hence, HEC-HMS is updated according to newly calculated curve numbers as a result of geo-processing. A GUI was developed using the MATLAB, for introducing new land cover map into ArcGIS for geoprocessing, and for replacing the curve numbers in the hydrological model with new ones. Through the GUI, the HEC-HMS hydrological model is run automatically, and results of hydrographs are extracted