1.   Purpose and objectives

     The SSARR model is a computerised watershed model plus a river and reservoir system model. It was developed to provide hydraulic simulations for system analyses for planning, design, and operation of water control works and for operational river forecasting.

2.   Description

     The model combines basin runoff techniques producing surface and subsurface flow with river and reservoir routing techniques. Special optional routines include snow accumulation and snowmelt, soil moisture, recommended for calibration.

3.   Input

     Daily data from multiple stations include observed precipitation and streamflow, plus forecasted precipitation, and maximum air temperature. Snow conditions, soil moisture, solar radiation forecast, etc. can either be input or allowed to be computed as functions of other parameters.

4.   Output

     Printed output can include all input data plus forecasted information including surface and subsurface flow, percentage runoff, snow water equivalent, snowline elevation, soil moisture, river stages and discharges, and reservoir inflows, outflows and storage volumes.

5.   Operational requirements and restrictions

     Installation and modification of the program needs professional personnel with specialised training. The program is written in FORTRAN and can be operated on a PC or UNIX computer system.

6.   Form of presentation

     User's manual is in English, although descriptive papers have been written in numerous languages. Both metric and English units can be used. The software and documentation are on CD.

7.   Operational experience

     Developed in 1966, the model has been successfully used in many locations around the world including North America, Central and South America, Europe, Southeast Asia, and the Indian peninsula under a variety of climatic conditions and basin sizes ranging from 5 to 444,000 sq km.

 8.  Originator and technical support

     US Army Corps of Engineers, North Pacific Division.

9.   Availability

     Software and documentation may be downloaded from www.nwd-wc.usace.army.mil or may be obtained from the HOMS National Reference Centre for USA.

10.  Conditions on use

     The Internet download is free; a standard handling fee is charged for the CD and documentation.