ASSESMENT AND APPLICATION OF BEDLOAD TRANSPORT EQUATIONS IN A COSTA RICAN RIVER

We assess the applicability of twelve bedload transport relations in a tropical mountain river in Costa Rica. The equations are initially evaluated based on the range of input variables for which they were developed. After discriminating based on these criteria, a subset of equations is then used to estimate bedload transport in the Peñas Blancas River, Costa Rica. In the absence of bedload transport measurements, we validate the results of the sediment transport equations by conducting a sediment balance using the suspended sediment concentration data measured at a gaging station, and bathymetric measurements available for a reservoir located in the watershed. Our results show that the sediment transport equations of Schoklitsch (1962), Rickenmann (2001), and Recking (2013), which are not based on a critical shear stress, are currently applicable to the Peñas Blancas River. Results with the latter equation were found to reproduce observed transport rates when using the specific discharge as main variable as opposed to the one based on hydraulic radius. Interestingly, grain size was found to have the largest effect on transport rate predictions.