Quantification of flash flood peaks using computer simulation for potential hill torrents of Pakistan: A modeling study

This study investigates rainfall runoff behavior of five major torrential Nullahs' of Dera Ghazi Khan (D. G. Khan) for flash flood events. The integration, and fusion of satellite‐based meteorological, topographical, and pedo‐transferred function's (PTF) derived soil hydraulic datasets at 250 m grid size substantially proves a viable approach for semi‐distributed rainfall runoff analysis. The five torrential watersheds were subdivided into a mesh of 478 sub‐catchments, topographically linked with each other to generate systematic runoff routing schemes. The infiltration losses are calculated using Green Ampt loss method. However, excess rainfall induced runoff is generated using PCSWMM model. The performance and reliability of semi‐distributed system is assessed using Kling‐Gupta Efficiency (KGE), Nash‐Sutcliffe Efficiency (NSE), Integral Square Error (ISE), Percentage Bias (PBIAS), Relative Error (RE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). The statistics indicate strong correlation between simulated and observed peak discharges (0.78 < KGE < 0.94, 0.79 < NSE < 0.92; 0.028 < ISE < 0.067, 2.7 < PBIAS < 21.47, −0.177 < RE < 0.151, 3273.95 < MAE < 6681.62, 4915.33 < RMSE < 9312.28). The reliable results reveal the robustness of semi‐distributed modeling approaches incorporated with ensembled and gridded data integration for the quantification of flood peaks.