Determination and assessment of phosphorus assimilation capacity applying Vollenweider approach for Hazar Lake

Abstract

Eutrophication is a natural process for natural lakes and dams and the hydraulic retention time of this process is directly related to whether the assimilation capacity is exceeded depending on the current water quality and pressures consists of point and diffuse sources. Exceeding assimilation capacity is accepted good for biological productivity however this situation cannot be desired for water resources any time and preventive actions need to be taken to sustain good water quality. The Vollenweider OECD Method is a widely used and accepted approach in order to calculate current phosphorus loads for phosphorus limiting lakes and dams. In addition to OECD method, rational method is used frequently in calculating the flowrates via surface run-off after precipitation. In this study, the calculation of the assimilation capacity for phosphorus limiting lakes and dams using the Vollenweider Method and rational method for calculation of flowrates were applied for Hazar Lake’s Basin example. When the apply proposed approach Hazar Lake’s TP loading might be increased 3.7 times a year for desired oligotrophic upper boundary condition and 13.7 times a year for mesotrophic state boundary condition.