Impacts of Climate Change on Blue and Green Water Resources in the Xiangjiang River Basin of the Yangtze River, China

Chang Feng,Liu Yang,Longfei Han

doi:10.3389/feart.2021.677191

Chang Feng, Liu Yang + Show 1 more

Open Access

https://doi.org/10.3389/feart.2021.677191

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Abstract

Green water resources, which are fundamental for plant growth and terrestrial ecosystem services, reflect precipitation that infiltrates into the unsaturated soil layer and returns to the atmosphere by plant transpiration and soil evaporation through the hydrological cycle. However, green water is usually ignored in water resource assessments, especially when considering future climate impacts, and green water modeling generally ignores the calibration of evapotranspiration (ET), which might have a considerable impact on green water resources. This study analyzes the spatiotemporal variations in blue and green water resources under historical and future climate change scenarios by applying a distributed hydrological model in the Xiangjiang River Basin (XRB) of the Yangtze River. An improved model calibration method based on remotely sensed MODIS ET data and observed discharge data is used, and the results show that the parallel parameter calibration method can increase the simulation accuracy of blue and green water while decreasing the output uncertainties. The coefficients (p-factor, r-factor, KGE, NSE, R2, and PBIAS) indicate that the blue and green water projections in the calibration and validation periods exhibit good performance. Blue and green water account for 51.9 and 48.1%, respectively, of all water resources in the historical climate scenario, while future blue and green water projections fluctuate to varying degrees under different future climate scenarios because of uncertainties. Blue water resources and green water storage in the XRB will decrease (5.3–21.8% and 8.8–19.7%, respectively), while green water flow will increase (5.9–14.7%). Even taking the 95% parameter prediction uncertainty (95 PPU) range into consideration, the future increasing trend of the predicted green water flow is deemed satisfactory. Therefore, incorporating green water into future water resource management is indispensable for the XRB. In general, this study provides a basis for future blue and green water assessments, and the general modeling framework can be applied to other regions with similar challenges.

Highlights

Many researchers have demonstrated in recent decades that climate change undoubtedly affects water resources worldwide (Haddeland et al, 2014; Reshmidevi et al, 2018)
Our results revealed the spatiotemporal distributions of blue and green water components and their uncertainties by simulating blue water (BW) resources, green water flow (GWF), and green water storage (GWS) in the context of climate change scenarios across the XRB:
This method could be effective for increasing the accuracy of blue and green water projections and for decreasing uncertainties in the studied basin, thereby providing more reliable estimates of the blue and green water components

Summary

Introduction

Many researchers have demonstrated in recent decades that climate change undoubtedly affects water resources worldwide (Haddeland et al, 2014; Reshmidevi et al, 2018). Assessing the impacts of climate change on water circulation and water resources at the basin scale is an important scientific issue (Sivapalan et al, 2011). In this context, it is more reasonable to link climate change and water resources according to water resource components, such as blue water and green water (Falkenmark and Rockström, 2010). It is more reasonable to link climate change and water resources according to water resource components, such as blue water and green water (Falkenmark and Rockström, 2010) The former has attracted widespread attention in many studies globally, the latter part needs further research in basin studies (Du et al, 2018). GWS refers to the SW content (Rockström et al, 2009) contained within the upper unsaturated soil layers and is derived from the infiltration of precipitation, which is a potential source of GWF (Glavan et al, 2013)

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