Groundwater Transport of Nitrate, Salts, and Age Tracers

For each of the 150 realizations of solute breakthrough we compute the 5th, 50th, and 95th percentile arrival time. This shows the probability density function ( ; lines analyzed on the left axis) and histogram (transparent bars with superposing colors, analyzed on the right axis) of early ( , i.e., time for 5% of the total recovered mass to reach a well), medium ( ) and late ( ) arrival times for heterogeneous (red) and equivalent homogeneous (blue) simulations.

The bigger the well, the simpler the modeling approach can be to understanding transport of nitrate, salt, and age tracers to the well

Christopher V. Henri

Thomas Harter

February 06, 2026

We quantify age and pollutant mixing that occurs due to (A) in-well mixing (B) aquifer heterogeneity (C) dispersion and (D) diffusion
In-well mixing dominates age/pollutant concentrations in large production wells, followed by aquifer heterogeneity effects
Typical age and pol

Tule River Groundwater Modeling Study Area

Giorgos Kourakos

Thomas Harter

July 01, 2014

The Tule River study area has been used as the pilot study area during the development of the tools.

Therefore the Tule River model has been simulated using various techniques and models.

The well and its source area are located in the Modesto region of the Central Valley, California

AgMAR (managed aquifer recharge on agricultural lands) and improved nutrient management improves groundwater quality, especially when focused in source areas of public supply wells.

Mehrdad Bastani

Thomas Harter

October 01, 2019

Nitrate in drinking water may cause serious health problems for consumers. Agricultural activities are known to be the main source of groundwater nitrate contaminating rural domestic and urban public water supply wells in farming regions.

a SAGBI-map of the study area (O’Geen et al. 2015), b suitable locations for winter recharge (excellent, good, and moderately good rating), and c location of alfalfa and almond fields in suitable locations at the last stress period of the simulation

Good annual (or longer term) average recharge and nitrogen loss data, rather than daily or monthly details, are key to good groundwater nitrate simulation models

Thomas Harter

Mehrdad Bastani

March 18, 2020

Managed aquifer recharge and changes in crop type or nutrient management on agricultural lands are promising approaches to address groundwater quality degradation by nitrate.