Talk:Geography of Nepal: Difference between revisions
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== Quibbles == |
== Quibbles == |
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Generally |
Generally good, but a few quibbles: |
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"Below 1,200 meters, the dominant form of vegetation consists of tropical and subtropical rain forests." |
"Below 1,200 meters, the dominant form of vegetation consists of tropical and subtropical rain forests." |
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"Nepal can be divided into three major river systems from east to west: the Kosi River, the Narayani River (India's Gandak River), and the Karnali River." |
"Nepal can be divided into three major river systems from east to west: the Kosi River, the Narayani River (India's Gandak River), and the Karnali River." |
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The Bagmati River draining the Kathmandu Valley lies between the Kosi and Narayani systems. Similarly the (west) Rapti River lies between the Narayani and Karnali systems, finally joining the Karnali in Gorakhpur, India where it is notorious for causing floods. With no glacial sources, |
The Bagmati River draining the Kathmandu Valley lies between the Kosi and Narayani systems. Similarly the (west) Rapti River lies between the Narayani and Karnali systems, finally joining the Karnali in Gorakhpur, India where it is notorious for causing floods. These rivers rise in the middle hills about halfway between the Mahabharat Range and the Himalaya. With no glacial sources, they are more variable in flow than the three largest rivers; nevertheless they flow through the dry season. |
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Other streams arise on the southern slopes of the Mahabharat Range, or in the Siwaliks. These are highly seasonal. During the dry season they may dry up completely, or disappear underground traversing the alluvial bhabhar zone, then reappear below it. Individually these streams are undeniably much less impressive than the three largest river systems, yet they are numerous, important collectively, and ought to have been mentioned. |
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"The word tarai, a term presumed to be derived from Persian, means "damp," and it appropriately describes the region's humid and hot climate." |
"The word tarai, a term presumed to be derived from Persian, means "damp," and it appropriately describes the region's humid and hot climate." |
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Although in Nepali "tarai" (or "terai") colloquially refers to any lowlands south of the Mahabharat Range, perhaps in a stricter sense it refers to a zone of abundant aquifers at the base of the Sivalik range. |
Although in Nepali "tarai" (or "terai") colloquially refers to any lowlands south of the Mahabharat Range, perhaps in a stricter sense it refers to a zone of abundant aquifers at the base of the Sivalik range. |
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The Siwaliks are the outermost, most recently uplifted sub-range of the greater Himalaya and are formed of alluvium washed down from older ranges to the north, but never buried deeply enough to be strongly metamorphosed, so the rock formations are poorly consolidated, permeable and easily eroded. Downslope from the exposed formations of this range is a belt of alluvium some kilometers wide called the Bhabhar. |
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| ⚫ | Rainfall |
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| ⚫ | Rainfall and streamflow from the higher parts of the Siwaliks tends to sink into the alluvial deposits of the bhabhar. It percolates downhill until the alluvium gives way to the finer, less permeable sediments of the Gangeatic Plains proper and this groundwater emerges in springs and marshes persisting long into or even completely through the dry season. |
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| ⚫ | The year-round supply of moisture favors the development of dense forests, whereas valley bottoms without abundant groundwater during the dry season would have more open, scrubbier forests or even open savanna and are more easily cleared for agriculture. |
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| ⚫ | The year-round supply of moisture favors the development of dense forests, whereas valley bottoms without abundant groundwater during the dry season would have more open, scrubbier forests or even open savanna and are more easily cleared for agriculture. These moister Terai forests also make ideal habitat for mosquitos, including varieties that transmit malaria. |
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As a defensive measure against British encroachment, the wet forest was protected from clearing by settlers and loggers, which would have exposed the ground to sunlight, making this zone drier and less malarial. |
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As a defensive measure against British encroachment, government decrees protected the wet forest zone against logging or clearing by settlers which would have exposed the ground to sunlight, making this zone drier and less malarial. With endemic malaria, it was nearly uninhabitable except by Tharus and perhaps a few other ethnic groups who had evolved a degree of malaria resistance and had developed behavioral adaptations minimizing exposure to the nocturnal mosquitos. |
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Evidently there is a similar wet alluvial and forested zone along the southern base of the higher Mahabharat Range. Terai forests are easily seen in the satellite image shown in this article along the base of the Sivaliks, and wherever there are inner-Terai valleys, also along the base of the Mahabharat Range. Below these forest belts, valley bottoms and the main Gangeatic Plains have been cleared for agriculture. |
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However after Nepal's isolation ended in the early 1950s DDT was applied in and around houses to suppress mosquitos and thus suppress the vector that transmitted the infecting parasite between people. This finally opened the Terai to settlement by land-hungry subsistence farmers from the middle hills, led to extensive clearing of forests and negatively impacted wildlife particularly the large mammals for which the Terai was famous. |
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The malarial zones were mainly populated by Tharus who had evolved some resistance to the parasite that causes the disease, but not immunity. Tharus also developed behavioral and architectural coping strategies to minimize exposure to the mainly nocturnal mosquitos. Nevertheless Tharu population densities remained low despite their land's considerable agricultural potential. Perhaps higher densities would have increased malaria transmission rates and therefore mortality. However after Nepal's isolation ended, DDT was applied to suppress mosquitos. The Terai's malaria belt then became habitable without genetic resistance and behavioral countermeasures, so there was resettlement by land-hungry subsistence farmers from the hills that negatively impacted both the Tharu and large mammals, especially rhinos, tigers and elephants. |
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Revision as of 18:45, 27 June 2006
== Headline text ==Bold textGeography of Nepal Tibet is located in the northwestern corner of nepal there is many plants and animals there.
