Monitoring Mountain Rivers From Space: A Pilot Study of Bedrock River Flow Measurement Using Ultra-High Resolution Optical Satellite Imagery

从太空监测山区河流：利用超高分辨率光学卫星图像进行基岩河流量测量的试点研究

• 批准号: 0550087
• 负责人: Colin Stark
• 金额: $ 3.5万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-15 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0550087&HistoricalAwards=false
• 关键词: Monitoring; Mountain; Rivers; Space; Pilot

The measurement of flood-stage discharge in mountain rivers is an enormous logistical challenge, particularly on large space and time scales, and the inevitable paucity of such data has impeded progressin our understanding of mountain landscape processes. We propose a novel solution that exploits newhigh resolution satellite imagery (2m, FORMOSAT-2) with unusually high revisit frequency (daily) overa region of very broad interest to the earth science community (Taiwan). Our proposed method entailsthe collation of a time series (2004-2005) of orthorecti*ed, georeferenced images of selected mountainriver channels, in tandem with contemporaneous stage measurements of discharge at the nearest gaugingstation downstream. Patterns of inundation along selected channel reaches will be mapped in eachimage. With the aid of cross-channel profiles mapped in the field at low stage, we will make estimatesof low width, depth, mean bed shear stress and mean low velocity. Once a broad range of dischargeshas been processed, we expect to be able to construct rating curves for these low measures as a functionof the directly observed, at-station stage data. Combination of the rating models with the multi-decadalarchive of station data in Taiwan will permit an assessment of the long-term probability distributions oflow widths, depths and shear stresses along and across the selected bedrock channels. Measurements ofthis kind, albeit indirect, will be of enormous interest to the geomorphology community. However, themethod is by no means guaranteed, because remote river gauging has never been attempted in mountaincatchments; it remains to be seen whether the precision of the anticipated rating curves will suffice forrivers akin to those of the Taiwan Central Range. The main task of the pilot project will be to addressthis issue and to lay the foundation for a more comprehensive, longer-term assessment of Taiwanesemountain river discharge.Broader outcomes: While low measurements in steep mountain rivers are particularly sought after bythose interested in bedrock channel processes, they are also of great interest beyond: from modelersof landscape evolution and the interaction between climate and tectonics, to hydrologists preoccupiedwith the assessment of flood hazard in populated mountain environments. Moreover, if the pilot projectproves successful it will provide the Taiwanese space agency with an excellent example of the value ofFORMOSAT-2 in natural hazard assessment, one of its principal missions. As a result, more attentionwill be paid to the regular acquisition of FORMOSAT-2 imagery in tropical mountain areas, an essentialstep if the elusive goal of a high-resolution, multitemporal image archive is to be achieved - at present,images of highland areas are a relatively low prioity (for FORMOSAT-2 and other equivalent satellites)and are only acquired daily during emergency periods (e.g. typhoons). Such an archive would be widelyappreciated across the discplines of earth sciences, hydrology, ecology, not to mention in remote-sensingR&D itself.A-1

山区河流洪水阶段流量的测量是一项巨大的后勤挑战，特别是在大空间和时间尺度上，并且不可避免地缺乏此类数据，这阻碍了我们对山地景观过程的理解。我们提出了一种新颖的解决方案，利用新的高分辨率卫星图像（2m，FORMOSAT-2），以异常高的重访频率（每天）覆盖地球科学界（台湾）非常广泛感兴趣的区域。我们提出的方法需要对所选山区河流渠道的正射、地理参考图像的时间序列（2004-2005）进行整理，并与下游最近的测量站的流量的同期阶段测量相结合。沿所选河道的淹没模式将映射到每个图像中。借助低水位现场绘制的跨河道剖面图，我们将估算低水位宽度、深度、平均河床剪应力和平均低速度。一旦处理了大范围的排放，我们期望能够根据直接观察到的站台数据来构建这些低测量值的评级曲线。将评级模型与台湾数十年台站数据相结合，将能够评估沿选定基岩河道和跨过选定基岩河道的低宽度、深度和剪应力的长期概率分布。这种测量虽然是间接的，但将引起地貌学界的极大兴趣。然而，该方法绝不是有保证的，因为从未在山区流域尝试过远程河流测量；预期评级曲线的精度是否足以满足与台湾中央山脉类似的河流的要求，还有待观察。该试点项目的主要任务将是解决这个问题，并为对台湾山区河流流量进行更全面、更长期的评估奠定基础。更广泛的成果：虽然对基岩河道感兴趣的人特别青睐陡峭山区河流的低测量值除了景观演化和气候与构造之间的相互作用的建模者，到专注于评估人口稠密的山区环境中洪水灾害的水文学家，它们也引起了极大的兴趣。此外，如果试点项目取得成功，它将为台湾航天局提供一个很好的例子，展示福尔摩沙二号在自然灾害评估（其主要任务之一）方面的价值。因此，福星二号热带山区影像的定期采集将受到更多关注，这是实现高分辨率、多时相影像档案这一难以实现的目标的重要一步——目前，高原地区的影像正在大量获取。优先级相对较低（对于 FORMOSAT-2 和其他同等卫星），并且仅在紧急时期（例如台风）每天获取。这样的档案将受到地球科学、水文学、生态学各个学科的广泛赞赏，更不用说遥感研发本身了。A-1