Determination of Evapotranspiration in SCM's Using a Weighing Lysimeter: An Experimental Approach

Current stormwater control measures (SCMs) often require significant land area in order to achieve the SCM goals of reduced peak outflows and water quality enhancement. Land area requirements can be reduced through more efficient technology gained by further understanding the water budgets associated with SCMs. For instance, evapotranspiration (ET) is a little understood portion of any SCM water budget, but may yield substantial volume reduction in a SCM when viewed from a longer term perspective. Research is currently being conducted at Villanova University to determine the ET occurring in a bioinfiltration basin, stormwater wetland, and green roof. This paper delineates the experimental setup to quantify ET in various SCMs. The experimental setup uses a weighing lysimeter, where the inflow, outflow, and infiltration are measured to determine the ET in three different SCMs. Additionally, preliminary experimental results are compared to potential ET as calculated by the Penman and Penman-Monteith equations.