Irrigation Definitions PDF

1 Definition 2.1 access areas areas open for public entry such as golf courses, public and private parks, playgrounds, schoolyards and playing fields, residential landscapes and industrial park landscapes 2.2 active storage volume of water stored in reservoir between the minimum water level...

1 Definition 2.1 access areas areas open for public entry such as golf courses, public and private parks, playgrounds, schoolyards and playing fields, residential landscapes and industrial park landscapes 2.2 active storage volume of water stored in reservoir between the minimum water level and normal water level 2.3 actual crop evapotranspiration rate of evapotranspiration equal to or smaller than predicted crop evapotranspiration as affected by the level of available soil water, salinity, field size or other causes 2.4 afflux elevation rise in maximum flood level from the original unobstructed flood level which result after an obstruction to the flow such as a dam, has been introduced 2.5 algal bloom overgrowths of algae in water producing dangerous toxins in fresh or marine water 2.6 application efficiency ratio of the average depth of irrigation water infiltrated and stored in the root zone to the average depth of irrigation water applied 2.7 aquifer geologic formation which contains water and transmits it at a rate sufficient to be economically developed for pumping artificially developed well 1 2.8 area cross-sectional area of the flow which is measured perpendicular to the direction of flow 2.9 basin field that is level in all directions, encompassed by a dike to prevent runoff, and provides an undirected flow of water onto the field 2.10 basin irrigation type of surface irrigation where water is applied to the basin through a gap in the perimeter dike or adjacent ditch; water is retained until it infiltrates into the soil or the excess is drained off 2.11 bearing capacity maximum average contact pressure between the foundation and the soil which should not produce shear failure in the soil 2.12 border irrigation method of irrigation which makes use of parallel border strips where the water flows down the slope at a nearly uniform depth 2.13 border strip area of land bounded by two border ridges or dikes that guide the irrigation stream from the inlet point of application to the ends of the strip 2.14 channel bed slope inclination or elevation drop per unit length of the channel bottom 2.15 confined aquifer groundwater that is confined by relatively impermeable layer 2.16 contamination introduction of substances not found in the natural composition of water that make the water less desirable or unfit for intended use 2.17 conveyance efficiency ratio between water received at the inlet for a block of fields to that released at the project’s headwork 2 2.18 conveyance loss loss of water from a channel during transport due to seepage and percolation 2.19 critical depth depth of water flow where the energy content is at minimum hence, no other backwater forces are involved 2.20 crop coefficient ratio of the actual crop evapotranspiration to its potential evapotranspiration 2.21 crop evapotranspiration rate of evapotranspiration of a disease-free crop growing in a large field (one or more ha) under optimal soil conditions, including sufficient water and fertilizer and achieving full production potential of that crop under the given growing environment; includes water loss through transpiration by the vegetation, and vaporation from the soil surface and wet leaves 2.22 cropping pattern sequence of different crops grown in regular order on any particular field or fields 2.23 crop water requirements amount of water used in producing crops which is the sum of evapotranspiration or consumptive use plus seepage and percolation losses 2.24 dam any barrier constructed to store water 2.25 dam height vertical distance from lowest point of the ground line to the dam crest 2.26 dead storage volume below the intake structure; sediment volume based on 25 years of accumulation in the reservoir 2.27 depth depth of water in the channel cross-section 3 2.28 designed height actual height of the embankment after settlement 2.29 design irrigable area maximum area which an irrigation project can serve considering the extent of arable lands and the available water supply 2.30 distribution uniformity numerical value on the uniformity of application for agricultural irrigation systems 2.31 diversion dam structure or weir provided across the river or creek to raise its water level and divert the water into the main canal to facilitate irrigation by gravity 2.32 diversion water requirement the total quantity of water diverted from a stream, lake, or reservoir, or removed from the ground in order to irrigate a crop