Modelling the effect of climate change induced soil settling on drinking water distribution pipes.

In the future, the more frequent occurrence of severe heat waves and long dry periods due to climate change can cause lowering of the ground water level and therefore consolidation of the soil. Consequently, increased differential settlements are expected that may damage underground water infrastructure. Models were developed to assess the impact of differential settlements on pipe failure. The main concept of these models is that the pipe-soil system is schematized as a beam on an elastic foundation using Winkler type springs. For climate change induced settling, a parametric function of the soil settlement is proposed. A Monte-Carlo analysis has been applied to predict pipe failure probabilities.     

Effect of climate change on the trends of evaporation of phreatic water from bare soil in Huaibei Plain,China

When the soil condition and depth to water table stay constant, climate condition will then be the only determinant of evaporation intensity of phreatic water from bare soil. Based on a series of long-term quality-controlled data collected at the Wudaogou Hydrological Experiment Station in the Huaibei Plain, Anhui, China, the variation trends of the evaporation rate of phreatic water from bare soil were studied through the Mann-Kendall trend test and the linear regression trend test, followed by the study on the responses of evaporation to climate change. Results indicated that in the Huaibei Plain during 1991-2008, evaporation of phreatic water from bare soil tended to increase at a rate of 5% on monthly scale in March, June and July while in other months the increase was minor. On the seasonal basis, the evaporation saw significant increase in spring and summer. In addition, annual evaporation tended to grow evidently over time. When air temperature rises by 1 °C, the annual evaporation rate increases by 7.24–14.21%, while when the vapor pressure deficit rises by 10%, it changes from-0.09 to 5.40%. The study also provides references for further understanding of the trends and responses of regional evapotranspiration to climate change.     

Effects of climate change on the groundwater system in the Grote-Nete catchment,Belgium

The effects of climate change on the groundwater systems in the Grote-Nete catchment, Belgium, covering an area of 525 km², is modeled using wet (greenhouse), cold or NATCC (North Atlantic Thermohaline Circulation Change) and dry climate scenarios. Low, central and high estimates of temperature changes are adopted for wet scenarios. Seasonal and annual water balance components including groundwater recharge are simulated using the WetSpass model, while mean annual groundwater elevations and discharge are simulated with a steady-state MODFLOW groundwater model. WetSpass results for the wet scenarios show that wet winters and drier summers are expected relative to the present situation. MODFLOW results for wet high scenario show groundwater levels increase by as much as 79 cm, which could affect the distribution and species richness of meadows. Results obtained for cold scenarios depict drier winters and wetter summers relative to the present. The dry scenarios predict dry conditions for the whole year. There is no recharge during the summer, which is mainly attributed to high evapotranspiration rates by forests and low precipitation. Average annual groundwater levels drop by 0.5 m, with maximum of 3.1 m on the eastern part of the Campine Plateau. This could endanger aquatic ecosystem, shrubs, and crop production.     

Modelling water retention and volume change behaviours of unsaturated soils in non-isothermal conditions

This study presents a simple approach to modelling the effect of temperature on the soil–water retention curves (SWRCs) of deformable soils and takes into consideration the following two aspects: (1) the effect of temperature on the liquid–gas interfacial tension and (2) temperature-induced deformation of the soil skeleton. The first aspect, the temperature effect, can be modelled using an equation proposed by Grant and Salehzadeh [18], but the second aspect is generally neglected in the literature. To quantify the thermo-hydro-mechanical (THM) deformation of unsaturated soils (i.e., the second aspect mentioned above), a simple volume change equation, referred to as the non-isothermal SFG volumetric equation, is proposed on the basis of the original SFG framework [37]. A three-dimensional THM yield surface in the space of net mean stress, suction and temperature is presented here. The proposed volume change equation is integrated into the non-isothermal SWRC by means of a simple hydro-mechanical coupling law [38]. The performance of the non-isothermal SFG volumetric equation and the non-isothermal SWRC equation is investigated through several numerical examples. A number of experimental results reported in the literature are employed to confirm the validity of the proposed non-isothermal SFG volume change equation and the non-isothermal SWRC equation.     

