Francisco Javier Sanz-Ronda

Modeling Water-Depth Distribution in Vertical-Slot Fishways under Uniform and Nonuniform Scenarios

AbstractVertical slot fishways are a type of fish pass of wide operating range that allow fish to move across obstacles in rivers. This study aims to model the performance of these structures, under uniform and nonuniform flow conditions, using discharge coefficients involving the downstream water level together with a logical algorithm. This will allow an explanation of the hydraulic behavior of this type of fishway under tailwater levels and flow variations on rivers. Two vertical slot fishways located in Duero River (North-Central Spain), subject to different hydraulic conditions, were studied for the validation of the proposed formulation. The observed values are consistent with the predicted results and, among others, demonstrate the importance of including variables that consider downstream water level. Consequently, the proposed discharge coefficients together with the algorithm have resulted in a method that enables the improvement of the performance of both existing and future vertical slot fishw...

Potamodromous brown trout movements in the North of the Iberian Peninsula: Modelling past, present and future based on continuous fishway monitoring

Brown trout uses river flow and thermal regimens as main stimuli for initiating and maintaining behavioral reactions such as migration and spawning. Therefore, anthropogenic alterations on these factors may have strong impacts on its populations. The aim of this work is to understand these consequences by assessing potamodromous brown trout movements in the past and present, and to model future responses. For this, brown trout movements in a fishway in the Marin River (Bidasoa basin, Northern Iberian Peninsula) have been monitored from 2008 to 2017. Random forest regression has been used to assess the influence of environmental variables on brown trout movements and to model the response under hypothetical climatic and hydrological scenarios. Results show that brown trout uses the fishway during the whole year, with more upstream movements during the spawning season. The model is able to predict accurately the timing and number of migrants. Its use under hypothetical climate change and flow regulation scenarios shows a delay in the migration time. Therefore, modelling using large time series can be a powerful tool to define management and conservation strategies and prepare compensation measures for future scenarios.