Simulating Groundwater-Streamflow Connections in the Upper Colorado River Basin

In mountain, snow driven catchments, snowmelt is supposed to be the primary contribution to river streamflows during spring. In these catchments the contribution of groundwater is not well documented because of the difficulty to monitor groundwater in such complex environment with deep aquifers. In this study we use an integrated hydrologic model to conduct numerical experiments that help quantify the effect of lateral groundwater flow on total annual and peak streamflow in predevelopment conditions. Our simulations focus on the Upper Colorado River Basin (UCRB; 2.8 × 10⁵ km²) a well-documented mountain catchment for which both streamflow and water table measurements are available for several important sub-basins. For the simulated water year, our results suggest an increase in peak flow of up to 57% when lateral groundwater flow processes are included—an unexpected result for flood conditions generally assumed independent of groundwater. Additionally, inclusion of lateral groundwater flow moderately improved the model match to observations. The correlation coefficient for mean annual flows improved from 0.84 for the no lateral groundwater flow simulation to 0.98 for the lateral groundwater flow one. Spatially we see more pronounced differences between lateral and no lateral groundwater flow cases in areas of the domain with steeper topography. We also found distinct differences in the magnitude and spatial distribution of streamflow changes with and without lateral groundwater flow between Upper Colorado River Sub-basins. A sensitivity test that scaled hydraulic conductivity over two orders of magnitude was conducted for the lateral groundwater flow simulations. These results show that the impact of lateral groundwater flow is as large or larger than an order of magnitude change in hydraulic conductivity. While our results focus on the UCRB, we feel that these simulations have relevance to other headwaters systems worldwide.     

Investigation of the dynamic behaviour of a storage tank with different foundation types focusing on the soil‐foundation‐structure interactions using centrifuge model tests

This paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage‐tank structure. It was used in the present study to investigate the soil‐foundation‐structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley & Sons, Ltd.     

Simulating the spatial diffusion of memes on social media networks

This article reports the findings from simulating the spatial diffusion processes of memes over social media networks by using the approach of agent-based modeling. Different from other studies, this article examines how space and distance affect the diffusion of memes. Simulations were carried out to emulate and to allow assessment of the different levels of efficiency that memes spread spatially and temporally. Analyzed network structures include random networks and preferential attachment networks. Simulated spatial processes for meme diffusion include independent cascade models and linear threshold models. Both simulated and real-world social networks were used in the analysis. Findings indicate that the numbers of information sources and opinion leaders affect the processes of meme diffusion. In addition, geography is still important in the processes of spatial diffusion of memes over social media networks.     

Predicting Blast-Induced Air Overpressure: A Robust Artificial Intelligence System Based on Artificial Neural Networks and Random Forest

Natural Resources Research - Blasting is the most popular method for rock fragmentation in open-pit mines. However, the side effects caused by blasting operations include ground vibration, air...     

Morphology and Dynamics of Alluvial Fan and Its Research Prospects

Alluvial fans can preserve historical records of sediment transport to middle and lower river systems or piedmont basins, which are considered to be sensitive recorders of climate change and tectonic activity. In this paper, the morphological characteristics, control factors and future development trend of alluvial fan are summarized and described. The main understanding is as follows: \mathrm{①} According to the gravity flow and traction flow process, fan can be divided into debris flow alluvial fan and fluvial fan. The former is formed under the action of debris gravity flow deposits, which is related to the occasional flood and burst flow in a short time. The latter is braided tributaries depositions which are gradually shallower and spread radially in the direction of fan toe under the traction water transport. \mathrm{②} The erodibility of underlying bedrock can affect the scale of downstream alluvial fan, which depends on the sediment production and store factors in the catchment. The easily eroded bedrock may produce more sediment, making the alluvial fan area larger. In the contrast, the erodibility of rocks in the source area can also affect the slope and hydrological characteristics of the valley so that more sediment is deposited in the upstream basin and the alluvial fan formed in the downstream is smaller. \mathrm{③} Tectonic activity is the pre-condition for the development of alluvial fans, which provides a space for alluvial fans depositions. Faulting in the piedmont can change the position and morphology of the ancient alluvial fan, and also cause deformation or distortion of the thick sedimentary sequence to record the regional tectonic activity. The quaternary alluvial fan sequence corresponds well to the climate change during the glacial-interglacial period. However, the influence of the flood events caused by extreme meteorological events on alluvial fan deposition should be focused on. \mathrm{④} The application of a series of new techniques and methods will help to carry out deep research on alluvial fan in the future, such as high-resolution observation technique, physical simulation experiment, and precise dating.     

"亚太六号"卫星发射日气象保障及数值模拟分析

2005年4月11～12日西昌发射场遭遇了一次寒潮天气过程,而这正值"亚太六号"卫星预定的发射日.针对这一情况,发射中心气象部门利用多种探测手段,综合分析各类气象信息,采取逐步逼近的方式,在复杂条件下抓住了有利战机,准确预报出了此次寒潮过程及对场区的影响程度,圆满完成了气象保障任务.此外,利用相关资料对发射日资料进行了数值模拟,结果表明,MM5模式较好地模拟了本次天气过程中的降水、降温和增压过程.     

Stochastic finite-fault ground motion simulation for the Mw 6.7 earthquake in Lushan,China

Natural Hazards - The Ya’an, Sichuan Mw 6.7 earthquake occurred on April 20, 2013. In this article, the stochastic finite-fault method (EXSIM) based on dynamic corner frequency, proposed by...     

Simulation of the Jiuzhaigou,China, earthquake by stochastic finite-fault method based on variable stress drop

Natural Hazards - An improved stochastic finite-fault method was used to simulate the Mw 6.6 earthquake that occurred on August 8, 2017, in Jiuzhaigou, Sichuan, China. A variation of the stochastic...     

抽出-处理技术抽出污染地下水——抽出效率及抽出终点

针对抽出-处理技术修复污染地下水过程中抽水井抽出效率随时间逐渐降低、抽出-处理技术运行终点（以下简称"抽出终点"）难以确定的问题,提出通过评估抽水井抽出效率,以分段、多次优化抽水方案提高抽出效率、降低修复成本、减少修复时间为工作思路,利用层次分析法和专家打分法实现方案优化时间节点选择。以青海某铬盐厂为例,通过建立抽水方案优化时间节点评价指标体系,可定量分析方案优化时间节点,合理确定抽出终点。结果显示：第1次优化结果为抽水井抽出效率在20%~40%时应重新布设抽水方案（P₃）,即采用原抽水方案抽水100 d后需重新布设抽水井;第2次优化结果为抽水井抽出效率在20%~40%时应与其他修复技术联用（P₇）,即采用一次优化后抽水方案继续抽水300 d后需联合其他修复技术开展治理。经评估,2次优化可有效提高抽水井抽出效率,使修复时间缩短600 d,相同时间内含水层中六价铬去除率增加8.31%。     

Prediction of Blast-Induced Ground Vibration in an Open-Pit Mine by a Novel Hybrid Model Based on Clustering and Artificial Neural Network

Natural Resources Research - Ground vibration (PPV) is one of the hazard effects induced by blasting operations in open-pit mines, which can affect the surrounding structures, particularly the...