Modelling the effects of climate change on methane emission from a northern ombrotrophic bog in Canada

Peatlands are a large potential source of methane (CH₄) to the atmosphere. In order to investigate the effects of climate change on CH₄ emission from northern ombrotrophic peatlands, a simulation model coupling water table dynamics with methane emission was developed for the Mer Bleue Bog in Ontario, Canada. The model was validated against reported values of CH₄ flux from field measurements and the model outputs exhibited high sensitivity to acrotelm thickness, leaf area index, transmissivity and slope of water table. With a 2–4°C temperature rise over the 4-year simulation period, the rate of CH₄ release dropped significantly to under 0.1 mg m⁻² day⁻¹. On the other hand, mean CH₄ emission increased by >26-fold when the increase in precipitation was >15%. When looking at the combined effects, the highest CH₄ release (13.3 mg m⁻² day⁻¹) was attained under the scenario of 2°C temperature rise and 25% precipitation increase. Results obtained in this study highlight the importance of avoiding more extreme climate change, which would otherwise lead to enhanced methane release from peatlands and further atmospheric warming through positive feedback.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

An overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes, so that it can continue maintaining its prospect and improving wellbeing. Nevertheless, climate change is more or less affecting society's functions at different scales, including both individuals and communities. In this review, we discuss the relationship between society and climate change in China from the aspects of the needs at different socioeconomic developing stages. The relationship as well as the current spatial pattern and future risks of the climate change impacts on societies are summarized. The complexity of social and climatic systems leads to the spatial heterogeneity of climate impacts and risks in China. To more effectively leverage increasing knowledge about the past, we advocate greater cross-disciplinary collaboration between climate adaption, poverty alleviation and Nature-based Solutions (Nbs). That could provide decision makers with more comprehensive train of thoughts for climate policy making.     

Static soil culvert interaction the effect of box culvert geometric configurations and soil properties

The response of box culverts to static loads is controlled by soil arching. Soil arching is a result of a complex soil culvert interaction (SCI) due to the relative stiffness between the culvert and the surrounding soil, and is a critical consideration in culvert design. The factors that affect soil arching on box culverts include the soil height above the culvert, the geometrical configuration of the box culvert and the properties of the soil around it. Box culverts are typically designed using formulae that assume simplified behaviors and in some cases rely on considerable empiricism. In the present study, small scale centrifuge physical model tests were conducted to investigate SCI considering the height and density of soil above the culvert and the geometry of the culvert. The results of these centrifuge tests were used to calibrate and verify a numerical model that was used to further investigate the response of box culverts to static loads. The results have been evaluated for bending moment and soil culvert interaction factors. The results demonstrated that the soil culvert interaction factors are not only a function of the height of soil column above the culvert, but also a function of the culvert thickness, soil elastic modulus and Poisson’s ratio. Therefore, the results were used to establish charts and equations that can be employed to assess the design values of the static soil pressure and static bending moment for box culverts.     

The effect of climate change on the mobility and stability of coastal sand dunes in Ceará State (NE Brazil)

The coast of Ceará State in NE Brazil is covered by vast fields of active and stabilized coastal sand dunes. Its tropical climate is characterized by two seasons, wet and dry, with wind intensity determined by the meridional shift of the Intertropical Convergence Zone. The wind power is negatively correlated with precipitation, and precipitation is negatively correlated with the difference between sea surface temperatures of the tropical Atlantic north and south of the equator. We present a model suggesting that during the Late Pleistocene wind power determined the mobility and stability of the dunes. Sand dunes accumulated during periods of high wind power (as it is today) and stabilized when wind power was low. Once the dunes were stabilized by vegetation they could not be activated even by increased wind power. Samples that were taken for luminescence dating from 25 stabilized dunes along the coasts of Ceará gave ages ranging from135 ka to < 100 yr. We postulate that these luminescence ages fall at the beginning of wet periods in NE Brazil characterized by low wind power. These paleoclimatic wet periods correlate well with the cold periods of stades in Greenland ice-core records.     

