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基于1982~2010年无定河流域的遥感影像、气象和土地利用数据,利用Priestley-Taylor公式计算出潜在蒸散发,进而得到干旱指数,将各气象因子与干旱指数差值进行叠加、逐象元相关分析,得到了无定河流域1982~2010年干旱指数的时空变化,并分析了气候和土地利用变化对干旱指数变化的影响。结果显示:(1)1982年、2010年干旱指数分别为2.01和2.13,总体趋势是趋干旱的;(2)干旱指数2.0以下的区域迅速减少,2.15以上的区域明显扩张;(3)干旱指数均呈现增加趋势,显著增加的区域集中于无定河流域中游和下游地区;(4)干旱指数变化同气温、水汽压、净辐射的变化成正相关,同降水量变化成负相关;(5)各种土地利用类型的干旱指数均呈现增长趋势,但是增长的幅度有所不同:林地>耕地>草地>建筑用地>水域>未利用地。(6)土地利用对干旱指数平均值的影响非常微弱,干旱指数的变化主要是由于气候变化导致的。
Based on the data of remote sensing images, meteorology and land use in the Wudinghe River basin from 1982 to 2010, the potential evapotranspiration was calculated by using the Priestley-Taylor formula to obtain the drought index. The differences between the meteorological factors and the drought index were superposed, Correlation analysis, the spatial and temporal variations of drought index in Wudinghe River Basin from 1982 to 2010 were obtained, and the influence of climate and land use change on the change of drought index was analyzed. The results showed that: (1) The drought indices of 1982 and 2010 were 2.01 and 2.13, respectively. The overall trend is toward drought; (2) the area below the drought index of 2.0 decreases rapidly and the area above 2.15 obviously expands; (3) The drought index (4) The change of drought index is positively correlated with the change of temperature, vapor pressure and net radiation, and negatively correlated with the change of precipitation; (5) Drought indices of all types of land use all showed an increasing tendency, but the growth range was different: forest land> arable land> grassland> construction land> water area> unused land. (6) The impact of land use on the average value of drought index is very weak, and the change of drought index is mainly caused by climate change.