Bahareh Jebalbarezi; Gholamreza Zehtabian; ِAli Tavili; Hassan Khosravi
Abstract
Investigation of the effect of plant community on limited water resources of deserts is an important issue in water resources management. Different species of Haloxylon are compatible with desert condition and can use groundwater resources due to deep roots and proper structural condition. The purpose ...
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Investigation of the effect of plant community on limited water resources of deserts is an important issue in water resources management. Different species of Haloxylon are compatible with desert condition and can use groundwater resources due to deep roots and proper structural condition. The purpose of this study was investigation of the effect of Haloxylon planted forests on groundwater resources in Jafarieh plain. For doing the study, at first the number of Haloxylon plants was determined in these forests using satellite images and JMicroVision software. Then using minimum water requirement of each plant, estimated with lysimeter, the number of surplus plants was determined based on their water requirement and rainfall of the region. Then groundwater level status was determined using GMS 8.3 software and MODFLOW model. The results showed that the number of Haloxylon plants in the study area was equal to 3746291 and the amount of groundwater evacuation by these plants was equal to 56.194 Mm3. The reduction of groundwater table was about 0.46 meter in the first study period (1992-2001) and 0.93 meter in the second study period (2002-2012) so that the reduction of groundwater level in the second study period was about 2 times bigger than the first study. This results showed that severe reduction of groundwater table has happened in recent decade because of planting Haloxylon. However the positive effects of these forests on reducing damages of dust storms should not be ignored.
Rasool Ghobadian; Zeynab Bahrami
Abstract
Increased exploitation of groundwater besides recent periods of drought caused a negative balance in Khezel aquifer located in Hamedan province, Iran. From 2000 to 2010, groundwater surface drop was estimated 5.8 meters. With regard to high potential of GMS in using GIS and careful stratification of ...
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Increased exploitation of groundwater besides recent periods of drought caused a negative balance in Khezel aquifer located in Hamedan province, Iran. From 2000 to 2010, groundwater surface drop was estimated 5.8 meters. With regard to high potential of GMS in using GIS and careful stratification of the aquifer, GMS was used in present study to investigate and predict the groundwater table fluctuations in Khezel aquifer. Thus, Quantitative modeling was performed using MODFLOW model. The model was calibrated (using trial and error method) in two conditions: steady state (in september 2009) and transient state (from October 2009 to July 2010). Also, the quantitative model validated for August 2010. The impact of groundwater artificial recharge (within 31 injection wells for 5 months from October to March) was evaluated by calibrated model. Results showed maximum rise of water level was 19 cm in April. Next, in the same flow simulation stress periods, qualitative modeling was carried out by MT3DMS model. Optimum values of longitudinal dispersion and distribution coefficient were achieved by trial and error method and the qualitative model was calibrated. Statistical results of qualitative modeling are as follow: R2=0.98, slope of regresion line (y=1.0079x), mean error (ME=4.56 ppm) and RMSE=3.36%. Finally, dispersion of point source pollution (leaching pit) was investigated as a scenario. The result indicated that the radius of influence of leaching pits varies from 150 to 200 m in different areas. In continue, in the same flow simulation stress periods , qualitative modeling was carried out by MT3DMS model. Optimimum valuse of longitudinal dispersion and distribution coefficient were achived By trial and error method and the qualitative model was calibrated. Statistical results of qualitative modelling including: R2=0.98, slope of regresion line (y=1.0079x), mean erroe(ME=4.56 ppm) and RMSE=3.36%. Finally, dispersion of point source pollution (leaching pit) was investigated as a scenario. The result indicated that, the radius impact of leaching pit varying from 150 to 200 m.