Impact of Land Use on Sediment and Nutrient Yields to Lake Malawi/Nyasa (Africa)
Impact of Land Use on Sediment and Nutrient Yields to Lake Malawi/Nyasa (Africa)
复制标题
土地利用对马拉维湖/尼亚萨（非洲）沉积物和养分产量的影响
DOI：
10.1016/s0380-1330(03)70544-9
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发表时间：
2003
影响因子：
2.2
通讯作者：
Murray L. Kingdon
中科院分区：
文献类型：
--
作者：
R. Hecky;H. Bootsma;Murray L. Kingdon
对从南部非洲马拉维流入马拉维/尼亚萨湖的13条河流进行了为期1年的研究，以估计从陆地集水区到湖泊的沉积物和营养物质的年产量。流域面积从113平方公里到12，110平方公里不等，但所有集水区高于湖平面的最大海拔相似，流域平均坡度差异很大。流量是季节性变化的低流量或无流量在长期旱季结束。年径流量从37毫米到617毫米不等，1997年大多数河流的流量低于平均水平。这些河流流域都在不同程度上受到自给农业的影响，而自给农业是马拉维的主要土地用途。沉积物和营养盐（C，N，P，Si）的浓度，负荷和产量是敏感的农业土地利用的程度在流域。最低的泥沙浓度，负荷和产量的特点是小，陡峭的集水区与高比例的完整的森林。最高浓度，负荷和产量的沉积物是从密集定居集水区广泛的农业活动。浓度，负荷和产量的营养物质往往遵循的颗粒通量作为溶解组分是不太响应盆地扰动。人口的增加和相关的农业发展可能已经使马拉维湖的营养负荷增加了50%，因为越来越多的森林被砍伐用于农业。
Thirteen rivers flowing into Lake Malawi/Nyasa from the country of Malawi in southern Africa were studied over 1 year to estimate annual yields of sediments and nutrients from the terrestrial catchments to the lake. The river basins ranged in size from 113 to 12,110 km2, but maximum elevations above lake level were similar in all the catchments yielding quite different mean basin slopes. Flow was seasonally variable with low or no flow at the end of the prolonged dry season. Annual runoff varied from 37 to 617 mm with most rivers having below average discharges in 1997. The river basins were all affected to varying degrees by subsistence farming which is the dominant land use in Malawi. Sediment and nutrient (C, N, P, Si) concentrations, loads, and yields were sensitive to the degree of agricultural land use in the basins. Lowest sediment concentrations, loads, and yields were characteristic of the small, steep catchments with a high proportion of intact forest. Highest concentrations, loads, and yields of sediments were from densely settled catchments with extensive agricultural activity. Concentrations, loads, and yields of nutrients tended to follow the particulate fluxes as dissolved components were less responsive to basin disturbance. Increasing populations and associated agricultural development may already have increased nutrient loading to Lake Malawi by 50% as forests have been increasingly cleared for agriculture.