Structural sediment connectivity as a tool in validating sediment fingerprinting results

Abstract

Sediment control in watersheds requires information about soil erosion and sediment yield hotspot areas. Sediment connectivity is an emerging concept contributing to this field and structural sediment connectivity is a concept derived from sediment connectivity. Determining structural sediment connectivity in a watershed can yield a comprehensive image of sediment management possibilities applicable at the watershed scale. However, in most studies, the validity of extracted sediment connectivity maps has not been evaluated holistically. The current study is, therefore, designed to determine a valid structural sediment connectivity map and to use it to validate findings of sediment fingerprinting of the Idelo watershed in Zanjan province, Iran. Digital elevation model (DEM), slope, vegetation cover, and flow accumulative layers have been used in compiling the structural sediment connectivity map. Field observations were made to calculate the field connectivity index. The results showed that the mean structural sediment connectivity index of the target watershed is −6.18. Moreover, areas in the downslope section near the outlet and the narrow strips around the watershed boundaries have moderate to high structural connectivity. The results of field validation showed there is an acceptable agreement between the field connectivity index and the structural connectivity map. Also, these results confirmed previous findings of sediment fingerprinting in the study area. Based on the findings of the current study, determining the structural sediment connectivity index is an efficient method to make management and conservation decisions and control erosion and sediment in the watershed.