Land subsidence and caprock dolines caused by subsurface gypsum dissolution and the effect of subsidence on the fluvial system in the Upper Tigris Basin (between Bismil–Batman, Turkey)

Karstification-based land subsidence was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land subsidence, where there are secondary and tertiary subsidence developments, reaches 140 km². Subsidence depth ranges between 40 and 70 m. The subsidence was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a subsidence with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of subsidence and formation of caprock dolines on loosely textured Upper Miocene–Pliocene cover formations. The Tigris River runs through the subsidence area between Batman and Bismil. There are four terrace levels as T1 (40 m), T2 (30 m), T3 (10 m) and T4 (4–5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by subsidence. The subsidence developed gradually throughout the Quaternary; however no terrace was formed purely because of subsidence.     

The 17 March 2005 Kuzulu landslide (Sivas, Turkey) and landslide-susceptibility map of its near vicinity

Landslides are common natural hazards in the seismically active North Anatolian Fault Zone of Turkey. Although seismic activity, heavy rainfall, channel incisions, and anthropogenic effects are commonly the main triggers of landslides, on March 17, 2005, a catastrophic large landslide in Sivas, northeastern of Turkey, the Kuzulu landslide, was triggered by snowmelt without any other precursor. The initial failure of the Kuzulu landslide was rotational. Following the rotational failure, the earth material in the zone of accumulation exhibited an extremely rapid flow caused by steep gradient and high water content. The Agnus Creek valley, where Kuzulu village is located, was filled by the earth-flow material and a landslide dam was formed on the upper part of Agnus Creek. The distance from the toe of the rotational failure down to the toe of the earth flow measured more than 1800 m, with about 12.5 million m³ of displaced earth material. The velocity of the Kuzulu landslide was extremely fast, approximately 6 m/s. The main purposes of this study are to describe the mechanism and the factors conditioning the Kuzulu landslide, to present its environmental impacts, and to produce landslide-susceptibility maps of the Kuzulu landslide area and its near vicinity. For this purpose, a detailed landslide inventory map was prepared and geology, slope, aspect, elevation, topographic-wetness index and stream-power index were considered as conditioning factors. During the susceptibility analyses, the conditional probability approach was used and a landslide-susceptibility map was produced. The landslide-susceptibility map will help decision makers in site selection and the site-planning process. The map may also be accepted as a basis for landslide risk-management studies to be applied in the study area.     

Comparative Planetary Space Physics

It has been 60 years since the space physics as new branch of geophysics started to grow in 1957 when the space age was opened by a small satellite called sputnik. The knowledge of Earth and planetary space has been significantly extended and deepened, but the questions we are facing today are more challenging. A consensus reached is that we have to regard the Earth (planet) as an integrated system including all spheres from the inner core to the magnetosphere, and we should try to investigate some questions standing on the ground of interdisciplinary study, especially those questions related to Earth’s (planetary) evolution. Space environment as the outer part of a planetary system, commonly exists in all planets but also exhibits strong diversity. Here, we introduce the short history of basic ideas and methods of comparative study, the advantages on understanding of some issues of global scale, and the prospect from comparative perspective.     

卫星红外遥感技术在我国环保领域中的应用与发展分析

本文较为系统地分析了卫星红外遥感技术在我国秸秆焚烧、沙尘、气溶胶、颗粒物、灰霾等大气环境遥感监测,水华、水质参数、水表温度、热污染、核电厂温排水等水环境遥感监测,以及土壤含水量、地表温度、干旱、城市热岛效应等生态环境遥感监测的应用。同时,指出目前国产卫星红外载荷业务化应用程度不高、辐射定标能力不足、应用反演算法原创性不强、地面观测和试验验证能力不足等问题;并提出需大力发展国产红外传感器、提高辐射定标能力、发展国内原创监测算法、建设大型环保应用综合试验场等建议,以促进红外遥感技术在环境保护领域的应用和发展。     

A feasible approach to predicting time-dependent bearing performance of jacked piles from CPTu measurements

Acta Geotechnica - In this paper, a simple but feasible approach is proposed to predict the time-dependent load carrying behaviours of jacked piles from CPTu measurements. The corrected cone...     

Radium-traced nutrient outwelling from the Subei Shoal to the Yellow Sea: Fluxes and environmental implication

The Subei Shoal is the largest sandy ridge in the southern Yellow Sea and is important source for nutrient loading to the sea. Here, the nutrient fluxes in the Subei Shoal associated with eddy diffusion and submarine groundwater discharge（SGD） were assessed to understand their impacts on the nutrient budget in the Yellow Sea. Based on the analysis of 223 Ra and 224 Ra in the field observation, the offshore eddy diffusivity mixing coefficient and SGD were estimated to be 2.3×10⁸ cm     

一种基于视觉特征的地形模型数据提取与快速显示方法

DEM模型是一种重要的地形模型，由于其数据量极其巨大，如何实现快速显示是一个难题。针对DEM地形模型，提出基于视点与观察分辨率的数据抽取及基于法矢量的模型简化的快速绘制方法算法，最后进行实验验证。结果表明，该方法数据压缩量大，绘制速度快，且逼真度无明显变化。     

北京一次大风和强降水天气过程形成机理的数值模拟

利用3维强风暴冰雹分档模式(IPA—HBM)对2001年8月23日北京的一次伴有大风、暴雨和冰雹的强对流天气过程进行模拟和分析，并与部分观测资料进行了比较分析。结果表明，该模式对此次强风暴的生命史、降水分布、降雹的大小等要素做了较好的模拟，并能够模拟出伴随强风暴过程所产生的强下沉气流和及地面强风速切变(下去暴流)。从云微物理学角度分析了此次局地性大风的形成原因，认为由高空冰雹粒子的拖曳产生的负浮力作用是促发强下沉气流产生的主要原因，其次是冰雹的融化和雨水蒸发冷却对下沉气流起加速作用，冰雹的拖曳和融化作用对下沉气流具有决定性作用。强风暴所产生的爆发性强下沉气流最终导致了局地大风的形成。     

水汽层析代数重构算法

讨论了代数重构算法在水汽层析应用中的各种问题,包括约束条件的构造、层析初值的选择、松弛因子的计算、终止条件的确定等,给出了计算最优松弛因子的黄金分割搜索法和确定终止条件的NCP规则,对比分析了Kaczmarz、Randkaczmarz、Symkaczmarz、SART、Landweber、Cimmino、CAV、DROP等8种常见的代数重构算法,并以香港SatRef的观测数据进行了试验。试验结果表明,以上8种代数重构技术都能够满足水汽层析的要求;迭代终止条件比松弛因子更为重要;采用文中计算最优松弛因子的黄金分割搜索法和NCP迭代终止条件,CAV算法结果最优,其次为Cimmino算法。