فهرست مطالب رسول پرهمت

Rising water demands and over-extraction of groundwater have caused critical problems in more than 50% of the aquifers in Iran. Simulating complex condition of such aquifers and selecting an appropriate management approach are required to compensate drawdown. Therefore, this study aimed to provide a management approach for the Ravansar-Sanjabi aquifer in Kermanshah using the MODFLOW model, an aquifer under a severe stress during last decades. After calibrating and evaluating the model, as well as providing a spatial distribution map for the actual drawdown during the period of 2007-2015, the aquifer is divided into four drawdown zones, including 0 to 5, 5 to 10, 10 to 20, and 20 to 45 meters, and then several options of combining scenarios were applied to compensate the drawdown in each of zones. The first scenario includes the condition of the last eight years of sources and sinks and recharge of the aquifer, which resulted in a7.2 m decline during the next eight years. In the second and third scenarios, with the effects of drought and wet conditions, the results showed that groundwater level would decline by 8.4 and 5.2 m, respectively. The results of the first three scenarios showed that the effect of climate fluctuations is not the main factor affecting the groundwater level decline. The results of the fourth scenario, with different combinations of 10% to 70% reduction in pumping rates, showed that the combination of 10% in zone1 and 20% in the other zones provides the best results in improving aquifer conditions.

Evaluation of infiltration and runoff in karstic areas is considerably important. These processes in karstic areas are more different from the other land coverages. Due to variation of factors affecting the infiltration and runoff in karstic areas, a specific formula cannot be set for these processes. In this study the amount of runoff and infiltration in a karstic catchment, named Delibajak in central Iran, were evaluated in both basin and plot scales. Precipitation and runoff components were continuously measured over the basin during research period and the runoff coefficient was estimated based on the collected data. Also, in plot scale, these components were evaluated on soil and rock coverages in 25 tests using sprinkler. Evaluated infiltration and runoff data in the basin-scale, show a very high infiltration capacity in Delibajak catchment, with very small runoff coefficients (1.5, 0.54 0.45 for events of 133, 130 and 95 millimeters of rain, respectively). Results of sprinkler data indicate a wide range of infiltration rate in Delibajak basin from almost zero to 40 percent.

Runoff coefficient and its threshold play an effective role in hydrological computation-specially to calculate the water balances and flood designs. Yet it seems that there are not specific equations to estimate these parameters. For this purpose، 25 field tests have been done in Delibajak karstic catchment in Sepidar region. This area is located in Kohgiluyeh and Boyer-Ahmad province. A rain simulator has used to study the runoff coefficient and its threshold. The results show that there is a wide range of infiltration capacity until the runoff starts. The range of infiltrated rain varies between 4 to more than 43 millimeter in 50 to 303. 5 millimeter per hour rains، respectively. Also another result shows that the crash limestone has the highest capacity of infiltration، so the 43 millimeter rain with 303. 5 millimeter per hour intensity does not have excess rainfall or runoff.