Spatiotemporal variability and driving factors of the shallow soil moisture in North China during the past 31 years

Evaluation of Terrestrial Water Storage and Flux in North China by Using GRACE Combined Gravity Field Solutions and Hydrometeorological Models

“…These data were subjected to quality control and validated to have good applicability in China [24,29]. The bilinear interpolation method, a two-dimensional spatial interpolation algorithm, is easy to implement with full consideration of the information of the neighboring points, therefore it was used here to downscale the original spatial resolution of 0.5 • × 0.5 • to 0.25 • × 0.25 • , in order to match the TWSA spatial map [40]. Evaporation is generally difficult to quantify accurately due to the limited measurements.…”

“…Pearson's correlation coefficient [40] (PR) and root mean squared error [28] (RMSE) are used to quantitatively assess the correlation and difference between the time series u i and v i , which are defined as follows:…”

“…However, Comparing Figure 9e with Figure 7e, we can see that TWF completely followed the changes in precipitation during the periods 2003 to 2007 and 2015 to 2016, indicating the key role of precipitation in controlling hydrological flux. However, from 2009 to 2013, the TWF ran counter to the change in precipitation, that is, precipitation increased while TWF decreased, which was induced by the enhanced evaporation and extensive water consumption by human activities [24,28,39,40,57], such as agriculture irrigation, industrial development and a rapidly growing population (analyzed in the subsequent Section 3.3). After adding the water diversion into the flux calculation (Figure 9f), TWF PERD remained virtually unchanged, implying that the effect of current water diversion was not obvious in alleviating the depletion of the vast water resources system of North China.…”

“…The water consumption constituents mainly include agricultural, industrial, domestic and ecological water, accounting for 63.61%, 15.19%, 17.41% and 3.79%, respectively. According to Feng et al [40], the agricultural land in North China reduced in the past decades with a rate of 7.16% from 2000 to 2020; hence, the agricultural water consumption decreased accordingly from 20.81 km 3 in 2003 to 18.74 km 3 in 2017. Additionally, industrial water consumption decreased to some extent.…”

“…Additionally, industrial water consumption decreased to some extent. However, the water saved by agriculture and industry was not stored but used for residents' lives and ecological construction due to the eye-popping expansion in population density [27,40], thus both domestic and ecological water consumption increased visibly. Therefore, it can be tentatively concluded that the decline of water flux is significantly related to human activities.…”