Comparison of two methods for estimating sedimentation in shallow lakes

摘要

The most widespread method to measure sedimentation in surface waters is sediment trapping (HORN & HORN 1990). The physical outline, dimensions and mode of suspension vary greatly, making methods of sedimentation measurement difficult (BLOMQVIST & HAKANSON 1981). Sediment traps were originally used to measure settling flux of organic matter in deep lakes. Later the method was applied in shallow lakes (KOZERSKI 1994); however, in shallow lakes most of the settling matter is the resuspended sediment (EVANS 1994). Several methods can differentiate between net sedimentation and sedimentation after resuspension, but none yield satisfactory results (KOZERSKI & KLEE-BERG 1998). This problem prevails in Lake Balaton, Hungary, due to the large surface (592 km~2) to depth (average 3.2m) ratio and to the long fetch, which results in frequent resuspension events. Another method, high frequency online registration of suspended solids concentration of the water, allows estimating net sedimentation. The aim of the present study is to compare this method with sediment trapping.