Estimation of water flux in urban area using eddy covariance measurements in Riverside, Southern California

Abstract:

Micrometeorological methods can direct measure the sensible and latent heat flux in specific sites and provide robust estimates of the evaporative fraction (EF), which is the fraction of available surface energy contained in latent heat. Across a vegetation coverage gradient in urban area, an empirical relationship is expected between EF and vegetation coverage, which provides the opportunity to quantify regional water flux. Here we deployed three eddy covariance (EC) systems to quantify the relationship between EF and vegetation coverage. First, two continuous systems were deployed at an industrial area with very low vegetation cover and another located in the orange orchid in Riverside, CA, to quantify the temporal dynamic of EF for the endpoints. Second, a mobile EC system was deployed to quantify the spatial distribution of EF across a gradient of vegetation coverage, during the summer time in Riverside, CA. These data showed the EF in high vegetation cover is 31.16±3.99%, but at the lower vegetation cover site EF is only 16.48±5.40%, which about 2 times lower in EF than the area with high vegetation cover. These results derived from the EC measurements provide essential data to quantify the temporal and spatial water fluxes in urban area and are needed to better understand and manage urban water use in response to drought.