Diurnal temperature fluctuations in a natural shallow water body

For many biological processes, the diurnal and annual behavior of the temperature of the water layer close to the water surface is very important. A simple one-dimensional model has been developed to simulate the temperature profile within small water bodies. An outdoor experiment has been conducted to estimate the model input parameters and to verify the model. The model simulations as well as the measurements show that during daytime a strong temperature stratification occurs in the water. Throughout the night, however, a well mixed layer develops growing from the water surface. Qualitatively, the model simulations agree with the measurement results. Quantitatively, however, it appears that for a small water body the one-dimensional model is too simple to simulate the temperature behavior of small water bodies accurately due to the spatial variability of the water body. It also appears that the temperature behavior is very sensitive to the extinction coefficient for short wave radiation which is closely related to the suspension of fine particles in the water. (C) 1997 Elsevier Science B.V.