A multi-storage groundwater concept for the SWAT model to emphasize nonlinear groundwater dynamics in lowland catchments

摘要

Hydrological models are useful tools to analyze present and future conditions of water quantity and quality. The integrated modelling of water and nutrients needs an adequate representation of the different discharge components. In common with many lowlands, groundwater contribution to the discharge in the North German lowlands is a key factor for a reasonable representation of the water balance, especially in low flow periods. Several studies revealed that the widely used Soil and Water Assessment Tool (SWAT) model performs poorly for low flow periods.This paper deals with the extension of the groundwater module of the SWAT model to enhance low flow representation. The current two-storage concept of SWAT was further developed to a three-storage concept. This was realized due to modification of the groundwater module by splitting the active groundwater storage into a fast and a slow contributing aquifer.The results of this study show that the groundwater module with three storages leads to a good prediction of the overall discharge especially for the recession limbs and the low flow periods. The improved performance is reflected in the signature measures for the mid-segment (percent bias -2.4% vs -15.9%) and the low segment (percent bias 14.8% vs 46.8%) of the flow duration curve. The three-storage groundwater module is more process oriented than the original version due to the introduction of a fast and a slow groundwater flow component. The three-storage version includes a modular approach, because groundwater storages can be activated or deactivated independently for subbasin and hydrological response unit level. Copyright (C) 2013 John Wiley & Sons, Ltd.