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112:, road creation, and grassland burningâcan contribute to lavaka formation, lavakas can also develop by purely natural processes. Work by Neil Wells and colleagues showed that air photos reveal remnants of ancient lavakas in recently deforested areas, showing that those areas were eroded by lavakas before the rain forests grew; and
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Lavaka can often cause a lot of damage to nearby communities. During the monsoon season, heavy rains carry away all the eroded material from the lavaka, which can destroy surrounding crops and infrastructure. This is the basis for much of the recent research that has been conducted on the variables
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The term "Lavaka" entered the international geography/geology vocabulary following the work of
Riquier (1954). To differenciate it from the generic hole vocabulary (aka, trou, in French, and lavaka in Malagasy), this new vocabulary should be capitalized in scientific usage. More importantly, since
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However, lavaka also have some benefits. They provided a sheltered environment for trees and other plants that would not survive on the grassy slopes, and in many cases farmers take advantage of more fertile soils and greater water availability within lavaka to grow crops.
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Udvardi, B., Raveloson, A., Visnovitz, F., Szabó, Cs., Kovåcs, I., Székely, B., 2012, Sedimentological features of lateritic and saprolitic horizons in a mid-slope lavaka, Central
Highlands, Madagascar. European Geoscience Union General Assembly April 22-27,
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Raveloson, A., Visnovitz, F., Székely, B., Molnår, G., Udvardi, B., 2012, A multidisciplinary study on lavaka (gully erosion) formation in
Central Highlands, Madagascar. European Geoscience Union General Assembly April 22-27,
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Voarintsoa, N. R. G.; Cox, R.; Razanatseheno, M. O. M.; Rakotondrazafy, A. F. M. Relation between
Bedrock Geology, Topography and Lavaka Distribution in Madagascar. South African Journal of Geology 2012, 115 (2), 225â250.
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indicates that some lavakas are up to 20,000 years old, meaning they were present in the
Malagasy landscape before the arrival of humans (human arrival in Madagascar is less than 2000 years before present).
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certain minerals from the rock and if the hydraulic conductivity of that rock is high enough, the water can carry those minerals away, which can cause the infrastructure of that rock to collapse and erode.
200:., Zentner, D.B., Rakotondrazafy, A.F.M., and Rasoazanamparany, C.F., 2010, Shakedown in Madagascar: Occurrence of lavakas (erosional gullies) associated with seismic activity.
190:., Bierman, P., Jungers, M.C. and Rakotondrazafy, A.F.M., 2009, Erosion rates and sediment sources in Madagascar inferred from Be analysis of lavaka, slope, and river sediment.
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Riquier, Jean, Etude sur les « lavaka », Mémoires de l'Institut
Scientifique de Madagascar, Tananarive, SĂ©rie D : Sciences de la Terre, 1954, p. 169-189.
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the word has been taken directly from the vernacular name, it should be considered as an irregular word. Thus, Lavaka can be singular or plural when used.
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136:, which allows water to seep into the more porous layer of saprolite underneath. This causes chemical reactions within the saprolite to
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Wells, N.A., Andriamihaja, B., Rakotovololona, H.F.S., 1991, Patterns of development of lavaka, Madagascar's unusual gullies:
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105:. They are usually shaped like a tear-drop with a steep, round headwall that narrows downhill into a shallow outlet channel.
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172:"Lavaka (erosional gullies) provide productive patch environments for flora and farming in Madagascar's grassy highlands"
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Wells, N.A., Andriamihaja, B., 1993, The initiation and growth of gullies in
Madagascar: are humans to blame?:
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involved in lavaka formation (especially in
Madagascar, where Lavaka pepper the Central Highland landscape).
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climate. Lavaka form where these hard laterites overlie thick (tens of metres)
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Active lavaka on right, with inactive, largely infilled older lavakas to left
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Williams
College Digital Collections: Team Lavaka image collection
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Among the natural controls on Lavaka formation are the amount of
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Lavaka are not landslides. They are a type of gully, formed via
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268:Lavaka image database by
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299:Geology of Madagascar
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