After collecting data first-hand from a lowland chalk stream site in Southern England, GIS techniques were used to create maps illustrating the conditions within the river in mid-February 2011.
Stream depth, water velocity and bed substrate were measured at regular intervals along the length of the sample length of stream and the values interpolated using GIS software to create a surface of continuous values. Combining the first-hand data with parameters obtained from literature, habitat suitability maps were produced to visualise the spatial distribution of suitable habitat for the salmonid species Salmo trutta (more commonly known as the brown trout). Some future plausible changes in depth, velocity and substrate in the stream as a result of a changing climate were applied and the consequent changes in available habitat for each life stage of Salmo trutta assessed. The study found that, under the hypothetical conditions modeled, habitat suitability for brown trout would be threatened and could lead to high stress exerted on populations in future- particularly worrying as brown trout are generally considered relatively adaptable species in English watercourses, and implications for other in-stream fauna under the same circumstances could be still more severe. The techniques used in this project could be applied to any watercourse and a multitude of riverine species given the appropriate parameters from literature.