Enhancement and Redevelopment of the Regional Lake Water Quality Model with Applications

Abstract

Water quality is a serious issue in most of the world in the 21st century. Many lakes are impaired with Harmful Algal Blooms (HABs). To provide better lake management and restoration, modeling of lakes is of utmost importance. MINLAKE is a very reliable water quality simulation tool that simulates water temperature and DO in all types of lakes. However, this model cannot portray the overall nutrient and phytoplankton scenario of the lake which is important to identify the condition of the lake. To capture these fluctuations, a daily model MINLAKE2020 is developed based on a one-dimensional, deterministic daily-time-step water quality model “MINLAKE2012”. MINLAKE2020 simulates chlorophyll-a, phosphorus, biochemical oxygen demand on a daily time step in addition to water temperature and dissolved oxygen simulation. Some of the model parameters were calibrated for six Minnesota lakes which include two shallow lakes, two medium-depth lakes, and two deep lakes. The accuracy of the model was assessed by comparing the chlorophyll-a, phosphorus, and dissolved oxygen with the observed ones at the study lakes. The overall results from the model are satisfactory for all lakes. This model can be successfully used to simulate water quality for all types of lakes. The long-term goal of developing MINLAKE2020 is to include/integrate it with a watershed model, SWAT, a popular watershed water quality simulation model. SWAT simulates reservoirs in a watershed as well-mixed waterbodies, which can be a possible source of error for water quality simulations. MINLAKE2020 simulating nitrogen, inflow, and outflow was developed but should be fully tested before integrating it with the SWAT model.