Flood Hazard Mapping of Nowshera City and Remediation

Abstract

The monsoon system during year 2010 exhibited a fast change and due to which mega floods occurred. It was such an unprecedented flood in Pakistan, which rose to the maximum levels in the known history. Particularly, Nowshera was hit badly by flood water. Due to less warning time, people of Nowshera were taken almost unaware. Civil Departments being unprepared to such hazards could not mount timely response. To meet the challenges, DDMA, and people of Nowshera have been pursuing host of action to control the flood of River Kabul but no visible hope so for. At present the protective arrangements across River Kabul at Nowshera city are awfully in-adequate in terms of extending safeguards to vulnerable populations against the flood hazard. In this regard, preparation of Flood Hazard Map (FHM), can play a pivotal role. This paper focuses on preparation of FHM for Nowshera city based on high flooding conditions as seen in August 2010, with a view to suggest remediation against flood hazard. A detailed methodology has been used and as first step; field study of the area has been carried out to ascertain the lateral extent of flooding and damages on both sides of the river. Then statistical analysis of hydro-meteorological data has been done with the help of 43 years record of precipitation of Peshawar Basin, 10 years record of snowmelt and 13 years record of discharge of River Kabul, in order to ascertain the reoccurrence period. In the process, the study of swelling of water on either side of the channel has been done by using DEM (30 M resolution). With the help of field/met data and Digital Elevation Model (DEM), the FHM of Nowshera City has been prepared. Basing on Flood Hazard Assessment and FHM, structural measures like, construction of flood protection bund / embankments, bypass channels/inundation canals, dam, breaching sections to dispose of excess water, removal of encroachments / slump settlements, tree plantation in catchment areas and non structural measures like updation of FHM annually, use of DEM, implementation of land use laws have been recommended. Key Words: Monsoon System, Flood Hazard Map, Digital Elevation Model, Hdro- Meteorological Factors, Precipitation, Structural and non Structural Measures.