CT: Ecological flows and water levels are a component of the overall environmental flow and water level, and are established to provide for the ecological values attributed to a particular water body. In the context of the proposed standard, ecological flows and water levels are defined as “the flows and water levels required in a water body to provide for the ecological function of the flora and fauna present within that water body and its margins”.
S: http://mfe.govt.nz/publications/water/proposed-nes-ecological-flows-water-levels-mar08/html/page2.html (last access: 25 February 2015)
N: 1. ecological (adj): 1899, see ecology (1873, oecology, “branch of science dealing with the relationship of living things to their environments,” coined in German by German zoologist Ernst Haeckel (1834-1919) as Ökologie, from Greek oikos “house, dwelling place, habitation” + -logia “study of”; in use with reference to anti-pollution activities from 1960s) + -ical (adjectival suffix, mostly the same as -ic but sometimes with specialized sense (such as historic/historical), Middle English, from Late Latin -icalis, from Latin -icus + -alis). Related: Ecologically.
flow (n): mid-15c., “action of flowing,” from flow (v.). Meaning “amount that flows” is from 1807. Sense of “any strong, progressive movement comparable to the flow of a river” is from 1640s.
2. Figures 4 and 5 illustrate environmental flows applied to river flow. The figures illustrate how specifying the environmental flow also determines the available water. The same concept applies to groundwater, lakes and wetlands, where the variable may be water levels or flow and the timescales, particularly for groundwater, may be years rather than days. The illustrations could apply to each component of environmental flows or water levels – flows could be those that provide for ecological, recreational, cultural and other values. The discussion below, therefore, relates to both ecological flows and the wider concept of environmental flows.
Figure 4 illustrates a very simple environmental flow which is defined by:
- a minimum flow specifying when abstraction must cease or be reduced
- a single allocation limit specifying the quantum of available water, which is over time except when it must be reduced to ensure that the minimum flow is not breached.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=ecological&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=flow&searchmode=none (25 February 2015). 2. http://mfe.govt.nz/publications/water/proposed-nes-ecological-flows-water-levels-mar08/html/page2.html (last access: 25 February 2015).