Coastal and Regional Sea Level Change and Subsidence - The Hazardous Potential in Indonesia and South East Asia (CoRSEA)

气候变化和波动是地球历史上不同时间尺度上发生的自然现象。除了这种自然变化之外，公众对人类引起的气候变化问题的认识也日益提高。海平面上升被广泛认为是人为气候变化的后果之一，具有重大的社会和经济影响。另一个引起人们注意的方面是，在人口稠密的沿海城市，区域SLR和沉降相结合的潜在危险。世界上大约三分之一的人口居住在沿海地区。大多数东南亚最大的城市都靠近沿海，因此容易受到SLR的影响。这种情况对正在遭受地面沉降的地区是不利的。了解沿海地区海平面变化及其近期预测对沿海规划、土地利用和经济发展至关重要。在过去的二十年里，雷达测高在监测海平面方面发挥了重要作用。自80年代中期以来，一些雷达高度计已经获得了大量的海平面数据，但即使在今天，也没有得出一致的海平面估计。根据修正的选择，发现了明显不同的区域海平面趋势。本项目将解决这些不足之处。长期趋势的推导是复杂的，气候引起的十年和长期海平面变化可以被季节，年度和年际变化所掩盖，这可能会成为噪音掩盖趋势。只有验潮仪才能提供海平面测量的长期时间序列，验潮仪对陆地的垂直运动很敏感，因此是相对海平面而不是绝对海平面的记录。近年来，全球导航卫星系统技术对于校正验潮仪的垂直变化变得越来越重要。结合特大城市的沉降估计准确确定海平面，以及结合不同大地测量方法预测城市地区近期海平面变化的挑战，对社会至关重要。我们计划（1）改进和联合收割机最先进的大地测量传感器数据，包括测高、验潮、GNSS和时间重力场，分别从全球角度和地面沉降角度量化区域海平面变化;（2）分析海平面模式，特别是在爪哇地区的沿海地区，并扩展到其他东南亚地区;（3）从局部沉降的角度研究局部海平面变化、验潮站记录的极端海平面和沿海洪水，重点研究雅加达和塞马朗;（4）将联合收割机海平面信息与其他方法获得的区域信息相结合，以评估脆弱性，并为社会经济发展提供背景信息。该项目旨在对过去和最近海平面上升的影响进行经济评估，并更好地了解灾害与社会之间的反馈系统以及与社区的互动。

Climate change and fluctuations are a natural phenomenon, which occurred over different temporal scales during the Earths history. Besides this natural variability, the question of human-induced changes of climate has gained increasing public awareness. Sea-level rise (SLR), which is widely recognized as one of the consequences of anthropogenic climate change, has a substantial social and economic impact. Another aspect receiving awareness is the hazardous potential of the combination of regional SLR and subsidence in highly populated coastal cities. Approximately 1/3 of the worlds population is living near the coast. Most of the largest cities of South East Asia are near-coastal, and thus vulnerable to SLR. This situation worsens for the regions suffering subsidence. Understanding sea level change and its near-time projection for coastal regions is essential to coastal planning, land use and economical development. For the last two decades, radar altimetry has played an important role in monitoring the sea level. Since the middle of the 80ties, several radar altimeters have acquired a substantial amount of sea level data but even today do not lead to consistent sea level estimates. Depending on the choice of corrections, distinctly different regional sea level trends are found. This project will address these deficiencies. The derivation of long-term trends is complicated by the fact, that climate-induced decadal and secular sea level changes can be concealed by seasonal, annual and interannual variations, which may act as noise masking trends. Long-term time series of sea level measurements are available only from tide gauges, which are sensitive to vertical land movements and are, thus, records of relative rather than absolute sea level. In recent years, GNSS technology became increasingly important to correct tide gauges for vertical changes. The accurate determination of sea level in combination with subsidence estimates of Megacities and the challenge of combining different geodetic methods to predict near-future sea level changes in urban areas is of paramount importance for the societies. We plan to (1) improve and combine state-of-art geodetic sensor data, including Altimetry, tide gauges, GNSS, and temporal gravity fields to quantify regional sea level changes with a global perspective and land subsidence respectively; (2) analyze sea level patterns especially for the coastal region in the area of Java and extensions to other SE Asia regions; (3) study local sea level changes, extreme sea level from tide gauge records and coastal flooding under the view of local subsidence, with a focus to Jakarta and Semarang; (4) combine sea level information with area information from other methods to assess vulnerability and to provide background information for socio-economic evaluation of past and recent sea level rise impacts and to better understand the feedback system between hazard and society and the interaction with communities.