On analysis of sediment sources toward proper characterization of hydro-geological hazard for mountain environments

Abstract

Event-induced sediment yield from mountain valley slopes to rivers may represent a problem for landscape safety if the total sediment volume supplied is larger than the transport capacity of the water courses, leading to riverbed aggradation and increased water levels. Multiple sediment sources are normally present in mountain basins; the former are characterized by different spatial and temporal scales, which makes a global analysis hardly possible. On the other hand, modeling of sediment yield furnishes the necessary boundary condition for that of sediment transport in rivers. In this study, several types of sediment sources were separately analyzed with reference to the Tartano basin, located in Northern Italy. A detailed analysis of the sediment volume from soil erosion and some preliminary analyses of a faulted valley were performed. The transport capacity of the major water courses was computed around the confluence among them, for comparison with the estimated yields. The analysis showed that not all the sediment sources contribute significantly to the solid volumes that must then be transported by the rivers. This enables simplified models to be used considering only the yields that are expected to represent a major load. It is hypothesized that such fi nding be valid for other basins, of course considering the specific features of each. Keywords hydro-geological risk, mountain basin, sediment transport, sediment yield Language: en