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Appendix A--Conversion factors
For those readers who may prefer to use metric rather than the inch-pound units used in this report, the factors for converting to the International System of Units (SI) and abbreviations are listed below:
| Multiply inch-pound unit | by | To obtain SI unit |
|---|---|---|
| Length | ||
| inch | 25.4 | millimeter (mm) |
| foot (ft) | 0.3048 meter | (m) |
| mile (mi) | 1.609 | kilometer (km) |
| foot per mile (ft/mi) | 0.1894 | meter per kilometer (m/km) |
| Area | ||
| acre | 4,047 | square meter (m2) |
| square mile (mi2) | 2.590 | square kilometer (km2) |
| Volume | ||
| gallon (gal) | 3.785 | liter (L) |
| gallon (gal) | 0.003785 | cubic meter (m3) |
| acre-foot | 1,233 | cubic meter (m3) |
| acre-foot per year (acre-ft/yr) | 1,233 | cubic meter per year (m+/yr) |
| Flow | ||
| gallon per minute (gal/min) | 0.000063 | cubic meter per second (m3/s) |
| gallon per day (gal/d) | 0.003785 | cubic meter per day (m3/d) |
| foot per day (ft/d) | 0.3048 | meter per day (m/d) |
| square foot per day (ft2/d) | 0.0929 | square meter per day (m2/d) |
| Temperature | ||
| degree Fahrenheit (°F) | 5/9 (°F - 32) | degree Celsius (°C) |
| Specific conductance | ||
| micromho per centimeter at 25° Celsius (µmho/cm at 25°C) |
1.000 | microsiemens per centimeter at 25° Celsius (µS/cm at 25°C) |
National Geodetic Vertical Datum of 1929 (NGVD of 1929): A geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called mean sea level. "NGVD of 1929" is referred to as sea level in this report.
Appendix B--Definition of terms
Anticline--A structural fold in rocks where strata are convex upward.
Aquifer--A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.
Artesian aquifer--An aquifer containing ground water under pressure significantly greater than atmospheric. Its upper limit is the bottom of a bed of distinctly lower hydraulic conductivity than that of the material in which the artesian ground water occurs.
Artesian well--A well deriving its water from an artesian aquifer. The water level stands above the top of the artesian water body in an artesian well.
Borehole geophysics--All techniques of lowering sensing devices down a well or test hole and recording some physical measurement that may be interpreted in terms of the physical characteristics of the rocks, the fluid contained in the rocks, and the construction of the well.
Classification of water for irrigation--(definitions were developed by the U.S. Salinity Laboratory Staff, 1954).
- Low-salinity water (C1)--Water can be used for irrigation with little likelihood that soil salinity will develop.
- Medium-salinity water (C2)--Water can be used if a moderate amount of leaching occurs.
- High-salinity water (C3)--Water cannot be used on soils with restrictive drainage; special management for salinity control may be required; and plants with good salt tolerance should be selected.
- Very high salinity water (C4)--Water is not suitable for irrigation purposes under ordinary conditions.
- Low-sodium water (S1)--Water can be used for irrigation with little danger of the development of harmful levels of exchangeable sodium in the soil.
- Medium-sodium water (S2)--Water will present an appreciable sodium hazard in fine-textured soil that has a high cation-exchange capacity, unless gypsum is present in the soil. This water can be used on coarse-textured or organic soils with good permeability.
- High-sodium water (S3)--Water may produce harmful levels of exchangeable sodium in most soils and will require special soil management, good drainage, high leaching, and organic conditions.
- Very high sodium water (S4)--Water is generally unsatisfactory for irrigation purposes except at low and perhaps medium-salinity levels.
Confining bed--A body of "impermeable" material stratigraphically adjacent to one or more aquifers.
Deflocculate--To convert into very fine particles.
Digital model--A simplified mathematical representation of a complex system, in which a computer program is used to solve groundwater-flow equations.
Formation--A body of rock that can be mapped or traced and is generally characterized by some degree of internal lithologic homogeneity or distinctive lithologic features.
Freshwater--For the purpose of this report, water containing less than 1,000 milligrams per liter of dissolved solids.
Geohydrologic unit--An aquifer, a confining bed, or a combination of aquifers and confining beds that comprise a framework for a reasonably distinct hydraulic system.
Hardness of water--A property of water generally related to its soap-consuming capacity; it is caused by the presence of polyvalent cations in the water that form insoluble compounds with soap. Hardness is reported in terms of an equivalent concentration of calcium bicarbonate.
| Hardness classification (from Hem, 1970) |
Hardness range (milligrams per liter of calcium carbonate) |
|---|---|
| soft | 0-60 |
| moderately hard | 61-120 |
| hard | 121-180 |
| very hard more than | 180 |
Hydraulic conductivity--The volume of water at the existing kinematic viscosity that will move in unit time under a unit hydraulic gradient through a unit area measured at right angles to the direction of flow.
Hydraulic gradient--The change in static head per unit of distance in a given direction.
Hydraulic head--Height of the potentiometric surface of an aquifer above a given subsurface point.
Hydrograph--A graph showing some property of water with respect to time, such as the hydraulic head measured in a well.
Lenticular--Shaped like a double convex lens, thick in the middle and thinning at the edges.
Piezometer--A special well in a selected location for observing fluid level and pressure changes.
Porosity--The ratio of the aggregate volume of interstices or voids in a rock or soil to its total volume, usually stated as a percentage.
Potable water--Water that is palatable and fit for human use; water that has been treated so as to be tolerably low in objectionable taste, odor, color, and turbidity, and of a temperature suitable for the intended use.
Potentiometric surface--A surface that represents the static head. It is defined by the levels to which water will rise in tightly cased wells.
Recharge--Amount of water added to the zone of saturation.
Resistivity--The resistance to the flow of electrical current through material. The electrical resistivity of a rock depends on physical properties of the rock and the fluids it contains.
Saline water--Water containing 1,000 milligrams per liter or more of dissolved solids.
| Classification of saline water (from Hem, 1970) |
Dissolved solids (milligrams per liter) |
|---|---|
| slightly saline | 1,000-3,000 |
| moderately saline | 3,000-10,000 |
| very saline | 10,000-35,000 |
| briny more than | 35,000 |
Saturated thickness--That amount of a water-bearing material in which all voids, large and small, are ideally filled with water under pressure greater than atmospheric.
Semiconfined aquifer--Aquifer in which semiartesian conditions exist. Confining beds leak water either to or from the aquifer.
Sodium-adsorption ratio (SAR)--Related to the adsorption of sodium from water by the soil to which the water has been added. It is determined by the following relation where ion concentrations of sodium (Na+), calcium (Ca+2), and magnesium (Mg +2) are expressed in milliequivalents per liter:
SAR = (Na+) / {([(Ca+2) + (Mg+2)]/2)1/2}
Specific conductance--The ability of a substance to conduct an electric current. It is the conductance of a body of unit length and unit cross section at a specified temperature. Specific conductance can be used as a measure of the concentration of dissolved solids in a water sample.
Spontaneous potential--An electrical method in which a spontaneous electrical field is developed between the borehole fluid and the surrounding rock material.
Storage coefficient--Volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head.
Syncline--A structural fold in rocks where strata are concave upward.
Transmissivity--The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width of the aquifer under a unit hydraulic gradient.
Unconfined aquifer--An aquifer having a water table.
Water table--The potentiometric surface in an unconfined aquifer at which the pressure is atmospheric. It is defined by the levels at which water stands in wells that penetrate the aquifer enough to hold standing water.
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Kansas Geological Survey, Geohydrology
Placed on web June 14, 2013; originally published 1985.
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