Evaluating the impacts of watershed management on runoff storage and peak flow in Gav-Darreh watershed, Kurdistan, Iran

Amini, A., et al., 2014. Arabian Journal of Geosciences

Original research (primary data)
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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.

Case studies

Basic information

  • Case ID: INT-034-1
  • Intervention type: Created habitats
  • Intervention description:

    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.

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Soil erosion  Positive 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."
    Freshwater flooding  Positive 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)
  • Approach implemented in the field: Yes
  • Specific location:

    Gav-Darreh watershed is located close to Sanandaj city of Kurdistan province, west of Iran, and corresponds with the Gheshlagh dam watershed

  • Country: Iran, Islamic Rep.
  • Habitat/Biome type: Created forest |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: Effectiveness description: change to: effectiveness compared to baseline, measure the variable before the intervention has been implemented and compare to measured variable afterwards. effectiveness of NbS vs alternative only with respect to flooding not erosion. for soil erosion: 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." therefore by stating improved bank stability and that soil particles were not being removed b/c plants were deformed rather than soil, code as positive AC & BT (coding notes) 5.27.2020 Similar to art-010, not coded for scenario modeling because - I wouldn't code this as scenario modelling because although they 'simulate pre- and post-management conditions in the watershed' these are based on field observations of the effects management had on the relevant parameters and real storm data that were used to calibrate the model essentially what all these studies have is actual data collected on how the intervention affected the ecosystem and based on this data, test using models what the effect on the climate impact then is. In that way they are analogous to the study from mainland china focusing on the effects of the GFG program which collect data on vegetation changes and then use models to calculate effects this change has on soil erosion (these don't actually have data for soil erosion, they use models to calculate it based on the relevant known parameters)
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Engineered approach(s)
  • Compare effectivness?: Yes
  • Compared to the non-NBS approach: More effective
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: No
  • Impacts for the ecosystem: Not reported
  • Ecosystem measures: n/a
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures: n/a
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: