I take directly from an informative of Center
"The Global Runoff Data Centre (GRDC) of the World Meteorological Organization (WMO) would like to inform you about the publication of GRDC-Report 43r1:
Dornblut, I. and R. Atkinson: HY_Features : a geographic information model for the hydrology domain. Concepts of the HY_Features common hydrologic feature model. - GRDC - Report; 43r1. - Koblenz: Federal Institute of Hydrology (BfG), 2013.
"Hydrologic features are abstractions of complex real world hydrologic processes, and relate to everyday concepts such as rivers, lakes, catchments etc. Different models of hydrologic processes, and different scales of detail, lead to a variety of information models to describe hydrologic features, and to different and mostly incompatible sets of feature identifiers.
This document describes the concepts of the HY_FEATURES common hydrologic feature model, a conceptual model for hydrologic features independent from approximate geometric representations at different scales. This model allows common reference to both the specific semantics and individual identifiers of hydrologic features across scientific sub-disciplines in hydrology.
The HY_FEATURES model is intended to form the basis for standard practices for referencing hydrologic features. These practices would be policy under the auspices of the WMO Commission for Hydrology (WMO-CHy) and recommended for general use in the wider community. HY_FEATURES is designed as a set of interrelated Application Schemas using ISO 19103 Conceptual Schema Language and ISO 19109 General Feature Model. It is factored into relatively simple components that can be reviewed, tested and extended independently. "
The GRDC-Report 43r1 is available at http://doi.bafg.de/BfG/2013/GRDC_Report_43,1.pdf and at the GRDC Website http://www.bafg.de/GRDC/EN/02_srvcs/24_rprtsrs/reports_node.html. Questions regarding this document should be directed to the contributing authors.
The GRDC is acting under the auspices of the World Meteorological Organization (WMO) and is supported by WMO Resolutions 21 (Cg XII, 1995) and 25 (Cg XIII, 1999). Its primary task is to maintain, extend and promote a global database on river discharge aimed at supporting international organizations and programs by serving essential data and products to the international hydrologic and climate research and assessment community in their endeavour to better understand the Earth system. The GRDC was established at the German Federal Institute of Hydrology (BfG) in 1988. The National Hydrological and Meteorological Services of the 191 WMO Member states and territories are the principal data providers for the GRDC."