Absorption: The process by which a substance is taken into and included within another substance, i. e., intake of water by soil, or intake of gases, water, nutrients, or other substances by plants.
Acre-foot: The volume of water equivalent to an area 1 acre and a depth of I foot.
Adsorption: The increased concentration of molecules or ions at a surface, including exchangeable cations and anions on soil particles.
Base runoff (base flow): Sustained or fair-weather runoff. In most streams, base runoff is composed largely of ground-water effluent.
Bulk density: The ratio of the mass of water-free soil to its bulk volume. Bulk density is expressed in pounds per cubic foot or grams per cubic centimeter and is sometimes referred to as "apparent density." When expressed in grams per cubic centimeter, bulk density is numerically equal to apparent specific gravity or volume weight.
Bypass water: Water diverted for irrigation, but returned to the river or source of supply without being applied to the agricultural land. See Waste.
Cation exchange: The interchange of a cation in solution with another cation on a surface-active material.
Cation exchange capacity: The total quantity of cations that a soil can adsorb by cation exchange, usually expressed as milliequivalents per 100 grams. Measured values of cation exchange capacity depend somewhat on the method used for the determination.
Coefficient of correlation: A statistic used in linear correlation that provides a measure of the proportion of variation in one variable that is associated with variation in another variable.
Cubic feet per second (cfs): A unit expressing rates of discharge.
Cfs-day: The volume of water represented by a flow of 1 cubic foot per second for 24 hours.
Chemical discharge (load): The weight of dissolved chemical constituents passing a stream section in a unit time.
Concentration: The quantity of dissolved material in a unit volume or weight of water. In this report, concentration is expressed in milligrams per liter, parts per million, equivalents per million, specific conductance in micromhos per centimeter at 25°C, and tons per acre-foot.
Concentration ratio: Ratio of the specific conductance or concentration of an ion in a sample of water to the specific conductance or concentration of the corresponding ion in the irrigation water.
Consumptive use: Use of water that is changed from the liquid to the gaseous state by evaporation or transpiration and is thereby lost from the soil-plant ecosystem. See Evapotranspiration.
Conveyance losses (L): Water lost from the canal and laterals by seepage and evaporation.
Deep percolation losses: The part of the irrigation water applied to the land that percolates below the crop root zone, and is not subject to consumptive use by the agricultural crops.
Degradation of water quality: A deterioration in water quality due to increased concentration of any substance classified as a pollutant.
Dilution: The reduction of concentration in water by the addition of water having a lesser concentration of a constituent.
Direct runoff: The runoff entering stream channels promptly after rainfall or snowmelt.
Drainage water: Surface and subsurface water coming from irrigated areas, which may be commingled with precipitation, surface runoff, and groundwater flow from nonirrigated lands.
Effective rainfall: Rainfall during the growing season for each crop.
Efficiency of irrigation: The fraction of the water diverted from a river or other source that is consumed by the crop, expressed as percent. See Consumptive use. Often applied to whole irrigation systems and takes account of conveyance losses.
Equivalent weight: The weight in grams of an ion or compound that combines with or replaces 1 gram of hydrogen. The atomic weight or formula weight divided by its valence.
Evapotranspiration: The consumptive use of water from the soil. Water lost as vapor from a given area of soil through the combined processes of evaporation from the soil surface and transpiration from plants.
Exchangeable cation: A cation that is adsorbed on the exchange complex, and that is capable of exchange with other cations.
Exchangeable sodium percentage: The degree of saturation of the soil exchange complex with sodium. It may be calculated by the formula:
E S P = [(Exchangeable sodium, in milliequivalents per 100 grams of soil / Cation exchange capacity, in milliequivalents per 100 grams of soil) X 100]
Farm delivery (I): Quantity of water delivered to farms for irrigation. Equal to irrigation water delivered to the district less conveyance losses and bypass water.
Hardness: The water property attributable to the presence of alkaline earths, mainly calcium and magnesium.
Infiltration: The downward entry of water into soil.
Irrigation reach: Reach of the Smoky Hill River adjacent to the main part of the irrigation district between stations at river miles 350.0 and 338.0.
Irrigation requirement: The quantity of water exclusive of precipitation required for crop production. This includes surface evaporation and other economically unavoidable wastes. It is usually expressed in depth (volume per unit area) for a given time. (American Society of Agricultural Engineers and American Society of Civil Engineers. )
Irrigation return flow: Any water diverted for irrigation purposes that finds its way back into a source of supply (stream or ground-water basin). This includes bypass water, deep percolation losses, tail-water runoff and seepage.
