Effect of land use change on flooding from integrated water resources management (IWRM) perspective

Abstract

Due to rapid urbanization and industrialization, the change in the land use pattern has resulted in irreversible anthropogenic disturbances to the hydrological processes. The increase in impervious area associated with urban development affects the hydrologic cycle and consequently there is an enhanced risk due to urban flooding. The increase in impermeable area decreases infiltration, increases the runoff and reduces the time of concentration. Hence, for a given amount of rainfall, greater flooding is realized. Even though flood is a natural hydrological phenomenon, human modification and new developments on flood plains had accentuated the problem. This may be due to little attention being paid to the social, political, environmental, ecological, institutional, economical and legal aspects of flooding while more emphasis is given to engineering aspects of flood control. The focus of the research is to bring the hydrologic, hydraulic, social and economic aspects of the flooding under the umbrella of Integrated Flood Management (IFM) that aims to combine all the characteristics of flooding and tries to give effective solution for the problem. It also argues that flood management measures will be successful if the policies are appropriate and adequate attention is paid to social issues involving stakeholders in the decision making process. The research aims to investigate the impacts of land use changes on runoff generation process and the problems associated with the flood management. In this study, Soft Systems Methodology (SSM) was used to address social and engineering problems arising due to flooding along Adayar River in Chennai, India. Two workshops were conducted in order to define and explore the problematic situation, the role of various actors involved, to develop the conceptual model, to rank decision-making criteria and to analyze the forces for and against the solution of the problem. It is found from the study that the effect of flooding tends to be severe due to formation of sand bar at the river