Quaternary climates: a perspective for global warming

This brief review provides an Earth Science perspective on present climate change (global warming) using evidence from past ice ages with details from the Quaternary ice age. It places the present (Quaternary) ice age in the context of Earth history and outlines possible causes of ice ages and the scale and style of ice age climate. Milankovitch climate forcing is described and explained as the cause of relatively predictable climatic variations within an ice age (and at other times), and this is followed by an outline of the factors likely to be responsible for short and rapid sub-Milankovitch climate variations that are superimposed on the predictable changes. Finally the anomalous, relatively constant climate of the last 11.5 ka (Holocene) is highlighted and explained in terms of human input of greenhouse gasses into the Earth's atmosphere.     

Potentiality of land and water resources in African Sahara: a case study of south Egypt

The investigated area is located south Egypt, between latitudes 22°00′N and 24°15′N, and longitudes 28°00′E and 30°00′E. It covers a total area of about 95,000.17 km². The area was remotely sensed to identify landscape and its land and water resources. A reconnaissance survey followed by detailed one was done to verify the information resulted from satellite images. The prevailing deposits of the area could be expressed as (1) the Nubian sandstone, (2) the Quaternary sediments, and (3) the sand dunes belt. Fourteen main and sub-main landforms were recognized, i.e., sand sheets (high, moderately high, moderate, and low), depressions (high, moderately high, moderate, and low), dry valleys, peniplains, footslopes, barchans, tablelands, and scattered hills. Associated soils were distinguished and classified as Typic Torripsamments, Typic Haplocalcids, Typic Torrifluvents, and Typic Haplodurids. Spatial variability of soil and water characteristics was identified through using ordinary Kriging interpolation method. Land surface temperatures in both summer and winter seasons were derived from thermal band, and soil temperature regimes were defined digitally as hyperthermic. Water potentiality was identified and classified according to salinity and sodicity hazards to C2-S1 and C3-S1. Using GIS techniques, soil potentiality spatial model (SPSM) was designed to get potentiality classes, i.e., high, moderately high, moderate, low, and very low.     

Time series analysis of mantle cycles Part I: Periodicities and correlations among seven global isotopic databases

In this study, seven isotopic databases are presented and analyzed to identify mantle and crustal episodes on a global scale by focusing on periodicity ranging from 70 to 200 million years (Myr). The databases are the largest, or among the largest, compiled for each type of data – with an objective of finding some samples from every region of every continent, to make each database as global as conceivably possible. The databases contain zircon Lu/Hf isotopic data, whole-rock Sm/Nd isotopic data, U/Pb detrital zircon ages, U/Pb igneous zircon ages, U/Pb non-zircon ages, whole-rock Re/Os isotopic data, and large igneous province ages. Part I of this study focuses on the periodicities of age histograms and geochemical averages developed from the seven databases, via spectral and cross-correlation analyses. Natural physical cycles often propagate in exact integer multiples of a fundamental cycle, referred to as harmonics. The tests show that harmonic geological cycles of ～93.5 and ～187 Myr have persisted throughout terrestrial history, and the cyclicities are statistically significant for U/Pb igneous zircon ages, U/Pb detrital zircon ages, U/Pb zircon-rim ages, large igneous province ages, mean ε_Hf(t) for all samples, mean ε_Hf(t) values for igneous-only samples, and relative abundance of mafic rocks. Equally important, cross-correlation analyses show these seven time-series are nearly synchronous (±7 Myr) with a model consisting of periodicities of 93.5 and 187 Myr. Additionally, the similarities between peaks in the 93.5 and 187 Myr mantle cycles and terminal ages of established and suspected superchrons provide a framework for predicting and testing superchron periodicity.     

Correction to: A novel methodological approach for land subsidence prediction through data assimilation techniques

Computational Geosciences - A Correction to this paper has been published: https://doi.org/10.1007/s10596-021-10079-6     

Utilization of a comparison of curvatures for land surface segmentation

Utilization of a new geomorphometric variable for land surface segmentation — the angle of absolute curvatures — is a main goal of the paper. The angle of absolute curvatures is defined as the difference between the orientation of maximal curvature (field independent) and the orientation of the greater of the profile or the tangential curvature. Land-forms separated by three types of borders (A, B, C) can be delimited from the field of angles of absolute curvatures. Borders of A type are connected with a local extreme of slope. Borders of B and C type are connected with a change to the priority of either profile or tangential curvature, as shown in computation, respectively. Fields of altitude, slope, profile curvature, tangential curvature and rotor curvature are reflected by an algorithm. Distinct borders in the field of the angles of absolute curvatures are connected with a sudden change of value and with zero isolines in the previously mentioned fields. Spatially closed entities generated by this proposed algorithm are considered to be a variant of the elementary forms of the land surface. The quality of information generated by this algorithm depends on the size of the grid mesh of the input digital elevation model. The algorithm in its current state is suitable for locating the borders of some elementary forms in the first stage of geomorphology mapping.     