A simple daily soil–water balance model for estimating the spatial and temporal distribution of groundwater recharge in temperate humid areas

Quantifying the spatial and temporal distribution of natural groundwater recharge is usually a prerequisite for effective groundwater modeling and management. As flow models become increasingly utilized for management decisions, there is an increased need for simple, practical methods to delineate recharge zones and quantify recharge rates. Existing models for estimating recharge distributions are data intensive, require extensive parameterization, and take a significant investment of time in order to establish. The Wisconsin Geological and Natural History Survey (WGNHS) has developed a simple daily soil–water balance (SWB) model that uses readily available soil, land cover, topographic, and climatic data in conjunction with a geographic information system (GIS) to estimate the temporal and spatial distribution of groundwater recharge at the watershed scale for temperate humid areas. To demonstrate the methodology and the applicability and performance of the model, two case studies are presented: one for the forested Trout Lake watershed of north central Wisconsin, USA and the other for the urban-agricultural Pheasant Branch Creek watershed of south central Wisconsin, USA. Overall, the SWB model performs well and presents modelers and planners with a practical tool for providing recharge estimates for modeling and water resource planning purposes in humid areas.

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Resumen La cuantificación de la distribución espacial y temporal de la recarga natural de agua subterránea es un requisito previo para una modelación y una gestión efectivas de las aguas subterráneas. Dado que se está incrementando el uso de los modelos de flujo para la toma de decisiones de gestión, existe una necesidad creciente de métodos simples y prácticos para delimitar las zonas de recarga y cuantificar los rangos de la misma. Los modelos existentes para la estimación de la distribución de la recarga requieren datos intensivos, una parametrización extensiva y una inversión de tiempo significativa para ser establecidos. El Servicio Geológico y de Historioa Natural de Wisconsin (WGNHS) ha desarrollado un modelo simple de balance diario de agua en el suelo (SWB) que usa de forma sencilla datos disponibles de suelo, de cobertera, topográficos y climáticos conjuntamente con un Sistema de Información Geográfica (GIS) para estimar la distribución espacial y temporal de la recarga de aguas subterráneas a escala de cuenca para zonas templadas húmedas. Para demostrar la metodología, aplicabilidad y el comportamiento del modelo, se presentan dos casos: uno en la cuenca boscosa de Trout Lake, en la zona Norte-Central de Wisconsin, USA y el otro en la Cuenca urbano-agrícola de Pheasant Branch Creek, Sur-Centro de Winconsin, USA. En conjunto, el modelo SWB funciona bien y presenta a los modeladores y planificadores una herramienta práctica para llevar a cabo una estimación de la recarga para propósitos de modelación y planificación de los recursos de agua en zonas húmedas.

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Résumé Quantifier les distributions temporelle et spatiale de la réalimentation naturelle des eaux souterraines est en règle générale un préalable à une modélisation et une gestion efficaces des eaux souterraines. Etant donné que les modèles numériques sont utilisés de manière croissante dans les prises de décisions en matière de gestion, il existe un besoin accru pour des méthodes simples et pratiques, afin de délimiter les zones d’alimentation et de quantifier les recharges associées. Les modèles existants, destinés à l’estimation de la répartition des réalimentations, demandent énormément de données, un paramétrage long, et un investissement conséquent en temps de mise en œuvre. Le Wisconsin Geologic and Natural History Survey (WGNHS) a développé un modèle simple basé sur un bilan en eau quotidien dans les sols (SWB); il utilise les données directement disponibles sur les sols, l’occupation des sols, la topographie et le climat, en conjonction avec un Système d’Information Géographique, afin d’estimer les distributions temporelle et spatiale de la réalimentation des eaux souterraines à l’échelle du bassin versant, pour les zones humides tempérées. Afin de démontrer la méthodologie, l’applicabilité et les performances du modèle, deux applications sont présentées: la première sur le bassin versant boisé de Trout Lake au centre-nord du Wisconsin (Etats-Unis), et le second sur le bassin versant agricole et urbanisé de Pheasant Branch Creek au centre-sud du Wisconsin. Le modèle SWB se comporte globalement bien, et offre aux modélisateurs un outil fonctionnel pour estimer les réalimentations, dans le cadre de modélisations et de plans de gestion des ressources en eau souterraine dans les zones humides.

