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发生在不同时间尺度上的一种自然现象。除了这种自然变化，人类引起的气候变化的问题也得到了越来越多的公众关注。海平面上升(SLR)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。人们认识到的另一个方面是区域SLR和人口稠密的沿海城市的沉降相结合的危险潜力。世界上大约三分之一的人口居住在沿海地区。东南亚大多数最大的城市都靠近沿海，因此容易受到SLR的影响。这种情况对下沉地区来说更是雪上加霜。了解海平面变化及其对沿海地区的近时间预测对于海岸规划、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，几个雷达高度计已经获得了大量的海平面数据，但即使在今天，也没有得到一致的海平面估计。根据改正的选择，发现了明显不同的区域海平面趋势。该项目将解决这些不足之处。由于气候引起的年代际和长期海平面变化可以被季节、年度和年际变化所掩盖，这一事实使长期趋势的推导变得复杂，这些变化可能起到噪声掩盖趋势的作用。海平面测量的长期时间序列只能从验潮仪获得，因为验潮仪对陆地垂直运动很敏感，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(GNSS)技术在校正验潮仪的垂直变化方面变得越来越重要。准确确定海平面并结合巨型城市的沉降量估算，以及结合不同的大地测量方法预测城市地区近期海平面变化的挑战，对这些社会来说至关重要。我们计划(1)改进和结合最新的大地传感器数据，包括高度计、验潮仪、GNSS和时间重力场，分别从全球视角和地面沉降来量化区域海平面变化；(2)分析海平面格局，特别是爪哇地区的沿海地区和延伸到东南亚其他地区；(3)从局部沉降的角度研究当地海平面变化、根据验潮仪记录的极端海平面和沿海洪水，重点是雅加达和三宝来；(4)将海平面信息与来自其他方法的区域信息结合起来，以评估脆弱性，为过去和最近海平面上升影响的社会经济评估提供背景信息，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.