Wind-Induced Sediment Resuspension and Export in Marsh Lake, Western Minnesota

摘要

Budgetary information and sediment resuspension dynamics were determined in MarshLake, located on the Minnesota River in western Minnesota. Resuspension and discharge of seston, particulate organic matter (POM), and total phosphorus (total P) were examined in Marsh Lake during June through September 1991 and May through September 1992. Based on a theoretical wave model, lakebed sediments at water sampling stations in Marsh Lake were susceptible to sediment resuspension at wind velocities as low as 10.5 km/h, depending on wind direction. Mean daily wind speeds were> 10 km/h on over 40 percent of the days during both study years, suggesting a strong potential for frequent sediment resuspension at these stations. Measured resuspension of seston, POM, and total P was much lower in Marsh Lake in 1991 than in 1992 as an apparent result of dense aquatic macrophyte beds that in 1991 covered nearly the entire lake. In 1992, when aquatic vegetation was absent from Marsh Lake, seston, POM, and total P concentrations increased substantially in the water column as a result of sediment resuspension. The results of these studies were used to critically evaluate management alternatives for habitat and water quality improvements in Marsh Lake.