Impacts of 1.5 and 2 °C global warming on water availability and extreme hydrological events in Yiluo and Beijiang River catchments in China

Abstract

In the discussion of climate impacts, 1.5 and 2°C have become iconic values. This study examines the impacts of 1.5 and 2°C global warming on water availability, runoff seasonality, and extreme monthly and daily runoff in two catchments, using the semidistributed hydrological model Hydrologiska Byråns Vattenbalansavdelning-D, based on a combination of five global climate models (GCMs) and four representative concentration pathways (RCPs). Subsequently, quantitative assessments were made for projection uncertainties from GCMs and RCPs. The two catchments are the Yiluo River catchment (YLC) in northern China and the Beijiang River catchment (BJC) in southern China. The results indicate wetter flood seasons for YLC and warmer mean annual temperatures, drier springs, and more severe floods over long return periods (25 and 50 years) for both catchments. The change magnitude of most indicators is expected to be larger in YLC than in BJC. Mean annual temperatures in both catchments are expected to have smaller changes under the 1.5°C scenario than under the 2.0°C scenario. However, the change magnitude of the other hydrological variables is projected to be approximately equivalent for both catchments under both scenarios. Uncertainties of projected impacts from GCMs are generally larger than those from RCP scenarios, for both catchments and warming scenarios, with the exception of mean annual temperature of BJC. These findings indicate that effective measures are required to Climatic Change (2017) 145:145-158 DOI 10.1007/s10584-017-2072 Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10584-017-2072-3) contains supplementary material, which is available to authorized users.

Potential Threats from Variations of Hydrological Parameters to the Yellow River and Pearl River Basins in China over the Next 30 Years

“…Among various versions of the HBV, HBV-D has also been used to project changes in runoff or to define rainfall thresholds from small watersheds to large basins under different climatic and physiographic conditions in China [6,36,37]. In this study, the performance of the HBV-D model was evaluated with three widely used criteria: the Nash-Sutcliffe efficiency (Ens, range between minus infinity and 1) [38], coefficient of determination (R 2 , range between −1 and +1), and percent bias (PBLAS, range −100% to infinity).…”

“…In China, trends of decrease in annual runoff have been observed in most rivers in the northern areas since the 1950s [4]. Another recent study projected an increase in runoff in a catchment within the Yellow River Basin, but slight decreases were projected in the Yangtze River and Pearl River Basins under 1.5 and 2 • C global warming [5,6]. In addition, alterations of seasonal discharge have also been projected [2,6,7].…”

“…Another recent study projected an increase in runoff in a catchment within the Yellow River Basin, but slight decreases were projected in the Yangtze River and Pearl River Basins under 1.5 and 2 • C global warming [5,6]. In addition, alterations of seasonal discharge have also been projected [2,6,7]. In some basins, wet seasons are expected to become wetter and dry seasons drier in a world changing from 2 • C warming to 4 • C warming [8].…”

“…In some basins, wet seasons are expected to become wetter and dry seasons drier in a world changing from 2 • C warming to 4 • C warming [8]. River basins dominated by a monsoonal in annual runoff, seasonal runoff, and hydrological extremes during different time slices during the 21st century based on the IPCC AR5 [6,7,26]. However, few studies have focused on such changes during the short term (2021-2050), or on the impacts of climate change and population growth on base-scale water management.…”

“…In comparison with the original HBV, the HBV-D has an improved description of land cover characteristics and has more physically sound evapotranspiration schemes, making it more appropriate for investigations of regional hydrological impacts of global change in large basins [28]. The HBV-D has been used previously in many basins or catchments in China from small catchments to large basins such as the Yellow River and Pearl River basins with various climatic conditions [6,26,29]. In this study, the HBV-D model was used to simulate runoff.…”