Streamflow simulation using the integrated water resources management model on the lower basin of the Diyala river, Iraq.

Water Evaluation and Planning (WEAP) is a simulation model commonly used for integrated water resources management. A calibration process is required to get ensure that the model can accurately represent actual circumstances, however. The goal of this paper is thus to identify the ideal parameter values for a given scenario using sensitivity analysis, as well as to obtain the optimised parameter value to ensure the highest simulation reliability value possible during the calibration procedure. Examining the process of performing sensitivity analyses on a variety of WEAP model calibration parameters demonstrates that some parameters have a common set of properties: the Root Mean Square Error (RMSE) value is directly proportional to the variation in the Initial relative storage (Z1) and Resistance Runoff Factor (RRF) values in that the greater the parameter value, the greater the resulting RMSE value. In contrast, variations in Relative storage (Z2) and Preferred Flow Direction (PFD) values are inversely correlated with RMSE. The remaining parameters, Deep Conductivity (DC), Soil Water Capacity (SWC), and Deep Water Capacity (DWC) show fluctuations in their relationships with RMSE. Based on the sensitivity analysis process, the Nash-Sutcliffe efficiency coefficient for the model was 0.88, while the root mean square error and correlation coefficient were 0.72 and 0.67, respectively. This suggests that the WEAP model is suitable for use on the lower basin of the Diyala River. [ABSTRACT FROM AUTHOR]