TURBIDITY INCREASE AND SEDIMENT RESUSPENSION IN LAKE KASUMIGAURA

Abstract

Considerable increases in turbidity and inorganic content in suspended solids were observed in Lake Kasumigaura during the last decade. Turbidity change in response to wind was analyzed to estimate the critical bottom shear stress and sediment resuspension rate; thus, a decrease in the stress and a rise in the rate were found to indicate a gradual attnuation in resistance to sediment resuspension. Turbidity and size-distribution of suspended particles were well simulated by a numerical model with these parameters, suggesting that the growth in sediment resupension resulted in turbidity increase during not only strong wind events but also calm periods. Then, the causes for the increased resuspenson were discussed roughly.