Comparing Three Approaches to Estimating Optimum White Water Kayak Flows in Western Norway

Background: Modern water management strategies aim to assess the impact of water regulation alternatives on all relevant ecosystem services, including white water (WW) recreation. Therefore it is important to estimate the optimum kayak flow range for river reaches that are potentially relevant for WW kayaking. Methods: We used the grade V run of the Teigdalselva River as an example and compared the results of three different approaches: (i) a hydro-morphological analysis of kayak runs using public data sources; (ii) a citizen science method that is based on photos and videos of kayak-activities on the web; and, (iii) interviews with elite kayakers. Results: For the hydro-morphological analysis, we found that some optimal flow ranges for WW kayak could be estimated based on empirical regional regression as a function of the natural mean flow and the geomorphic run type. The interviewed kayakers suggested a wider range of optimal flows, in particular, higher maxima. The test of the citizen science approach provided flows that ranged in the middle of the estimates made by the two other approaches for prescribing optimum kayak flow ranges. Conclusions: We recommend a combination of different methods for water management studies that are related to flow requirements for white water kayak. Estimations based on the empirical regression functions should be always complemented by at least one other approach.