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绿洲土地利用对地下水矿化度时空变化影响模拟的关键在于如何在模型中体现土地利用的影响。论文在已建立对流-弥散溶质运移方程模拟地下水矿化度模型的基础上,把土地利用对地下水矿化度的影响视做地下水矿化度模型的源汇项,作为面上因子处理,并且把土地利用对地下水溶质变化的影响方式归纳为两点:入渗水把溶质带入地下水体和排泄地下水带走溶质。入渗水带入地下水的溶质数量就是从土壤剖面中淋洗到地下水的盐分,可以用试验确定一定入渗水量下土体脱盐率的方法计算。地下水排泄带走的溶质数量可以用排泄的地下水量与其矿化度积的方法计算。土地利用单元的土体含盐量和地下水矿化度用GIS和FEFLOW结合计算。入渗水带入地下水的溶质数量和排泄水带出地下水的溶质数量的和即为土地利用单元上的源汇量。把模拟结果与历史情况结合分析,证实预测的地下水矿化度变化趋势与历史上类似的土地利用引起的地下水矿化度结果是比较符合的,证明这种处理土地利用对地下水矿化度影响的原则和方法是可行的。而且说明目前的土地利用模式发展下去会导致地下水矿化度的上升,将导致土地盐渍化程度加重,从而影响到土地利用。
The key point to simulate the effect of oasis land use on the temporal and spatial variation of groundwater salinity lies in how to reflect the impact of land use in the model. On the basis of establishing the convective-disperse solute transport equation to simulate the groundwater salinity model, the paper treats the effect of land use on the salinity of groundwater as the source and sink term of the groundwater salinity model, and treats it as an in-plane factor The effects of land use on the change of groundwater solute are summarized as two points: infiltration water brings the solute into the groundwater body and excretes the groundwater and removes the solute. The amount of solute infiltrated into the groundwater is the amount of salt that has been rinsed into the groundwater from the soil profile. This can be calculated experimentally to determine the amount of soil desalination at a given infiltration rate. The amount of solute that is drained by groundwater can be calculated by the amount of groundwater drained and the product of its salinity. Land use unit soil salinity and groundwater salinity using GIS and FEFLOW combined calculation. The sum of the amount of solute infiltrated into groundwater and the amount of solute expelled from groundwater is the source volume on the land-use unit. Combining the simulation results with the historical data, it is proved that the trend of predicted groundwater salinity is in good agreement with the historical result of groundwater salinity caused by similar land use, which proves that the impact of land use on the salinity of groundwater Principles and methods are feasible. Moreover, it shows that the current land use pattern will lead to the increase of groundwater salinity, which will lead to the aggravation of land salinization and land use.