Methodology for evaluation of potential sites for large-scale riverbank filtration

Despite being a simple and inexpensive pretreatment technology, the cost-effectiveness of riverbank filtration (RBF) depends on complex hydrogeological and hydrogeochemical variables. One of the most important issues for decision makers regarding RBF is optimal site selection. Therefore, a methodology for multicriteria site evaluation for large-scale RBF schemes is offered. The methodology is primarily designed as a prescreening method, applied over a wide area, but can also serve as a guide for evaluating individual RBF sites. To facilitate further discussion about improvements on the methodology, the reasoning behind each relevant factor and its weight in the evaluation is presented. The methodology is divided into three sequential steps through which a site can be assessed. The first step is to establish the existence of connectivity between the river and aquifer. This is termed the essential criterion, and is a binary determination of site suitability. If the site is determined to be suitable, it is then assessed via a set of quantity criteria, which measure the aquifer capacity and amount of bank filtrate that can be effectively abstracted. Lastly, water quality criteria are assessed by means of surface-water and groundwater quality. The quantity and quality criteria form a result expressed as the site suitability index (SSI), which ranges from 0 to 1, where higher scores represent increased suitability. Finally, the methodology is applied to evaluate existing sites of large-scale RBF application as a demonstration of its applicability. The success of these existing sites is compared to the calculated SSI value and discussed.

     

Investigation of the accelerated carbonation of a MgO-based binder used to treat contaminated sediment

A MgO-based binder developed to simultaneously solidify/stabilize contaminated sediment and store CO₂ has been described previously. The objectives of the study presented here were to investigate the kinetics of the carbonation reactions of the binder and the extent to which carbonation occurred and to identify the optimal conditions for using the binder. The carbonation reaction was clearly faster and the degree of carbonation higher at CO₂ concentrations of 50 and 100% than in the ambient atmosphere (which contains 0.04% CO₂). A modified unreactive core model adequately described the kinetics. The rate constants were 0.0217–0.319 h^?1 and were proportional to the degree of carbonation. A high degree of carbonation, 93.8%, was achieved at a CO₂ concentration of 100%. The water to sediment ratio strongly affected carbonation, the optimal ratio being around 0.7. The relative humidity did not strongly affect the carbonation performance. The carbonation products were magnesite (MgCO₃) and nesquehonite (MgCO₃·3H₂O). X-ray diffraction analysis showed that brucite (Mg(OH)₂) was not present, suggesting that brucite was very quickly transformed into magnesium carbonates, the presence of which was confirmed by thermal gravimetric analysis. The results indicated that, in 7 d, 1 kg of binder could sequester up to 0.507 kg of CO₂ in a 100% CO₂ atmosphere. The results indicate that the MgO-based binder has great potential to be used to sequester CO₂ under accelerated carbonation conditions.     

Toward state-of-the-art techniques in predicting and controlling slope stability in open-pit mines based on limit equilibrium analysis,radial basis function neural network,and brainstorm optimization

Acta Geotechnica - This study aims to propose state-of-the-art techniques in predicting and controlling slope stability in open-pit mines based on limit equilibrium analysis, artificial neural...     

华南、巽他和掸邦地块之间边界断裂的上新世—第四纪大规模构造反转

印度- 亚洲碰撞后，大陆板块沿着大型的左行走滑断裂挤出。规模最大的哀牢山- 红河剪切带(ASRR)将印支地块(巽他地块)与华南地块分隔开来。长约1000 km的红河活动断裂(RRF)沿哀牢山的北侧延伸，目前呈现出右行走滑兼正断的活动性质。本文在讨论了红河断裂系及其周缘的第三纪和现今变形特征(滑移性质反转、渐新世/第四纪位错、全新世滑动速率、GPS测量、地震机制等)基础之上，重点论述了其在上新世—第四纪从云南东南部到越南西北部、北部湾西部、再到更南的沙巴地区的断裂分布和运动学特征。新的数据证实，跨过三联点和越南西北部的奠边府断层之后，华南地块与巽他地块之间的现今大部分右行走滑主要沿着Da River断裂向Day Nui Con Voi(或称大象山)东南方向延伸。Da River断裂与RRF大致平行，是2020年M w 5. 0莫州地震的发震断层。进一步研究表明，Da River断裂很可能沿着渐新世—中新世莺歌海/宋红盆地西缘和越南东南海岸(归仁剪切带)向南延伸得更远，至少延伸到“Ile des Cendres”火山群，并可能继续延伸到沙巴- 文莱逆冲带的西端，靠近婆罗洲北部的近海活动边缘。最后，我们讨论了在菲律宾群岛、台湾岛和巽他群岛之间南海大部分地区大规模构造反转的运动学效应。     

