首页> 外文会议>Asian conference on remote sensing >DETECTION OF OLD AGRICULTURAL TERRACES IN STEEP, VEGETATED TERRAIN USING AIRBORNE LIDAR: CASE STUDIES FROM HONG KONG
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DETECTION OF OLD AGRICULTURAL TERRACES IN STEEP, VEGETATED TERRAIN USING AIRBORNE LIDAR: CASE STUDIES FROM HONG KONG

机译:机载激光雷达检测陡峭,植被繁茂的草原中的旧农业土地:以香港为例

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Old agricultural terraces and associated features are common on steep hillsides throughout the Hong Kong Special Administrative Region (HKSAR) and, since the late 1960s, most have been obscured by dense vegetation. Some of these terraces may date from a thousand or more years ago and some are still actively cultivated today. Based on aerial photograph interpretation (API) of older aerial photographs, particularly from 1963, and more recent field observations, generally these features can be classified as earthen step-form terraces, rubble wall terraces, and other forms of anthropogenic activity (e.g., military, prospecting/mining, quarrying, and ad hoc cuts/spoil). Their influence on slope stability is not yet well understood, however they need to be identified so that any relationship with landslide susceptibility can be better understood. Currently, these unknowns remain a potential source of residual risk for landslide hazards. With the aim of continuous improvement of natural terrain hazard assessments, suitable detection and mapping of the terraces and other features should first be systematically undertaken. A dense tropical vegetative canopy presents an obstacle to terrace detection. Much of the HKSAR has undergone revegetation due to changing land uses, government regulations, reforestation, and rapid natural growth over the last 30 - 40 years. Many terraces and other features are visible in 1963 aerial photographs, when hillsides were relatively bare of vegetation. Additionally, many of the oldest features are degraded and, when combined with the modern, dense vegetation, may be confused with natural landscape-forming processes when observed in the field. To assist in identification, a topographic position index (TPI) was applied to digital elevation models (DEM) derived from airborne LiDAR for three case studies. The result is an emerging, indirect mapping approach complemented by integrated API and field work to detect and map old terraces.
机译:在香港特别行政区(HKSAR)的陡峭山坡上,古老的农业梯田和相关特征很常见,自1960年代后期以来,大多数植被被茂密的植被所遮盖。其中一些阶地的历史可追溯到一千年或更早,而今天仍在积极地进行耕种。根据较旧的航空照片(尤其是1963年以来的航空照片)的航空照片解释(API)和最近的野外观察,通常可以将这些特征分类为土阶阶地,碎石墙阶地和其他形式的人为活动(例如军事目的) ,勘探/开采,采石场和临时砍伐/弃土)。它们对边坡稳定性的影响尚未得到很好的理解,但是需要对其进行识别,以便可以更好地理解与滑坡敏感性的任何关系。目前,这些未知因素仍然是潜在的滑坡灾害潜在风险来源。为了不断改善自然地形的危害评估,首先应该系统地进行梯田和其他特征的适当检测和制图。茂密的热带植物冠层为梯田探测提供了障碍。由于过去30到40年间土地用途的变化,政府法规,重新造林以及自然的快速增长,香港特别行政区的大部分地区都进行了植被恢复。在1963年的航拍照片中可以看到许多阶地和其他特征,当时山坡上相对没有植被。此外,许多最古老的特征都已退化,当与现代茂密的植被结合使用时,在野外观察时,可能会与自然景观形成过程相混淆。为了帮助识别,将地形位置指数(TPI)应用于从机载LiDAR导出的数字高程模型(DEM)进行了三个案例研究。结果是出现了一种新兴的间接映射方法,并辅以集成的API和现场工作来检测和绘制旧梯田。

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