Author(s): Mario Morales-Hernandez; Javier Murillo; Pilar Garcia-Navarro
Linked Author(s): Pilar García-Navarro
Keywords: Water quality; River flow; Transient storage areas; Unsteady flow; Finite volumes
Abstract: Nutrient load to water in rivers has become a great concern in the industrialized countries as their concentration increased exponentially since the sixties, mainly due to the increased use of mineral fertilizers and phosphorus compounds. The impact of human activity on surface stream habitats has been extensively studied throughout the world, forming the basis for many stream restoration efforts mostly based on one-dimensional (1D) models that assume steady state and uniform cross-sectional parameters. That simplification is not always adequate to represent a real river or stream. The Ebro River (NE Spain) presents flooding episodes when snow melts in the Pyrenees. To avoid flooding in living areas, some storage areas outside the city are prepared to be flooded. A simplified example inspired in the mentioned river is presented. A benchmark river reach provided with three lateral floodplain areas connected through three regulated gates that allow water to flow in both senses is assumed. A concentration inlet function is introduced under different flooding scenarios. The objective of the solute regulation could be the reduction of the river pollutant at the outlet section, the maximization of the solutes in the inundation floodplain areas or the mitigation of sudden changes in the water temperature. Unsteady events over complex geometry including flooding areas require a 2D hydraulic model. The implementation of a predictive water quality model in a finite volume unsteady 2D shallow flow simulation model is proposed in this work. The coupled system of equations includes the 2D hydraulic model as well as the nitrate and ammonium transport equations. When solved, it provides information about the variables in time and space
Year: 2013