Impacts of abrupt temperature changes and warming hiatuses on water resources in the mid-and-low-latitude regions of the temperate continental-monsoon transition zone

Abstract

The global climate has undergone significant changes in the past 100 years, yet the extent to which abrupt temperature changes (ATCs) and warming hiatuses (WHs) impact runoff remains unclear. This study used the water balance model (WBM) to quantitatively assess the impacts of climate change and human activities on the measured runoff at representative runoff stations in the mid-and-low-latitude regions of the temperate continental-monsoon transition zone and further analysed the impacts of ATCs and WHs on the runoff at the representative stations. The results show the following. The runoff in the study area decreased overall, and the runoff at five stations located in the northeast and west was essentially not impacted by human activities, while the runoff at seven stations in the central part of the study area was significantly impacted by human activities, with a maximum degree of impact of more than 70%. The average temperature of each basin in the study area underwent a significant abrupt increase in the 1990s, which had a negative driving effect on runoff, reducing the runoff depth by 1.92–2.98 mm. The runoff between Hailar and Halaqin in the central part of the study area was significantly impacted by human activities, with a maximum degree of impact of more than 70%. After removing the impact of human activities, evaporation tended to decrease after the abrupt temperature increase; i.e., an “evaporation paradox” phenomenon occurred in these regions. During this period, the amount of precipitation was stable, and the ATC increased the runoff by 0.27–11.74 mm; the runoff changes at the Yingluoxia and Zhengyixia stations in the west were only slightly impacted by human activities, and the ATC significantly increased the runoff, which reached 13.86 mm. In 2007, the average temperature in some basins experienced a WH, which had a relatively small impact on the runoff and a negative driving effect, reducing the runoff by 0.13–5.19 mm. In terms of the contribution to runoff changes around the ATC and WH, the contribution of temperature to runoff changes after the ATC was slightly greater after than that before the ATC, while the contribution of temperature to runoff changes before and after the WH did not exhibit a clear variation pattern.