Quantifying Spatial Variability of Evapotranspiration Flux Using a Distributed Network of LI-710 Sensors

Understanding the spatial variability of evapotranspiration (ET) is critical for managing water resources, predicting climate change impacts, and optimizing agricultural practices. The eddy covariance (EC) technique is a widely used method for measuring ET fluxes, providing high temporal resolution data. However, traditional single-point EC measurements may not adequately capture the spatial heterogeneity of ET in heterogeneous landscapes. To address this limitation, a system of distributed eddy covariance measurements has been developed. This system deploys multiple novel eddy covariance ET sensors (LI-710) across different land cover types and management practices within a landscape, enabling the assessment of spatial variability in ET fluxes. The distributed EC approach facilitates the collection of data that can be used to upscale point measurements to regional scales, improving the accuracy of ET estimates. This work presents an overview of the distributed EC system, including the ET sensor and Water Node, as well as their design, deployment, and data integration strategies. Results from field deployments demonstrate significant spatial variability in ET fluxes, underscoring the importance of considering spatial heterogeneity in ET studies. The findings highlight the potential of distributed EC measurements to enhance our understanding of water and energy fluxes in complex landscapes.