Water facts 1 WATER AND RIVERS COMMISSION JANUARY 1998 Anoxia Water words Deficiency of oxygen in the water. These Water Facts sheets and other Aquaculture literature on water issues contain a Farming of fresh or saltwater fish, molluscs, crustaceans or plants, usually for commercial purposes. variety of geographic and water resource terms. This sheet explains commonly- Aquatic used terms to help the reader. Living in, growing in, or frequenting water. Aquifer Acid(ic) A geological formation or group of formations capable of See pH. receiving, storing and transmitting significant quantities of water (see Fig. 1). Aerobic Organisms living or active only in the presence of Artesian aquifer free oxygen. A form of confined aquifer in which the pressure in the aquifer is sufficient to cause the well to flow at the surface. Algae A diverse group of aquatic plants containing chlorophyll Figure 1: Schematic diagram showing occurrence of groundwater Unconfined aquifer in and other photosynthetic pigments. Many are microscopic fractures of impermeable rock (often being single cells) but some can be large, including the large seaweeds. They grow as single cells or aggregations Leakage through semi-impermeable Unconfined aquifer sedimentary layer of cells (colonies) (see Phytoplankton and Macroalgae). Salt water wedge SEA Confined aquifer in sedimentary basin Algal bloom Permeable sedimentary rocks The rapid excessive growth of algae, generally caused by SEDIMENTARY BASIN Impermeable rocks high nutrient levels and favourable conditions. Can result Impermeable sedimentary layer Unconfined groundwater Confined groundwater in deoxygenation of the water mass when the algae die, Watertable BASEMENT ROCK leading to the death of aquatic flora and fauna. Beneficial use Alkaline The current or future uses for a water resource which have See pH. priority over other potential uses because of their regional significance to the community. Beneficial use designations Alluvial provide guidance in determining the management and Transported by water flow processes e.g. alluvial plain. protection of the quality and quantity of the resource. Alluvium Benthic organisms (benthos) Ecologically recent sediment deposited by flowing water. Sedentary organisms (plants and animals) that dwell on the sediment at the bottom of a water body. Anaerobic Anoxic; lacking oxygen. Anaerobic organisms can or must Billabong live without oxygen. An Australian term for pools associated with a river which become isolated from the main channel when the river Angiosperms ceases to flow. Flowering plants. Biological control Dam Control of pests using biological means such as natural A structure constructed across a drainage system to store enemies. surface water flow for water supply use or release in a controlled manner for downstream use. A dam can be Biomass constructed across a river valley or at the side of a valley to The amount (weight) of living material (plants or animals) store water pumped into it from “run of river” flow. Dams (see Biota). also store water for farm use. (See Fig. 4). Biological pollution Deoxygenation Pollution by micro-organisms e.g. bacteria and viruses Depletion of oxygen. (see Pollution). Desalination Biota The process of removing salts from water to produce Flora and fauna in a given region. fresher water (see Salinity). Blue greens Destratification Blue greens or Cyanobacteria are an ancient group of Breaking down stratification or layering in a water mass. photosynthetic bacteria without a nucleus which produce their own energy from sunlight. Some can assimilate Detritus dissolved gaseous nitrogen. A number of species produce Organic material, including animal waste products and the toxins. Cells can also cause irritation of the skin and eyes remains of animals, plants and micro-organisms, together on contact. with the associated microbial community (bacteria and fungi). Bore A narrow, lined hole drilled to monitor or withdraw Diatoms groundwater (see Well). Single-celled algae found in most waters. Each cell is surrounded by two overlapping silica cases which show Borefield characteristic patterns. Diatoms are the primary producers A group of bores to monitor or withdraw groundwater. in many food chains. Brackish water Diffuse source pollution See Salinity. Pollution originating from a widespread area e.g. urban stormwater runoff, agricultural runoff. The opposite of Brine point source. Water containing high quantities of sodium chloride. Dinoflagellates Catchment A unicellular microscopic plant characterised by two The area of land which intercepts rainfall and contributes flagella. They are divided into two groups; ‘naked’ with a the collected water to surface water (streams, rivers, thin cell wall and “amoured’ with a theca