Urbanization impacts upon catchment hydrology and gully development using mutli-temporal digital elevation data analysis

Urbanization can change catchment hydrology, accelerating gully erosion and causing serious damage to urban structures like roads, bridges and buildings. Increased impervious surfaces lead to large, rapid increases in surface runoff in urban catchments during storm events, as well as changes in the upslope contributing area due to rerouting of urban runoff that can exacerbate erosion. Accounting for changes in surface drainage patterns Gama City, Brazil, is used to predict areas prone to accelerate gullying and develop a method of assessing the potential for gully erosion produced by urbanization. The method is based on the analysis and comparison of detailed digital elevation models (DEMs) of the natural condition before urbanization and the topography after urbanization. The study site is located in an area where changes in drainage patterns associated with rapid urbanization in the last 30 years have resulted in severe gullying. Our analysis identifies areas potentially susceptible to gullying and highlights the erosional influence of increased flow concentration caused by urban occupation, a finding that has implications and applications for strategies to prevent gully development in cities or areas undergoing urban expansion. Copyright (C) 2010 John Wiley & Sons, Ltd.