Monitoring land use/land cover change using multi-temporal Landsat satellite images in an arid environment: a case study of El-Arish,Egypt

Environment in arid conditions is dynamic and needs more investigation to understand the complexity of change. This spatiotemporal study will help to assess and monitor the land use and land cover change in the arid region of El-Arish area, where the climate and human activities are the major threats to rural development. In the past 11 years, dramatic changes of environment have been recorded in case studies. The post-classification comparison method was used to observe the changes using multi-temporal satellite images which were captured in the years 1999, 2001, 2005, and 2010. The overall accuracy of the produced thematic images was assessed regarding to the quantity and allocation disagreements. Five classes were defined in this investigation: bare soil, vegetation, urban, sand dunes, and fertile soil. From the year 1999 to 2010, fertile soil was increased by 13 %. Bare soil class occupied more than 50 % of land in the case study during for over a decade. From year 1999 to 2010, vegetation cover witnessed a dramatic increase. Soil and water management are the keys of land development and positive land use and land cover dynamics. Changing agricultural policies of using the available water resources are needed in the case study to prevent severe food shortage in the future.     

The spatial organization of services in new land settlement: experiences and trends

Conclusion Despite its uniqueness, the vitality inherent in the rural structure of Israel is of particular interest to other developing regions with a predominant rural-agricultural population. Latin American countries, for example, are investing considerable resources in the development of new lands through construction of penetration roads and other infrastructure. Several countries have created regional development authorities; some have policies designed to attract private investments into virgin areas.¹³⁾ The general emphasis tends increasingly toward state-initiated and planned settlement, often in conjuction with agrarian reform programs — an approach dictated both by economic efficiency and welfare criteria.Past experience has shown that the rural population has to be organized in viable communities in order to become amenable to economic and cultural integration. Communities must likewise be spatially organized in an optimal way that will make it possible to provide them with amenities and so direct their production for the purpose of achieving economic status. At the same time, maximum flexibility must be preserved to fit varying developmental stages, since physical plans once carried into effect are extremely difficult to modify.In order to reduce the social and economic pull of existing urban centers it may be advisable to develop new settlement areas as self-sufficient enclaves, independent to some extent from the facilities existing in the region. The settlements would share the national infrastructure of communications and public services, but would gear their production to regional as well as extra-regional demand, bypassing the traditional local market place. Then, as the new communities consolidate as social and economic entities, the options for collaboration or competition with existing central places can be laid open on a more equitable basis.Admittedly such sheltered development may affect the role of the local intermediary and lessen the commercial activities of the urban sector, but it would also stimulate the development of an independent framework of handling, marketing, and an increasing degree of processing the settlements' produce. These complementary activities would help to retain part of the added value of the production and generate new sources of employment for successive village generations. The delay in the growth for the region's total output may well be worthwhile for achieving that social and economic transformation which in turn may lead to a more balance and sustained development of the entire region.¹⁴⁾     

Annual variation of temperature sensitivity of soil organic carbon decomposition in North peatlands: implications for thermal responses of carbon cycling to global warming

Temperature sensitivities of microbial respiration and dissolved organic carbon (DOC) production were investigated by using a novel method, thermal gradient (2–20°C) temperature bar, in two typical peatlands (bog and fen) in North Wales, UK over 12 months. The study indicated that temperature sensitivity of soil organic carbon decomposition in North peatlands was regulated not only by temperature but soil water content, dry–rewet event and phenologies. Potential decreases of Q₁₀ (CO₂) with increasing soil temperature were confirmed in both peatlands, but Q₁₀ (DOC) increase with increasing soil temperature in both bog and fen sites. These results imply, if other factors such as the so-called CO₂ fertilization effect are simultaneously taken into account, that the feedback of global warming induced CO₂ release from peatlands to climate change may be overestimated in current biogeochemical models. However, global warming might have been nonlinearly accelerating DOC thermal production, and therefore it helps explaining the causes of remarkable increase of DOC in surface water in the Northern Hemisphere during last several decades.     

地下洞室群对地面运动影响问题的级数解答:SH波入射

采用波函数展开法给出平面SH波入射下半空间中洞室群对地面运动影响问题的一个级数解答，并分析了入射波频率和入射角以及两洞室之间距离等参数对地面运动的影响。数值结果表明，地下洞室群对沿线地面运动具有显著的放大作用：两个洞室情况地面运动可以达到单个洞室情况的1．6倍、无洞室情况的3．5倍以上。建议地铁等地下工程在设计和规划时应考虑工程建设后对沿线设计地震动的影响。     

Adjoint retrieval of prognostic land surface model variables for an NWP model: Assimilation of ground surface temperature

Based on a 2-layer land surface model, a rather general variational data assimilation framework for estimating model state variables is developed. The method minimizes the error of surface soil temperature predictions subject to constraints imposed by the prediction model. Retrieval experiments for soil prognostic variables are performed and the results verified against model simulated data as well as real observations for the Oklahoma Atmospheric Surface layer Instrumentation System (OASIS). The optimization scheme is robust with respect to a wide range of initial guess errors in surface soil temperature (as large as 30 K) and deep soil moisture (within the range between wilting point and saturation). When assimilating OASIS data, the scheme can reduce the initial guess error by more than 90%, while for Observing Simulation System Experiments (OSSEs), the initial guess error is usually reduced by over four orders of magnitude. Using synthetic data, the robustness of the retrieval scheme as related to information content of the data and the physical meaning of the adjoint variables and their use in sensitivity studies are investigated. Through sensitivity analysis, it is confirmed that the vegetation coverage and growth condition determine whether or not the optimally estimated initial soil moisture condition leads to an optimal estimation of the surface fluxes. This reconciles two recent studies. With the real data experiments, it is shown that observations during the daytime period are the most effective for the retrieval. Longer assimilation windows result in more accurate initial condition retrieval, underlining the importance of information quantity, especially for schemes assimilating noisy observations.     

