摘要：Spatial and temporal variations in the suspended sediment concentration (SSC) of supraglacial lakes in debris-covered areas were investigated on the Lirung Glacier in the Langtang region of central Nepal from May to Octorber 1996. Twenty-eight lakes of various sizes were observed on the glacier. SSC varied widely among the lakes from 0 to 364 mg l-1. Monthly observations showed that SSC of lakes also varied temporally, but there was no common trend in seasonality among the lakes. Measurement of the settling rate of suspended sediment in lake water indicated that SSC rapidly decreased from 37 mg l-1 to 4 mg l-1 within a day. Our results suggest that in lakes where SSC is high it is maintained mainly by a supply of high SSC meltwater to the lakes and that the low SSC of other lakes is due to little meltwater inflow to the lakes. Variations in SSC among lakes probably result from heterogeneous distribution of debris thickness and ice cliffs that affect the melting of glacial ice around the lakes. Seasonal changes in SSC are probably due to changing meteorological conditions and/or debris cover and ice cliffs around the lakes. The availability of lake turbidity would enable quicker and safer determination of the meltwater supply of lakes via remote-sensing techniques, and may be useful for elucidating the status of supraglacial lakes and glacier melting on debris-covered glaciers.
