International Research Fellowship Program: Risk Analysis of a Near-Future Urban Water Crisis in Turkey's Mega-City, Istanbul from Natural Processes

国际研究奖学金计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。 该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。该奖项将支持丽莎多纳博士22个月的研究奖学金，与纳米克M。土耳其伊斯坦布尔55%以上的饮用水依赖于两个沿海湖泊：Terkos湖和Buyukcekmece湖。这两个湖泊都是自然形成的泻湖河口，在1883年被筑坝并变成了湖泊; Terkos在100多年后，在1989年被建成。如果这两个湖泊中的任何一个失去了淡水来源，伊斯坦布尔将面临立即和严重的水资源短缺，但这两个湖泊都不是地质稳定的特征。这些盆地正在经历自然过程，在短期和长期的时间尺度上发挥作用，限制了它们作为淡水湖的寿命。不幸的是，几乎没有人知道湖泊过去和现在的沉积速率，湖泊盆地下的海洋水位深度，或者影响这两个地点的海啸（潮汐波）的频率。该项目与伊斯坦布尔技术大学合作，正在研究通过自然（渐进和灾难性）过程丧失这些淡水资源的风险。逐渐影响湖泊的过程包括湖泊容量和整体水质的损失，由于沉积物填充，藻类过度生长和盐水入侵。这些渐进的过程是重要的短期风险，因为其他因素，如极端气候事件，可以联合收割机与渐进的变化结合并放大。本项目主要研究藻类的填充率和藻类生长对水质的影响。它还为这两个湖泊绘制了第一张现代湖泊深度和盐水水位深度图。Terkos湖和Buyukcekmece湖今天被水坝和屏障加固物与海洋隔离。这些屏障是每个盆地完整性的最薄弱点，如果进一步削弱，很容易发生灾难性的崩溃。该项目正在研究屏障完整性的变化，使用过去30年屏障宽度的卫星图像，并检查屏障两侧沉积物沉积和侵蚀的模式。另一个渐进的过程是斑马贻贝的入侵，这是一种来自里海（黑海东北部）的物种，已经开始出现在土耳其的湖泊中。到目前为止，它的传播记录很少。因此，在这个项目中，从这些沿海湖泊的表面样本，以及在马尔马拉海周围的湖泊网络的定期采样策略，正在被用来创建一个基于GIS的分布图系列，为这个物种，可用于管理和保护未受感染的流域。土耳其地震活跃，未来几十年内伊斯坦布尔附近发生强震的可能性很高（60%）。除了地震对水坝和海洋屏障造成的破坏外，这些沿海泻湖还面临着海啸的危险。该项目正在通过沉积物特征的变化来寻找过去与地震有关的事件的证据，这些变化表明淡水和盐水环境之间的急剧转变，以及大规模流域扰动的迹象。

0401836DonerThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-two month research fellowship by Dr. Lisa Doner to work with Dr. Namik M. Cagatay at the Istanbul Technical University in Maslak, Istanbul, Turkey.Istanbul, Turkey relies on two coastal lakes for more than 55% of it's drinking water: Terkos Lake and Buyukcekmece Lake. Both of these lakes are naturally occurring lagoonal estuaries that were dammed and turned into water lakes; Terkos in 1883 and Buyukcekmece over 100 years later, in 1989. Istanbul would face an immediate and severe water shortage if either of these two lakes were lost as freshwater sources, yet neither lake is a geologically stable feature. The basins are undergoing natural processes, acting over short and long timescales, that limit their lifespan as freshwater lakes. Unfortunately, almost nothing is known about the lakes' past and present sedimentation rates, the depth of the marine water table beneath the lakes' basins, or the frequency of tsunami (tidal wave) affecting either site. This project, in partnership with Istanbul Technical University, is examining the risk of losing these freshwater resources through natural (gradual and catastrophic) processes. Gradual processes affecting the lakes include the loss of lake capacity and overall water quality due to sediment infilling, excessive algal growth, and saltwater intrusion. These gradual processes are important short-term risks because other factors, such as an extreme climate event, can combine with and amplify the progressive change. This project is studying the infilling rate and the affect of algal growth of water quality. It is also producing the first modern maps of lake depth and depth of the saltwater table for both lakes. Terkos and Buyukcekmece lakes are isolated from the sea today by dams and barrier reinforcements. These barriers are the weakest points in the integrity of each basin and are susceptible to catastrophic collapse if further weakened. The project is studying the change in barrier integrity, using satellite images of barrier width covering the last 30 years, and examining the pattern of sediment deposition and erosion on both sides of the barrier. Another gradual process is invasion of the zebra mussel, an species from the Caspian Sea (northeast of the Black Sea), which has started to appear in lakes in Turkey. The spread of it is poorly documented so far. So, in this project, surface samples from these coastal lakes, as well as a regular sampling strategy at a network of lakes around the Sea of Marmara, are being used to create a GIS-based distribution map-series for this species which could be used in management and protection of uninfected watersheds.Catastrophic loss of the lakes' water can result from earthquake and/or tsunami. Turkey is seismically active and there is a high (60%) probability of a strong earthquake near Istanbul for the next few decades. Aside from the damage to the dams and marine barrier caused by earthquake, these coastal lagoons face tsunami hazards. This project is looking at evidence of past seismic-related events, through changes in sediment characteristics that indicate a sharp transition between fresh and saltwater environments, and indications of massive watershed disturbance.