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Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by a variety of factors, such as climate change and overexploitation of soil as a result of human activity.
Erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature reserves. It can also be caused by immobile, travel restricted populations of native or non-native wild animals.
Mauritania, a country in the western region of the continent of Africa, is generally flat, its 1,030,700 square kilometres forming vast, arid plains broken by occasional ridges and clifflike outcroppings. Mauritania is the world’s largest country lying entirely below an altitude of 1,000 metres (3,300 ft). It borders the North Atlantic Ocean, between Senegal and Western Sahara, Mali and Algeria. It is considered part of both the Sahel and the Maghreb. A series of scarps face southwest, longitudinally bisecting these plains in the center of the country. The scarps also separate a series of sandstone plateaus, the highest of which is the Adrar Plateau, reaching an elevation of 500 metres or 1,640 feet. Spring-fed oases lie at the foot of some of the scarps. Isolated peaks, often rich in minerals, rise above the plateaus; the smaller peaks are called Guelbs and the larger ones Kedias. The concentric Guelb er Richat is a prominent feature of the north-central region. Kediet ej Jill, near the city of Zouîrât, has an elevation of 915 metres or 3,002 feet and is the highest peak.
Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and animals. In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind (aeolean) erosion, zoogenic erosion and anthropogenic erosion such as tillage erosion. Soil erosion may be a slow process that continues relatively unnoticed, or it may occur at an alarming rate causing a serious loss of topsoil. The loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage networks. Soil erosion could also cause sinkholes.
The Sahel is a region in Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid climate, it stretches across the south-central latitudes of Northern Africa between the Atlantic Ocean and the Red Sea.
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth. Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts.
Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and bush fires.
Nick Middleton is a British physical geographer and supernumerary fellow of St Anne's College, Oxford. He specialises in desertification.
The Sahel region of Africa has long experienced a series of historic droughts, dating back to at least the 17th century. The Sahel region is a climate zone sandwiched between the Sudanian Savanna to the south and the Sahara desert to the north, across West and Central Africa. While the frequency of drought in the region is thought to have increased from the end of the 19th century, three long droughts have had dramatic environmental and societal effects upon the Sahel nations. Famine followed severe droughts in the 1910s, the 1940s, and the 1960s, 1970s and 1980s, although a partial recovery occurred from 1975-80. The most recent drought occurred in 2012.
Farmer-managed natural regeneration (FMNR) is a low-cost, sustainable land restoration technique used to combat poverty and hunger amongst poor subsistence farmers in developing countries by increasing food and timber production, and resilience to climate extremes. It involves the systematic regeneration and management of trees and shrubs from tree stumps, roots and seeds. FMNR was developed by the Australian agricultural economist Tony Rinaudo in the 1980s in West Africa. The background and development are described in Rinaudo's book The Forest Underground.
Andrew Shaw Goudie is a geographer at the University of Oxford specialising in desert geomorphology, dust storms, weathering, and climatic change in the tropics. He is also known for his teaching and best-selling textbooks on human impacts on the environment. He is the author, co-author, editor, or co-editor of forty-one books and more than two hundred papers published in learned journals. He combines research and some teaching with administrative roles.
The Ader Doutchi Maggia Rural Development Project (PDR-ADM), better known as Keita Project, is a development project in Keita Department in central Niger. The Project has taken place in four phases, the first starting in 1983 and the most recent beginning in 2003. It was run initially by the Italian government's Italian Development and Cooperation Bureau, as part of its 'Italian Initiative for the Sahel', with significant help from the United Nations. The fourth phase is being run by the UNDP. As of September 2009, the Project has cost approximately US$88 million, with the majority of funding coming from the Italian government.
The land imprinter is a no-till device for establishing grass cover in arid environments and deserts. The imprinter consists of a metal roller, with steel angles welded to the surface in various configurations. The angled teeth of the imprinter cut through weeds and brush to form a mulch, while the teeth press seeds of grasses and other plants into the soil. The imprints remain stable for approximately two years. During that time, imprints funnel water toward seedlings, protect them from wind, and concentrate nutrients for plant growth.
Michael Mortimore was a British geographer and a prolific researcher of issues in the African drylands. He was an academic in Nigerian universities for over 25 years. He ran a British research consultancy, Drylands Research. He is best known for an anti-Malthusian account of population-environment relationships, More People, Less Erosion, and field-based studies of adaptation to drought.
A nabkha, nebkha or nebka is a type of sand dune. Other terms used include coppice dune and dune hummock or hummocky dune, but these more accurately refer to similar, but different, sand dune types. Authors have also used the terms phytogenic hillock, bush-mound, shrub-coppice dune, knob dune, dune tumulus, rebdou, nebbe, and takouit.
Large swathes of the Sahel region, which were once covered by grasslands, savannah, woodlands and scrub, suffer from land degradation. Soils have become degraded in locations where farmers have cleared perennial vegetation to grow crops and graze animals, exposing the soil to erosion by wind and water. In total, one-third of the world's population lives in drylands where land degradation is reducing food supplies, biodiversity, water quality and soil fertility.
The Bibliography of Aeolian Research (BAR) is a comprehensive 2015 bibliography focused on the study of the detachment, transport, and deposition of sediments by wind.
Paul A. Shaw is a physical geographer and a Fellow of the Royal Geographical Society.
The Chinese Loess Plateau, or simply the Loess Plateau, is a plateau in north-central China formed of loess, a clastic silt-like sediment formed by the accumulation of wind-blown dust. It is located southeast of the Gobi Desert and is surrounded by the Yellow River. It includes parts of the Chinese provinces of Gansu, Shaanxi and Shanxi. The depositional setting of the Chinese Loess Plateau was shaped by the tectonic movement in the Neogene period, after which strong southeast winds caused by the East Asian Monsoon transported sediment to the plateau during the Quaternary period. The three main morphological types in the Loess Plateau are loess platforms, ridges and hills, formed by the deposition and erosion of loess. Most of the loess comes from the Gobi Desert and other nearby deserts. The sediments were transported to the Loess Plateau during interglacial periods by southeasterly prevailing winds and winter monsoon winds. After the deposition of sediments on the plateau, they were gradually compacted to form loess under the arid climate.
References
- ↑ "Batterbury, S.P.J. & A.Warren. 2001. Desertification. in N. Smelser & P. Baltes (eds.) International Encyclopædia of the Social and Behavioral Sciences. Elsevier Press. pp. 3526–3529". Simonbatterbury.net. 26 December 1996. Retrieved 17 June 2021.
- ↑ Warren A, Agnew C. 1988 An assessment of desertification and land degradation in arid and semi-arid areas . London: IIED 72p.
- ↑ "Info". www.eldis.org. Retrieved 17 June 2021.
- ↑ "WEELS - Wind Erosion on European Light Soils". Archived from the original on 19 April 2012. Retrieved 5 May 2012.
- ↑ "Report" (PDF). www.geog.ox.ac.uk. Retrieved 17 June 2021.
- ↑ Warren A, Chappell A, Todd MC, Bristow C, Drake N, Engelstaedter S, Martins V, M'bainayel S, Washington R. 2007. Dust-raising in the dustiest place on earth. Geomorphology 92(1–2):
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