The Mainstems data model implements the catchment and flowpath concepts from WaterML2 Part 3: Surface Hydrology Features (HY_Features) for persistent, cross-scale, identification of hydrologic features. The data model itself provides a focused and lightweight method to describe hydrologic networks with minimum but sufficient information. The design is intended to provide a model for data integration that can be used for network navigation and persistent hydrologic indexing (hydrographic addressing) functionality. Mainstems is designed to provide long-term stability with minimal maintenance requirements. The data model is not meant to advance hydrologic process representation or uniquely represent geomorphic characteristics. The principle assumption in Mainstems is that all drainage basins have one - and only one - headwater source area and a single mainstem that flows to a single outlet. Using these base feature types, (headwater, outlet, mainstem, and drainage basin) a nested set of drainage basins - and the associated dendritic network of mainstems - can be identified.

Mainstems数据模型实现了WaterML2第3部分：地表水文特征（HY_Features）中的汇水和流径概念，用于持久，跨尺度的水文特征识别。数据模型本身提供了一种集中的，轻量级的方法来描述具有最少但足够信息的水文网络。该设计旨在为数据集成提供一个模型，该模型可用于网络导航和持久性水文索引（水文寻址）功能。Mainstem旨在提供长期稳定性，而维护需求却最少。数据模型并非意在推进水文过程表示或唯一表示地貌特征。Mainstems中的基本假设是流域仅有一个头水源区和一个流向一个出口的单一主干。使用这些基本要素类型（上游水源，出口，主干和排水盆地），可以识别出一套嵌套的排水盆地-以及相关的主干树突状网络-。