ADB_book_18 April.qxp - Himalayan Document Centre - icimod

Table 3.3: Change in Agricultural and Forest Lands by RegionRegionAgricultural Land(%)Per Capita Agricultural Land(ha)Forest Land(%)Per Capita Forest Land(ha)1986 a 2000 b 1986 a 2000 b 1986 a 2000 b 1986 a 2000 bMountain 5.33 10.02 0.19 0.31 27.50 31.03 0.99 0.95Hill 33.37 28.06 0.24 0.17 50.06 62.89 0.36 0.38Terai 41.57 56.17 0.16 0.17 50.43 38.88 0.20 0.12Nepal 23.52 28.20 0.19 0.18 42.20 46.12 0.34 0.29ha = hectareNote: The population for de nsity computation of agricultural and forest resources in 1986 and 2000 is based on the 1991 and 2001 population censusesrespectively.Source: a LRMP (1986); b JAFTA (2001)Environments and ecosystems are increasinglymore controlled or disrupted and degraded byhuman activities. Landslides, topsoil erosion,siltation, and salinization are different forms of landdegradation. Visible forms of land degradationinclude dust storms, deep gullies, and landslides.Figure 3.1: Land Degradation and Financial Loss Due toFloods and LandslidesCauses of Land DegradationThe magnitude of land degradation in a placedepends on the local geology, land type, landform,land use, rainfall intensity, and human activity. Landdegradation results from any causative factor orcombination of factors that reduces the physical,chemical, or biological status of land and which mayrestrict the land’s productive capacity. Landdegradation is due to (a) natural (biogeophysical)causes, (b) human causes, or (c) a combination ofboth. Owing to the complex features of the mountainterrain, the nature of land degradation varies greatlyin Nepal.Landslides are the most important factor in landdegradation in Nepal. Landslides occur almost everyyear, particularly in the sloping areas of highmountains and low hills during the monsoon season.The consequences of landslides include topsoilerosion; damaged and destroyed roads, trails, andbridges; loss of land, lives, and property; and siltationin low-lying areas resulting in unproductive land(Figure 3.1). About 1.8 million ha (13%) of the land inthe Mountains is estimated to be severely degradedby landslides (CBS 1998).Table 3.4 provides information on soil erosionrates for different land uses, rock types, and slopelevels in the country. The soil erosion rate is higher inthe unmanaged land use category and on steepslopes than in the managed land use category.Similarly, intensity of soil loss is found less incultivated lowlands than in rain-fed sloping terraces,ranging from as low as 7.8 tons/ha/year in theforested Siwalik hills to as much as 570 tons/ha/yearin the unforested midhills (CBS 2004). In the middleHills of Nepal the rate of soil loss in grassland is 0.7-Source: CBS (1998)Bare Land Exposed to Erosion, MustangB. PradhanChapter 3: Land Resources and Land Degradation33