Assessment of river recreation safety using spatial river recreational index by integration of hydrodynamic model and fuzzy logic

Abstract As the demand for recreational activities in rivers has increased, the assessment of the existing safety measures of these activities has become crucial to prevent accidents. Current safety measures have mainly focused on water quality factors, while the safety of in-water activities is also influenced by river hydraulic conditions. Hence, we proposed a spatial river recreational index (SRRI) that considers hydraulic parameters to evaluate the safety of recreational activities in rivers. Using a 3D hydrodynamic model, we reproduced the spatial distribution of hydraulic parameters under various discharge conditions to estimate the SRRI based on fuzzy logic. The application of the SRRI at the confluence of the Nakdong-Guemho River in South Korea revealed that each hydraulic parameter contributed differently to the safety according to discharge and morphological conditions. For instance, flow direction decreased safety in the near-field of the river confluence, while water depth played a significant role in the meandering reach of the Nakdong River. Flow velocity was the most critical factor for nonpowered activities, such as sailing and paddling/wading, under high-flow conditions. Sailing was found to be unsafe in the main flow zone and near-field of the river confluence due to its sensitivity to discharge change. In contrast, paddling/wading and leisure boats were less sensitive to discharge changes and could be partly allowed under high-flow conditions, except in the deep-water zone in the meandering reach. Therefore, SRRI is expected to help many users with safe recreational activities in rivers by providing spatial safety information based on various hydraulic conditions.