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首页> 外文期刊>Science of the total environment >Assessing N emissions in surface water at the national level: Comparison of country-wide vs. regionalized models
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Assessing N emissions in surface water at the national level: Comparison of country-wide vs. regionalized models

机译：在国家一级评估地表水中的N排放：全国模型与区域模型的比较

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Many countries are developing models to estimate N emissions in rivers as part of national-scale water quality assessments. Generally, models are applied with national databases, while at the regional scale, more detailed databases are sometimes available. This paper discusses pros and cons of developing regionalized models versus applying countrywide models. A case study is used to support the discussion. The model used, called Nutting-N (NUTrient Transfer modelING-Nitrogen), relies on a statistical approach linking nitrogen sources and watershed land and river characteristics and aims to evaluate the risk of water bodies failing to reach quality objectives defined by national and federal policies. After calibration and evaluation at the national scale (France), the predictive quality of the model was compared with two regionalized models in a crystalline massif (Brittany, western France, 27,000 km~2) and in a sedimentary basin (Seine, Paris basin, 78,000 km~2), where detailed regional databases are available. The national-scale model provided robust predictions in most conditions encountered in France (efficiency = 0.69). Terrestrial retention was related mainly to specific runoff, and its median value was estimated at 49% of the N surplus, whereas median river retention represented 18% of incoming N discharge. Regionalizing the model generally improved goodness-of-fit, as the root mean squared error was reduced by 6-24%. However, precision of parameter estimates degraded when too few monitoring basins were available or when variability in land and river characteristics was too low in the calibration dataset. Hence, regional-scale models should be advocated only after the trade-off between improvement of fit and degradation of parameter estimates is examined.
机译：许多国家正在开发模型，以估算河流中的N排放，作为国家规模水质评估的一部分。通常，模型与国家数据库一起使用，而在区域范围内，有时可以使用更详细的数据库。本文讨论了开发区域化模型与应用全国性模型的利弊。通过案例研究来支持讨论。使用的模型称为Nutting-N（NUTrient传递模型氮），该模型依赖于将氮源与流域土地和河流特征联系起来的统计方法，旨在评估水体未能达到国家和联邦政策所定义的质量目标的风险。经过国家级（法国）的校准和评估后，该模型的预测质量与两个区域模型（在法国西南部布列塔尼（Brittany），27,000 km〜2）和沉积盆地（塞纳河，巴黎盆地， 78,000 km〜2），那里有详细的区域数据库。在法国遇到的大多数情况下，国家级模型提供了可靠的预测（效率= 0.69）。陆地滞留主要与特定径流有关，其中位数估计为氮过剩的49％，而河流滞留中值占传入氮排放的18％。对模型进行区域划分通常会提高拟合优度，因为均方根误差减少了6-24％。但是，当可用的监测盆地太少或校准数据集中土地和河流特征的变化性太低时，参数估计的精度就会降低。因此，只有在研究了拟合度提高和参数估计值降低之间的权衡之后，才应提倡区域规模模型。

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