陕西渭北旱塬种植业结构调整的水资源问题及对策

Problems of Water Resources and the Measures for the Regulation of Planting Structure in the Weibei Rainfed Highland,Shaanxi Province

陕西渭北旱塬地处西北内陆黄土高原腹地 ,是陕西省小麦主产区 ,也是中低产区 ,该区属暖温带半湿润易旱区 ,年降水量 4 2 0mm～ 70 0mm ,降水时空分布不均且变率较大 ,与冬小麦的需水规律不相吻合 ,加之田间蒸发量大 ,使得田间水分相对不足 ,限制了渭北旱塬小麦产量的进一步提高。由于果树产量高、经济效益好 ,自 2 0世纪 80年代中后期以来 ,渭北旱塬农村种植业由传统的粮食生产转为大面积的栽种果树。但由于种植业结构的调整 ,农田大面积改种果树 ,势必加重区域水资源的供需矛盾 ,导致水分生态的新态势。在分析渭北旱塬作物种植业结构调整引起的水资源问题基础上 ,指出 :渭北旱塬种植业结构调整必须以水资源为约束。

Located in the hinterland of the Loess Plateau in northwest China,the Weibei Rainfed Highland with a total area of 3.0×10 4 km 2 is a main producing area of winter wheat in Shaanxi Province,is also a mesoyield and low-yield region,and the per unit area yield of winter wheat is about 1500 kg/hm 2. The highland belongs to a warm-temperate semi-humid area where droughts occur frequently,the annual precipitation varies in a range of 420～700 mm,the temporal and spatial distribution of precipitation is uneven and does oot accord with the requirement of irrigating winter wheat. Moreover,the evaporation here is high,the moisture in the wheat fields is deficient,and the increase of wheat yield in the Weibei Rainfed Highland is restricted. Since the 1908's,the partial traditional growing of cereals has been replaced by planting fruit trees in large areas in the Weibei Rainfed Highland because the fruit yield and its economic returns are high. The contradiction between the water consumption and the water resources in the highland becomes more serious due to the regulation of planting structure. In this paper,the existing problems in the utilization of water resources, which are caused by the regulation of planting structure in the highland,are analyzed. It is considered that the regulation of the planting structure must be based on the water resources in this region. Therefore,some measures are put forward,which are to scientifically and rationally utilize water resources,store rainwater,save water resources,and breed the drought-resistant varieties of crops.