Modeling erosion and sediment delivery from unpaved roads in the north mountainous forest of Iran

Abstract

Forest road networks are usually a main source of sediment in forested watersheds. An understanding of sediment delivery from roads to streams is important to aid in mitigating the adverse impacts to the environment. In this study an empirical model based on the Washington road surface erosion model was employed to estimate the effects of unpaved roads on erosion rates in the north mountainous (Caspian) forest of Iran. The main expected advantages of the chosen model were the ability to deal with different environmental settings, and simulate the effects of road-related best management practices (BMPs). Data required for modeling were obtained either by using of a GIS-automated technique or through field-based measurement. The outputs of the model show estimated annual sediment yields from unpaved roads, and predict the impacts of road management on sediment yields. The results suggest that (1) nearly 298 t/year of sediment is produced from road erosion in the study forest; (2) \(\sim \)6 % of the sediment is delivered to the streams; (3) BMPs need to be employed in the Caspian forest for reducing sediment delivery to the streams. These results can be used as basic data to develop prudent long-term management plans for forest road construction.