Abstract
Understanding historical trends in temperature, precipitation, and runoff is important but incomplete for developing adaptive measures to climate change to sustain fragile ecosystems in cold and arid regions, including the Balagaer River watershed on the Mongolian Plateau of northeast China. The objective of this study was to detect such trends in this watershed from 1959 to 2017. The detection was accomplished using a Mann-Kendall sudden change approach at annual and seasonal time scales. The results indicated that the abrupt changes in temperature preceded that in either runoff or precipitation; these abrupt changes occurred between 1970 and 2004. Significant (α = 0.05) warming trends were found at the minimum temperatures in spring (0.041 °C a−1), summer (0.037 °C a−1), fall (0.027 °C a−1), and winter (0.031 °C a−1). In contrast, significant decreasing trends were found in the precipitation (−1.27 mm a−1) and runoff (−0.069 mm a−1) in the summer. Marginally increasing trends were found in the precipitation in spring (0.18 mm a−1) and fall (0.032 mm a−1), whereas an insignificant decreasing trend was found in the runoffs in these two seasons. Both precipitation and runoff in the wet season exhibited a significant decreasing trend, whereas in the dry season, they exhibited a marginally increasing trend. Sudden changes in spring runoff and sudden rises in temperature are the main causes of sudden changes in basin rainfall.
Highlights
The interactive relationships between hydrological and meteorological elements and the environment are dynamic [1,2,3], as evidenced by the fact that changes in temperature, precipitation, and runoff usually drive the evolution of ecosystems
The data had a complete record and good quality for the purposes of this study. Statistical analysis techniques, such as linear trend analysis, Mann-Kendall trend and mutation analysis, and the Spearman rank correlation coefficient were used [10,21,22,25] in this paper
The maximum annual precipitation (284.6 mm) occurred in July, which accounted for 86.2% of the total annual average precipitation
Summary
The interactive relationships between hydrological and meteorological elements and the environment are dynamic [1,2,3], as evidenced by the fact that changes in temperature, precipitation, and runoff usually drive the evolution of ecosystems. Investigations on the changing properties of temperature and precipitation and fluctuations in river runoff are of great importance in view of the significant impacts of climate variations and human activities on the hydrological cycle and ecological environment [4]. With global warming of more than approximately 1 ◦ C, the water-holding capacity of air increases by about 7%, which leads to increased water vapor in the atmosphere. This probably creates the biggest influence on precipitation [5]. During 1960–2010, the air temperature in the arid region of northwest China experience a significant rising trend (p < 0.001), at a rate of
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