Groundwater, located beneath the earth's surface in soil porespaces and in the fractures of rock formations, isa natural storage of rainwater that can be accessed at any time. A unit of rock or an unconsolidated deposit is called an aquife rwhen it can yield a usable quantity of water. Groundwater is recharged from, and eventually flows to, the surface naturally; natural discharge often occurs at springs and seeps, and can form oases or wetlands, emerges out of the ground surface. Depth to groundwater or the water table depends on hydrogeology of the ground and needs to be understood for sustainable management of groundwater.
Groundwater, which forms an important source for drinking purposes, is often withdrawn for agricultural, municipal and industrialuse by constructing and operating extraction wells. Extraction of water requires energy. In the olden times when the source of power was limited to animal irrigation with groundwater was limitedgroundwater was rightly considered as an abundant resource, since the withdrawals were less than the recharge of groundwater.In South Asia, inexpensive treadle pumps have been successful in extracting irrigation water from shallow aquifers, allowing farmers to make good use of the household labour and increase production and income.With the advent of fossil fuels, use of mechanised pumps, and wide distribution of electricity, particularly in semi-arid regions, the groundwater provides an opportunity for equitable growth through irrigated agriculture.
Over-use, oroverdraft, has resulted in continuous lowering of water table, amounting to mining of groundwater and resulting in major problems for human use as well as to the environment such as groundwater-related subsidence and saltwater intrusion.
Importance of groundwater to ecosystems to sustain rivers,wetlandsandlakes, as well as subterranean ecosystems withinkarstor alluvial aquifersis not fully understood and is often overlooked.‘Groundwater recharge', that involves capturing rainwater that would otherwise run-off, and using it to refill aquifers is a possible solution. However, such a recharge should be based on the understanding of the hydrogeology and full caution against potential of polluting groundwater. Movement of water and dispersion within the aquifer can spread the pollutant over a wider area, which can then intersect with groundwater wells or daylight into surface water such asseepsandsprings, making the water supplies unsafe for humans and wildlife. Presence of natural impurities in groundwater such as Arsenic in Bangladesh, and other parts of the world, in water used to grow crops could degrade soils, reduce yields – and find its way into food.
Today, more than 30% of irrigated areas around the world sources groundwater, particularly in China, India, Pakistan and Mexico. At the same time due to over exploitation of groundwater beyond the recharge capacity and the continuous lowering of water table large chunks of energy is being consumed making groundwater irrigation unsustainable in the long term. Groundwater management principles need to be evolved based on scientific assessments, institutionally and legally supported, and implemented by empowering various stakeholders.
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Irrigation
Sources of Irrigation
Irrigation History +
Sources of Irrigation +
IMPROVING SOIL MOISTURE +
Ponds +
Tanks +
Diversion Weirs +
Dams and Reservoirs +
Groundwater +
Conjunctive Water Use +
Wastewater +
Poor Quality Water +
Application of Irrigation water
Canal Irrigation +
Flood Irrigation +
Deficit Irrigation +
Supplemental Irrigation +
Sprinkler Irrigation +
Drip Irrigation +
Lift Irrigation +
Centre Pivot Irrigation +
Tidal Irrigation +
Micro-Irrigation Technologies for Small Holders +
Automatic Irrigation Systems +
Pressurized Irrigation +
Irrigation in Viticulture +
Purpose of Irrigation
Instruments and implements of Irrigation
Pumps +
Centrifugal Pumps +
Submersible Pumps +
Turbine and Jet Pumps +
Conveying Pipes +
Sprinklers +
Drippers +
Canal Automation Systems +
Irrigation Management
Economics of Irrigation System +
I&D System Types +
I&D Investment Functions +
I&D Management Issues +
Participatory I&D Management +
Equity in Irrigation +
Irrigation Services +
Irrigation and environment
Pollution and Irrigation +
Irrigation and Climate Resilience +
Environmental Aspects of Irrigation +
Environmental Impacts of Irrigation +
Green Lawn Irrigation +
Safe Use of Waste Water in Irrigation +
Organic Agriculture +
Soil Health +
Soil Health Management +
Quality of Irrigation Water +
Capacity Development
Drainage
Drainage Types and Systems
Agricultural Drainage +
Field Drainage systems +
Canal Irrigation and Drainage +
Surface Drainage Systems +
Subsurface Drainage +
Mole Drainage +
Bio-Drainage +
Regional Bio-Drainage +
Drainage Issues
- Geohydrology, Hydrogeology or Groundwater hydrology
- Groundwater runoff
- Groundwater storage
- Groundwater province
- Groundwater
- Capillary groundwater, or Fringe water
- Groundwater table
- Free groundwater, Phreatic water, or Non-artesian water
- Confined water, or Confined groundwater
- Perched water, or Perched groundwater
- Semiperched groundwater
- Fixed groundwater
- Attached groundwater
- Groundwater flow
- Groundwater reservoir
- Groundwater artery
- Groundwater divide
- Water-table contour, or Groundwater contour
- Groundwater cascade
- Groundwater dam
- Groundwater ridge
- Interstream groundwater ridge
- Groundwater mound, or Groundwater hill
- Groundwater trench
- Groundwater withdrawal, or Groundwater extraction
- Water surface (groundwater)
- Effective velocity (of groundwater), Actual velocity (of groundwater), True velocity (of groundwater), or Field velocity (of groundwater)
- Apparent velocity (of groundwater)
- Average velocity (of groundwater)
- Critical velocity (of groundwater )
- Groundwater turbulent flow
- Groundwater recharge
- Groundwater balance, or Groundwater budget
- Groundwater increment, or Groundwater accretion
- Groundwater decrement
- Groundwater inventory
- Groundwater equation
- Groundwater management
- Groundwater model
- Groundwater balance
- Groundwater basin
- Groundwater conservation
- Groundwater mining
- Groundwater overdraft
- Groundwater storeys
- Observation well, Groundwater station, Monitor well, or Piezometer
- Prospecting (groundwater)
- Irrigation from groundwater
- Groundwater table
- Groundwater table
- Groundwater contamination
- Groundwater flooding
- Artificial groundwater recharge
- Groundwater system, or Groundwater basin
- Groundwater investigations, or Geohydrological investigations