Historical and future trends in wetting and drying in 291 catchments across China

Abstract

Abstract. An increasingly uneven distribution of hydrometeorological factors related to climate change has been detected by global climate models (GCMs) in which the pattern of changes in water availability is commonly described by the phrase dry gets drier, wet gets wetter (DDWW). However, the DDWW pattern is dominated by oceanic areas; recent studies based on both observed and modelled data have failed to verify the DDWW pattern on land. This study confirms the existence of a new DDWW pattern in China after analysing the observed streamflow data from 291 Chinese catchments from 1956 to 2000, which reveal that the distribution of water resources has become increasingly uneven since the 1950s. This pattern can be more accurately described as drier regions are more likely to become drier, whereas wetter regions are more likely to become wetter. Based on a framework derived from the Budyko hypothesis, this study estimates runoff trends via observations of precipitation (P) and potential evapotranspiration (Ep) and predicts the future trends from 2001 to 2050 according to the projections of five GCMs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under three scenarios: RCP2.6, RCP4.5, and RCP8.5. The results show that this framework has a good performance for estimating runoff trends; such changes in P play the most significant role. Most areas of China, including more than 60 % of catchments, will experience water resource shortages under the projected climate changes. Despite the differences among the predicted results of the different models, the DDWW pattern does not hold in the projections regardless of the model used. Nevertheless, this conclusion remains tentative owing to the large uncertainties in the GCM outputs.

Drought Trend Analysis Based on the Standardized Precipitation–Evapotranspiration Index Using NASA’s Earth Exchange Global Daily Downscaled Projections, High Spatial Resolution Coupled Model Intercomparison Project Phase 5 Projections, and Assessment of Potential Impacts on China’s Crop Yield in the 21st Century

“…Precipitation and temperature in China are highly uneven in space and time. Previous research has found that mean precipitation decreases from southeast to northwest and has varied from 15 to over 2700 mm; and the mean temperature gradually decreases from south to north and has varied from −12 to 25 • C annually during 1961-2013 [10,11]. ( Figure 1) according to the topography and climate features following the National Assessment Report of Climate Change (National Report Committee, 2011) [64].…”

“…The historical spatiotemporal changes in wetting and drying areas over China have been investigated in previous research [7,[10][11][12][13]. Recently, a series of severe and extensive droughts in both 2006 and from 2009 to 2011 had swept across southwest China, resulting in tremendous economic losses and disruption of society [14].…”

An Improved Conceptual Model Quantifying the Effect of Climate Change and Anthropogenic Activities on Vegetation Change in Arid Regions

“…In previous studies, the watershed coupled water-energy balance equation (i.e., Budyko framework) relates evapotranspiration (E) with precipitation (P) and potential evapotranspiration (E 0 ) [82], and the equation includes a unique empirical parameter (n) related to vegetation [83]. Under the Budyko framework, many studies have analyzed the response of runoff to changing environment [84,85], yet based on the assumption that n is constant. In fact, the parameter n is changing with changing environment, and one of its main drivers is vegetation for a particular catchment [86], with a relationship of n = f L region , • • • between n and LAI [87].…”

Evaluating the impact of climate change on surface water resources in the upper Ganjiang River Basin, China

“…In contrast with the hydrological model, the water-balance method is identified as an alternative technique for its fewer model parameters and simpler calculation principles, and this approach has received tremendous attention in speculating the hydrological process under changing environments. Chen et al (2017) analyzed that .60% watersheds in China would confront with water deficiency and revealed the increasingly unbalanced distribution of water resources since the middle of the last century. Xing et al (2018) established an elasticity method to estimate future runoff in 35 catchments across China, and the Wang-Tang equation was the most reasonable water-balance equation to strengthen the prediction reliability.…”