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根据渭河上游渭源等11县(区)国家基本(一般)气象站1971年-2008年逐月气温、降水量、相对湿度、日照时数、风速等资料及渭河上游北道水文站1971年-2008年径流量资料,利用Penman-monteith(98版)公式计算了该区域的潜在蒸散量。建立了评价该地区干湿状况的干燥指数模型,对该区域气候、潜在蒸散量、干湿指数的变化特征及其干湿状况对地表水资源的影响进行了分析。结果表明,自1971年以来,渭河上游区域气温以0.3℃/10a的线性趋势上升;降水量呈较明显的周期变化;潜在蒸散以23mm/10a的线性趋势增加。干燥指数总体呈上升趋势,变化阶段性较强。1971年-1984年以0.826/10a的线性趋势降低,1984年-1997年以0.852/10a的线性趋势升高。渭河干流区域干燥指数较高,干燥指数较高的区域,正好与甘肃河东区域气候上的“干舌”相对应。1971年-2008年径流量以2567×104m3/10a的线性趋势减少。1984年-1997年径流量以9023×104m3/10a的线性趋势减少。干燥指数持续增大比较明显地影响了上游地表水资源,在一定程度上对下游水资源安全造成威胁。
According to the monthly temperature, precipitation, relative humidity, sunshine hours, wind speed and other data of 11 basic counties (regions) in Weihe County, Weiyuan County, etc from the basic state (general) weather stations in the upper reaches of Weihe River from 1971 to 2008 and the upstream hydrological station of North Weihe River from 1971 to 2008 Annual runoff data were calculated using the Penman-monteith (98th edition) formula for potential evapotranspiration in the region. A dryness index model was established to evaluate the wet and dry conditions in this area. The characteristics of climate, potential evapotranspiration, wetting and drying index and the influence of wet and dry conditions on the surface water resources were analyzed. The results show that since 1971, the temperature in the upper reaches of the Weihe River has risen linearly with 0.3 ° C / 10a, and the precipitation has obvious periodic changes. The potential evapotranspiration has increased linearly with 23 mm / 10a. The overall dry index upward trend, strong changes in the stage. From 1971 to 1984, the linear trend of 0.826 / 10a decreased from 1984 to 1997, with a linear trend of 0.852 / 10a. The area with a higher dry index and higher dryness index in the mainstream of the Weihe River corresponds to the “dry tongue” on the climate in the eastern Hedong region of Gansu. From 1971 to 2008, the runoff decreased with the linear trend of 2567 × 104m3 / 10a. From 1984 to 1997, the runoff decreased with the linear trend of 9023 × 104m3 / 10a. The continuous increase of the drying index has obviously affected the upstream surface water resources, to a certain extent, threatening the safety of downstream water resources.