DefinePK

Abstract

Baluchistan, a largest province of Pakistan, has faced multiple instances of flash flooding in recent past. The study focuses on the Nasirabad Division that is sandwiched between the several catchments including Catchments of Bolan and Mulah rivers. There, among other surrounding rivers have given excessive peak discharge volumes in year-20222.Despite frequent flood occurrences, it is not feasible to prevent the floods completely by constructing large storages. Rather, their adverse impacts could be minimized by flood risk management. Although, many institutions are available to reduce the harmful impacts of floods however there is inadequate focus on pre-flood planning measures that includes ascertaining the potential flood magnitudes. Where, in data scarce catchments of Baluchistan, long term record of discharge is not available; therefore, data of rainfall is used to compute discharge volumes in the catchments surrounding Nasirabad by using SCS-CN method with the help soil type and land cover data. These estimated peak discharge volumes could be used in planning and design of hydraulic structures and communicating flood risk warning in time. It is found that the Peak storm precipitation in the catchments surrounding Nasirabad: Bolan River, Mullah river, Chattar River, Tank Pusht River, Gorri river, Sorri River and Talli Tangi river catchment are 125mm, 127.2mm, 91mm ,91mm, 91mm, 91mm and 108mm respectively in a period between 1914 to 2022. Where, data of same precipitation gage is used to approximate the rainfall of Chattar, Tank Pusht, Gorri and Sorri River. The peak discharge by SCS-CN method in same period. The maximum estimated peak discharge varies from 0.68 BCM against the peak precipitation of 155 mm in the 1889.7 Sq. mile catchment of Bolan River to 0.01 BCM against the precipitation of 91 mm in the 41 Sq. mile catchment of Gorri River.