IMPACT ASSESMENT OF LAND USE DYNAMICS ON URBAN FLOODING

Abstract

A study was undertaken with the objective to understand the impact of change in land use on urban runoff. Studies across the world reveal that changes in land use will affect the runoff pattern. Cellular automata based land use models are used to generate what if scenario. The integration of land use model with event based rainfall runoff model has given invaluable information for the runoff response for storm water modeling and urban flooding. In the present study an attempt has been made to incorporate the forecasted map from the land use change model to study the hydrological response of an urban watershed. The city of Saharanpur was selected for the purpose of study. Analysis of land use changes occurred during 1990 to 2000 shows that urban area has increased near the area where suitable factors for the urbanization were available. During this period dense urban area has increased sharply. It has been found built up land has increased around 82.01 % from 1990 to 2000 in the study area. On the basis of cellular automata model it can be assessed that built up land will further increase around 18.14 % from 2000 to 2010 in the study area. The city of Saharanpur is divided in three catchments. The largest catchment is considered for runoff analysis. The runoff depth calculated for a rainfall event in the main watershed for year 1990, 2000 and 2010 are 57.64 mm, 62.63 mm and 66.67 mm. Runoff depth in 2010 is approximately 5.8% higher than the runoff depth in year 2000. This 5.8% change is the result of increase in built up land around 15.13% from 2000 to 2010 in the largest catchment. If the current trends and factors contributing to the changes do not change, it is expected that built-up land in main watershed will grow up to 1330.58k hectare in 2010.