Prediction of the arrival of peak nitrate concentrations at the water table at the regional scale in Great Britain
Prediction of the arrival of peak nitrate concentrations at the water table at the regional scale in Great Britain
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DOI：
10.1002/hyp.8164
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发表时间：
2012-01
影响因子：
3.2
通讯作者：
Lei Wang;Marianne Stuart;J. Bloomfield;A. S. Butcher;D. Gooddy;Andrew McKenzie;Melinda Lewis;A. T. Williams
中科院分区：
文献类型：
--
作者：
Lei Wang;Marianne Stuart;J. Bloomfield;A. S. Butcher;D. Gooddy;Andrew McKenzie;Melinda Lewis;A. T. Williams
一个简单的基于过程的方法来预测地下水中硝酸盐的区域尺度负荷在英国的GIS中实施。这将硝酸盐输入函数、不饱和带厚度和硝酸盐不饱和带移动的岩性依赖率联系起来，以估计硝酸盐到达地下水位的时间。硝酸盐输入函数是土体底部的荷载，并通过非饱和带孔隙水剖面进行了验证。非饱和带厚度使用地下水水位，地下水水位基于区域尺度观测，插值后的河流基准面填充。非饱和带移动速率的估计来自区域尺度水文地质填图。结果表明，对于许多含水层，硝酸盐峰值可能已经到达地下水位，但在非饱和带相对较厚的地方还没有达到。对于具有相似非饱和带速度的两个主要含水层，主要是低起伏的二叠-三叠系砂岩和白垩系，形成了显著的地形特征，结果形成了对比。对于约60%的白垩，峰值输入尚未达到地下水位，并将在未来60年内继续到达地下水位。该方法易于转移，并提供了一种稳健的方法来估计任何弥漫性保守污染物的峰值到达时间，其中输入函数可以在区域尺度上定义，只需要地下水深度和水文地质分类。该方法是可扩展的，因为如果有可用的附加信息，可以很容易地将其合并到模型方案中。英国地质调查局©NERC 2011。水文过程©2011 John Wiley & Sons， Ltd
A simple process‐based approach to predict regional‐scale loading of nitrate at the water table was implemented in a GIS for Great Britain. This links a nitrate input function, unsaturated zone thickness, and lithologically dependent rate of nitrate unsaturated zone travel to estimate arrival time of nitrate at the water table. The nitrate input function is the loading at the base of the soil and has been validated using unsaturated zone porewater profiles. The unsaturated zone thickness uses groundwater levels based on regional‐scale observations infilled by interpolated river base levels. Estimates of the rate of unsaturated zone travel are attributed from regional‐scale hydrogeological mapping. The results indicate that peak nitrate loading may have already arrived at the water table for many aquifers, but that it has not where the unsaturated zone is relatively thick There are contrasting outcomes for the two main aquifers which have similar unsaturated zone velocities, the predominantly low relief Permo‐Triassic sandstones, and the Chalk, which forms significant topographic features. For about 60% of the Chalk, the peak input has not yet reached the water table and will continue to arrive over the next 60 years. The methodology is readily transferable and provides a robust method for estimating peak arrival time for any diffuse conservative pollutant where an input function can be defined at a regional scale and requires only depth to groundwater and a hydrogeological classification. The methodology is extendable in that if additional information is available this can easily be incorporated into the model scheme. British Geology Survey © NERC 2011. Hydrological Process © 2011 John Wiley & Sons, Ltd