ABSTRACT
Morphological characteristics are important parameters for the assessment of biological conditions in rivers. In particular the wetted width is one of the main physical parameters required in fish population models and for the definition of minimum flows. The paper presents results of a pilot study where information about the wetted width of 10 salmon rivers was obtained from publicly available aerial images. The rivers belonged to various geographic regions including the northern, central and southern part of Norway, with drainage areas between 88 and https://www.w3.org/1998/Math/MathML"> 6,257 k m 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429069246/b59e18fc-9e1d-4389-b000-a1069c1cd27e/content/eq13025.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> . At selected sites situated close to gauging stations, the wetted width was extracted for different discharges over reach lengths ranging between 200 and https://www.w3.org/1998/Math/MathML"> 2,500 m https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429069246/b59e18fc-9e1d-4389-b000-a1069c1cd27e/content/eq13026.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> . The results show that rivers with larger drainage areas tend to be wider than rivers with lower drainage areas, as it was published for other regions. The study revealed also a large variation of wetted width values within the investigated river reaches for a given discharge. The preliminary results suggest the possibility to describe wetted width based on hydraulic geometry coefficients and river type specific distribution functions. A much larger data set and the inclusion of low flow data are necessary for the derivation of statistically firm regression models.
