Estimation of groundwater recharge using water table fluctuation method and unsaturated zone flow simulation (Marvdasht aquifer, Fars province, Iran)

Articles in Press

Document Type : Research Paper

Authors

1 Department of Water Engineering and Management, Tarbiat Modares University, Tehran, Iran

2 School of Engineering, University of Northern British Columbia, British Columbia, Canada

10.22059/jwim.2025.399355.1246

Abstract

Groundwater recharge in the Marvdasht aquifer was estimated using two approaches: the water table fluctuation (WTF) method and unsaturated zone flow simulation with the HYDRUS-1D model. In the first approach, recharge was calculated based on variations in groundwater level and specific yield, whereas in the second approach, it was estimated using soil column hydraulic properties within the unsaturated zone. The average recharge for the entire study area was estimated at 291.3 million cubic meters using HYDRUS-1D and 204.7 million cubic meters using the WTF method, indicating a difference of 29.7%. This discrepancy can be attributed to the fundamental differences in the assumptions underlying the two approaches. HYDRUS-1D simulates infiltration and recharge dynamically by solving Richards’ equation and considering the soil hydraulic parameters and boundary conditions, while the WTF method indirectly estimates recharge based on groundwater level fluctuations and specific yield, and is therefore sensitive to the accuracy of these observations. Zonation maps revealed that both methods produced similar spatial recharge patterns. Moreover, analysis of water infiltration delay through the unsaturated zone indicated that the lag time varied between 30 and 730 days, depending on soil texture and the thickness of the unsaturated zone. It is recommended that, where data availability permits, multiple methods be applied to assess groundwater recharge, thereby obtaining more reliable estimates of this critical parameter and supporting sustainable management and optimal utilization of groundwater resources.

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Main Subjects

Water and Irrigation Management

Articles in Press, Accepted Manuscript
Available Online from 18 October 2025

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