بررسي روند تغييرات نفوذ در سدهاي خاكي كوتاه از طريق بيلان مخزن

Investigation of infiltration trend change in reserve of small earth dam reservoir water balance

Regarding the importance of water in the life of human being and all other living beings, water deficiency has always been one of the big problems, especially in today society. Destruction of agriculture that will certainly result in economic problems, decreasing of familyʹs income, inoccupation, and finally immigration in many social societies. Luckily, outbreak of this problem in recent years, set on many experts and authorities, to pay more attention to theis problem. Respecting the problem, many efforts have been done. It includes construction of many short earth dams in various places of Kerman province, in order to recharge the aquifers. This research is conducted to study the efficiency of the dams, in recent years. The short earth dam in basin of Dareh Morid was studied. In order to determining the amount of daily water infiltration, balance equation is used. Daily evaporation was measured by a class A evaporation pan, lateral water leakage by constructing drainage canal, and the entered water by a spillway. For measuring the changes of water level in the reservoirs, some gages were installed in various parts of the reservoirs and daily changes were recorded. The amount of water infiltration into the aquifers was calculated from the difference between the water balance value and the change of water level in the reservoir, in two successive days. One of the problems encountered with such dams, is sedimentation that often decreases the amount of water infiltration, and alter the reservoir into the evaporation pond. One of the aims of this study will be studying the trend of changes in the amount of water infiltration, during the years of usage of the dam. Therefore the amounts of infiltrated water in selected dams were measured. 40.80 and 29.74 % of entered water was infiltrated, and the sedimentation was 43.144 and 77.418 m\ during the first and second years, respectively. The result indicates a 27% of decrease in water infiltration. Generally, the results of such studies help the administrating organizations to make better decisions in management of such dams.