Complex response of runoff-precipitation ratio to the rising air temperature: the source area of the Yellow River, China

摘要

The impact of climate warming on the water cycle and water resources is an important issue in science and for sustainable socioeconomic development. The drainage area above Tangnaihai station is the source area of the Yellow River, which is located in the Qinghai-Tibet Plateau and yields 41.3 % of the river's total natural runoff. Thus, it is known as the "water tower of the Yellow River." Based on climate and hydrometric data from 1956 to 2008, the purpose of this study is to deal with the influence of climate wanning on the water cycle in this region and thereby to provide some knowledge for sustainable water resources management of the Yellow River. The statistical analysis shows basically no trend in annual precipitation, but a significant rising trend in air temperature. Hence, this area is ideal to study the response of the water cycle system to climate warming. We found nonlinear variations in annual runoff (Q_w) and the runoff-precipitation ratio (R_(rp)): they increased to a peak and then decreased. According to the response of R_(rp) to rising temperature, we established a three-stage descriptive model for the complex response of runoff generation to the rising air temperature. The mechanism of the complex response is explained based on the evidence of environmental changes previously reported in the study area, driven by rising temperatures.