| Hehei River is China’s second largest inland river, upstream is the runoff producing of the entire basin, and is key guarantee to implement the western development strategy, the runoff and climate change of upstream has not only has directly influence optimal water resources allocation in midstream and downstream, but also affect the ecological environment. In recent years, there is shrinking natural vegetation and serious deterioration of grasslands in the upper reaches of Heihe River basin especially. and A significant decline in water conservation capacity, due to the impact of climate change and human activity. Upstream has few water output, Climate change may become main fact that impact runoff in upstream of Heihe basinBased on the measured data of the temperature, precipitation, evaporation and runoff of upstream in the Heihe river from 1981 to 2102, annual variation, decade Change of Climate, Mutations and correlation of climate facts and runoff were analyzed with several statistical methods in this paper. The results shows that :(1) Temperature. 1981-2012, which is 32 years, temperature tended to increase, and increasing at a rate of 0.48 ℃ increase per decade. In the 1990 s and the 21 st century, the temperature continues to rise,and the jump mutation occurred in 1990、2001、1999, the largest jump of 1.2 ℃; annual variation of temperature is large, temperature of all optional stations have appeared warming trend, and the trend of rising temperatures far exceeding the significance test level of 0.05; Relationship between temperature and runoff through the correlation coefficient show: Spring 3-5 :0.44,0.51,0.39 autumn 10-11: 0.43,0.47 and 0.05,the significant test was past. Relationship between summer and winter temperatures and runoff was not significant, and correlation 0f summer runoff and temperature was showed weak, 6-8: correlation coefficient-0.25,-0.11,-0.21 respectively.(2) Precipitation. 1981-2012, which is 32 years, precipitation tended to slightly increase in the rate of 4.43 mm / 10 a.Distribution of precipitation during the year is very uneven, rainfall concentrated in 5-9 months, and accounting for 77.1%-90% of the annual precipitation; rainfall has large regional differences, 80 s generally is flat water(positive anomaly), 90 s generally is flat water(negative anomaly), after 2000 generally is flat and enrich water widespread overabundant, except Zama Marsh, recreation, stations have emerged in precipitation increasing trend, except for stations of Zamashike 、Dayekou、Kangle. and the increased trend is far over significant test 0.05 level; Precipitation and runoff relations by correlation coefficient showed that: correlation of precipitation in the summer and the same period runoff and the annual runoff was significant and the correlation coefficients were 0.71,0.68, and by the significance test 0.01, second. In addition to winter, precipitation and runoff with the same period exhibited a significant correlation, which further illustrates the precipitation and runoff(except in winter) on the seasonal scale synchronization(3) Evaporation. 1981-2012, which is 32 years, evaporation showed a declining trend in the rate of 1.73 mm / 10 a. Evaporation has large different in space and time, after 2000,evaperation change was evident, and evaporation is mainly reduce, and each station has mutation jump, jumping mutations are mostly concentrated in 1987 and 2000; Evaporation and runoff relations by correlation coefficient showed that: almost all the value of evaporation and runoff coefficient was negative, indicating evaporation played a negative role about the increased of runoff, except for winter, spring, summer, autumn the correlation coefficient of evaporation and runoff of the same period were: 0.32,0.62,0.58, and by the 0.05 significance test, while evaporation in the winter and spring have some continuity and hysteresis in runoff. Evaporation in the summer have the strongest runoff.for temperature, precipitation and evaporation of Heihe upstream areas. rainfall make the maximum contribution to the runoff, and evaporation ranked the second, a minimum contribution of temperature, rainfall is the main fact of affecting runoff. Slightly increase runoff in the upper reaches of the Heihe River is mainly due to a increase of rainfall in summer and a decrease of evaporation in spring and summer.(4) Runoff. runoff has increased. And the runoff distribution of the year is uneven, the annual runoff distribution concentrated in the flood season(May to October), a large proportion of runoff accounts for five months; flow increases trend is clearly at stations of Yingluoxia、 Qilian, jump mutation of Yingluoxia、Qilian occurred in 2004 and 1998 respectively, and flow increased significantly; jump mutation of Zha ma shi ke occurred in 2006, and flow increased no significant.(5) Runoff forecast. The trunk and tributaries of Heihe upstream 2013-2020 average annual flow of the predicted value Show: water resource increase. 2013-2015 average flow of optional stations in the three-year has increased trend; and the risk of flooding in the upper reaches of Heihe is steady, increasing the risk of drought. |
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