Aquifer-yield continuum as a guide and typology for science-based groundwater management

Suzanne A. Pierce 0 1 2 3 John M. Sharp 0 1 2 3 Jr. 0 1 2 3 Joseph H. A. Guillaume 0 1 2 3 Robert E. Mace 0 1 2 3 David J. Eaton 0 1 2 3 0 R. E. Mace Water Science and Conservation Division , The Texas Water Development Board, 1700 North Congress Avenue, P.O. Box 13231, Austin, TX 78711-3231, USA 1 J. H. A. Guillaume National Centre for Groundwater Research and Training, Integrated Catchment Assessment and Management Centre, Fenner School of Environment and Society, Australian National University , Building 48A, Linnaeus Way, Canberra 0200, Australia 2 J. M. Sharp Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, 1 University Station , C9000, Austin, TX 78712, USA 3 D. J. Eaton Lyndon B. Johnson School of Public Affairs, The University of Texas at Austin , 2315 Red River St., Austin, TX 78712-1536, USA Groundwater availability is at the core of hydrogeology as a discipline and, simultaneously, the concept is the source of ambiguity for management and policy. Aquifer yield has undergone multiple definitions resulting in a range of scientific methods to calculate and model availability reflecting the complexity of combined scientific, management, policy, and stakeholder processes. The concept of an aquifer-yield continuum provides an approach to classify groundwater yields along a spectrum, from non-use through permissive sustained, sustainable, maximum sustained, safe, permissive mining to maximum mining yields, that builds on existing literature. Additionally, the aquifer-yield continuum provides a systems view of groundwater availability to integrate physical and social aspects in assessing management options across aquifer settings. Operational yield describes the candidate solutions for operational or technical implementation of policy, often relating to a consensus yield that incorporates human dimensions through participatory or adaptive governance processes. The concepts of operational and consensus yield address both the social and the technical nature of science-based groundwater management and governance. - Over the last two centuries, the concepts by which groundwater resources are managed have gradually, but dramatically evolved. In 1856, Henry Darcy identified a method for finding a reliable, safe, and potable water source for the city of Dijon, France, and simultaneously created a founding principle of hydrogeology (Darcy 1856; Bobeck 2004), conservation of mass. Darcys observations led to quantitative techniques that helped him apply an innovative solution for describing the behavior of water flowing through porous media that explained groundwater flow and became the underpinning of management. Advances in drilling and extraction in the early 1900s were accompanied by the concept of safe yield. Lee (1915) defined it as . . . the limit to the quantity of water which can be withdrawn regularly and permanently without dangerous depletion of the storage reserve. Safe yield was later refined as a rate of withdrawal for human use limited to economic feasibility (Meinzer 1920, 1923) by protecting rights to surface water (e.g. Conkling 1945), to preventing subsidence, and water-quality degradation. Theis (1940) recognized the impact of pumping on capturing natural discharge and altering recharge and groundwater storage. In the intervening years, groundwater science and management has transitioned to sustainable yield, reflecting decades of active disciplinary debate about how to delineate aquifer yield (Zhou 2009; Devlin era after World War II led to the use of optimization for and Sophocleous 2005; Kalf and Wooley 2005; Alley and groundwater management as hydrogeologists adapted Leake 2004; Sophocleous 2000; Alley et al. 1999; numerical methods, classical and non-classical optimizaDomenico 1972; Todd 1959; Kazmann 1968, 1956; tion for simulating groundwater behavior and optimizing Thomas 1951; Conkling 1945). management regimes (Zheng and Wang 2002, 1999; Six factors influence determination of sustainable yield Ahlfeld and Mulligan 2000; Gorelick 1983; Bredehoeft including: (1) recharge rates and storage conditions, (2) and Young 1970). After the passage of the Clean Water water quality, (3) discharge rates and environmental flows, Act (USC 1972), US groundwater management embraced (4) legal constraints, (5) economic feasibility, and (6) water-quality preservation and rejuvenation, actions that issues of inter-generational equity. The first several factors were spurred by advances in water-quality detection, are in the traditional realm of hydrogeology, as is monitoring, and mitigation (Georgopoulos and Lioy economic feasibility when evaluating pumping design. 2006; Focazio et al. 2002; Mandel and Shiftan 1981). Together these six factors of sustainable yield reflect the The 1970s and 80s achieved lower water-use intensities needs of modern society and recognize the multi-criteria through technological advances such as multi-stage pumps nature of groundwater resource management. Based on and drip irrigation producing a coincident plateau in consideration of these factors, Fig. 1 presents a conceptual consumption and use of groundwater by agriculture, typology that sheds light on the functional distinctions industry, and energy (Wright et al. 2006). Since the within the definition of sustainable yield as it relates to 1990s, as data collection and monitoring technologies scientific knowledge of aquifers and governance struc- improved, public investment in programs that collect and tures. Sustainable yield is a concept that allows the leap record the raw information necessary to assess groundwafrom case-specific studies of groundwater availability to a ter system behavior and response to management in the more generalized form of science-based groundwater United States began to decrease (SWAQ 2004; USGS management that can explain decisions across aquifer 2002), which is unfortunate given the recognized need for settings and provide insights into phenomenon and good, trustworthy information in resource management behaviors across cases (Villa et al. 2009; Margerum (Dietz et al. 2003). In the last two decades, advances in 2008; Moore and Koontz 2003). computational efficiency and methodologies that address As groundwater systems are dynamic and heteroge- parameterization and uncertainty enable new approaches neous in space, time, and social values, aquifer yields can to modeled experiments, multi-model analysis, and uncerbe viewed through the lens of an adjustable continuum. tainty (Matott et al. 2009; Banta et al. 2006; Doherty and By pairing the concept of a continuum with the six factors Skahill 2006; Doherty 2004; Doherty 2003; Hamby 1994; (summarized in Fig. 1), a framing device for describing Hill 1998; Poeter and Hill 1998). Recent public concern the selection of an aquifer yield emerges. Aquifer over groundwater use and availability has led to discussions performance factors reflect physical proces (...truncated)