Leana Weissberg

Leana Weissberg

ET by Method

2016 Urban Fellow

Research Topic: Water Resources

Faculty Advisor: Gaboury Benoit

Closing the Water Budget in an Experimental Urban Watershed: A Comparative Assessment of Methods for Estimating Evapotranspiration

Three methods for the measurement of evapotranspiration were tested for
quantitative agreement and ease of implementation at the Yale Experimental
Watershed on the Yale University campus. Methods were employed over the
course of the 2016 growing season (July – October, 2016) and included a
micrometeorological heat budget (Penman FAO 24 model), pan evaporation,
and soil moisture profiles. Penman FAO 24 and pan evaporation showed a
modest linear relationship in a multiple linear regression model accounting
for seasonality. However, inter-method variability, calculated as the root
mean square error, typically showed better agreement between pan
evaporation and soil moisture profiles. The use of a micrometeorological
heat budget was the most cost-effective and feasible method tested for the
measurement of urban evapotranspiration. Quantifying this crucial water
budget component in urban environments could incentivize urban design
that either reduces runoff or increases storage on the landscape, depending
on the requirements of the climate in question.