made of thick wetlands) or groundwater. plates. Some species are toxic. Conservation Discharge The management of human use of the biosphere so that it Volumetric outflow rate of water, typically measured in may yield the greatest sustainable benefit to present cubic metres per second. generations while maintaining its potential to meet the needs and aspirations of future generations. Discharge area Area where groundwater discharges to the surface. Confined aquifer An aquifer saturated with water under pressure and Dissolved oxygen (DO) situated between relatively impervious layers (see Fig. 1) The concentration of oxygen dissolved in water or (see Artesian aquifer). effluent, measured in milligrams per litre (mg/L). Confluence Running together, flowing together or intermingling e.g. where a tributary joins a river. Divertible (renewable) water Floodplain The average annual volume of water which, using current The portion of a river valley next to the river channel practice, could be removed from developed or potential which is or has been periodically covered with water surface or groundwater sources on a renewable during flooding (see Fig. 2). (sustainable) basis at rates capable of serving urban, irrigation, industrial or extensive stock uses. Floodprone land All land subject to flooding including the floodway, flood Drainage basin fringe and flood plain. An area delimited by the Australian Water Resources Council as a basis for presenting surface hydrological data Flood - 100 year (see Catchment). Refers to a severe flood which has a statistical probability of occurring once in 100 years. The 100 year flood level is Ecology generally defined as a contour through the floodplain to The study of the interrelationships between living which this flood will rise. The flood has a 1% chance of organisms and their environment. occuring in any given year; on average it will occur once in every 100 years (see Fig. 2). Ecosystem A term used to describe a specific environment, e.g. lake, Flood fringe to include all the biological, chemical and physical The area of the floodplain, outside the floodway, which resources and the interrelationships and dependencies that is affected by flooding. This area is generally covered by occur between those resources. still or very slow moving waters during the 100 year flood (see Fig. 2). Effluent The liquid, solid or gaseous wastes discharged by a process, Floodway treated or untreated (see Wastewater). The river channel and portion of the floodplain which forms the main flow path of flood waters once the main Entrance bar channel has overflowed (see Fig. 2). Deposit of sand or silt across the entrance to an estuary. Estuary An enclosed or semi-enclosed coastal body of water having an open or intermittently open connection to marine waters and fresh input from land runoff which measurably reduces salinity. Water levels vary in response to ocean tides and river flows. Eutrophication A natural process of accumulation of nutrients leading to increased aquatic plant growth in lakes, rivers, harbours Flora and estuaries. Human activities contributing fertilisers and Plant life. other high nutrient wastes can speed up the process, leading to algal blooms and deterioration in water quality. Flushing time (See Nutrient enrichment, Algal bloom and Trophic status). The time in days that it takes for the water in a semi- enclosed water body to be renewed. Evaporation Loss of water from the water surface or from the soil Foreshore surface by vaporisation. Area of land next to a waterway. Evapotranspiration Fresh water The combined loss of water by evaporation and See Salinity. transpiration. Geomorphology Fauna The study of the origin, characteristics and development of Animal life of a particular area or period of time. landforms. Gigalitre Hydrologic cycle (water cycle) 1000 000 000 litres or 1 million cubic metres or 1 million The continual cycle of water between the land, the ocean kilolitres (kL). and the atmosphere. Grey water Water which has been used for domestic purposes not including sewage. Groundwater Water which occupies the pores and crevices of rock or soil (see Surface water) (see Fig. 1). Groundwater mound Unconfined (shallow) groundwater sometimes forms “mounds” where the watertable slopes away from a high Hydrology central area with groundwater flowing outward to ocean or The study of water, its properties, distribution and rivers. The Gnangara Mound is 70 metres above sea level utilisation above, on and below the earth’s surface. at its highest point. Hypersaline Groundwater and surface water Having a salinity greater than seawater (i.e. above management areas 35 parts per thousand) (see Salinity). Groundwater Area Integrated catchment management (ICM) An area proclaimed under