Simulating Coupled Reactive Salinity Transport in an Agricultural Groundwater System
Tuesday, September 22, 2015: 4:10 p.m.
Saman Tavakoli
,
Department of Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
Ryan T. Bailey
,
Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
Timothy K Gates
,
Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
The Lower Arkansas River Valley (LARV) in southeastern Colorado is a key resource for stakeholders in southeastern Colorado due to its valuable agriculture production. Because of a rising water table due to excessive irrigation and canal seepage, mobilization of native salts, and evaporative concentration, much of the soil-aquifer system in the valley has become salinized, thereby negatively impacting crop yield. High groundwater salinity loading to the Arkansas River stream network also impacts downstream areas, with saline river water diverted for application on irrigated fields. The overall aim of this project is to develop a numerical modeling framework capable of simulating the transport of salt ions within the stream-aquifer-soil system, so that current conditions of salinity can be assessed and possible remediation strategies in the region can be explored. Results of simulating the fate and transport of sulfur species (principally sulfate SO4) in a 500 km2 region of the LARV using the UZF-RT3D groundwater reactive transport model indicate that advection-dispersion processes, first-order kinetic reactions, and sources/sinks alone cannot account for the high groundwater SO4 concentrations and loadings to the Arkansas River. Hence, a comprehensive salinity module that can be coupled with the UZF-RT3D model and that accounts for salt ions equilibrium chemistry and precipitation-dissolution processes is being developed. Initial model testing with the nested equilibrium module occurs at the field scale, with model results compared with collected salinity data from a lysimeter site at the Arkansas Valley Research Center in Rocky Ford, Colorado.
Saman Tavakoli, Department of Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
Saman Tavakoli is a graduate student at Colorado State University and is doing his Ph.D. with presentation co-authors Dr. Ryan Bailey and Dr. Timothy Gates. He is working on the salinity movement on groundwater systems.
Ryan T. Bailey, Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
Ryan Bailey’s research focuses on the sustainability of watershed management practices in regards to water quantity and water quality. Recent projects have focused on the development of process-based, dynamic numerical modeling codes to identify sustainable management practices within environmental systems, and have provided a foundation for ongoing and future research. Projects include the assessment of selenium and nitrogen reactive transport in agricultural groundwater systems through field, laboratory, and numerical modeling; assessing impacts of agricultural dry-up scenarios on watershed processes; linking watershed and groundwater flow and transport models to assess the movement of water and nutrients in watersheds; and investigating best management practices for pollutant remediation. These projects have involved model development and application to large-scale systems in the western United States, and have afforded opportunities to mentor undergraduate and graduate students. Bailey also has been involved with the assessment of groundwater resources of small oceanic islands using field and modeling methods and the analysis of small-island water supply during drought and extreme-climate events, with projects in the Federated States of Micronesia and the Republic of Maldives. Work in the western Pacific has offered opportunities to train local water resource managers in optimizing water supply for island communities.
Timothy K Gates, Civil and Environmental Engineering, Colroado State University, Fort Collins, CO
Timothy Gates is a water resources systems analyst and a Professor of Civil and Environmental Engineering at Colorado State University. His research has focused on analysis, design, and operation of open channel flow systems; stochastic simulation and optimization of water resources systems; modeling and analysis of shallow groundwater flow and salt transport; management of water quality (especially salinity and selenium) for irrigated agriculture; drainage of salinity affected regions; multi-objective river basin planning; and monitoring and evaluation of irrigation and drainage systems. Gates has directed or co-directed research and training projects with total funding of about $8 million over the last 24 years. He has taught academic courses in open channel flow, fluid mechanics, hydraulic engineering, hydraulic structures/systems, hydrology, groundwater engineering, and solid dynamics. In addition, he has served as an independent consulting engineer with the United States Agency for International Development; the United Nations Development Program; Camp, Dresser & McKee Inc.; Keller-Bliesner Engineering; D’Appolonia Environmental Services; the Denver Water Department; the Governance Committee of the Platte River Cooperative Agreement; Devon Energy; Pennaco; Riverside Ditch Co.; ARCADIS & GM; Greg Lewicki and Associates; Pueblo Wastewater; Boxelder Sanitation District; and Central Mutual Insurance Co. on projects related to irrigation-and-drainage hydraulics, river hydraulics, seepage from earthen channels, salinization of irrigated agricultural regions, water quality for irrigated agriculture, irrigation-induced pollutant loading to rivers, modeling of open-channel flow, and river-basin modeling. He has designed and conducted numerous short courses and special training programs in open channel flow, irrigation and drainage engineering, and groundwater. Gates spent a total of about four years in Egypt working on various irrigation projects. He also has consulted in India, Sri Lanka, and Australia on irrigation projects and has presented visiting lectures on irrigation and water resources in China at Wuhan University and at the Beijing Institute of Technology.
