Prediction of the Surface Run off in Semirom Mehregerd Watershed Using ARIMA Model

By understanding the temporal and spatial variations of water resources in a region, the better management and planning of water resources and water consumptions can be done. Time series modeling, if used correctly, will lead to acceptable results in this regard. For this purpose, the monthly runoff time series for 28 years was prepared at the hydrometric stations of Mehregerd region and the presence of trend was studied using the Mann-Kendall method. Then, different patterns of ARIMA were fitted to the data using the univariate Box-Jenkins method, and the most suitable pattern for predicting the future years was chosen. The results indicated that runoff had a decreasing trend in all months and seasons. The role of increased water consumption in the process of decreased water resources of the area was investigated and it was observed that the water consumption in the region has significantly increased since 2006. The consumption level in this basin is estimated about 46 Mm3/year. The forecast of runoff by 2023 using ARIMA (0, 1, 0) * (0, 1, 1) was performed as the most suitable model and it was found that the surface water resources in the upcoming years would experience a significant decrease if the current trend of exploitation is continued.