Monitoring Land Use Land Cover Change and its Impact on Runoff Generated in Urban Catchment of India using ARC-GIS and HEC-HMS
The land use land cover changes due to increasing urbanisation (as a result of the growing global population and unchecked migration to urban cities), especially in major metro cities of India, makes the study of its effects on hydrological fluxes such as direct runoff very important, so that we can quantify the changes in the runoff volume due to the increasing impervious area. Alteration of the hydrological cycle, caused by rendering large areas of land impervious, and reduction of depression and interception storage, results in quicker overland flow for similar climatic conditions. In order to understand the effect of changing land use land cover on the possible variations in the runoff generated in Indian metro cities, HEC-HMS event-based simulation using SCS-CN method has been employed in this study. The Bangalore metropolitan region is selected for the analyses. The changes in the runoff characteristics are investigated under an identical climatic condition of same-designed storm determined using alternating block method, occuring uniformly over the entire catchment. Dominant changes of various land use land cover classes, namely urban, agricultural, forest, wasteland, grassland, etc. in each sub-catchment are identified to correlate the change in runoff occurring in the same catchments under changing land use land cover conditions over the study period from 1985 to 2013. In the study area, major change has been seen in conversion of agricultural area to urban area where both changes had a correlation of 0.86. The Pearson Bivariate correlation showed a strong correlation with increase in urban area with r=0.60 and a negative correlation with the change in agricultural area with r=-0.68. This study is hence made to extract any similarities in the effects of rapid urbanization on hydrological fluxes.
Keywords: LULC change, ArcGIS, IDF curves, Alternating block method, HEC-GeoHMS, HEC-HMS, SCS-CN method, LULC change and runoff change correlation