Abstract
The dependence of water use efficiency (WUE) on changes in land cover types is crucial for understanding of long-term water availability and assessment of water-saving strategies. Investigating the impact of land cover types on ecosystem WUE has important implications when revealing water dynamics and land management. However, the determination of WUE and its dominant factors have always been subject to high data dependency and large calculation consumption within large basins. This paper proposes a framework for processing actual evapotranspiration (AET) and WUE calculation by coupling the Maximum Entropy Production (MEP) method with the Google Earth Engine (GEE). By employing the proposed framework and three data sources available in the GEE platform, results for actual ET and WUE from 2001 to 2020 were obtained in the Yellow River Basin (YRB). The results show that the proposed framework provides an acceptable estimation of actual ET via validation with Eddy Covariance flux sites in the YRB. The calculated WUE values varied greatly in different sub-basins within the YRB, indicating a cumulative growth rate of about 56% during the past 20 years. The dominant factor that led to these changes was the transition from Grasslands into other land-use types. Our results suggest that the use of the GEE platform coupled with the MEP method offers new possibilities for advancing understanding of water exchange and water resource management.
Highlights
Understanding ecosystem productivity responses to limited water resources is important worldwide, especially in water-constrained regions
The main objective of the present study is to propose a framework for processing actual ET and water use efficiency (WUE) calculation as well as analyzing spatial–temporal and tendency characteristics by coupling the Maximum Entropy Production (MEP) method and Google Earth Engine (GEE) to take advantage of the GEE platform and MEP theory for robust estimation of actual evapotranspiration (AET) and WUE
With ongoing changes in land cover, it has become important to investigate the impact of land cover changes on ecosystem WUE
Summary
Understanding ecosystem productivity responses to limited water resources is important worldwide, especially in water-constrained regions. Ecosystem water use efficiency (WUE) is defined as the ratio of gross primary productivity (GPP) to actual evapotranspiration (AET) and has long been used as an essential indicator of the water and carbon cycles [1,2]. By investigating ecosystem WUE and its spatial–temporal characteristics, different water resource management strategies can be designed by policymakers as well as by residents in different regions [3]. Several researchers have pointed out that land-use changes, precipitation, and temperature will likely alter ecosystem functions, as indicated by changes in the WUE [4,5,6,7,8].
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