ABSTRACT
Computer models for quantification of instream flow needs have been applied to several rivers in both Norway and abroad during the last decade. The main application of the models has been to estimate impacts of changes in river flow on conditions for fish, and as a tool in determining minimum flow regimes in regulated rivers. The model supports several hydraulic models and a variety of habitat-modelling options. For the comparison, three hydraulic models were applied to the problem. The one-dimensional hydraulic model used in this study was Hec-2. Hec-2 is a model for calculating water levels at steady-state conditions. The friction loss is calculated by use of Manning’s formula. Bathymetric data are collected in a random fashion with a special emphasis on covering the variation in the bottom structure. The data collection procedure is dependent of the river size.
