Integrated Catchment Modelling

Low-Flows in Deterministic Modelling: A Brief Review

“…Modelling of groundwater outflow on this basis may deal relatively well with small-scale (less than 100 m to 1 km) groundwater flow and simple aquifers during low-flow recession periods (e.g., Rocha et al, 2007). For complex aquifers or large scale models with "hydrologic response units" larger than one square kilometre the groundwater storage "tank" is in effect a non-physical "black box" that may bear little relation to actual groundwater flow or storage in the basin and may not allow adequate simulation of groundwaterfed baseflow (e.g., Wardlaw et al, 1994). Hydrology models with this type of "black box" groundwater representation are also virtually incapable of dealing with spatially distributed groundwater withdrawals, where the distance of the withdrawal wells from the streams is a critical aspect of their effects on low-flow (e.g., Bredehoeft, 2002 In some regions of Canada, heavy demands are being placed on both surface water and groundwater for water supply.…”

“…Some papers consider the modelling of physical processes relevant to low flows, such as Moore (1993) for glacierized basins, Stadnyk et al (2005) for groundwater contributions to flow, and Davison et al (2006) and Pomeroy et al (2007) for latelying snow drifts, but none of these studies explicitly consider the capability of the models to predict lowflows. A number of other case studies also make use of hydrologic models coupled with groundwater models (e.g., Wardlaw et al, 1994;Abbey et al, 2007;Ford and Wexler, 2007;and AquaResource, 2008) or just groundwater models (e.g., Clausen and Rasmussen, 1993;Clausen et al, 1994;Lanen et al, 1993) for water management purposes, but again the focus was not specifically on low-flows. In a special European volume of hydrological studies, Tallaksen (1993) used a variant of the HBV model to examine the effects of land-use change on mean and low flows in the central Scottish highlands, concluding that the forestation of a small basin consisting of upland pasture and heather would shift the flow duration curve downwards.…”