Natural- and Human-Induced Influences on Terrestrial Water Storage Change in Sichuan, Southwest China from 2003 to 2020

Abstract

A quantitative understanding of changes in water resources is crucial for local governments to enable timely decision-making to maintain water security. Here, we quantified natural-and human-induced influences on the terrestrial water storage change (TWSC) in Sichuan, Southwest China, with intensive water consumption and climate variability, based on the data from the Gravity Recovery and Climate Experiment (GRACE) and its Follow-on (GRACE-FO) during 2003–2020. We combined the TWSC estimates derived from six GRACE/GRACE-FO solutions based on the uncertainties of each solution estimated from the generalized three-cornered hat method. Metrics of correlation coefficient and contribution rate (CR) were used to evaluate the influence of precipitation, evapotranspiration, runoff, reservoir storage, and total water consumption on TWSC in the entire region and its five economic regions. The results showed that a significant improvement in the fused TWSC was found compared to those derived from a single model. The increase in regional water storage with a rate of 3.83 ± 0.54 mm/a was more influenced by natural factors (CR was 53.17%) compared to human influence (CR was 46.83%). Among the factors, the contribution of reservoir storage was the largest (CR was 42.32%) due to the rapid increase in hydropower stations, followed by precipitation (CR was 35.16%), evapotranspiration (CR was 15.86%), total water consumption (CR was 4.51%), and runoff (CR was 2.15%). Among the five economic regions, natural influence on Chengdu Plain was the highest (CR was 48.21%), while human influence in Northwest Sichuan was the largest (CR was 61.37%). The highest CR of reservoir storage to TWSC was in Northwest Sichuan (61.11%), while the highest CRs of precipitation (35.16%) and evapotranspiration (15.86%) were both in PanXi region. The results suggest that TWSC in Sichuan is affected by natural factors and intense human activities, in particular, the effect of reservoir storage on TWSC is very significant. Our study results can provide beneficial help for the management and assessment of regional water resources.

The Influence of Climate Change on Droughts and Floods in the Yangtze River Basin from 2003 to 2020

“…It may be due to the continuous hydropower development in the UY in recent decades. Cui et al [ 35 ] indicate that the contribution of reservoir water storage to TWSC in Sichuan (UY) reached 43.32%. And the area of Sichuan accounts for nearly 50% of the UY.…”

“…This difference is mainly due to human factors. According to statistics, the water storage capacity of reservoirs in Sichuan Province (UY) has increased sharply, from 12.241 billion cubic meters in 2009 to 52.908 billion cubic meters in 2020, an increase of nearly 5 times [ 35 ]. Therefore, the main factor that affects floods and droughts in the UY and MLY is PPT.…”

“…Among many human activities, reservoir water storage has the greatest influence on TWSC in the YRB, especially in the UY. Take Sichuan Province, the largest province in the UY, as an example, the contribution of reservoir water storage to TWSC is as high as 42.32% [ 35 ]. Although reservoir water storage can prevent floods and droughts, it also brings serious adverse effects to the regional TWSC.…”

The Drought Events over the Amazon River Basin from 2003 to 2020 Detected by GRACE/GRACE-FO and Swarm Satellites

“…Due to the discrepancies in the SH solutions from different institutions, it may lead to inconsistent results [43]. To improve the reliability of our results, we used the GTCH method to evaluate the uncertainties of TWSC results from six GRACE solutions.…”

“…The observations series can be decomposed into the long-term trend change term, acceleration term, seasonal change term (annual change and semi-annual change), and residual term. The expression is as follows [43]:…”