Investigating the Effect of Crescent Catchment Systems on Runoff Collection and Management (Case study: Chadroyeh watershed, Fars)

This study investigates the effectiveness of precipitation storage operations, specifically crescent catchment systems, as an innovative and beneficial approach for rangeland restoration in arid and semi-arid regions of the country. The Chadaroyeh basin was selected as the study area, where four biological and biomechanical implementation programs were designed to manage and collect existing runoff. A total area of 93.23% of the Chadaroyeh watershed was designated for crescent catchment systems, incorporating seeding efforts. Additionally, three mortar rock weirs and fivedry weirs were strategically designed at the basin outlet, taking into account the annual inflow and the morphology of the main waterway. Two mortar rock weirs were constructed to control sedimentation and protect the soil upstream, while a sediment-retaining mortar rock weir was built at the outlet of the CH1 and CH2 sub-basins. The remaining five dry weirs were positioned around the aforementioned structures and in secondary and tertiary waterways. The SCS method was employed to estimate flood volumes for various return periods. Results from estimating the water intake capacity of the crescent catchments revealed that, by applying this method to 1796.76 ha of the Chadaroyeh watershed, a total of 2,454,515.79 m³ of surface runoff would be stored annually. When considering the flood volumes for different return periods, the total storage capacity of the three mortar rock structures was estimated to be 88,000 m³ for a 25-year return period, which accounts for only 11.9% of the total 25-year flood volume. However, these structures manage and store 75.3% and 25.8% of the total flood volume in the Chadaroyeh watershed for 2- and 5-year return periods, respectively