陇东黄土区地质灾害气象预警方法与应用——以泾川县为例

在地质灾害详细调查的基础上,基于GIS平台以地质灾害点密度为依据生成初步地质灾害易发性区划图.从诱发地质灾害的内部因素出发将地层岩性、地形坡度、地貌类型、植被覆盖率、多年降雨量分级后,叠加到初步易发性区划图中,生成了地质灾害气象预警区划基图.以降雨作为诱发地质灾害的主导外在因素,重新对泾川县进行了地质灾害气象预警区划,...     

Net economic effects of achieving maximum economic yield in fisheries

Improving the economic performance of fisheries is becoming increasingly important in fisheries management, and in some cases, maximum economic yield (MEY) is set as a key management target. However, recent critics of MEY as a management target have argued that a decline in the level of fishing activity necessary to achieve the target will result in a subsequent loss of economic activity elsewhere in the economy and, potentially, a net loss to society. In this paper, an input–output framework is used to estimate the net economic effects of achieving MEY in several Australian fisheries for which there is information on their short- and long-term performances when moving towards MEY. While overall losses were found in the short term, achieving MEY was found to result in a net economic benefit to society in the longer term. Local coastal communities in particular were found to benefit, although some losses were incurred elsewhere in the economy.     

Cyclic Shearing Deformation Behavior of Saturated Clays

The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clay’s strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The de- formations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deforma- tion and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.     

灰色灾变模型在蒋家沟泥石流年输沙量短期预测中的应用

根据蒋家沟泥石流年输沙量最近8年的实测资料,运用灰色系统理论的灾变预测方法建立了泥石流年输沙量的灾变预测模型,对未来可能出现的年输沙量超过200万立方米的灾变年份进行了预测,并引入等维新息模型,使短期灾变预测得以连续进行。     

THE GROUNDWATER RESOURCES AND ITSSUSTAINABLE DEVELOPMENTIN THE SOUTH EDGE OF TARIM BASIN

1 INTRODUCTIONSustainability as present understand comes fromword protection strategy commission, which firstly putforward some wide excepted environmental sustainability principles and three important identifications forlife support system: soil, air and water. Then, in thereport of Our Common Future (WCED, 1987), theconcept of sustainable development is put to an outstanding level. Sustainable groundwater resources development is then a great issue in the recent years andthe future (…     

Implementation algorithm for a single hardening constitutive model for frictional materials

An advanced elasto‐plastic constitutive model for frictional materials, whose incremental version is presented in a companion paper (Int. J. Numer. Anal. Meth. Geomech., 2002; 26 :647), is implemented in a user‐defined material module. The general calculation strategy inside this module is presented and discussed, including the initial intersection of the yield surface and the techniques for updating of stresses and hardening modulus. Several integration schemes are implemented in the module and their capabilities in relation to the advanced, three‐dimensional constitutive model are evaluated. The forward Euler, modified Euler, and Runge–Kutta–Dormand–Prince integration schemes are explained in detail, compared, and evaluated in view of error tolerances and computational efficiency. Copyright © 2002 John Wiley & Sons, Ltd.     

Spatial non-stationary characteristics between grass yield and its influencing factors in the Ningxia temperate grasslands based on a mixed geographically weighted regression model

