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108/09/24 16:00 Dr. Philip S. J. Minderhoud（Department of Physical Geography, Utrecht University, Utrecht, the Netherlands） 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2019-09-20演 講 公 告
地點：中央大學科學一館S-325教室
摘要：
講題：Shallow compaction of Holocene deposits following Mekong delta evolution over the past 4000 years
主講人：Dr. Philip S. J. Minderhoud
Department of Physical Geography, Utrecht University, Utrecht, the Netherlands
時間：09月24日（星期二）下午4點
地點：中央大學科學一館S-325教室
摘要：
Subsidence is a natural phenomenon in deltas worldwide. Soft deltaic sediments compact following organic matter oxidation and natural loading by newly deposited sediments and water. Human activities related to land use, such as draining wetlands for cultivation, extracting groundwater for irrigation and loading of the surface by buildings and infrastructure, often amplify natural subsidence rates. In the Vietnamese Mekong delta annual subsidence rates up to several cm are observed. Over the past decades, the delta experienced major alterations of human land use during which the majority of the wetlands and forested areas were turned into agriculture. These land use changes and different land-use histories are expected to cause different present-day subsidence rates.
We used a newly created time series of land-use maps together with INSAR-based subsidence observations to unravel the relationship between land use, land-use history and subsidence in the Mekong delta. Different land-use types and land-use change pathways experienced different subsidence rates. These could be related to specific human-induced subsidence drivers, revealing the indirect, causal relationship between land use and subsidence. Natural land-use classes like marshland and wetland forest showed lowest subsidence rates (6-7 mm yr-1), while classes with intensive agriculture and built-up areas experienced highest rates (18-20 mm yr-1). Variation in subsidence rate within a current land-use class can be (partly) explained by differences in land-use history over the previous 20 years. Our spatially explicit evaluation of dominant land-use change pathways provides valuable insights to aid sustainable land-use planning in both subsiding and currently stable areas of the Mekong delta and similar deltas.
最後修改時間：2019-11-06 PM 12:52
