Both talks will be held at theWRRC Sol Resnick Conference Room (350 N. Campbell Ave.) at the University of Arizona in Tucson.
Surface Water/Groundwater Interactions in Arizona: Physical Realities and Experiences in the Real World
Date: Thursday, December 4, 2014
Time: 12:00 pm – 1:30 pm
Speaker: James Leenhouts, Director, USGS Arizona Water Science Center
Streams and aquifers are hydraulically connected in many hydrologic systems across Arizona. Such a connection occurs when the groundwater level in an aquifer intersects a stream, spring, or even the roots of riparian plants. In these hydraulically-connected systems, the surface water and groundwater interact as a stress imposed on one part has an effect on the other. Often this interaction is observed as a reduction in stream base flow caused by groundwater withdrawals from a connected aquifer — a process often called “streamflow depletion” or “capture”. An aquifer recharge project or a change in climate represents stresses that also have effects. The nature of the connection between surface-water and groundwater was thoroughly described and established in the literature by C.V. Theis in 1940. The timing of the effect, and where it is observed, however, varies greatly among hydrologic systems, and depends on only two factors: (1) distance between the stress and the connected stream, and (2) the diffusive hydraulic properties of the aquifer. Hydrologists often understand the nature of these relationships, but many in the public and many resource managers hold misperceptions. For example, a common misperception is that the amount of recharge to an aquifer affects capture—often the perception is that systems with greater recharge should be impacted less by groundwater pumping. However, the timing and rate of capture is independent of recharge and inflows and outflows of the flow system. Hydrologists at the Arizona Water Science Center have worked across the state to develop groundwater-flow models for assessing and communicating groundwater/surface-water interactions. These tools have been used for making various resource management decisions, but they have also initiated useful and revealing dialogs regarding the connections of surface water to groundwater.
Jim joined the USGS Arizona Water Science Center as a hydrologist in 2000. From 2000 to 2007, Jim worked first on three projects in the Upper San Pedro Basin. The first was to quantify the groundwater and surface-water requirements of the riparian vegetation and the second was to quantify stream-aquifer interactions as part of the groundwater model development. Following these projects, Jim led the “Section 321” project that evaluated the water budget and hydrogeology for the San Pedro basin and summarized findings in annual reports to congress. A key aspect of this work was interpreting the wide variety of data collected and working with the Upper San Pedro Partnership to assess progress toward sustainable withdrawals of groundwater. From 2007 to 2013, Jim has served as the Center’s Associate Director and Investigations Section Chief. In that role Jim has worked in the Verde River basin to explain surface-water/groundwater interactions as represented by the USGS Northern Arizona Regional Groundwater Model. Currently, Jim is the Director of the Arizona Water Science Center.
Colorado River Simulation System (CRSS) — Overview and Use in Planning and Operation of the Colorado River
Date: Wednesday, January 28, 2015
Time: 12:00 pm – 1:30 pm
Speaker: Don Gross, Water Resources Engineer, Colorado River Management Section, ADWR
Don Gross’s Brown Bag presentation will include a brief history of the development the Colorado River Simulation System (CRSS), and its structure. This will be followed by an overview of the various planning studies in which CRSS was used, and information on how CRSS is utilized in operation of the Colorado River.
Don Gross has more than 40 years of experience in water resources planning and management in the Southwest. He is currently a water resources engineer with ADWR’s Colorado River Management Section. He is involved in numerous aspects of the Colorado River, which include supply, water use, accounting, contracts, hydrology, Colorado River modeling, and the Central Arizona Project. Don was ADWR’s lead technical specialist for the Colorado River Basin Water Supply and Demand Study. Don has been with ADWR for 26 years and has worked in the following areas: water rights adjudications, surface water rights, dam safety, and program management.
Prior to working for ADWR, Don was a project manager for the United States Army Corps of Engineers, Los Angeles District for 16 years. He was responsible for water resource planning studies including; the Phoenix Urban Study, the Las Vegas Wash and Tributaries Water Resource Study, and the Los Angeles County Drainage Area Study. Don was also the Corps’ lead project engineer for the Central Arizona Water Control Study, a cooperative water resource planning study with the Bureau of Reclamation. This study resulted in the construction of Plan 6, which included dam safety repairs.