Correction to: Assessing real options in urban surface water flood risk management under climate change

Windblown dust originating in China and Mongolia causes health effects and agricultural damage in its source areas and causes Asian dust events in Japan. An early warning system that could be combined with weather forecasts would be helpful in preventing serious damage. However, it is difficult to specify source areas of dust with current dust modeling systems because land surface information, including vegetation coverage and land surface soil water content, is inadequate. To find and monitor dust source regions, a semi-real-time dust erodibility map was developed based on MODIS satellite data that focuses particularly on the threshold wind speed in a target area of northeast Asia including China and Mongolia (35°–50°N, 75°–120°E). The mapping system incorporates satellite data on snow cover, areas of frozen soil, surface soil water content, and vegetation cover.     

瑞雷面波在填海造地强夯检测工程中的应用

瑞雷面波在填海造地强夯效果检测中 ,较常规静力学方法具有成本低、效率高、适宜大面积检测的人工地震勘测方法。本文以漳州后石电厂填海造地的强夯效果检测为例 ,给出瑞雷面波检测方法在强夯效果检测应用的技术途径、技术方案 ,并对检测效果进行分析     

Geotechnical investigation of sewage wastewater disposal sites and use of GIS land use maps to assess environmental hazards: Sohag, upper Egypt

Land application is the only currently available technique for sewage wastewater disposal along the Nile Valley in Upper Egypt. Wastewater disposal projects have been established in the lowland desert zone extending between the cultivated floodplain and the Eocene Limestone plateau. The plan is to use the treated wastewater in irrigating woody farmlands. Some wastewater disposal sites are already operating, and several others will be established in the near future. The proposed wastewater disposal sites are located in a sensitive desert zone that is extremely narrow and situated very close to vital resources including the cultivated floodplain, reclaimed lands, residential areas, and surface water resources. In addition, the subsurface sediments of this zone (Pleistocene sand–gravel succession) constitute a significant part of the Quaternary aquifer of the valley. The objective of this study is to characterize and investigate the wastewater disposal sites and assess their probable environmental hazards. The study showed that the available lands are insufficient to accommodate the projected quantities of wastewater. At the currently operating sites, excess raw wastewater is accumulating on the ground surface forming large uncontrolled ponds. Such wastewater ponds represent a potential environmental hazard and might cause disastrous health effects, where chemical and bacteriological pollution of soil, crops and water resources may occur.     

Time calibration of a PT-path from the Western Tauern Window,Eastern Alps: the problem of closure temperatures

New Hornblende K-Ar and ³⁹Ar-⁴⁰Ar and mica Rb-Sr and K-Ar ages are used to place specific timemarks on a well-constrained pressure-temperature path for the late Alpine metamorphism in the Western Tauern Window. After identification of excess ⁴⁰Ar, the closure behavior of Ar in hornblende is compared with that of Sr and Ar in phengite and biotite. Samples were collected in three locations, whose maximum temperatures were 570° C (Zemmgrund), 550° C (Pfitscher Joch), and 500–540° C (Landshuter Hütte).The average undisturbed age sequence found is: Phengite Rb-Sr (20 Ma)>hornblende K-Ar (18 Ma)>phengite K-Ar (15 Ma)>biotite Rb-Sr, K-Ar (13.3 Ma)>apatite FT (7 Ma). Except for the phengite Rb-Sr age, the significance of which is debatable, all ages are cooling ages. No compositional effects are seen for closure in biotite. Additionally, Rb-Sr phengite ages from shearzones possibly indicate continuous shearing from 20 to 15 Ma, with reservations regarding the validity of the initial Sr correction and possible variations of the closure temperatures. The obviously lower closure temperature (T _c) for Ar in these hornblendes than for Sr in the unsheared phengites indicates that the T _c sequence in the Western Tauern Window is different from those observed in other terrains. In spite of this discrepancy, valuable geological conclusions can be drawn if the application of closure temperatures is limited to this restricted area with similar T, P and : (1) All ages of samples located on equal metamorphic isotherms decrease from east to west by about 1 Ma which is the result of a westward tilting of the Tauern Window during uplift. (2) In a PT-path, the undisturbed cooling ages yield constantly decreasing uplift rates from 3.6 mm/a to 0.1 mm/a. (3) Use of recently published diffusion data for Ar in hornblende (T _c=520° C) and biotite (T _c=320° C) suggests an extrapolated phengite closure temperature for Sr at 550° C. This suggests that the prograde thermal metamorphism at this tectonic level of the Tauern Window lasted until some 20 Ma ago.