The multitude of data formats for storing river network, geometry, and flow data presents a challenge for the sharing of information both internally between software applications and externally between agencies. An analysis of existing software applications and data models used for one-dimensional hydraulic modelling of river systems was performed. The commonalities and differences between the model inputs were identified in order to determine the necessary characteristics of a common transfer language. A prototype transfer language was developed using Unified Modeling Language (UML) and implemented as an Extensible Markup Language (XML) schema. This prototype is intended to serve as a first step towards developing an international open standard to facilitate the sharing of hydraulic data. This work was performed in cooperation with the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) and the Open Geospatial Consortium/World Meteorological Organisation Hydrology Domain Working Group.