Understanding Uncertainties in Water Budget for Large Constructed Wetlands

Temporal water budget assessments are necessary for short- and long-term water resources management and operational planning. However, these estimates are subject to a variety of potential sources of error, some of which are not easily quantifiable. Several past water budget studies have focused on quantifying residual errors and improving the water budget balance using statistical methods. In the current study, a weighted mass balance equation, solvable by using mathematical programming models at different time scales, is proposed and investigated. The mathematical programming models employ mixed-integer, non-linear programming formulations and binary variables to estimate weights that can improve the water budget by reducing residual errors. The formulations developed were tested and evaluated for a large constructed wetland operated and managed by the South Florida Water Management District for nutrient control. Hydraulic and hydrologic data from the wetland were used to test the methodology proposed in the current study. Results suggest reduction in residual errors and identify variables that need improvement in measurements and estimation for accurate water budgeting.