Estimating Annual Flow Frequency Function Using HEC-HMS and GIS: A Case Study Mula River in Jhal Magsi, East Balochistan

Water is a basic necessity for life, and it is the most abundant natural resource on our planet. Its usefulness is vast and at times becomes hazardous when not properly managed. Balochistan is a region suffering from extreme events of flood and drought conditions. The study area, Jhal Magsi, located in central Balochistan, Pakistan, is one of the most vulnerable regions to flash flooding. The SRTM DEM for Jhal Magsi was used in HEC-GeoHMS, an ArcGIS extension for terrain pre-processing, basin processing, and catchment delineation. Hydrological models are used to simulate the impact of climate on water resources. Integrating Remote Sensing abilities and Geographic Information System techniques with the hydrological modeling approach is very useful to understand problems and enhance the methods of investigation for better decision making. Based on the results of the watershed delineation, this analysis identified the basin characteristics, estimated rainfall distributions. HEC-DSS is used to store and retrieve data to give input to HEC-HMS for flood frequency studies and AEP calculations. The tabular results consist of three tables. The frequency curve shows the percent chance of exceedance ordinates. The expected probability frequency curve is between a 5% and 10% chance of exceedance confidence limit of the observed values. Calibration and validation had been done, and statistical analysis as well. The graphical results show outliers to predict extreme events, which are expected once in the coming 50 years. The research will be helpful for hydrological modeling and future prediction in the data-sparse regions of Balochistan for damage reduction studies using HEC-RAS.