Application of hydrological model to assess river flow in the transboundary cryosphere and data-scarce watershed, a case study: Chitral-Kabul River Basin (C-KRB) in Pakistan

Severe water crises in Pakistan and growing demands in Afghanistan require a bilateral agreement on the Kabul River Basin (KRB) but precise stream-flow data is a critical matter. The aim of this research is to assess the stream-flow of the data-scarce transboundary Chitral-Kabul River Basin (C-KRB) in Pakistan using a hydrologic modeling approach. The HEC-HMS model was applied for predicting peak-flow and simulating runoff of the C-KRB. The model was calibrated over the period 2010–2011 (66% of all data) and validated for 2012 (33% of all data). Our findings showed that the Nash–Sutcliffe efficiency (NSE) and R2 were 0.70 and 0.89 respectively. The simulated peak-outflow was 850 m3/s on 1 August, which was quite close to the observed peak-flow of 861 m3/s on 3 August 2012. The difference in peak-flow (Dp) was −4.45% and the deviation of runoff volume (Dv) was −26.95%. It was concluded that HEC-HMS can be applied as a rapid tool in predicting future flow using the freely accessible rainfall and snow-cover data. Furthermore, this approach can be utilized for water users, developers and planners to provide first-hand information for formulating any bilateral agreement on shared water of the KRB between Pakistan and Afghanistan.