First, as far as field observations are concerned, eddy covariance (EC) flux observations have been widely used around the world to analyze and validate model estimates, including ecosystem carbon fluxes [16; 17; 18], ET [19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29], and WUE [30; 31]. Second, more attention has been paid to carbon-water coupling. Previous research showed coupling of the carbon and water cycles to understand the interactions for GPP and ET and the management of water processes from the field scale [32; 33; 34] to the regional scale [35; 36; 37; 38; 39; 40; 41; 42]. For example, based on observations from 22 EC flux sites at the field scale, [PERSON] et al. [43] reported that annual WUE is related to annual precipitation, GPP, and growing season length, and found that the WUE of higher-product ecosystems (e.g., forests and coastal wetlands) was higher than that of lower-product ecosystems (e.g., grasslands and croplands). With the development of field observations and remote sensing technologies, regional-scale analyses and their associated results have prominently improved the perception and handling of biomass production, water consumption, and water products [44; 45]. For example, based on Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2011 over terrestrial ecosystems in China, [PERSON] et al. [44] reported a national mean WUE of 0.79 gC/kgH\({}_{2}\)O. [PERSON] et al. [45] found that WUE was reduced due to the effect of drought on carbon and water utilization and the related response of photosynthesis and transpiration using the 2000-2011 MODIS data. [PERSON] et al. [46] found that during the drought period, WUE in some high-yield forest areas in northeastern and southern China increased, while that in the northwestern and central parts of the country decreased. [PERSON] et al. [47] found that drought enhanced WUE in arid regions and reduced it in semi-arid and sub-humid regions in hydro-climatic conditions using global monthly 0.5\({}^{\circ}\) gridded WUE evaluations from 1982 to 2011. [PERSON] et al. [48] noted that ecosystem WUE was sensitive to abrupt changes, and its response to drought showed large differences in various regions and biomes with different hydrological climatic conditions. However, the carbon-water relationship (i.e., water-use efficiency) processes are complicated, and are attributed to differences in environmental responsiveness, as well as to human activities, for example, irrigation or fertilizer application, which often alter GPP and ET, ultimately affecting WUE [15]. Thirdly, most spatiotemporal variations and trends in WUE and the associated water use (ET) and product (GPP) are mainly used for regional and global analyses with coarse resolution (1000 m). Thus, these results cannot completely apply to fine spatiotemporal characterizations of WUE to improve the protection and management of cropland ecosystems for different cropland cover types at the plot and local scales. Therefore, to better quantify the temporal variations and spatial patterns of the carbon (GPP)constraint on ET, it is critical to obtain continuous ET and GPP data at a fine spatiotemporal resolution. The Heihe River Basin (HRB), one of the most vulnerable hydrological regions of Northwest China and the world, is located in a typical arid and semi-arid region [49; 50]. In recent years, as a result of the increasing use of irrigation in the middle reaches and the urgent ecological water demand downstream, water shortages and water-use conflicts have become more intense between the middle and lower reaches of the HRB. As the first step to solve these contradictions, it is necessary to conduct spatial full coverage and dynamic monitoring of the surface ET, GPP, and WUE with high spatiotemporal resolution in order to support water resource management and the formulation of green development approaches and sustainable development decisions in the HRB. Thus, estimations of ET and GPP with high spatiotemporal resolution are needed.