黄河上游水电工程对局地气候的影响

本文阐述了黄河上游段水电工程概况，并以刘家峡和龙羊峡水库为主对库周各站建加前后各５年或１０年的气象资料进行了对比分析，揭示了水库对周围地区各气候因子影响程度。

INFLUFNCE OF WATER CONSERVANCY AND POWER PROJECTS ON LOCAL CLIMATE AT UPPER REACHE OF THE YELLOW RIVER

A survey of the water conservancy and power projects at the upper reaches of the yellow River is briefly introduced. The influence of Liujiaxia Reservior and Longyangxia Reservior on the local climate is studied by comparing the analyzed results of the meteorological data from the meteorological stations near the two reservoirs. The results are as follows. (1) After the reservoirs were built, the mean annual air temperatures and water temperatures go up, and the daily differences of air temperatures and water temperatures lower respectively at the areas near two reservoir and lower reache of the Yellow River due to the heat storage of the reservoirs. (2) The reservoir are relatively the cold sources in spring and summer and warm sources in autumn and winter, which make the water temperatures and air temperatures lower in spring and summer and go up in autumn and winter obviously at the area near two reservoirs areas and lower reaches. (3) After the reservoires were built,atmospheric layer is stablitated, with makes the convections, low-level cloud and thunderstorms decrease and sunshine duration increasc at the reservoir areas due to the enlargement of water area and the increase of heat capacity for ground surface. (4) After the reservoirs were built. the uneven ground surface at the reservoir areas is changed into smooth water surface, and the friction of ground surface is lowered. Thus, the direction of prevailing wind become stable, and wind speed increases obviously. (5) After the reservoirs were built, the relative humidity lowers in summer and increases in othcr seasons near Liujiaxia Reservoir, and it lowers all year round near Longyangxia Reservoir. Evaporation decease in winter half year and increases in summer half year near Liujiaxia Reservoir, it decreases in the first half year and increases in the second half year near Longyangxia Reservoir.