Quibbles
Generally good, but a few quibbles:
"Below 1,200 meters, the dominant form of vegetation consists of tropical and subtropical rain forests."
In the more populated areas, "rain forests" are attentuated by human activity such as grazing, collecting fodder, and woodcutting that opens the forest floor to sunlight and decreases humidity.
Also the climate tends toward dry and hot in the spring before the monsoon arrives. Dryness intensifies to the west, and there are moderate rain shadows, for example north of the Mahabharat Range. One may encounter dry forest rather than rainforest below 2,000 meters, and often higher on carbonate substrates, despite the correlation between rainfall and elevation.
"Nepal can be divided into three major river systems from east to west: the Kosi River, the Narayani River (India's Gandak River), and the Karnali River."
The Bagmati River draining the Kathmandu Valley lies between the Kosi and Narayani systems. Similarly the (west) Rapti River lies between the Narayani and Karnali systems, finally joining the Karnali in Gorakhpur, India where it is notorious for causing floods. These rivers rise in the middle hills about halfway between the Mahabharat Range and the Himalaya. With no glacial sources, they are more variable in flow than the three largest rivers; nevertheless they flow through the dry season.
Other streams arise on the southern slopes of the Mahabharat Range, or in the Siwaliks. These are highly seasonal. During the dry season they may dry up completely, or disappear underground traversing the alluvial bhabhar zone, then reappear below it. Individually these streams are undeniably much less impressive than the three largest river systems, yet they are numerous, important collectively, and ought to have been mentioned.
"The word tarai, a term presumed to be derived from Persian, means "damp," and it appropriately describes the region's humid and hot climate."
Although in Nepali "tarai" (or "terai") colloquially refers to any lowlands south of the Mahabharat Range, perhaps in a stricter sense it refers to a zone of abundant aquifers at the base of the Sivalik range.
The Siwaliks are the outermost, most recently uplifted sub-range of the greater Himalaya and are formed of alluvium washed down from older ranges to the north, but never buried deeply enough to be strongly metamorphosed, so the rock formations are poorly consolidated, permeable and easily eroded. Downslope from the exposed formations of this range is a belt of alluvium some kilometers wide called the Bhabhar.
Rainfall and streamflow from the higher parts of the Siwaliks tends to sink into the alluvial deposits of the bhabhar. It percolates downhill until the alluvium gives way to the finer, less permeable sediments of the Gangeatic Plains proper and this groundwater emerges in springs and marshes persisting long into or even completely through the dry season.
The year-round supply of moisture favors the development of dense forests, whereas valley bottoms without abundant groundwater during the dry season would have more open, scrubbier forests or even open savanna and are more easily cleared for agriculture. These moister Terai forests also make ideal habitat for mosquitos, including varieties that transmit malaria.
As a defensive measure against British encroachment, government decrees protected the wet forest zone against logging or clearing by settlers which would have exposed the ground to sunlight, making this zone drier and less malarial. With endemic malaria, it was nearly uninhabitable except by Tharus and perhaps a few other ethnic groups who had evolved a degree of malaria resistance and had developed behavioral adaptations minimizing exposure to the nocturnal mosquitos.
However after Nepal's isolation ended in the early 1950s DDT was applied in and around houses to suppress mosquitos and thus suppress the vector that transmitted the infecting parasite between people. This finally opened the Terai to settlement by land-hungry subsistence farmers from the middle hills, led to extensive clearing of forests and negatively impacted wildlife particularly the large mammals for which the Terai was famous.