Estimation of Sediment Yield from Forest Roads Using SEDMODL

Abstract

Forest roads are constructed to access forest interior, wood extraction, conservation, afforestation  and  recreation. In forest road construction project, the trees and vegetation cover are removed and the soil structures are damaged. So, this causes  to  increase  sediment  production  in  forest  roads.  Increasing  of  the  yield  of sediment to river can damage water quality and aquatic ecosystem. Nowadays, there are  different  models  for  prediction  of  sediment  yield  and  this  can  be  helpful  for researchers to predict amount of sediment production in forest roads. In this research, SEDMODL  was  used  to  estimate  mean  of  annual  production  of  sediment  in  forest roads. A road with a length of 2260 meter which is located in compartments of 26, 27  and  32  of  Darabkola  forests  was  selected.  Then,  the  road  length,  road  width, production rate of sediment with considering geology condition, road surface factor, traffic factor, longitudinal slope, rainfall and sediment delivery factor were calculated using GIS maps, forest management plan handbook and field survey. Results showed that  the  production  rate  of  sediment  in  roads  was  77.514  ton  per  year  and  of  this value, 13.175 ton per year is imported to stream canals and rivers. Besides, the slope, distance  of  road  to  stream  canals  and  cut  slope  height  were  the  most  important factors in sediment production and delivery to stream canals.