What is a rain gauge?
A gauge is a device for measuring quantities, so a rain gauge measures the amount of liquid precipitation that has fallen over a set period of time. A similar type of gauge is a snow gauge, which measures solid precipitation. A rain gauge is also known as a udometer or a pluviometer.
Basically rain is collected in a cylinder or bucket, then the amount collected is measured to determine the average rainfall in a given time, say over 24 hours. The frequency of readings depend on the collection requirements of the agency, and can be done manually or by an Automatic Weather Station (AWS). In some cases the rain is kept for further testing, such as the determine the level of pollutants in the precipitation.
Rain gauges also several a few limitations to their usefulness. For example, rain gauges can only collect data for a localised area, as levels of precipitation vary across regions. Extreme weather conditions can also hamper efforts to collect rain data, such as conditions with violent winds (e.g. in hurricanes). Even the gauge itself can be unreliable, as drops will invariably stick to the sides or the funnel, making it slightly inaccurate. In very cold conditions, rain can freeze and not allow any subsequent rain to pass through.
Types of Rain Gauges
Most rain gauges are quite simple devices, including graduated cylinders, weighing gauges, tipping bucket gauges and buried pit collectors.
However one of the more advanced gauges is the optical rain gauge. This device has a row of collection funnels, under which each has a laser diode and a phototransistor detector. When a drop of water is formed and falls to the bottom it traverses the path of the laser beam. This scatters the light making it flash, which is then read by the photodetectors and transmitted or recorded.
Scarcity of Water Resources
There are two core concerns in regards to water resources: water is an essential for the continuation of human life on Earth as well as to support all other life and ecosystems on the planet. This is particularly relevant to Australia where protracted drought and the long-term effects of climate change have made water quite scarce.
Actually, according to the second UN World Water Development Report, if present levels of consumption continue, two-thirds of the global population will live in areas of water stress by 2025. Water stress includes lack of access to safe drinking water and tensions over the regulation and management of shared or common sources of water. This is increasingly a focus of academics and politicians as part of the environmental security school of thought concerned with resource scarcity.
Water Management
Three main elements of managing our water resources include water quality, water efficiency and water conservation. The management of water quality usually refers to drinking water, to ensure that is safe for humans as well as ecosystems. Water quality involves the physical, chemical and biological characteristics of water, of which standards vary. Generally, it seeks to reduce contaminants or maintain water at an appropriate quality for its identified use. The majority of surface water is neither potable (suitable for drinking) nor toxic, even if the salty oceans are excluded.
Water efficiency seeks to accomplish necessary tasks with the minimum amount of water feasible to operate. Proponents of water efficiency promote small behavioural changes by consumers in order to reduce water wastage throughs strategies such as using water efficient devices, fixing leaking taps, only using dishwashers when they have a full load, etc.
Water conservation seeks to reduce the absolute amount of water used as well as recycle waste water. Water conservation efforts in Australia were highlighted during the most severe period of the drought, and included proposals for recycling sewage, waterless car washes, and rainwater harvesting.