Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Parajuli, Prem

Committee Member

Paz, Joel

Committee Member

Feng, Gary

Committee Member

Ramirez-Avila, John

Committee Member

Tagert, Mary Love; Parajuli, Prem

Date of Degree

8-7-2025

Original embargo terms

Visible MSU Only 2 Years

Document Type

Dissertation - Campus Access Only

Major

Engineering (Biosystems Engineering)

Degree Name

Doctor of Philosophy (Ph.D.)

College

James Worth Bagley College of Engineering

Department

Department of Agricultural and Biological Engineering

Abstract

Groundwater plays a critical role in sustaining agricultural productivity in the Mississippi Delta, where irrigation depends almost entirely on withdrawals from the alluvial aquifer. However, persistent over-pumping, particularly during the growing season, has led to significant groundwater level (GWL) declines, raising concerns about long-term sustainability. Historically, groundwater studies in the region have relied on biannual measurements, limiting insight into seasonal GWL fluctuations. This creates a research gap, particularly during peak irrigation periods when withdrawals are highest. More frequent data, on a daily or monthly scale, would enable earlier trend detection and more responsive groundwater management. Accurate pumping data is also limited due to voluntary reporting and the scarcity of installed flowmeters, making it difficult to quantify actual groundwater use. This study addresses these gaps by analyzing daily GWL data and introducing a novel method to estimate daily agricultural pumping across the Delta and at the counties, an essential step toward improving groundwater models. Another key gap lies in modeling groundwater using daily data, which allows for faster responses to level changes and better tracking of evolving trends compared to infrequent seasonal observations. Moreover, research into the long-term effects of climate and land use change on groundwater in the Delta remains in its early stages. This study integrates observational data, modeling, and future projections to assess past, present, and potential future groundwater dynamics. It captures detailed spatiotemporal GWL fluctuations and estimates groundwater withdrawals at seasonal, monthly, and daily scales based on crop distribution and irrigation demand. Simulations using the GMS-MODFLOW platform demonstrate that GWLs are highly sensitive to recharge variability, pumping intensity, and aquifer properties. In addition, future projections under three climate scenarios (SSP126, SSP245, SSP585) suggest recharge rates may generally decline and cropping patterns may shift, likely intensifying groundwater stress, especially in the central Delta. However, these impacts will differ across time and space. These findings underscore the need for high-resolution data and adaptive, forward-looking water management strategies to ensure the sustainable use of this critical resource.

Sponsorship (Optional)

USDA-ARS (award #: 58-6066-1-027) and the Mississippi Agricultural and Forestry Experiment Station (MAFES)

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