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Water storage is a broad term referring to storage of both potable water for consumption, and non potable water for use in agriculture. In both developing countries and some developed countries found in tropical climates, there is a need to store potable drinking water during the dry season. In agriculture water storage, water is stored for later use in natural water sources, such as groundwater aquifers, soil water, natural wetlands, and small artificial ponds, tanks and reservoirs behind major dams. Storing water invites a host of potential issues regardless of that waters intended purpose, including contamination through organic and inorganic means.[citation needed]

Great Nile Dam, at first cataract, Egypt., 1908, Copyright, 1908, by Stereo-Travel Co. Brooklyn Museum Archives

Types of water storage

Groundwater

Groundwater is located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. There are two broad types of aquifers: An unconfined aquifer is where the surface is not restricted by impervious rocks, so the water table is at atmospheric pressure. In a confined aquifer, the upper surface of water is overlain by a layer of impervious rock, so the groundwater is stored under pressure.[citation needed]

Soil moisture

Soil moisture is the water held between soil particles in the root zone (rhizosphere) of plants, generally in the top 200 cm of soil. Water storage in the soil profile is extremely important for agriculture, especially in locations that rely on rainfall for cultivating plants. For example, in Africa rain-fed agriculture accounts for 95% of farmed land.[1]

Wetlands

Wetlands span the surface/sub-surface interface, storing water at various times as groundwater, soil moisture and surface water. They are vital ecosystems that support wildlife and perform valuable ecosystem services, such as flood protection and water cleansing. They also provide livelihoods for millions of people who live within and around them. For example, the Inner Niger River Delta in the Western Sahel zone supports more than a million people who make their living as fishermen, cattle breeders or farmers, using the annual rise and fall of the river waters and its floodplains.[2]

Ponds and tanks

Ponds and water tanks can be defined as community-built and household water stores, filled by rainwater, groundwater infiltration or surface runoff. They are usually open, and therefore exposed to high levels of evaporation. They can be a great help to farmers in helping them overcome dry spells. However, they can promote vector-borne diseases such as malaria or schistosomiasis.[citation needed]

Dams and reservoirs

In the past, large dams have often been the focus of water storage efforts. Many large dams and their reservoirs have brought significant social and economic benefits. For example, Egypt's Aswan High Dam, built in the 1960s, has protected the nation from drought and floods and supplies water used to irrigate some 15 million hectares. However, dams can also have great negative impacts. Because sediment is trapped by the Aswan High Dam, the Nile no longer delivers nutrients in large quantities to the floodplain. This has reduced soil fertility and increased the need for fertilizer.[3]

Planting basins

Rainfed agriculture constitutes 80% of global agriculture. Many of the 852 million poor people in the world live in parts of Asia and Africa that depend on rainfall to cultivate food crops. As the global population swells, more food will be needed, but climate variability is likely to make farming more difficult. A range of water stores could help farmers overcome dry spells that would otherwise cause their crops to fail. Field studies have shown the effectiveness of small-scale water storage. For example, using small planting basins to 'harvest' water in Zimbabwe have been shown to boost maize yields, whether rainfall is abundant or scarce. In Niger, they have led to three or fourfold increases in millet yields.[4]

Nyalual Deng Joak carries a distribution of buckets back to her community. As well as constructing latrines and conducting health campaigns, Oxfam provides essential materials such as buckets, soap and mosquito nets that help people store water safely and protect family members from fatal illness.

Contamination

As of 2010, it was reported that nearly half of the global population depends on in-home water storage due to a lack of adequate water supply networks.[5] Many of the in-home solutions have improvised from available materials. It has been suggested that the lack of proper tools and equipment for construction, leads to a system more likely to contain breaches, making them more susceptible to contamination from the environment and users.[5]

Common Factors

  • Roofing Materials [6]
  • Hand-washing: When water is stored in tanks for consumption hand-washing can become a factor in the tank lacks a proper faucet system, or if there is a lack of education on the risks posed by using hands for water consumption. It was found in a 2009 study that water tanks in Tanzania contained 140-180% more fecal indicator bacteria than the water they were supplied with.[5]
  • Fertilizer Runoff [7]

Common Risks

See also

References

  1. ^ Finding ways to boost productivity and reduce poverty through better water management in Africa Success Stories, Issue 4, 2010, IWMI.
  2. ^ The Wetlands and Poverty Reduction Project, Wetlands International, 12-2005
  3. ^ McCartney, M. and Smakhtin, V. Blue Paper. Water storage in an era of climate change: Addressing the challenge of increasing rainfall variability, IWMI
  4. ^ Diverse water sources key to food security: report, Reuters, September 5, 2010
  5. ^ a b c Pickering, Amy J.; Davis, Jennifer; Walters, Sarah P.; Horak, Helena M.; Keymer, Daniel P.; Mushi, Douglas; Strickfaden, Rachelle; Chynoweth, Joshua S.; Liu, Jessie (2010-05-01). "Hands, Water, and Health: Fecal Contamination in Tanzanian Communities with Improved, Non-Networked Water Supplies". Environmental Science & Technology. 44 (9): 3267–3272. doi:10.1021/es903524m. ISSN 0013-936X. 
  6. ^ Kashmiri, S. V.; Hotchkiss, R. D. (September 1975). "A study of Pneumococcal merodiploids at the molecular level". Genetics. 81 (1): 9–19. PMC 1213391Freely accessible. PMID 1324. 
  7. ^ Wigginton, Nicholas S. (2015-09-18). "Fertilizing water contamination". Science. 349 (6254): 1297–1298. doi:10.1126/science.349.6254.1297-g. ISSN 0036-8075. 

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