Groundwater contribution to river flows – using hydrograph separation, hydrological and hydrogeological models in a southern Quebec aquifer

摘要

Groundwater contribution to river flows, generally called base flows, often accounts foruda significant proportion of total flow rate, especially during the dry season. The objectiveudof this work is to test simple approaches requiring limited data to understandudgroundwater contribution to river flows. The Noire river basin in southern Quebec isudused as a case study. A lumped conceptual hydrological model (the MOHYSE model),uda groundwater flow model (MODFLOW) and hydrograph separation are used to provideudestimates of base flow for the study area. Results show that the methods are complementary.udHydrograph separation and the MOHYSE surface flow model provide similarudannual estimates for the groundwater contribution to river flow, but monthly base flowsudcan vary significantly between the two methods. Both methods have the advantage ofudbeing easily implemented. However, the distinction between aquifer contribution andudshallow subsurface contribution to base flow can only be made with a groundwater flowudmodel. The aquifer renewal rate estimated with the MODFLOW model for the NoireudRiver is 30% of the recharge estimated from base flow values. This is a significantlyuddifference which can be crucial for regional-scale water management.