Spatial models are effective in obtaining local details on grassland biomass, and their accuracy has important practical significance for the stable management of grasses and livestock. To this end, the present study utilized measured quadrat data of grass yield across different regions in the main growing season of temperate grasslands in Ningxia of China (August 2020), combined with hydrometeorology, elevation, net primary productivity (NPP), and other auxiliary data over the same period. Accordingly, non-stationary characteristics of the spatial scale, and the effects of influencing factors on grass yield were analyzed using a mixed geographically weighted regression (MGWR) model. The results showed that the model was suitable for correlation analysis. The spatial scale of ratio resident-area index (PRI) was the largest, followed by the digital elevation model, NPP, distance from gully, distance from river, average July rainfall, and daily temperature range; whereas the spatial scales of night light, distance from roads, and relative humidity (RH) were the most limited. All influencing factors maintained positive and negative effects on grass yield, save for the strictly negative effect of RH. The regression results revealed a multiscale differential spatial response regularity of different influencing factors on grass yield. Regression parameters revealed that the results of Ordinary least squares (OLS) (Adjusted R² = 0.642) and geographically weighted regression (GWR) (Adjusted R² = 0.797) models were worse than those of MGWR (Adjusted R² = 0.889) models. Based on the results of the RMSE and radius index, the simulation effect also was MGWR > GWR > OLS models. Ultimately, the MGWR model held the strongest prediction performance (R² = 0.8306). Spatially, the grass yield was high in the south and west, and low in the north and east of the study area. The results of this study provide a new technical support for rapid and accurate estimation of grassland yield to dynamically adjust grazing decision in the semi-arid loess hilly region.     

Adaptive criterion curves describing incipient motion of sediment under wave and current conditions

Sediment incipient motion is a fundamental issue in sediment transport theory and engineering practice. Whilst Shields curve often is used to determine the threshold of sediment movement under unidirectional current conditions, it is unclear whether it can be directly applied for the wave or combined wave-current conditions. The study developed adaptive criterion curves describing incipient motion of sediment under wave and current conditions based on the flow pattern around the sediment particles. Firstly, the flow pattern law for fixed particles was recognized based on the friction law under various dynamic conditions (wave, current, and their combinations), and the flow pattern demarcations for incipient sediment motion were obtained with the threshold conditions for sediment movement under various dynamic conditions combined. Secondly, the exact shape of the Shields curve in each flow regime was derived under the current condition. By combining the flow pattern demarcations for incipient sediment motion under the wave condition, the criterion curve under the wave condition was derived. By combining the flow pattern demarcations for incipient sediment motion under the combined current-wave condition, the criterion curve for sediment incipient motion under the combined current-wave condition was derived. The results indicated that the flow pattern around incipient particles includes laminar, laminar-rough turbulent transition, and rough turbulent regimes. The criterion curves for sediment incipient motion under various dynamic conditions stayed the same in the laminar and rough turbulent regimes, but different in the transition regime. Depending on the relative strengths of the currents and waves, the shape of the criterion curve under the combined current-wave condition transitions adaptively between the criterion curve under the current condition and the criterion curve under the wave conditions.     

河南平顶山平煤矿区天然地震和人工爆破的波形特征及识别判据

基于河南测震台网记录的平顶山平煤矿区及周边发生的天然地震和人工爆破资料,按照直观、可快速识别的要求,选用发震时刻、P波初动方向、振幅比、振幅与尾波持续时间比等方法,对该地区天然地震和人工爆破进行对比分析。结果表明,P波与S波最大振幅之比（Pm/Sm）是识别该地区地震类型的最有效判据;P波初动振幅与S波最大振幅之比（Pc/Sm）和S波最大振幅与尾波持续时间之比（Sm/T）2种方法可以作为辅助判据,以提高识别地震类型的准确性。     

基于SWAT模型的无资料流域产流产沙模拟

准确预报无资料地区的产流产沙,对土壤侵蚀治理具有重要的实践意义。为了研究南方红壤侵蚀区无观测资料流域的产流产沙情况,以福建省长汀县朱溪小流域为研究区,其次一级流域游屋圳子流域和高陂塅子流域分别为参证流域和无观测资料流域。采用相对误差(Re)、决定系数(R2)以及Nash-Sutcliffe效率系数(Ens)评价了SWAT模型在游屋圳子流域的产流产沙模拟的适用性,基于地形指数判定了两子流域的水文相似性。结果表明:SWAT模型适用于游屋圳子流域的产流产沙模拟;游屋圳子流域与高陂塅子流域具有水文相似性,说明两子流域间可以进行模型参数移植;经模型参数移植,模拟得2010年高陂塅子流域年径流量为1.32×107m3,年产沙量为2 200 t。模拟结果不仅为小流域的水土保持治理提供参考,也为其他无资料流域的产流产沙模拟提供方法借鉴。