Recently, water and soil resource competition and environmental degradation due to inadequate management practices have been increased and pose difficult problems for resource managers. Numerous watershed practices currently being implemented for runoff storage and flood control purposes have improved hydrologic conditions in watersheds and enhanced the establishment of riparian vegetation. The assessment of proposed management options increases management efficiency. The purpose of this study is to assess the impact of watershed managements on runoff storage and peak flow, and determine the land use and cover dynamics that it has induced in Gav-Darreh watershed, Kurdistan, Iran. The watershed area is 6.27 km2 which has been subjected to non-structural and structural measures. The implemented management practices and its impact on land use and cover were assessed by integrating field observation and geographic information systems (GIS). The data were used to derive the volume of retained water and determine reduction in peak flow. The hydrology of the watershed was modeled using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model, and watershed changes were quantified through field work. Actual storms were used to calibrate and validate HEC-HMS rainfall-runoff model. The calibrated HEC-HMS model was used to simulate pre- and post-management conditions in the watershed. The results derived from field observation and HEC-HMS model showed that the practices had significant impacts on the runoff storage and peak flow reduction.
Intervention description: Afforestation... Gav- Darreh watershed requires the establishment of vegetation cover on the steepest hill slopes where cultivated agriculture was not practiced. Thus, a seedling becomes established in 43.4 ha as well. To preserve the biological treatments, there usually has been an attempt to exclude livestock for a period of time while seedlings become established (Lopes and Meyer 1993). In the study area, this has been accomplished using paid caretakers rather than fencing and has resulted in limited natural reestablishment of native grasses and shrubs within the plantations....in all an area of 184 ha in S1 and S2 sub-watersheds was brought under green cover to improve land cover. However, for quality, the vegetation was poorly established owing to lack of water and animal trampling. Therefore, the land with improved cover was found to be much less than the initial accomplishment.
|Climate change impacts
|Effect of Nbs on CCI
|no specific measure stated (although may have been measured through 'soil conservation service') but regardless it is stated in results "Vegetation took water from the soil, which increases the capacity for infiltration and improved bank stability by water withdrawal. The exposed stalks, stems, branches, and foliage provided resistance to the runoff, causing the flow to lose energy by deforming the plants rather than by removing soil particles."
|flow velocity, time to peak, rate of surface runoff, runoff storage based on watershed hydrological parameters such as curve number, concentration time, and lag time (authors do not properly define each of these parameters however so unclear how to link to the reported measures)
Gav-Darreh watershed is located close to Sanandaj city of Kurdistan province, west of Iran, and corresponds with the Gheshlagh dam watershed