Determining appropriate sub-watershed for different forest harvesting practices due to decrease the impact of flooding in Hyrcanian forest, northern Iran
کد مقاله : 1000-GIAN15
مقداد جورغلامی *
بلوار شهید چمران- نرسیده به میدان امام حسین- کد پستی 3158777878
چکیده مقاله:
The present study developed a method to consider the impact of flow-routing and time-sharing of sub-watersheds on outlets and for virtual forest harvesting operations on the outlet hydrograph and prioritization of forest logging to minimize flooding. To calibrate and validate the HEC-HMS model, the 25 yr flood return period for Kheyrud watershed was simulated using US Soil Conservation Service (SCS) software; then, 20 scenarios were considered by increasing the curve number for each virtual sub-hypothetical reform measure. Increased curves number for each sub watershed scenario was then implemented and the effect of different harvesting intensity in each sub-watershed on peak flow, outlet flood volume, and flood indicators were studied. F% predicts flooding of the watershed for a large exploited area and f indicates the impact of removal of the area. Results indicate that increasing the values for each sub-watershed curve has an exponential relationship with peak flow and flood outlet volume. It can be said that the threshold effect of the operation can be defined as the point at which increased exploitation will significantly influence the hydrological characteristics of the watershed. The results show that the value of this threshold varies according to the current sub-watersheds curve values. The threshold values of the sub-watersheds were: A1: 10%; A2: 14%; B1, B3, and A3: 16%; B2: 22%; A4: 30%. Implementation of different harvesting intensity scenarios indicated that A1 showed the greatest increase in the rate of flow and volume of flooding at the outlet. Alternations in flooding indicators F% and f using different harvesting intensity scenarios demonstrated that the A1 sub-watershed was the primary source of flooding hazard.
کلیدواژه ها:
Flooding hazard, Flow-routing, Forest hydrology, Time-sharing
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