It is important to keep clearly in view the fact that many--perhaps most--of the problems involving water resources are not hydrologic or geologic problems. We can identify three classes of problems: political, technical, and scientific.
The term political is used in its broadest sense, relating to the process of determining and implementing societal values and goals. Questions such as whether to dam a free-flowing stream to provide flood control or water supplies, or whether to maintain some elevation of the ground-water table or to deplete ground-water reserves by pumping at rates greater than the safe yield level, are fundamentally political decisions. Scientists can offer information on the probable effects of a given action or the best way to achieve a particular goal, but the ultimate value judgment is not scientific in nature.
Technical problems are those in which some well-defined information is needed and obtainable in a straightforward fashion, but not available at present. Also termed assessment, characterization, or monitoring studies, these problems are typically solved by the application of scientific measurements or calculations to a hydrologic system that can be described in a standard fashion. The design and placement of a dam or the determination of whether water quality is adequate for a municipal supply are examples of problems or questions in this category.
Scientific questions are those requiring research--problem definition, experimental design, observation or calculation, and interpretation. They often involve systems too large, too complex, or with too long a time constant to be completely described. Models and sampling strategies must be designed and validated to produce adequate information within the time and resources available. Determining the safe yield of an aquifer system or the origin and pathways of ground-water contamination are real examples of problems in this category.
In keeping with the scientific mission of the Kansas Geological Survey, the problems we identify as critical for the future of Kansas ground water are scientific in nature--but we note that their importance is due in large part to the deficit in the water budget discussed earlier. Demand for water exceeds the long-term supply in many areas, and ground water is being withdrawn much faster than the rate of recharge. Adding to the complexity of the problem is the fact that surface-water and ground-water resources are interconnected and interactive. Among the critical areas where improved understanding will help us to make the most effective use of our limited water supply are:
- Deep aquifer characterization: Deep aquifers, such as the Dakota, represent the next available source of ground water once the shallower aquifers are depleted, and these deep aquifers are already being used in some areas. In some areas they provide avenues for the flow of saltwater that mixes with and degrades freshwater in the deep or shallower aquifers. The extent, hydrologic characteristics, and distribution of water quality in these aquifers needs to be much better known to understand both their water-resource potential and the safe yield at which they can be exploited.
- Stream-aquifer interactions: We need a much better understanding of the dynamics of ground-water discharge and recharge in stream systems. The relationship between recharge and streamflow needs to be studied over a range of time scales and water levels to provide an information base for managing the combined resource on a long-term basis. Some of the questions involve alteration of the hydrologic character of the system. High flow rates and floods can act to scour out a stream channel, so human control or reduction of streamflow may result in a gradual reduction of the permeability of the channel and change the coupling of the ground water and surface water.
- Water-quality issues: Water quality can be a problem because of natural factors or because of artificially introduced contaminants. Kansas faces both types of problems.
- Mineral intrusion: The salt beds and brine-containing aquifers that are near the surface in much of central Kansas represent a special problem for water supply and management. Freshwater heads and flow rates can often be maintained at a level adequate to either keep the underlying saltwater from discharging or to dilute it to tolerable levels where it does discharge. However, managing this sort of balanced system requires a detailed understanding of the hydrology, geology, and geochemistry of multiple interacting aquifers. It is a challenging research problem, but the issues are important. A substantial fraction of the irrigated agriculture and municipal water supplies of south-central Kansas are vulnerable to salt problems, and aquifers tend to have a memory effect--a temporary introduction of brine into a freshwater aquifer may leave behind long-term residual contamination.
- Human contamination: The so-called point sources of ground-water contamination (landfills, industrial discharge, underground storage tanks, injection wells, etc.) are gradually being brought under regulatory control that will reduce some of the problems in the future, but improved methods for locating and predicting the movement of contaminant plumes resulting from past practices are still needed. As attention turns to the non-point sources of pollution (such as agricultural chemicals or urban runoff), we find that we need a greatly improved understanding of how both water and contaminants move through the unsaturated zone and mix into the ground water. Such studies can improve our understanding of the recharge process as well as of pollution-related mechanisms.
- Regional-scale hydrology: We have mentioned several times the fact that hydrologic observations are made at a very local scale, and that our climate and budgetary insights work best at a very large scale. The National Research Council has identified the link between local (watersheds or sites) and continental-scale hydrologic systems as one of critical importance. This focus on dimensions typical of aquifers or river basins is particularly relevant to the Kansas approach to water planning based on river basins. It is also critical to the future of water planning, since this is the scale of understanding required to link global or regional climate-change effects to local water resources.
The aim of this book is to provide useful information about ground water and its place in the larger water-resource picture. An introductory volume of this sort limits the details we can provide; the appendices that follow provide some suggestions, additional reading, and lists of agency responsibilities. Above all, we hope that we have convinced the reader that "out of sight" should not be "out of mind," that Kansas ground water is a vital and valuable resource that cannot be taken for granted.
We wish to acknowledge the following individuals and agencies for reviewing the manuscript of this book: James J. Butler and Margaret A. Townsend of the Kansas Geological Survey, the Division of Water Resources of the State Board of Agriculture, the Kansas Water Office, and the U.S. Geological Survey-Water Resources Division.
Kansas Geological Survey, Kansas Ground Water
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Web version Jan. 2005. Original publication date August 1993.