Seasonal stratification effects on risk quantification of contaminant spreading in a warm monomictic lake under different hydrodynamic conditions: a case study in Lake Constance, Germany

Seasonal stratification plays a significant role in contaminant spreading in a warm monomictic lake. If any accident related to pollutant spills occurs in a warm monomictic lake, different risk levels will result depending on the type of lake stratification, location of pollutant release, and hydrodynamic conditions. In this study, seasonal stratification effects on risk of contaminant spreading in the warm monomictic lake was investigated through simulating the distribution of tracers (contaminants) in Lake Constance under different hydrodynamic conditions when wind speed and wind direction were varied. All tracers were released at the lake bed around the drinking water intake of Bodensee‐Wasserversorgung near Sipplingen, Germany. The modelling results illustrated that the arrival time of tracers at the drinking water intake was dependent on seasonal stratification, wind direction, wind speed, distance of tracer away from the water intake and the depth where tracer was released. During winter stratification, tracers arrived at the intake earlier than that during summer stratification due to lake mixing in winter. The arrival concentration level of tracer also varied in a complex manner depending on seasonal stratification and hydrodynamic condition.