Long-Term Projection of Water Cycle Changes over China Using RegCM

Chen Lu,Xiuquan Wang,Tangnyu Song,Jianyun Zhang,Guohe Huang,Guoqing Wang

doi:10.3390/rs13193832

Abstract

The global water cycle is becoming more intense in a warming climate, leading to extreme rainstorms and floods. In addition, the delicate balance of precipitation, evapotranspiration, and runoff affects the variations in soil moisture, which is of vital importance to agriculture. A systematic examination of climate change impacts on these variables may help provide scientific foundations for the design of relevant adaptation and mitigation measures. In this study, long-term variations in the water cycle over China are explored using the Regional Climate Model system (RegCM) developed by the International Centre for Theoretical Physics. Model performance is validated through comparing the simulation results with remote sensing data and gridded observations. The results show that RegCM can reasonably capture the spatial and seasonal variations in three dominant variables for the water cycle (i.e., precipitation, evapotranspiration, and runoff). Long-term projections of these three variables are developed by driving RegCM with boundary conditions of the Geophysical Fluid Dynamics Laboratory Earth System Model under the Representative Concentration Pathways (RCPs). The results show that increased annual average precipitation and evapotranspiration can be found in most parts of the domain, while a smaller part of the domain is projected with increased runoff. Statistically significant increasing trends (at a significant level of 0.05) can be detected for annual precipitation and evapotranspiration, which are 0.02 and 0.01 mm/day per decade, respectively, under RCP4.5 and are both 0.03 mm/day per decade under RCP8.5. There is no significant trend in future annual runoff anomalies. The variations in the three variables mainly occur in the wet season, in which precipitation and evapotranspiration increase and runoff decreases. The projected changes in precipitation minus evapotranspiration are larger than those in runoff, implying a possible decrease in soil moisture.

Highlights

The global water cycle is becoming more intense in a warming climate; increases in precipitation, evapotranspiration, and runoff can be widely observed over the world [1,2].The resulting extreme rainstorms and heavy runoff can themselves lead to losses of life and damage to infrastructure, not to mention that they may cause flood events that are of more devastating consequences [3]
Validation results for near-surface temperature, precipitation, evapotranspiration, and runoff are shown in Figures 1–4, respectively
The columns of each figure are for different datasets

Summary

Introduction

The global water cycle is becoming more intense in a warming climate; increases in precipitation, evapotranspiration, and runoff can be widely observed over the world [1,2].The resulting extreme rainstorms and heavy runoff can themselves lead to losses of life and damage to infrastructure (such as urban drainage systems), not to mention that they may cause flood events that are of more devastating consequences [3]. The global water cycle is becoming more intense in a warming climate; increases in precipitation, evapotranspiration, and runoff can be widely observed over the world [1,2]. The delicate balance of the three variables deserves attention, as, according to the surface water budget equation dS/dt = P − E − R (where S denotes the subsurface storage of water substances, P is precipitation, E is evapotranspiration, and R is runoff) [2,4], they are closely associated with variations in soil moisture. In cases where meteorological drought occurs (i.e., long-term rainfall deficit), the interactions among the water cycle components could affect how the meteorological drought is propagated to hydrological drought A series of flood events that occurred in the Yangtze River Basin in 2020, in which the inflow to the Three Gorges Dam once reached

Objectives

Methods

Results

Conclusion