Coupling SWAT Model and CMB Method for Modeling of High-Permeability Bedrock Basins Receiving Interbasin Groundwater Flow

Abstract

This paper couples the Soil and Water Assessment Tool (SWAT) model and the chloride mass balance (CMB) method to improve the modeling of streamflow in high-permeability bedrock basins receiving interbasin groundwater flow (IGF). IGF refers to the naturally occurring groundwater flow beneath a topographic divide, which indicates that baseflow simulated by standard hydrological models may be substantially less than its actual magnitude. Identification and quantification of IGF is so difficult that most hydrological models use convenient simplifications to ignore it, leaving us with minimal knowledge of strategies to quantify it. The Castril River basin (CRB) was chosen to show this problematic and to propose the CMB method to assess the magnitude of the IGF contribution to baseflow. In this headwater area, which has null groundwater exploitation, the CMB method shows that yearly IGF hardly varies and represents about 51% of mean yearly baseflow. Based on this external IGF appraisal, simulated streamflow was corrected to obtain a reduction in the percent bias of the SWAT model, from 52.29 to 22.40. Corrected simulated streamflow was used during the SWAT model calibration and validation phases. The Nash–Sutcliffe Efficiency (NSE) coefficient and the logarithmic values of NSE (lnNSE) were used for overall SWAT model performance. For calibration and validation, monthly NSE was 0.77 and 0.80, respectively, whereas daily lnNSE was 0.81 and 0.64, respectively. This methodological framework, which includes initial system conceptualization and a new formulation, provides a reproducible way to deal with similar basins, the baseflow component of which is strongly determined by IGF.

Evaluating the Potential of GloFAS-ERA5 River Discharge Reanalysis Data for Calibrating the SWAT Model in the Grande San Miguel River Basin (El Salvador)

“…It is used to model rainfall runoff at the basin scale [10]. Several global studies have applied the SWAT model to investigate hydrological and water quality processes [45][46][47], the impact of human pressure on water resources [48][49][50], and the consequences of climate change [36,[51][52][53]. The model's GIS interface [54] allows for simple and quick data processing, such as watershed delineation and spatial and tabular data handling.…”

Impacts of Climate on Renewable Groundwater Resources and/or Stream–Aquifer Interactions

“…Since the call for papers was announced in March 2019, and after a rigorous peer-review process, six papers have been accepted for publication [1][2][3][4][5][6]. To gain a better insight into the essence of the Special Issue, we offer brief highlights of the published papers below.…”

“…The paper "Coupling SWAT Model and CMB Method for Modeling of High-Permeability Bedrock Basins Receiving Interbasin Groundwater Flow" [3] couples the Soil and Water Assessment Tool model and the chloride mass balance (CMB) method to improve the modeling of streamflow in high-permeability bedrock basins receiving interbasin groundwater flow (IGF), i.e., the naturally occurring groundwater flow beneath a topographic divide contributing to the streamflow. The Castril River basin in southern Spain was the case study chosen.…”

Impact Assessment of Gridded Precipitation Products on Streamflow Simulations over a Poorly Gauged Basin in El Salvador

“…The Soil and Water Assessment Tool (SWAT) model [18] is one of the most popular models used at the basin scale. SWAT has been widely applied in numerous studies around the world to resolve several processes, such as water balance, climate and land-use changes, agricultural pollution from nonpoint sources, and land management [19][20][21][22][23][24]. Recent SWAT studies [1,17,25,26] showed a growing trend towards the use of alternatives to rain gauge networks.…”