Evaluate the effects of watershed management operations in water harvesting and collecting runoff in Dadabad Watershed

Rainwater collection using various techniques and methods in arid and semi-arid regions for supplying greater volumes of water for agriculture, drinking, and industries is called water harvesting (WH). In most cases, water harvesting is an irrigation method, with the difference that the user does not have the required time for using the water and has to somehow store water resulting from rainfall and use it when needed. This research intended to evaluate the effects of water storage ponds(Turkeynest) on water harvesting and on collection of runoff resulting from rainfalls in the Dadabad basin. Mapping and determining the volume of the structures and their numbers, status, and characteristics constituted as the first step of this research. The mathematical model HEC-HMS was then employed to estimate flood volumes. Results of simulations and comparison of the observed and simulated hydrographs indicated the model had the required efficiency for simulating the Dadabad basin and was very sensitive to the parameters of curve number and initial loss. The capability of the storage ponds in storing runoff was then determined through calculating their volumes. The behavior of floodwater for the various return periods was simulated to determine the response of the basin to design storms by applying the changes that had happened in the input part of the model. Results indicated the water storage ponds could collect and store more than 80 percent of the runoff resulting from rainfalls with return periods of 2 and 5 years. In return periods of 10, 25, 50 and 100 respectively, 63.4, 54.3, 38.8 and 28.6 percent of the runoff stored in the ponds and the remaining water removes from the basin from its outlet. In all, the water harvesting systems in the Dadabad basin could store 236,645 cubic meters of runoff.