Document Type : Research Paper
Authors
1
PhD student in Water Resources, Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran.
2
Associate Prof., Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran
3
Associate Prof, Agricultural and Natural Resources Research and Education Institute, Technical and Engineering Research Department, Hamedan, Iran.
10.22092/jwra.2026.371359.1100
Abstract
In the present study, the soil-water environment and the aquifer of the Hamedan-Bahar Plain were modeled and simulated for 2018-19 to 2022-23, utilizing a system dynamics approach within the Vensim software environment. The degree of fit between the measured and simulated groundwater level values was assessed through the calculation of statistical indices, specifically the root mean square error (RMSE), the normalized root mean square error (NRMSE), the Nash-Sutcliffe model efficiency coefficient (EF), and correlation coefficient (R²). The estimated values of these indices for the calibration period (2018-2021) were RMSE = 0.57, NRMSE = 0.02, EF=0.96, R² = 0.96 and PBIAS=-0.0056, while for the validation period (2021-2023), the values were RMSE= 0.45, NRMSE= 0.01, EF=0.99, R²= 0.99 and PBIAS=0.0054. These results indicate a high degree of accuracy in the model's simulation of groundwater levels. Initial investigations revealed that groundwater extraction exceeded the permitted limits. To evaluate the economic impacts of this over-extraction, an agricultural subsystem comprising of seven key crops (wheat, potato, alfalfa, barley, corn, vegetables, and summer crops) was integrated into the model. The actual performance and net profit derived from the sale of these strategic crops in the Hamedan-Bahar Plain were simulated. Ultimately, two irrigation scenarios were defined based on the water requirements of the crops and the constraints imposed by groundwater withdrawal limits. Consequently, the optimal cultivation pattern for the study area was proposed. The results indicated that the highest net profit for irrigated crops, based on actual conditions during the 2018-2019 amounted to 531,848, 538,363, and 504,579 M. Rials under the three irrigation modes actual conditions, water requirement, and harvest limitation, respectively. The implementation of irrigation practices aligned with crop water requirements not only sustained economic advantages but also minimized damage to the aquifer. This approach resulted in an increase in water levels by three meters relative to the current conditions and facilitated an annual water savings of 26.98 M.m3.
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