Research on the Impacts of Warming Rate on Drought-flood in Huang-huai-hai River Basin of China

In this study, the sequential Mann-Kendall and Yamamoto test analysis are used to determine abrupt changes in temperature in Huang-huai-hai River Basin, while time series analysis via the traditional Mann-Kendall test and linear regression analysis for the different period is used to identify the basic trend of temperature. The results suggest that the temperature data can be divided into three periods: 1961-1985, 1986-1995 and 1996-2011. The slope of annual temperature during 1961-1985, 1986-1995 and 1996-2011 were -0.07°C(10yr)−1, 0.40°C(10yr)−1 and 0.04°C(10yr)−1 respectively. These three stages were defined as follows: Stage A (low temperature with no significant change), Stage B (sharp increase of temperature) and Stage C (stagnation of temperature increase). The drought/wet magnitude was assessed based on China-Z index and the area of drought/wet was calculated. The relationship between drought/wet area and temperature during the three stages was then analyzed and compared. The results showed that: during Stage A (low temperature with no significant change), flood area is comparatively big and drought area is small, but with acute interannual variation; during Stage B (sharp increase of temperature), flood area decreased but the drought area still increased; during Stage C (stagnation of temperature increase), flood area and drought area both had big interannual variation.