Quantitative changes assessment of Myandarband groundwater resources due to irrigation and network of Gaveshan Dam in wet and dry Periods

In order to manage water resources, it is necessary to know the current situation of the resources and predict it in the future .In this research, in order to investigate the nutritional effects of irrigation and drainage network of Gaveshan Dam in wet and dry periods on underground water resources of Myandarband plain, after collecting geological, meteorological, hydrological and hydrogeological information, geophysical tests and exploratory boreholes, rainfall statistics and the level of the underground water level in the discharge wells and the construction of a conceptual model, simulation, calibration and verification of the underground water level were done using the GMS10.1 software. The results of the calibration of the model indicate a very good fit of the observed and calculated water level data of the model with R²=0.99. According to the recalibrated model, the effects of return water from the irrigation and drainage network of Gaveshan Dam in two periods, wet and dry, which were determined through the trails test, were predicted with the percentage of infiltrations of 10, 20 and 40% for the spring season of 2016. The results of the research clearly show the positive effect of the construction of irrigation and drainage network on the increase of the underground water level, as well as the difference of the positive effect in wet and dry conditions.