Overland flooding is generally caused due to extreme rainfall event or hydrological response from the rivers or streams. The site selection is one of the important criteria for establishing new project, with respect to the hydrological response it is receiving. Improper site selection may result in overland flooding during monsoon season or intense rainfall event. This book covers geographic information system (GIS) based integrated hydrological and hydraulic modelling to study the cause of flooding and providing the flood mitigation measures. US, Hydrologic Engineering Center softwares HEC-HMS and HEC-RAS were successfully applied and the results obtained were used for providing mitigation measure. Two alternative frameworks were developed and one of the solution has been implemented on site and working successfully.