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首页> 外文期刊>Lakes & Reservoirs >Modelling the impact of historical land uses on surface-water quality using groundwater flow and solute-transport models
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Modelling the impact of historical land uses on surface-water quality using groundwater flow and solute-transport models

机译：使用地下水流和溶质运移模型对历史土地利用对地表水质量的影响进行建模

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Groundwater age, and its influence on contemporary water chemistry, needs to be accurately described to quantify the temporally varying impacts of land use on water quality. The time lags between solute inputs at the land surface and impacts on stream chemistry can be an important factor for managing land use in regional watersheds. Our approach uses a modified groundwater flow code to simulate reverse groundwater flow, regional flow and the solute-transport model where a unit concentration of a conservative solute serves as a proxy for groundwater age. Solute-contour lines represent groundwater travel time, which can then be coupled with Geographic Information System analyses to examine the relationship between water quality and historical land-use patterns. The reverse flow and solute modelling produced a reasonable distribution of groundwater travel times across the watershed, given the hydrology of the system. These groundwater flow paths would be unexpected if surface topography or even surface hydrology were used to predict groundwater movement. Approximately 70% of the watershed has a groundwater lag of≤30 years. When the temporal lags for individual drainage areas within the watershed are compared, flush times vary dramatically. This variability is related both to the size of the sourceshed and its geology. The influence of a particular land use on stream chemistry changes depending on the time scale considered, and also depending on the sourceshed in question as a result of landscape diversity. The results suggest that land-use management practices to reduce solute loading to a watershed might not result in water-quality improvements for many years, especially if implemented on land far from streams. The influence of long groundwater flow paths that integrate past and current land uses must be considered in the interpretation of land-use effects on surface-water quality.
机译：需要准确描述地下水年龄及其对当代水化学的影响，以量化土地利用对水质的时间变化影响。陆地表面溶质输入之间的时间差与对河流化学的影响可能是管理区域流域土地使用的重要因素。我们的方法使用修改后的地下水流代码来模拟地下水的反向流，区域流和溶质运移模型，其中保守性溶质的单位浓度可作为地下水年龄的代表。溶质轮廓线代表地下水的传播时间，然后可以与地理信息系统分析结合使用，以检验水质与历史土地利用模式之间的关系。在给定系统水文条件的情况下，逆流和溶质模型可以在整个流域内合理分配地下水的传播时间。如果使用地表地形甚至地表水文学来预测地下水运动，那么这些地下水流动路径将是出乎意料的。流域约有70％的地下水滞后≤30年。当比较流域内各个排水区域的时间滞后时，冲洗时间变化很大。这种可变性既与源棚的大小有关，又与地质有关。特定土地利用对河流化学的影响取决于所考虑的时间尺度，也取决于景观多样性导致的有关源地。结果表明，减少流域溶质负荷的土地利用管理实践可能不会导致多年来水质的改善，尤其是在远离河流的土地上实施时。在解释土地利用对地表水质量的影响时，必须考虑将过去和当前土地利用结合在一起的长地下水流路径的影响。

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