water Article Changes in Annual, Seasonal and Monthly Climate and Its Impacts on Runoff in the Hutuo River Basin, China Fei Xu 1,2, Yangwen Jia 1,*, Cunwen Niu 1, Jiajia Liu 1 and Chunfeng Hao 1 1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Water Resources Department, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;
[email protected] (F.X.);
[email protected] (C.N.);
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[email protected] (C.H.) 2 College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China * Correspondence:
[email protected]; Tel.: +86-10-6878-5616 Received: 25 January 2018; Accepted: 4 March 2018; Published: 6 March 2018 Abstract: Much attention has focused on the effects of precipitation (P) and temperature (T) changes on runoff (R); however, the impacts of other climatic factors need to be studied further. Moreover, the monthly and seasonal scale also need to be investigated. In this paper, we investigated the characteristics of changes in annual, seasonal, and monthly hydroclimatic variables, including R, P, T, sunshine duration (SD), relative humidity (RH), and wind speed (WS), between 1956 and 2015 in the Hutuo River basin (HTRB) using the nonparametric Mann-Kendall test, the cumulative anomaly test and the Precipitation-Runoff double cumulative curve method. Additionally, we assessed the contributions of climatic factors to changes in R in the HTRB between 1956 and 2015 using the climate elasticity method. The results indicated that significant downward trends were found for both annual and seasonal R, SD, RH, and WS.