Relationship between Lakeshore Configuration and Siltation in the East Coast of the Northern Basin of Lake Biwa

Abstract

The relationship between lakeshore configuration and siltation was studied in the east coast of the northern basin of Lake Biwa. The data of a survey report on siltation in the littoral zone of the northern basin of Lake Biwa in Shiga Prefecture were used in the analysis. The organic matter and silt contents of the bottom sediment increased at the observation sites with a steep lakeshore slope of over 5%. Furthermore, siltation was enhanced at the offshore area of sites with a large slope change. Acoustic doppler current profilers (ADCP) were set at the observation sites with heavy siltation (Chomeiji) and light siltation (Echi River). The result showed that there was no difference in the average, maximum, and minimum flow speed between the two sites. However, the water flow at Chomeiji was oscillated, whereas at Echi River was unidirectional. Thus, it was suggested that the oscillating flow contributes to siltation by preventing the transport of fine particles such as silt into the offshore zone.