Springs, seen and interpreted in the context of groundwater flow-systems (a suggested hydrogeological approach to subsu

1. Springs, seen and interpreted in the context of groundwater flow-systems(a suggested hydrogeological approach to subsurface sounding) J. Tóth “50 Years of Hydrogeology at GSA: Looking Back and Looking Forward” GSA Annual Meeting October18-21, 2009 Portland, Oregon, U.S.A.

2. KEY POINTS OF THE TALK(not an “Outline”) Looking back: Hydrogeology Division and Groundwater Flow Systems; Looking around,I see: Flow Systems without Springs and Springs without Flow Systems; Looking forward, I suggest: the “Virtual Spring”, or, Springs in the context of Flow Systems, because: “Virtual Spring” + Flow Systems = Subsurface (Hydrogeological) Sounding

3. Hydrogeology Division and Flow Systems Looking back: The founding of GSA’s Hydrogeology Division (1959) and the recognition of gravity-driven groundwater flow-systems (early 1960s) were, closely timed. A fortuitous and fortunate timing. Fortuitous: the two events were totally independent. Fortunate: The O. E. Meinzer Award drew attention to the concept, and high caliber researchers kept developing it further. It has thus turned out to be the starting point for many new fields of hydrogeologically related inquiry.

4. FLOW SYSTEMS without SPRINGS (“system concept” was born within 3 to 4 years from creation of GSA’s Hydrogeology Division) “Drainage ditch” (line sink: in thalweg);“The Unit Basin”:(area-sink: all lower half);“Composite basin”:(multiple sinks:local depressions)(Hubbert, 1940, Fig. 45. Tóth, 1962, Fig. 3; 1963, Fig. 3, courtesy T. Winter)

5. Acting Chairman Stan Lohman, of GSA’s Hydrogeology Division presents the Division’s first O.E. Meinzer Award given for the theory of gravity-driven groundwater flow- systems (without springs!),Kansas City, November 6, 1965.M. King Hubbert liked it. After all, it all started withФ = gh = gz + p/ρ.(Photos: courtesy GSA, 1965)

6. Looking around (i. e., the present):SPRINGS without FLOW SYSTEMS Studies of various spring attributes abound (rock type, orifice morphology, volume, temperature, discharge rate, periodicity, flora, fauna, etc.) Their purpose is chiefly utilitarian and management issues (water supply, water balance, health, recreation, mineral water, mineral resource, etc.). They do not pay attention to the feeding (i.e. parent) flow-systems. Yet…! (E.g., Stevens and Meretsky, 2008)

7. YET: SPRINGS + FLOW SYSTEMSThe “Effects of the Hydrogeologic Environment on springs” depend on the springs’ parent flow-systems, i.e., the springs bear imprints of their subsurface environment..(Tóth, 1971, Fig. 2.) frequent rainfall events rare rainfall events

8. Looking forward, I suggest:“The Virtual Spring”a conceptual entity defined as:All discharge phenomena considered together as one single entity in the terminal area of a groundwater flow-system(Springs +: phreatophytes, all plant types ,soil/rock mechanics, soil salinity/mineral deposits, swamps and their water chemistry, well-water temperature, etc.)

9. Virtual springs Effects and manifestations of regional groundwater flow: “The Virtual Spring”(modified from Tóth, 1980)

10. “Virtual spring”, Norris Geyser Basin, Yellowstone Park, comprising:springs, seeps, steam, salts, gases, mud-boils, high pressure, heat, phreatophytes, minerals (iron, travertine, etc), bacteria;all, plus others, due to groundwater discharge. (Photo: Tóth, 1967)

11. The flow-system concept used to explain the place of provenance of thermal spring water from environmental isotope composition, Montecatini Terme, Italy(One of, if not, the first explicit applications of the flow-system theory combined with isotopes; Fritz, 1968) local system regional flow system

12. Field of geothermal heat modeled without and with groundwater flow, Tongue Creek watershed, Colorado:note dependence of springs’ temperature on flow-system order (Lazear, 2006, Figs. 14, 16) Areal distribution of spring-water temperature fits flow-systems context

13. ↑Modeled changes, (“anomalies”) in temperature due to groundwater flow;←Spring locations vs. flow patterns: i) at change in slope below ridges, ii) at concentration of flow(Lazear, 2006, Figs. 18, 12)

14. Simulated groundwater flow-systems, calibrated to: springs, phreatophytes, runoff, Grote-Nete drainage basin, N.E. Belgium.Legend:numbers 1-18: flow system; solid line: flow-system boundary (“demarcation”); gray scale: discharge areas and flow times in years (time determined by capture-zone modeling, increases toward lighter shades, resp. <10, 10-50, 50-100, >100(Batelaan et al., 2003, Fig. 10)

15. ”Fig. 1. Epigenicand hypogenic karst in the context of basinal groundwater flow.” (Klimchouk, 2007, “Adopted and modified from Tóth, 1999”)(Klimchouk, A.B., 2007: Hypogene Speleogenesis: Hydrogeological and Morphogenetic Perspective. Special Paper no. 1, National Cave and Karst Research Institute, Carlsbad, NM, U.S.A.160 p.)(Klimchouk distinguishes between “epi-” and “hypo-”genic karst based on chemical, mineralogical and geothermal signatures found in caves and attributed by him to flow systems of different order)

16. Conceptual model of groundwater flow-system and geochemical processes (left) causing high radon content of St. Placidus spring, Switzerland (right)(Figs. 6.1, Gaignon, 2008; and 8, Gaignon et al., 2007) Recharge area Discharge area hydraulic mid line Eh+ 238U 222Rn FeOOH Redox front 238U Eh+ 226Ra 226Ra Eh- Fe, Mn

17. CONCLUSION An expanded spring concept, the “Virtual Spring”, is defined and proposed as: “all discharge phenomena taken together as one single entity in the terminal areas of groundwater flow-systems”; The “virtual spring” reflects the subsurface conditions of its parent flow-system. It thus facilitates inferences of the hydrologic, hydraulic, thermal and chemical attributes of the system’s rock body in one or two specific ways, i.e.: i) by explaining features of the virtual spring from known properties of the rock body, or/and ii) by inferring attributes of the rock bodyfrom observed features of the virtual spring; Springs can thus be seen, interpreted and used for practical and scientific purposes in the context of groundwater flow-systems.