RESSASS - A software package to facilitate the measurement and prediction of reservoir volume changes due to sedimentation
RESSASS enables engineers to quantify reservoir storage volume reductions due to sedimentation, and the impact of reservoir operating polices on these losses.
Background
Sediment deposition in reservoirs is an inevitable and often serious problem in regions where rivers carry appreciable sediment loads. Sediment deposits progressively reduce the volume of water that can be stored, and in some cases has reduced the effective life of reservoirs to just a few years.

Reservoir operators and water resource planners need to determine the rates at which existing storage capacity is being lost They also need to predict the impact of future sedimentation on storage volumes, and the effect of reservoir operating policies in reducing sedimentation rates.

Surveys are expensive, and there is a need to minimise field survey activities while maintaining an acceptable accuracy in the volume predictions that are obtained. There is also a requirement for a rapid and convenient means of correcting and processing the survey data.

The software
RESSASS (REServoir Survey Analysis and Sedimentation Simulation) enables engineers to quantify reservoir storage volume reductions due to sedimentation, and the impact of reservoir operating polices on these losses. RESSASS caries out computations in a user friendly software package.

RESSASS will run on a 486 or Pentium PC running windows 3.1 (or later)

   What it covers
The RESSASS software package is a combination of three programmes:

· Volume analysis - A method for computing reservoir volumes from rangeline surveys that maximises the speed and accuracy of volume predictions. It uses the Stage Width Modification Method to compute water and sediment volumes, and contains powerful user friendly graphical facilities for data checking and editing. Stage volume curves and the distribution of sediment deposits through a reservoir are produced.
· Volume prediction - A simple method to predict the impact of future sedimentation on stage capacity curves, using empirical methods requiring minimal data input.
· Numerical model - A numerical model to simulate the impact of alternative operating policies or changed water and sediment inputs on future sedimentation.

Examples of applications of the software are given in a series of tutorials in the accompanying user manual.

Contributors
HR Wallingford Ltd, UK.

Intended users
The software is intended for use by engineers, surveyors or reservoir operational staff.

Engineers with a basic understanding of reservoir surveying and analysis can carry out volume analysis and volume prediction computations relatively simply. Users of the numerical model should ideally be familiar with the sediment transport concepts and numerical modelling.


For a copy of the software, including manuals, contact:
International Development Group, HR Wallingford Ltd, Howbery Park, Oxon, OX10 8BA, UK
Tel: +44 (0) 1491 835381, Fax: +44 (0) 1491 826352, E-mail: w5outputs@hrwallingford.co.uk