     

基于衬砌长期渗漏水影响的隧道施工扰动诱发超孔隙水压消散及地层固结沉降解

基于Terzaghi-Rendulic固结理论,采用保角映射和分离变量法,计算得到隧道衬砌半渗透漏水边界条件下,盾构施工扰动引起的隧道周围土体超孔隙水压力消散解和地表土体固结沉降,通过工程实例进行验证,发现理论方法与实测数据趋势一致;此外,利用参数分析获得了土体固结沉降和超孔隙水压力的分布影响规律。结果表明:衬砌与土体的相对渗透比越大,固结沉降的初始速率越大,但不影响最终收敛值;土体弹性模量越小,最终固结沉降量越大;土体中超孔隙水压力随着时间增加,在隧道开挖后较短时间里以较大幅度逐渐消散,消散到约为初始值的1/10时减幅放缓;距离衬砌外壁越远,土体初始超孔隙水压力越小,其消散速度也越慢。     

The influence of the depth of the ground water table on free field road traffic-induced vibrations

This paper describes the influence of seasonal variations of the ground water table on free field traffic-induced vibrations. The passage of a truck on two types of road unevenness is considered: a joint in a road pavement consisting of concrete plates and a speed bump with a sinusoidal profile. Free field vibrations are computed with a two-step solution procedure, where the computation of the vehicle axle loads is decoupled from the solution of the road–soil interaction problem. The impedance of the soil is calculated using a boundary element method, based on the Green's functions for a dry layer on top of a saturated half-space. It is demonstrated that, in the low-frequency range of interest, wave propagation in the saturated half-space can be modelled with an equivalent single phase medium as an alternative to Biot's poroelastic theory for saturated porous media. The relation between the free field velocity and the depth of the ground water table is dominated by three phenomena: (1) the compressibility of the soil decreases due to the presence of the pore water, (2) the ground water table introduces a layering of the soil which may cause resonance of the dry layer and (3) refracted P-waves in the dry layer interfere with surface waves. If the depth of the ground water table is large with respect to the wavelength of the vibrations in the soil, the response tends to the response of a dry half-space. The average free field velocity is equal to the velocity in the absence of ground water. If the depth of the ground water table is small with respect to the wavelength of the vibrations in the soil, the response tends to the response of a saturated half-space and resonance of the dry layer does not occur. The average free field velocity is smaller than the velocity in the absence of ground water. The interference of refracted P-waves and surface waves causes an additional oscillation of the response as a function of the excitation frequency and the distance between the road and the receiver. Copyright © 2004 John Wiley & Sons, Ltd.     

Spatial analysis of land use change effect on soil organic carbon stocks in the eastern regions of China between 1980 and 2000

Spatial distributions of 0-20 cm soil carbon sources/sinks caused by land use changes from the year 1980 to 2000 in an area of 2.97 × 10~6 km~2 in eastern China were investigated using a land use dataset from a recent soil geochemical survey.A map of soil carbon sources/sinks has been prepared based on a spatial analysis scheme with GIS.Spatial statistics showed that land use changes had caused 30.7 ± 13.64 Tg of surface soil organic carbon loss,which accounts for 0.33%of the total carbon storage of 9.22 Pg.The net effect of the carbon source was estimated to be ~ 71.49 Tg soil carbon decrease and ~40.80 Tg increase.Land use changes in Northeast China(NE) have the largest impact on soil organic carbon storage compared with other regions.Paddy fields,which were mainly transformed into dry farmland in NE,and constructed land in other regions,were the largest carbon sources among the land use types.Swamp land in NE was also another large soil carbon source when it was transformed into dry farmland or paddy fields.Dry farmland in the NE region formed the largest soil organic carbon sink,as some were transformed into paddy fields,forested land,and other land use types with high SOCD.