Abstract
The variations of climate and water resources in the Buqtyrma River Basin (BRB), which is located at the cross-section of the Altai Mountains, Eurasian Steppe and Tian Shan Mountains, have a great significance for agriculture and ecosystems in the region. Changing climatic conditions will change the hydrological cycle in the whole basin. In this study, we examined the historical trends and change points of the climate and hydrological variables, the contributions of climate change and human activities to runoff changes, and the relative changes in the runoff to the precipitation and potential evapotranspiration from 1950 to 2015 by using the Mann–Kendall trend test, Pettitt test, double cumulative curve and elasticities methods. In addition, a multi-model ensemble (MME) of the six general circulation models (GCMs) for two future periods (2036–2065 and 2071–2100) was assessed to estimate the spatio-temporal variations in precipitation and temperature under two representative concentration pathways (RCPs 4.5 and 8.5) scenarios. Our study detected that the runoff change-point occurred in 1982. The impacts induced by climate change on runoff change were as follows—70% in the upstream, 62.11% in the midstream and 15.34% in the downstream area. The impacts of human activity on runoff change were greater in the downstream area (84.66%) than in the upstream and midstream areas. A continuously increasing trend was indicated regarding average annual temperature under RCP 4.5 (from 0.37 to 0.33 °C/decade) and under RCP 8.5 (from 0.50 to 0.61 °C/decade) during two future periods. Additionally, an increasing trend in predicted precipitation was exhibited under RCP 4.5 (13.6% and 19.9%) and under RCP 8.5 (10.5% and 18.1%) during both future periods. The results of the relative runoff changes to the predicted precipitation and potential evapotranspiration were expected to increase during two future time periods under RCP 4.5 (18.53% and 25.40%) and under RCP 8.5 (8.91% and 13.38%) relative to the base period. The present work can provide a reference for the utilization and management of regional water resources and for ecological environment protection.
Highlights
The hydrological cycle is the driving factor for the physical and ecological processes on the Earth’s surface and has a huge impact on the survival of living organisms, human beings [1]
The results show that the lower part of the runoff change was the result of a combination of human interaction and climate change, which led to a positive effect on the runoff during 2006–2015 (Table 3)
We analyzed the differences in the temperature, precipitation and potential evapotranspiration series and calculated the runoff in three different elevation zones over the last 65 years to detect the variations and clarify the effects of climatic factors on runoff in Buqtyrma River Basin
Summary
The hydrological cycle is the driving factor for the physical and ecological processes on the Earth’s surface and has a huge impact on the survival of living organisms, human beings [1]. Because the hydrological cycle is the most important process on the Earth’s surface, runoff is closely related to each aspect of human activity—influencing agricultural irrigation, vegetation growth, land use and the quality and quantity of regional water use [2,3]. Changes in runoff may result in numerous environmental and hydrological problems, and this is especially crucial for water-limited areas, due to its determining role in regional economic growth and sustainable development [7]. The impact of various factors on runoff has been explored by previous studies, among which climate change and human activities have great significance. Wang et al analyzed the impact of climate variability and land use changes on runoff in Haihe River Basin, and their result showed that the forest has the most significant effect on runoff under a variable climate [11]. It is necessary to conduct a study for this confluence area which will be helpful to devise proper management strategies
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