Journal of Aquifer and Qanat
In collaboration Iranian Hydraulic Association

Groundwater Storage Change Estimation in the Sefidrud River Basin and Zanjan Aquifer via Integration of GRACE Satellite Data and Local Hydrological Model Components

Articles in Press

Document Type : Original Article

Authors

Tahereh Gohari 1
Mostafa Naderi 2

1 1. PhD student, Geophysics, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran.

2 2. Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran.

10.22077/jaaq.2026.11810.1154
Abstract
In this study, the Sefidrud River Basin in northwestern Iran was selected as the study area. Monthly GRACE satellite data with a spatial resolution of 0.5 degrees were employed; however, due to their coarse resolution, direct application at the aquifer scale is challenging. After computing monthly variations and constructing the cumulative time series, these data were integrated with water balance components derived from a calibrated SWAT model, including groundwater recharge, runoff, and soil moisture. First, a relationship was established between the cumulative values of water storage change and net recharge for each GRACE cell. Water storage changes were then estimated for areas lacking aquifers, and finally, groundwater storage changes were downscaled for the Zanjan aquifer. The results indicated that the exponential downscaling method exhibits strong capability in reconstructing cumulative groundwater storage changes; the coefficient of determination exceeded 0.97 in 36 out of 42 GRACE cells, and exceeded 0.99 in a substantial portion of them. Validation using data from 66 piezometric wells in the Zanjan aquifer yielded a coefficient of determination of 0.846, confirming the method's satisfactory performance. Owing to its reliance on the linearity of the water resources balance equations, this method serves as an effective tool for monitoring and managing groundwater resources in data-scarce basins.

Keywords

Groundwater Storage
Downscaling
SWAT Model
Sefidrud River Basin
Zanjan Aquifer
Subjects
Journal of Aquifer and Qanat

Articles in Press, Accepted Manuscript
Available Online from 11 October 2026

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