Document Type : Research Article
Authors
1 Professor, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran
2 MSc in Watershed Management, Faculty of Natural Resources, Yazd University, Yazd, Iran
3 Associate Professor, Faculty of Natural Resources, Yazd University, Yazd, Iran
4 MSc in Watershed Management, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Iran
Abstract
Land use change is one of the most important factors affecting flow hydrology, erosion and sedimentatio that sometimes causes biodiversity destruction. The purpose of this research was evaluating runoff generation process in current land use condition in comparison with the optimized land use condition in Nahre Azam watershed of Shiraz. To do this, after preparating current and optimized (land use types regarding land capability) land use maps, the impacts of land use on runoff generation were evaluated for the two mentioned conditions using SCS hydrological model. The comparison of the land uses in these conditions indicates that agricultural areas do not show considerable differences. However, there is 8.1% decrease in urbanized area and 17.18% increase in range lands in optimal land use condition comparing to the current land use condition. The results also show that the overall value of CN in current land use condition is 82.6 while it is 75.2 in the optimized land use condition. The percentage of decrease in the runoff in the optimized land use condition over the current land use condition decreases as the return period is increased, and the highest decreas of runoff belongs to return periods of 2, 5, 10 and 25 years which is respectively 37.47%, 29.97%, 26.54%, and 23.32%. The results show that identification of the capability of the lands is very important and land use planning based on the land potential plays an important role in reducing flood damages and runoff loss.
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