近50多年来澜沧江流域农业灌溉需水的时空变化

Variations of Agricultural Water Requirements in Lancang River Basin in Last 50 Years

利用澜沧江流域云南境内8个气象站1950s-2007年的逐月气象数据,现状作物种植、农业耕作、田间水分管理等资料,应用Mann-Kendall法和R/S分析法,探索50多年来流域区的干湿变化、农业灌溉定额转折变化趋势及分布规律。结果表明:年、季平均温度普遍地显著升高,降水量干季增加、湿季减少;大部分地区的参照作物腾发量ET0在年度及干、湿季都呈增加趋势,仅在流域中段大理、剑川、耿马的部分时段为减少,干湿指数大多数地区都是降低;水稻及农业综合灌溉需水定额从流域上游到下游逐渐呈减少、增-减并存到增加的趋势。气象因子、ET0、干湿指数、水稻灌溉及农业综合灌溉定额发生转折变异现象都集中在澜沧江中下段的耿马、思茅、景洪、勐腊等地,且时间系列的转折变异点在1960s-1990s的各个时期均有出现。水稻灌溉定额随纬度方向变化的相关系数为0.513,随海拔高程变化为0.610,最高值出现在维西,最低值为勐腊;农业综合灌溉定额受作物种植结构和水稻种植面积的影响较大,二者相关系数达到0.826,但其与纬度、海拔的变化规律不明显,最高值在大理,最低值在维西。灌溉定额在小范围内的多样性变化,表明在纵向岭谷特殊环境对地表水汽输送、气温和气流场分布等的"通道-阻隔"作用下,澜沧江河谷农业灌溉需水量时空变化的复杂性。

Weather data of 8 meteorologic stations in the Lancang River Basin from the 1950s to 2007 and current cropping pattern,field water moisture management,etc.,were collected and used to investigate changes in humidity and crop irrigation water requirements using Mann-Kendall and the Rescaled Range Analysis methods.The results show that in the whole basin,annual and dry-season average temperatures significantly increased,and dry-season rainfall increased while wet-season rainfall decreased.Evaportranspiration（ET 0） increased during both dry and wet seasons at all the stations except Dali,Jianchuan and Gengma,and the aridity-humidity index decreased at most stations.The turning points of weather factors,ET 0,the aridity-humidity index,paddy irrigation requirements and total agricultural water requirements occurred from the 1960s to the 1990s.The spatial changing tendency of paddy irrigation quota increased with the increase of altitude and latitude,and the coorelation coefficients are 0.513 and 0.610,respectively.The maximum value in Weixi,while the minimum in Mengla.