Relationship of water demand and supply for the protection forest system along Tarim Desert Highway

本文通过对塔里木沙漠公路防护林生态工程沿线地下水、土壤水环境的动态监测以及水资源量的估算，阐述了沙漠公路防护林的生态耗水过程；阐明了沙漠公路防护林体系的供需水平衡关系；该研究可以为防护林的正常生长、确保其防护功效的长期发挥和维持公路沿线生态环境稳定提供理论指导。主要结论研究如下： （1）沙漠公路沿线地下水总储量为：16.29×108m3；动态补给量在9671.0×104 m3~9931.0×104 m3范围；可开采资源量为：3859.08×104 m3。（2）开采试验水均衡分析证明：在按等于或大于需水量的抽水期间，动水位降到设计降深以前便相对稳定下来。经过719min的恢复，观测井内水位都能恢复到开采前的水平，说明试验区地下水资源处于均衡开采状态，其补给是能够得到保证的。（3）生长季内沙拐枣、柽柳、梭梭平均液流通量分别为：24.97 g/cm2?h、25.66g/cm2?h、16.16g/cm2?h。在塔克拉玛干沙漠，植物的蒸腾耗水量高于其它地方的测定结果，在水分供应充足的的条件下，荒漠植物并不会限制自身的蒸腾。（4）依据茎干液流通量和各年龄段单株植物基部截面积可以估算出不同林龄单株植物的日平均耗水量，然后根据防护林带总的植物株数、单株日耗水量和生长季天数，估算得出防护林带全年耗水量约为：389.12×104 t。（5）根据棵间蒸发试验与同期林带水面蒸发的关系估算林带全年土壤水分蒸发量为285×104m3，春夏秋冬各个季节林带土壤水分蒸发量占全年土壤水分蒸发量的比例分别为：16.52%、42.57%、35.24%、5.71%；生长季节内林地土壤水分蒸发总量为：263×104m3。（6）根据综合分析计算，地下水资源目前尚处于安全开采期，能够满足目前防护林生态工程用水量的需要，地下水开采量占可采资源量的17%左右，地下水处于安全开采期，是可以持续利用的。In this paper, the process of ecological water consumption of the desert highway was found out by dynamic monitoring underground water and its environment and estimating water resource amount along Tarim desert highway; finally constructed optimized irrigation system of the shelter-forest according to season, forest age and plant species, all of them provide theoretical guidance for normal growth and long efficiency of the shelter-forest and maintaining ecological environment stability along Tarim Desert Highway. The main results are below: (1)There has rich groundwater resources with total groundwater reserves 16.29×108 m3 along Desert Highway; Dynamic supplying groundwater reserves was between 9671.0×104 m3~9931.0×104 m3; The recoverable resources was 3859.08×104 m3. (2)We can see from the pumping test that dynamic water level relatively stabilized before get down to designed water drawdown during pumping water with ≥ water requirement; groundwater level may be able to revert back to the level before pumping water in every observation well in 719 minutes recovery time, That is to say, groundwater resources is balance exploitation basically and Its recharge capacity is guarantee. (3) Average sap flow density of Calligonum spp. , Chinese Tamarisk, Haloxylon ammodendron were respectively 24.97 g/cm2?h、25.66g/cm2?h、16.16g/cm2?h. Consumption water quantity of plant transpiration in Taklimakan desert was more than that of other areas; and desert plant transpiration was normal in spite of enough water supplies. (4) Mean daily water consumptions of various plants with different ages were calculated according to basal sectional areas of these plants; similarly, annual water consumption of the shelter-forest belt was about 389.12×104 t estimated with total plant number, daily water consumption of single plant, day of growth season of the shelter-forest belt. (5) Annual soil water evaporation amount of the shelter-forest belt was 285×104 m3 estimated according to the relationship of evaporation between plants and water surface evaporation of the forest belt, the forest belt soil water evaporation amounts in spring summer, august and winter respectively accounted for 16.52%、42.57%、35.24%、5.71% of total annual soil water evaporation amount; Soil water evaporation accumulative amount of the forest land was 263×104 m3. (6) We can find from above analyses that groundwater resource of Tarim Desert Highway is in safe exploration stage, which may satisfy the expect water need of The shelter-forest ecological project. The groundwater exploitation resources account for 17% of the recoverable resources from total groundwater resources