**4.1 Models developed by international research and consulting organizations**

However, reservoir/river system models are developed throughout the world. Three examples of the many non-U.S.-based modeling systems are cited as follows. The proprietary MIKE BASIN, WEAP, and OASIS software products were developed and are marketed by organizations that provide consulting services in applying the models. The developers and others have applied the models to reservoir/river systems throughout the world.

The Danish Hydraulic Institute (http://www.dhi.dk/) has developed a suite of models dealing with various aspects of hydraulics, hydrology, and water resources management. MIKE BASIN, the reservoir/river system component of the DHI family of software, integrates geographic information system capabilities with modeling river basin management. MIKE BASIN simulates multiple-purpose, multiple-reservoir systems based on a network formulation of nodes and branches. Time series of monthly inflows to the stream system are provided as input. Various options are provided for specifying reservoir operating rules and allocating water between water users.

The Water Evaluation and Planning (WEAP) System developed by the Stockholm Environmental Institute (http://www.weap21.org/) is a reservoir/river/use system water balance accounting model that allocates water from surface and groundwater sources to different types of demands. The modeling system is designed as a tool for maintaining water balance databases, generating water management scenarios, and performing policy analyses.

The Operational Analysis and Simulation of Integrated Systems (OASIS) model developed by HydroLogics, Inc. (http://www.hydrologics.net/) is based on linear programming. Reservoir operating rules are expressed as goals and constraints defined by the model-user using a patented scripting language that is similar to the Water Resources Engineering Simulation Language (WRESL) in the WRIMS-CALSIM model discussed next.
