Date of Award
1-1-2024
Document Type
Dissertation
Degree Name
Ph.D. in Engineering Science
First Advisor
Robert M. Holt
Second Advisor
Gregg R. Davidson
Third Advisor
Lance D. Yarbrough
School
University of Mississippi
Relational Format
dissertation/thesis
Abstract
In this dissertation, three studies related to understanding and predicting recharge are presented. First, geospatial techniques were used to identify potential groundwater recharge areas in the High Plains Aquifer. Second, a precipitation generator was developed to produce site specific synthetic precipitation series that depend on daily precipitation occurrences, particularly on the distribution of wet spells for sites to be used in numerical modeling. Third, the unsaturated flow code VS2DI was modified to allow the simulation of chloride accumulation from recharge, and this model was used to evaluate errors in the Chloride-Mass-Balance (CMB) method for estimating recharge due to heterogeneity.
In Chapter 2, geospatial techniques were used to delineate or rank areas of the High Plains Aquifer based on recharge potential, where precipitated water is expected to percolate into subsurface replenishing groundwater. The result can help us choose the area of interest or concern for in depth recharge estimation studies involving improved identification of recharge pathways and quantification of recharge rates. Different thematic layers were prepared, and a GIS model based on weighted overlay analysis was implemented to predict the potential zones.
In Chapter 3, a precipitation generator was developed using a first-order two-state Markov chain model and multi-decadal data to predict daily rainfall scenarios at single sites in the High Plains for numerical modeling. Stochastic generation of precipitation are probabilistic models that produce synthetic time series data mimicking observed weather while keeping the statistical signature.
Chapter 4 focuses on the simulation of the flow and transport of chloride through the unsaturated zone of the Ogallala, Antlers, and Gatuna Formations in west Texas to illustrate how preferential flow caused by heterogeneity impacts recharge calculations using the one-dimensional chloride mass balance (CMB) method. The findings illustrate how the estimated recharge values can transition from representative realistic values to overestimated impossible values on a local scale. In conclusion, this dissertation contributes to the field of hydrogeology by cautioning future usage of CMB method for robust groundwater assessment and management when heterogeneity is involved, paving the way for site specific methods.
Recommended Citation
Mukherjee, Arindam, "Establishing Recharge Rates in the High Plains Aquifer: Mapping, Precipitation Modeling, and an Evaluation of the Chloride Mass-Balance Method" (2024). Electronic Theses and Dissertations. 2961.
https://egrove.olemiss.edu/etd/2961