Assessment of Groundwater Recharge in Agro-Urban Watersheds Using Integrated SWAT-MODFLOW Model

Abstract

Numerical models are employed widely to evaluate the hydrological components of a watershed but, traditionally, watershed models simplify either surface or subsurface flow module. In this setup, as a bridge between groundwater and surface water regimes, aquifer recharge is the most affected segment of the water balance. Since the watershed processes are increasingly changed, the need for a comprehensive model with detailed conceptualizing capacity of both groundwater and surface water flow systems is growing. This work focuses on the spatiotemporal groundwater recharge assessment in gauged and ungauged agro-urban watersheds in South Korea using the updated SWAT-MODFLOW model, which integrates the Soil and Water Assessment Tool (SWAT2012) and Newton–Raphson formulation for Modular Finite Difference Groundwater Flow (MODFLOW-NWT) in a single executable code. Before coupling, the setup, calibration, and verification of each model were performed separately. After integration, irrigation pumps and drain cells mapping to SWAT auto-irrigation and subbasins were initiated. Automatic calibration techniques were used for SWAT and MODFLOW-NWT models, but a manual calibration was used for the integrated model. A physical similarity approach was applied to transfer parameters to the ungauged watershed. Statistical model performance indicators revealed that the low streamflow estimation was improved in SWAT-MODFLOW. The spatiotemporal aquifer recharge distribution from both the stream seepage and precipitation showed a substantial change, and most of the aquifer recharge occurs in July–September. The areal annual average recharge reaches about 18% of the precipitation. Low-lying areas receive higher recharge consistently throughout a year. Overall, SWAT-MODFLOW exhibited reasonable versatility in evaluating watershed processes and produced valuable results with reasonable accuracy. The results can be an important input for policymakers in the development of sustainable groundwater protection and abstraction strategies for the region.

Use of Multidisciplinary Approaches for Groundwater Recharge Mechanism Characterization in Basement Aquifers: Case of Sanon Experimental Catchment in Burkina Faso

“…According to the state of art, several methods have been developed for estimating aquifer recharge rates. These methods include empirical [15][16][17], physical [15,18,19], and chemical methods [12,[20][21][22], as well as hydrogeological modeling [17,[23][24][25][26][27]. Since each method carries its own uncertainties, some authors [17,18,28,29] have recommended a combination of several methods to estimate a robust range for the amount of groundwater recharge.…”

Abacus to Predict Groundwater Recharge at Non-Instrumented Hydrographic Basins

“…Despite the discussion about the limitation of the model SWAT-MODFLOW, the results obtained by Araujo [42] indicate that the model's recharge estimations are more reliable. In this model, the simulation of surface and groundwater flows are integrated, exploring the strengths from each original model-SWAT simulating surface water flow and MODFLOW simulating groundwater flow-thus making the global modelling more robust to represent every flow in the hydrographic basin [55]. Using the integrated model, Araujo [42] compared simulated flow rates with measured flow rates, obtaining satisfactory results for the performance indexes, which indicate SWAT-MODFLOW model's ability to represent the hydrological processes in a Cerrado environment.…”

Effect of Recharge and Abstraction on Groundwater Levels

“…This study seeks to fill this gap by using the SWAT model to estimate recharge and coupling it loosely with the MODFLOW model to determine the effect of groundwater recharge and abstraction on groundwater levels. The SWAT model has been used to estimate groundwater recharge in various places, such as BJC Australia, where it provided an alternative to point scale modeling and spatial recharge distribution [19]; India in the lower Chenab canal [20]; Ghana in the Volta river basin, annual recharge was estimated to be 8% of the annual rainfall [21]; central Kuwait [19,22] and Australia [23]. The model has proved to be reliable and handy in the estimation of groundwater recharge.…”