The determination of water quality along a river drainage network is of paramount importance for many environmental applications. Whereas several codes have been proposed to deal with this problem along a single reach of a river, no simple solution has been proposed for a complex river network. In this contribution, a methodology is presented for preliminary screening of river water quality at the watershed-scale and at steady state. The solution process exploits the information contained within the watershed's space-filling drainage network (SFDN), that is automatically computed by processing the raster map of the watershed's elevations. To this end, a visiting algorithm for non-binary trees is coupled to a Newton-Raphson method that locally solves the system of nonlinear water-quality mass balances. We believe that the resulting framework will be especially valuable for initial screening analyses in data-poor watersheds. A free code called Q2T that implements the described methods is provided.

对于许多环境应用而言，确定沿河排水网络的水质至关重要。尽管已经提出了若干条代码来处理一条河流的单个问题，但是还没有为复杂的河网提出简单的解决方案。在这项贡献中，提出了一种用于在流域规模和稳定状态下初步筛选河流水质的方法。解决过程利用集水区的空间排水网络（SFDN）中包含的信息），这是通过处理分水岭高程的栅格图自动计算得出的。为此，将非二叉树的访问算法与Newton-Raphson方法耦合，该方法可以局部求解非线性水质质量平衡系统。我们认为，由此产生的框架对于数据贫乏的流域的初步筛选分析将特别有价值。提供了实现上述方法的称为Q2T的免费代码。