Analysis of River Tributaries’ Streamflow Contribution Using WEAP Model: A Case of the Ngwerere and Kanakatampa Tributaries to the Chongwe River in Zambia

Ngwerere and Kanakatampa Streams are the main tributaries of Chongwe River. The stream originates from city Lusaka meanders through City Town for an approximate distance 41 km before joining into upper part Stream is a tributary It Area approximately 52 discharging middle River Catchment which sub-catchment Zambezi Basin drew attention researchers policymakers when started drying up in dry seasons causing water crisis particularly downstream regions catchment. Therefore, it important resources management perspective, to assess contribution flows streams socially, economically, environmentally surrounding area. This study, therefore, concentrated on evaluating flow two using Water Evaluation And Planning (WEAP) tool. streamflow data (1970-2010) recorded at Great East Road Bridge gauging station were used WEAP embedded Parameter ESTimation (PEST) auto-calibration tool calibrate (1970-1999) validate (2000-2010) model. monthly model calibration validation results assessed correlation coefficient (CC), Coefficient determination (R2), Nash-Sutcliffe Efficiency (NSE), Percent bias (PBIAS). performance achieved PBIAS 1.24%, CC = 0.81, R2 0.66 NSE 0.62 during period positive 2.94%, 0.67 period. median (Q50) was obtained historical duration curves (FDCs) generated averaged intervals 10-year 1970 2019. showed that average, contribute 52.8% 29.6% respectively, Catchment. also discharge has been reducing historically rate 0.65% per decade 1.35% respectively over 50 years (1970-2019). Suggestions sustainable such as provided this study.