Hydrologic modelling of the effect of snowmelt and temperature on a mountainous watershed

Snowmelt-runoff modelling in a mountainous basin is perceived as difficult due to the complexity of simulation. Theoretically, the snowmelt process should be influenced by temperature changes. It is still controversial as how to incorporate the temperature changes into the snowmelt-runoff model in a mountainous basin. This paper presents the results of a study in the North Fork American River basin where the snowmelt-runoff mechanism is modelled by relating the temperature changes to the elevation band in the basin. In this study, a distributed hydrologic model is used to explore the orographic effects on the snowmelt-runoff using the snowfall-snowmelt routine in Soil and Water Assessment Tool (SWAT). Three parameters, namely maximum snowmelt factor, minimum snowmelt factor, and snowpack temperature lag were analysed during the simulation. The model was validated using streamflow data from October 1, 1991 to September 30, 1994 with and without considering the elevation band. The result of this study suggests that the snowmelt-runoff model associated with the elevation band better represents the snowmelt-runoff mechanism in terms of Nash–Sutcliffe coefficient (E _NS ), R ², and Root Mean Square Error (RMSE).     

文13西块油藏岩石形变对采收率影响研究

低渗透、异常高压油藏弹性能量充足,储层欠压实,岩石易发生弹塑性变形。根据这些油藏特性,从达西定律的角度推导出了室内一维岩芯中最终采出程度与岩石物性变化的近似关系式,并引入渗透率变化因子分析采收率的影响因素,进而以文13西块油藏岩石为例,通过不同流体介质的渗透率压敏性试验,以及不同加压方式下渗透率变化试验,结合降压弹性开采试验和水驱物理模拟试验,以渗透率变化因子为基础,分析并讨论该类油藏的开采方法。结果表明：该类油藏在保持较慢降压速度、较高孔隙压力水平时,能够获得较高的油藏采收率。     

海南农村民居抗震性能调查与研究

海南农村民居以砌体结构为主,具有门窗开口大、层高较高和整体性强等特点.为了研究分析这类民居的抗震性能与抗震对策,在收集大量当地农村民居样本的基础上,综合出典型结构模型,并对该典型模型及基于该模型的隔震模型和加强结构模型分别进行了模拟地震振动台试验.试验结果表明:隔震技术能明显降低结构地震反应,在高烈度地区应适当推广和运用.原结构模型基本满足7.5度设防标准.在8度大震作用下,结构遭遇严重破坏但未倒塌,说明其具有一定的抗倒塌能力.结构加固后,整体抗震性能得到了加强.结合试验结果,给出了相应对策与建议.     

中国大陆地磁场Z 分量日变幅的时空特征分析

通过分析中国大陆76个地磁台站2008年1月1日至2010年12月31日地磁场Z分量日变幅的时空特征,得到结论如下:①在时间上,回归分析和傅里叶分析结果表明,所有台站地磁Z分量的日变幅均有明显的周期性变化,周期主要有365天、183天、122天、73天等,其中365天的周期振幅最大(即年周期)。②空间上,地磁场Z分量日变幅随纬度整体呈非线性变化,在25°N附近存在拐点(极大值点),在15°～25°N,日变幅随纬度的增加而增加,在25°～50°N,Z的日变幅随纬度的增加而减小。③通过地磁场Z分量日变幅时空分布与等效电流对比,结果显示地磁场Z分量日变幅的时空变化特征主要是由等效电流的时空演化决定的。④若粗略地把地磁场Z分量日变幅最大值所处的纬度视为等效电流的焦点所在的纬度,则焦点所在纬度夏季最高,春秋季次之,冬季最低,逐日焦点变化最大可达10°。     

Frequency‐domain acoustic‐elastic coupled waveform inversion using the Gauss‐Newton conjugate gradient method

We developed a frequency‐domain acoustic‐elastic coupled waveform inversion based on the Gauss‐Newton conjugate gradient method. Despite the use of a high‐performance computer system and a state‐of‐the‐art parallel computation algorithm, it remained computationally prohibitive to calculate the approximate Hessian explicitly for a large‐scale inverse problem. Therefore, we adopted the conjugate gradient least‐squares algorithm, which is frequently used for geophysical inverse problems, to implement the Gauss‐Newton method so that the approximate Hessian is calculated implicitly. Thus, there was no need to store the Hessian matrix. By simultaneously back‐propagating multi‐components consisting of the pressure and displacements, we could efficiently extract information on the subsurface structures. To verify our algorithm, we applied it to synthetic data sets generated from the Marmousi‐2 model and the modified SEG/EAGE salt model. We also extended our algorithm to the ocean‐bottom cable environment and verified it using ocean‐bottom cable data generated from the Marmousi‐2 model. With the assumption of a hard seafloor, we recovered both the P‐wave velocity of complicated subsurface structures as well as the S‐wave velocity. Although the inversion of the S‐wave velocity is not feasible for the high Poisson's ratios used to simulate a soft seafloor, several strategies exist to treat this problem. Our example using multi‐component data showed some promise in mitigating the soft seafloor effect. However, this issue still remains open.     

Submarine groundwater discharge revealed by aerial thermal infrared imagery: a case study on Jeju Island,Korea

Submarine groundwater discharge (SGD) is a global phenomenon that carries large volumes of groundwater and dissolved chemical species such as nutrient, metals, and organic compounds to coastal zones. We report the influence of SGD on the coastal waters of Jeju Island, Korea, using high‐resolution aerial thermal infrared (TIR) mapping techniques and field investigations. An aircraft‐based system was implemented using a cost‐effective TIR camera for aerial TIR mapping. Ground‐based calibrations and system integration with GPS/IMU (global positioning system/inertial measurement unit) were performed for the aerial systems. The aerial surveys showed distinct low‐temperature signatures of SGD along the coasts of Jeju Island, revealing large groundwater inputs from the coastal aquifers to the ocean. Multiple aerial surveys over a range of seasons and tidal stages revealed that SGD rates dynamically affect the sea surface temperature (SST) of the coastal zone. The in‐situ measurements supported that SGD has a substantial influence on the coastal water chemistry as well as SST. Our observations highlight the extent to which aerial‐based TIR mapping can serve as a powerful tool for studying SGD and other coastal processes. Copyright © 2016 John Wiley & Sons, Ltd.     

Performance evaluation of ultrafine cement as a grout for reservoir impermeability improvement

Acta Geotechnica - Although Ordinary Portland Cement (OPC) has been widely used as one of the significant grouting materials, there are many drawbacks to its application in the field. In this...     

基于Datist的测震分析月报自动产出技术研发

针对四川测震台网运行月报中关于测震分析章节编写过程中的程序化工作流程,依托于数据专家(Datist)自动化流程实现了数据源读取、数据清洗、目录统计、绘制震中分布图、计算速报结果自评和报告自动产出等功能,辅助完成月报生成。实践证明该成果可有效减轻地震监测人员的工作负担,提高工作效率。     

Effect of spatially variable saturated hydraulic conductivity with non-stationary characteristics on the stability of reservoir landslides

Stochastic Environmental Research and Risk Assessment - Conventional landslide analyses, based on deterministic methods or simple random variable methods, cannot consider the spatial variability...