Hydraulic and earth engineering – Drainage or irrigation – Control means responsive to sensed condition
Reexamination Certificate
2000-05-19
2002-10-22
Shackelford, Heather (Department: 3673)
Hydraulic and earth engineering
Drainage or irrigation
Control means responsive to sensed condition
C405S040000, C405S045000, C405S052000, C210S170050, C210S747300
Reexamination Certificate
active
06467994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to long-term underground water recharge, and in particular, to the use of storm and other run-off water, or water that has been collected, to cause such recharge and produce additional benefits therefrom.
2. Problems in the Art
Soil functions as a plant growth medium, a regulator and partitioner of water flow, and as a buffer of environmental change. A National Research Council report reviews soil's role in the hydrologic cycle (National Research Council. 1993. Soil and Water Quality: An Agenda for Agriculture. National Academy Press. Washington, D.C.). Rainfall in terrestrial ecosystems falls on the soil surface where it either infiltrates the soil or moves across the soil surface into streams or lakes. The condition of the soil surface determines whether rainfall infiltrates or runs off. If it infiltrates the soil, it may be stored and later taken up by plants, move into ground waters, or move laterally through the earth, appearing later in springs or seeps. This partitioning of rainfall between infiltration and run-off determines whether a storm results in a replenishing rain or a damaging flood. The movement of water through soils to streams, lakes, and ground water is an essential component of recharge and base flow in the hydrological cycle (Stephens, D.B. 1995. Vadose Zone Hydrology . Lewis Publications, Boca Raton, Fla. 347 pp.).
Current engineering practices in the Southwest United States and other places often reduce infiltration and increase run-off by collecting and conveying storm water quickly and efficiently for ultimate discharge to an existing surface water course. The goals of this management strategy are to reduce hazards to the public and minimize property damage. Although this strategy maximizes the objectives in terms of safety and risk reduction, it prevents the beneficial use of storm waters through recharge. Conveyance times are minimized while flow rates are maximized to remove it from highways, streets and public areas. With concern growing over the availability of water supplies for public and industrial use, alternative uses of storm water must be considered, and if practical, implemented.
Root systems can increase soil saturated hydraulic conductivity over an order of magnitude (Prieksat, M. A., T. C. Kaspar, and M. D. Ankeny. 1994. Positional and temporal changes in ponded infiltration in a corn field. Soil Sci. Soc. Am. J. 58:181 -184). Increased root biomass results in more root channels as well as an associated increase in faunal activity creating wormholes and other channels. These preferential flow paths increase saturated hydraulic conductivity. In arid and semi-arid systems, plant growth is usually limited by water availability. Because plants maintain fairly constant root:shoot ratios, root mass and soil hydraulic conductivity are often directly correlated with water availability.
Therefore, current practices might produce beneficial results in one sense, namely the more efficient removal of run-off water, and in another sense it can be detrimental.
Most previous buffer zone and riparian zone research (primarily from the Northeast and the Midwest) has operated on the premise that vegetation is necessary to establish control to run-off. In the western United States (U.S.), establishment of vegetation is often problematic due to intermittent water supply. Thus, contrary to what is typically found in the eastern U.S., run-off must be controlled to (re)establish vegetation in arid and semi-arid areas. Run-off control can provide water for establishment of vegetation. One problem is obvious: to obtain the benefits of vegetated buffer zones in arid and semi-arid areas, we need effective methods to convert transient run-off into a steady water source for establishment of vegetation.
Healthy riparian areas provide numerous benefits when viewed as a component of the basic hydrologic unit, i.e., the watershed. Woody riparian species provide channel and bank stability and thus prevent incisement of the channel. Local ground-water levels are maintained due to slow release of bank storage. Natural fluvial processes create channels which efficiently transport water. Water quality is improved where sources of sediment from destabilized banks are eliminated. Shading reduces extreme fluctuations in temperature and evaporative losses from perennial streams. Additionally, riparian zones can attenuate high flood flows while promoting sediment deposition and ground water recharge. These attributes optimize the hydrologic response of a watershed with regards to the storage and discharge of water.
From a soil science perspective, grazing and cropping practices have often reduced soil water storage capacity and increased run-off. A common result has been lowering of local water tables with permanent stream reaches becoming intermittent. From a hydrological perspective (e.g., Menzel, B.W. 1983. Agricultural management practices and the integrity of instream biological habitat. pp. 305-329, in Agricultural Management and Water Quality, F. W. Schaller and G.W. Bailey, eds. Iowa State University Press. Ames, Iowa), these same agricultural practices lead to an exaggerated seasonal flow regime and increase the frequency, severity, and unpredictability of high-volume flows.
Subsurface flow, including that from recharge galleries, generally provides a more constant source of water than surface flow. Obligate phreatophytes, such as cottonwoods, require a constant source of water for survival. Facultative phreatophytes, such as salt cedar (Tamarix sp.), tolerate drier periods. In southwestern riparian zone forests (bosques), replacement of native vegetation (such as willow and cottonwood) by exotics (such as salt cedar and Russian olive) has occurred with watershed degradation over time. The recharge component of the water balance considered critical for maintaining base flow in streams is therefore important in maintaining desired vegetation.
Surface water have been diverted and infiltrated for thousands of years in various parts of the world (Bruins, J. J., M. Evenari, and U. Nessler. 1986. Rainwater-harvesting agriculture for food production in arid zones: the challenge of the African famine. Appl. Geography. 6:13-32). Wills (1988) summarizes much of the literature on prehistoric southwestern U.S. agriculture and water harvesting (Wills, W. H. 1988. Early prehistoric agriculture in the American southwest. 188 pp. School of American Research Press, Santa Fe, N.Mex.). The primary objective of water harvesting is short-term water storage in the soil profile for crop growth. In the southwest, Native American farmers place fields to optimize water and sediment trapping These relationships among soil, vegetation, and erosion/deposition are discussed by Jenny (Jenny, H. 1980. The Soil Resource. Springer-Verlag, New York). Soils derived from aeolian deposits, alluvium and colluvium are generally considered unsuitable for agriculture because of their high infiltration rates (Tabor, J. A. 1995. Improving crop yields in the Sahel by means of water-harvesting. J. of Arid Environments. 30:83-106).
While water erosion processes are complex, as evidenced by an abundant and growing amount of technical literature, the principals of erosion control are often stated as these relatively simple principles. Plant, plant residue, or mulch cover should be increased in intensity or in time to decrease energy and volume of run-off water. In the west, local increase of recharge also may facilitate erosion control. The rationale is this: Increased recharge results in increased bank vegetation, and increased bank vegetation reduces bank erosion. Bank erosion is a major contributor to the sediment load in many western streams.
Therefore, the potential benefit can be seen in the encouragement of vegetation growth, not only for reducing possible erosion, and not only for the increased ability for long-term recharge of underground infiltration galleries, but vegetation can actually increase the holding potential
Ankeny Mark D.
Kelsey James A.
Daniel B. Stephens & Associates, Inc.
Lagman Frederick L.
McKee Voorhees & Sease, P.L.C.
Shackelford Heather
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