Estimation of historical diffused recharge by tracer method in Hashtgerd plain

In this study, rainfall, runoff, groundwater and unsaturated water tracers sample were measured and analyzed. The average historical recharge through rainfall was calculated by interpreting of unsaturated water tracer in Hasthgerd plain. Four index profiles in Nazarabad, Jafarabad, Ghalechendar and Savojbolaq were dug for measuring of unsaturated water tracer concentration. Chloride concentrations in profiles soil samples were measured and interpreted to provide temporal estimates of recharge. Applying the chloride mass balance technique to the profiles soil water improved the boundary conditions associated with wet and dry climate in last times and the long-term mean recharge rate. Recharge rate means were estimated in profiles equal to 3.42, 3.53 6.42 and 7.44 (mm/yr) with rainfall chloride concentration average that was measured equal to 1.653 mm in Hashtgerd Plain. It was concluded that concentrated recharge (CR) supplies groundwater rapidly and significant more than diffused recharge (DR) by rainfall. Concentrated recharge is fulfilled by watershed grand works such as flood spreading structural measures.