黑河流域不同生育期生态用水量变化分析

根据不同农作物、森林等植被的生物学特性,采用张掖和额济纳旗的气象资料,估算了3~10月各旬平均的作物生态需水量,分析了张掖人工绿洲近20 a来主要农作物的种植面积和灌溉面积、作物以及下游天然绿洲的生态需水量的生育期变化。结果表明,绿洲产业结构调整的结果是,经济作物种植面积有所增加,粮食作物种植面积下降了26.6%。通过对黑河流域中游人工绿洲和下游天然绿洲逐旬生态需水量的估算发现,人工绿洲的主要粮食作物小麦、玉米与下游天然绿洲的生态需水量在生育期上不同步,小麦、玉米需水高峰分别在6月中旬和8月中旬,用水量分别为6.14 mm/d和8.6 mm/d;天然绿洲的需水高峰出现在8月下旬,为8 mm/d。张掖人工绿洲的区域平均生态需水量高峰在6月中旬,为6.37 mm/d,天然绿洲的需水高峰在8月下旬,区域最大需水量为6.06mm/d。对于整个流域,最大需水量高峰在6月中下旬,为6.03 mm/d。中游人工绿洲与下游天然绿洲生态用水的时间差,为水资源的合理调配提供科学依据。

Analysis on variations of ecological water demand in growth period in Heihe valley

Based on the biological characters of different vegetations,the ecological water demand of crops in every 10 days from March to October was estimated,and the variations of the planting area of crops,the irrigation area and the water demand of croplands and natural oasis in recent 20 years were analyzed,by using the meteorological data of Zhangye and Ejinaqi observatories.The results showed that the area of cash crops was increased while that of grain crops was dropped by 26.6%,as a result of industry structure adjustment in the oasis region.There were differences of the apex of water demand among wheat,corn and forests,i.e.,their apex time was the middle ten days of June,the middle ten days of August and the last ten days of August,and the apex quantity of was 6.14mm,8.6 mm and 8.0 mm respectively.The apex time and amount of regional average ecological water demand in the artificial oasis was the middle ten days of June and 6.37 mm/d,and that in the natural oasis was the last ten days of August and 6.06 mm/d.As for the whole Heihe valley,the apex time of water demand was the middle and last ten days of June,and the apex amount was 6.03 mm/d.The time discrepancy of water demand between the artificial oasis in the middle reaches and the natural oasis in the lower reaches of Heihe valley provides the basis for reasonable distribution of water resource.