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Desert, Desertification and Land Degradation
Published in Ajai, Rimjhim Bhatnagar, Desertification and Land Degradation, 2022
Although in many parts of the world, dryland farming is dependent exclusively on rainfall, yet, groundwater is also generously used in many places. In countries like Canada and the United States, dryland farming often depends on stored soil water at the time of crop sowing in addition to the rainfall (Dregne and Willis 1983). In India, 60% of irrigated agriculture is produced by mining groundwater (Gandhi and Bhamoriya 2011). But groundwater does not recharge very well due to the typical soil properties, variable rainfall and poor land management practices. Even if it gets recharged well, the rate of its consumption supersedes the rate of recharge. With regard to groundwater recharge, the major players are the water holding capacity of the soil and the land use management practice. Because much of the rainfall is lost by evapotranspiration or run-off, the groundwater is recharged only by means of seepage through the soil profile, which is an extremely slow process. Furthermore, the available water for use in drylands is sometimes also affected by salinity (Armitage 1987) which hampers its direct use as potable water or for farming. In some regions, fossil water reservoirs (groundwater that has remained in aquifer since ages) exist and are mined and used by human beings. Examples of such reservoirs are the deep aquifer under the North China Plain and the Saudi aquifer. In many places like North China, these reserves are used for farming.
Water
Published in John C. Ayers, Sustainability, 2017
The use of fossil water is especially unsustainable. Fossil water is very old water contained in deep aquifers. It is considered a nonrenewable source of water because the recharge rate is so low that it would take hundreds or thousands of years to replace water that is withdrawn. If we harvest aquifers too quickly, aquifer water becomes a nonrenewable resource, and over time water production follows a Hubbert curve, peaking and then declining (Figure 12.2). This is particularly worrisome in arid regions where food is unsustainably produced by harvesting fossil water. The permanent loss of groundwater supplies could seriously jeopardize food security. As noted by Charles Bowden, “Humans build their societies around consumption of fossil water long buried in the earth, and these societies, being based on temporary resources, face the problem of being temporary themselves.4”
Water Systems (Drinking Water Quality)
Published in Herman Koren, Best Practices for Environmental Health, 2017
About 1% of the fresh water in the world is available for human use, and this has stayed constant over many centuries despite the fact that there is an enormous demand for water created by huge increasing populations, which will continue to grow in the foreseeable future. There is a vast difference in the distribution of fresh water in various parts of the world as well as in the United States. Climate change, increasingly more powerful storms, and droughts are making the situation worse in certain areas. This is compounded by substantial population pressure in coastal areas and the growth of large cities and communities. Certain water sources, such as fossil water which has been trapped for a very substantial amount of time, may be used but not replenished. While the demand for safe drinking quality water is expanding rapidly, the supplies are diminishing.
Profitability of irrigation and value of water in Oklahoma and Texas agriculture
Published in International Journal of Water Resources Development, 2018
Increasing scarcity of water for agricultural production has been a long-term problem in many US states, especially in the High Plains region over the Ogallala Aquifer. Spanning several states (Texas, Oklahoma, Colorado, New Mexico, Kansas, Nebraska, Wyoming and South Dakota), the Ogallala Aquifer is one of the world’s largest. It contains fossil water, which is defined as groundwater trapped in uncontained places in an aquifer for millennia. In most parts of the Ogallala Aquifer (except for Nebraska) this fossil water is a non-renewable resource due to very low recharge rates resulting from the lack of or low precipitation. Those fossil water resources have been over-exploited for many years, with groundwater levels in some states declining by 75% between 2011 and 2013 (see Figure A1 in the supplemental online material, https://doi.org/10.1080/07900627.2017.1353410).