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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Reduced channel morphological response to urbanization in a flood-dominated humid tropical environment
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Reduced channel morphological response to urbanization in a flood-dominated humid tropical environment

机译：在以洪水为主的潮湿热带环境中，对城市化的渠道形态响应降低

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摘要

Urbanization through the addition of impervious cover can alter catchment hydrology, often resulting in increased peak flows during floods. This phenomenon and the resulting impact on stream channel morphology is well documented in temperate climatic regions, but not well documented in the humid tropics where urbanization is rapidly occurring. This study investigates the long-term effects of urbanization on channel morphology in the humid sub-tropical region of Puerto Rico, an area characterized by frequent high-magnitude flows, and steep coarse-grained rivers. Grain size, low-flow channel roughness, and the hydraulic geometry of streams across a land-use gradient that ranges from pristine forest to high density urbanized catchments are compared. In areas that have been urbanized for several decades changes in channel features were measurable, but were smaller than those reported for comparable temperate streams. Decades of development has resulted in increased fine sediment and anthropogenic debris in urbanized catchments. Materials of anthropogenic origin comprise an average of 6% of the bed material in streams with catchments with 15% or greater impervious cover. At-a-station hydraulic geometry shows that velocity makes up a larger component of discharge for rural channels, while depth contributes a larger component of discharge in urban catchments. The average bank-full cross-sectional area of urbanized reaches was 1.5 times larger than comparable forested reaches, and less than the world average increase of 2.5. On average, stream width at bank-full height did not change with urbanization while the world average increase is 1.5 times. Overall, this study indicates that the morphologic changes that occur in response to urban runoff are less in channels that are already subject to frequent large magnitude storms. Furthermore, this study suggests that developing regions in the humid tropics shouldn't rely on temperate analogues to determine the magnitude of impact of urbanization on stream morphology.
机译：通过增加不透水的覆盖物来实现城市化可以改变流域的水文状况，常常导致洪灾期间洪峰流量增加。在温带气候地区，这种现象及其对河道形态的影响已得到充分证明，但在城市化迅速发生的潮湿热带地区却没有得到充分证明。这项研究调查了波多黎各亚热带湿润地区的城市化对河道形态的长期影响，该地区的特征是频繁的高水流量和陡峭的粗粒河。比较了从原始森林到高密度城市集水区的土地利用坡度的粒度，低流量通道粗糙度和溪流的水力几何形状。在已经城市化了几十年的地区，河道特征的变化是可测量的，但比可比的温带河流要小。几十年的发展导致城市化集水区的细沙和人为碎片增加。人为来源的物质在集水区的不透水层中平均占床层物质的6％。车站的水力几何学表明，速度构成了农村河道排放量的较大部分，而深度在城市集水区则占排放量的较大部分。城市化河段的平均河岸横断面面积是同类森林河段的1.5倍，但低于世界平均水平2.5。平均而言，随着城市化的发展，全岸高处的河道宽度没有变化，而世界平均水平增长了1.5倍。总体而言，这项研究表明，在已经遭受频繁的大暴风雨的河道中，响应城市径流而发生的形态变化较少。此外，这项研究表明，潮湿热带地区的发展中地区不应依赖温带类似物来确定城市化对河流形态的影响程度。

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