西藏拉萨河谷灌溉供需水分析

以拉萨河下游河谷地区为研究对象,依据1989-2010年拉萨、墨竹工卡气象站气象资料和Landsat卫星遥感影像提取的主要作物(青稞、冬小麦及油菜)种植面积,计算不同典型年份研究区总灌溉需水量;结合拉萨水文站1989-2010年径流序列资料,分析区域灌溉用水的供需平衡.结果表明:拉萨河谷地区的种植模式以粮食作物为主,河谷区种植面积在1990-2010年间增长约8%,作物种植结构没有发生显著性的变化.农作物种植面积的增加引致灌溉需水量大幅度增加,2010年的灌溉需水量达到16亿m³,比1990年增长约35%,青稞为灌溉需求最大的作物.河流径流量及灌溉用水需求的季节性变化存在差异,每年4-6月灌溉供需关系较为紧张,灌溉量占径流量近10%~20%,每年12月至次年4月正值河流枯水季,尽管该期间灌溉需水量较低,但对水资源造成的压力也是不容忽视的.拉萨河谷地区水资源供需关系较为紧张.

Analysis of irrigation water demand and supply in the Lhasa River valley,Tibet

Investigations into the balanced relationship between irrigation water demand and supply would provide the theoretical basis for irrigation water management in the period of crop growing and water resources comprehensive development. Taking the lower Lhasa River valley as the study area, the total irrigation water requirement in different typical years was calculated according to the meteorological data from Lhasa and Mozhugongca meteorological station in 1989-2010 and the stable crop(highland barley, winter wheat and oilseed rape)planting area extracted from Landsat remote sensing images in the same period. The balance between the irrigation water demand and supply was analyzed based on the runoff sequence from 1989 to 2010 in Lhasa hydrological station and the irrigation water demand. The major results could be summarized as follows: the planting structure in the Lhasa River valley was dominated by food crops. The planting area increased by about 8% from 1990 to 2010 and there was no significant change in crop planting structure. The increase in crop acreage resulted in a significant increase in irrigation water demand. The irrigation water demand reached 1.6 billion cubic meters in 2010, up 35% over 1990. Highland barley is the crop with the greatest need for irrigation. Seasonal changes in river runoff and irrigation water demand were different. The relationship between irrigation demand and supply from April to June is relatively tight with the proportion of irrigation close to 10% to 20%. The river is in a dry season from December to April of each year. Despite the fact that the irrigation water requirement during the same period was relatively small, the pressure of irrigation water requirement on water resources cannot be ignored. The relationship between water supply and demand in the Lhasa River valley is relatively intense.