Leaching: The process of removal of soluble material by the passage of water through soil.
Milliequivalents per liter (me/l): A unit for expressing the concentration of chemical constituents in terms of the interacting values of the electrically charged particles, or ions, in solution.
Milligram per liter (mg/l): A unit for expressing the concentration of dissolved chemical constituents by weight, as milligrams of constituents per liter of solution.
Moisture percentage: 1. Dry-weight basis. The weight of water per 100 units of material dried to constant weight at a standard temperature. 2. Depth basis. The equivalent depth of free water per 100 units of depth of soil. Numerically this value approximates the volume of water per 100 units of volume of soil.
Net drainage: Inflow, excluding canal and lateral waste, to the reach of the Smoky Hill River between Cedar Bluff Fish Hatchery and the station near Schoenchen during periods of stable streamflow.
Net gain (or loss): Increase (or decrease) in water or chemical discharge in each reach of the river during a seepage-salinity survey.
Net input (N): Quantity of irrigation water delivered to the district less waste (W). The algebraic sum of deliveries to farms (I) and losses (L) from the canal and laterals.
Net seepage gain (or loss): Net gain minus tributary inflow to each reach of the river during a seepage-salinity survey. Net seepage gains represent unmeasured inflow, normally effluent ground water, directly to the main stem. Net seepage losses represent unmeasured losses or withdrawals from the channel or stream.
Nutrients: Compounds of nitrogen, phosphorus, potassium, and other elements essential for plant growth.
Percent sodium: The ratio, expressed in percentage, of the sodium ion to the sum of the positively charged ions (calcium, magnesium, sodium, and potassium); all ions, in milliequivalents per liter.
Perennial stream: A stream that flows continuously.
Permeability: The specific property governing the rate or capacity of a porous medium to transmit fluids under standard conditions.
Pesticides: Chemical compounds used for the control of undesirable plants, animals, or insects. The term includes insecticides, weed killers, rodent poisons, fungicides, and growth regulators.
pH: The negative logarithm of the concentration of hydrogen ions, in moles per liter. It is lower than 7 in acid solutions and higher than 7 in basic solutions.
Pollutants: Substances that may become dissolved, suspended, absorbed, or otherwise contained in water, that impair its usefulness.
Pollution: The presence of any substance (organic, inorganic, biological, thermal, or radiological) in water at intensity levels that tend to impair, degrade, or adversely affect its quality or usefulness for a specific purpose.
Salinity: The dissolved-mineral content or total concentration of solids in solution.
Salt balance: The quantity of salt entering an area by way of the irrigation water as compared with the quantity of salts removed from the area by return water.
Salts: Dissolved mineral matter or soluble inorganic salts.
Saturated soil paste: A particular mixture of soil and water. At saturation the soil paste glistens as it reflects light, flows slightly when the container is tipped, and the paste slides freely and cleanly from a spatula for all soils except those with high clay content.
Saturation extract: The solution extracted from a soil at saturation percentage.
Saturation percentage: The moisture content of a saturated soil paste, expressed on a dry-weight basis.
Seepage gains: Unmeasured inflow to the river mainly from small tributaries and from nearby areas.
Seepage losses: That water which is lost from the conveyance channels of rivers or other water-supply systems.
Sodium-adsorption ratio: A ratio for soil extracts and irrigation waters used to express the relative activity of sodium ions in exchange reactions with soil.
where the ionic concentrations are expressed in milliequivalents per liter.
Soil extract: The solution separated from a soil suspension or a soil at a particular moisture content.
Soluble sodium percentage: A term used in connection with irrigation waters and soil extracts to indicate the proportion of sodium ions in solution in relation to the total cation concentration. It may be calculated by the formula:
SSP = [(Soluble sodium concentration, in milliequivalents per liter / Total cation concentration, in milliequivalents per liter) X 100]
Specific conductance: A measure of the ability of a water to conduct an electrical current expressed in micromhos per centimeter at 25°C.
Standard deviation: A statistic used to measure the dispersion of a set of values around their mean.
Tail-water runoff: Irrigation water that runs off the surface of irrigated fields. Sometimes referred to as waste water or surface return flow.
Waste (W): Water discharged from the end of canals and laterals to maintain flow through the system. See Bypass water.
Water table: The upper boundary for ground water. The upper surface of the locus of points at which the pressure in the ground water is equal to atmospheric pressure.
Water year: The 12-month period, October 1 through September 30, designated by the calendar year in which it ends.
Kansas Geological Survey, Geohydrology
Placed on web Nov. 2012; originally published 1975.
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