REDD+ Readiness progress across countries: time for reconsideration

Efforts towards Reducing Emissions from Deforestation and Forest Degradation plus conservation, sustainable management of forests and enhancement of carbon stocks (REDD+) have grown in importance in developing countries following negotiations within the United Nations Framework Convention on Climate Change (UNFCCC). This has favoured investments in processes to prepare countries for REDD+ at the national level (a process referred to as REDD+ Readiness). Yet, little attention has been given to how Readiness can be assessed and potentially improved. This article presents a framework for Readiness assessment and compares progress in REDD+ Readiness across four countries, namely Cameroon, Indonesia, Peru, and Vietnam. The Readiness assessment framework comprises six functions, namely planning and coordination; policy, laws, and institutions; measurement, reporting, verification (MRV), and audits; benefit sharing; financing; and demonstrations and pilots. We found the framework credible and consistent in measuring progress and eliciting insight into Readiness processes at the country level. Country performance for various functions was mixed. Progress was evident on planning and coordination, and demonstration and pilots. However, MRV and audits; financing; benefit sharing; and policies, laws and institutions face major challenges. The results suggest that the way national forest governance has been shaped by historical circumstances (showing path dependency) is a critical factor for progress in Readiness processes. There is need for a rethink of the current REDD+ Readiness infrastructure given the serious gaps observed in addressing drivers of deforestation and forest degradation, linking REDD+ to broader national strategies and systematic capacity building.     

Apport des spectres des ondes SH a l'etude des repliques sismiques

The SH wave spectra from some sequences of earthquakes of Kuril Islands and Chili regions, are examined following the dislocation model of seismic sources. We show by this way that, in a same sequence, it's difficult to correlate the magnitude with geometrical dimensions of the fault. We also make appear the persistence of the radiation, by developing for that, one method based on the comparison of the low frequency level with an isotropic quantity.

Résumé

On étudie le spectre des ondes SH, pour quelques séquences de séismes des Kouriles et du Chili, dans le cadre des modèles dislocatifs des sources sismiques. On montre ainsi que dans une même séquence, il est difficile de corréler la magnitude avec les dimensions géométriques de la faille. On met également en évidence la conservation de la radiation au cours d'une même séquence; on propose pour ceci une méthode, basée sur la comparaison des niveaux basses fréquences des spectres avec une quantité isotrope.     

Mean and variance evolutions of the hot and cold temperatures in Europe

In this paper, we examine the trends of temperature series in Europe, for the mean as well as for the variance in hot and cold seasons. To do so, we use as long and homogenous series as possible, provided by the European Climate Assessment and Dataset project for different locations in Europe, as well as the European ENSEMBLES project gridded dataset and the ERA40 reanalysis. We provide a definition of trends that we keep as intrinsic as possible and apply non-parametric statistical methods to analyse them. Obtained results show a clear link between trends in mean and variance of the whole series of hot or cold temperatures: in general, variance increases when the absolute value of temperature increases, i.e. with increasing summer temperature and decreasing winter temperature. This link is reinforced in locations where winter and summer climate has more variability. In very cold or very warm climates, the variability is lower and the link between the trends is weaker. We performed the same analysis on outputs of six climate models proposed by European teams for the 1961–2000 period (1950–2000 for one model), available through the PCMDI portal for the IPCC fourth assessment climate model simulations. The models generally perform poorly and have difficulties in capturing the relation between the two trends, especially in summer.     

Prediction of Blast-induced Air Over-pressure in Open-Pit Mine: Assessment of Different Artificial Intelligence Techniques

Air over-pressure (AOp) is one of the products of blasting operations for rock fragmentation in open-pit mines. It can cause structural vibration, smash glass doors, adversely affect the surrounding environment, and even be fatal to humans. To assess its dangerous effects, seven artificial intelligence (AI) methods for predicting specific blast-induced AOp have been applied and compared in this study. The seven methods include random forest, support vector regression, Gaussian process, Bayesian additive regression trees, boosted regression trees, k-nearest neighbors, and artificial neural network (ANN). An empirical technique was also used to compare with AI models. The degree of complexity and the performance of the models were compared with each other to find the optimal model for predicting blast-induced AOp. The Deo Nai open-pit coal mine (Vietnam) was selected as a case study where 113 blasting events have been recorded. Indicators used for evaluating model performances include the root-mean-square error (RMSE), determination coefficient (R²), and mean absolute error (MAE). The results indicate that AI techniques provide better performance than the empirical method. Although the relevance of the empirical approach was acceptable (R²?=?0.930) in this study, its error (RMSE?=?7.514) is highly significant to guarantee the safety of the surrounding environment. In contrast, the AI models offer much higher accuracies. Of the seven AI models, ANN was the most dominant model based on RMSE, R², and MAE. This study demonstrated that AI techniques are excellent for predicting blast-induced AOp in open-pit mines. These techniques are useful for blasters and managers in controlling undesirable effects of blasting operations on the surrounding environment.

     

Novel Soft Computing Model for Predicting Blast-Induced Ground Vibration in Open-Pit Mines Based on Particle Swarm Optimization and XGBoost

Natural Resources Research - Blasting is a useful technique for rocks fragmentation in open-pit mines, underground mines, as well as for civil engineering work. However, the negative impacts of...