h. fahmi

Irrigation water quality is a critical aspect of agricultural production especially in terms of human health and the environmental aspects. The aim of this study was to estimate the level of surface runoff and groundwater pollution used in the production of agricultural products in the south of Tehran.

Sampling points included 14 points of surface water collection and disposal network and irrigation canals of agricultural lands and 7 points of underground wells in the 19th district of Tehran. The quality of the collected samples was analyzed for BOD, COD, nitrate, dissolved oxygen, electrical conductivity, ammonium, phosphate, turbidity, total hardness, pH and SAR using WQI software.

The results of Water Quality Index (WQI) showed that the level of surface water pollution in 14 sampling points was moderate to very bad. 57% of surface water points were highly polluted, 36% were relatively bad and 7% were moderate in terms of pollution index.

Agricultural products of areas 3, 4 and 5, if consumed, can endanger the health of consumers. Because the samples collected from these areas had the highest level of contamination. Therefore, in order to manage the challenges and future crises in these areas, within the framework of the environmental assessment program, management solutions are proposed in four groups: planning, implementation and monitoring, monitoring and review.

Land-surface models are widely used to simulate and predict the movement of momentum, energy, and matter between the biosphere and the atmosphere at local, regional and global scales. In this study, in order to evaluate the performance of this model in daily simulation of discharge in Gharesou watershed, using a spatial resolution of 0.125 degrees, satellite imagery and global databases to provide inputs for the model during the period from 01/01/2003 to 30/09/2008 for calibration and 01/01/1993 to 31/12/2003 for Validation. The results of the evaluation of the model's efficiency with the statistical indices of the Coefficient of Determination and Nash- Sutcliff efficiency coefficients were 0.75 and 0.73 in the calibration period, and 0.72 and 0.74, in the Validation period, indicate the high performance of the model. Generally, discharge simulated by the model, the trend of simulated and observed discharge is the same and due to the scales of VIC-3L and using of its in-watershed scales, it can be stated VIC-3L has a high performance.