The measurement of hait at ground level

Abstract

The purpose of this study was to measure, with the help of a sensor measuring the impact of hailstones, the physical characteristics of hailfalls point‐by‐point, and to extend these measurements to a larger surrounding area.

The results of calibrations and data‐handling methods, applying to a type of hailpad used in France and in Switzerland, are presented. The sources of error due to the pad, to the natural variability of the hailfalls and to the integration of the data over area are then reviewed.     

Effect of climate change and increased atmospheric CO2 on hydrological and nitrogen cycling in an intensive agricultural headwater catchment in western France

Climate change and increased atmospheric CO₂ concentration can impact hydrological and nitrogen cycling at the catchment scale. The objective of this study is to assess these impacts in an intensive agricultural headwater catchment in western France. A calibrated and validated agro-hydrological model was driven by output of the climate model ARPEGE under the A1B emission scenario over 30-year simulation periods. Our study indicated that with climate warming and increased atmospheric CO₂, the main trends in water balance were a decrease in annual actual evapotranspiration (AET), a decrease in annual discharge and wetland extent, and a decrease in spring and summer of groundwater recharge and soil-water content. Not considering the effects of increased atmospheric CO₂ in the agro-hydrological model led to overestimating discharge decrease and underestimating AET decrease and wetland extent. Climate change could influence N cycling by increasing soil N mineralisation, increasing soil denitrification in wetlands and upstream areas, and decreasing NO₃–N load to streams. Since wetlands appear to be sensitive to climate change, improving modelling to better predict their responses is an important issue, especially to help plan sustainable management of these vulnerable areas.     

Indigenous frameworks for observing and responding to climate change in Alaska

Despite a keen awareness of climate change, northern Indigenous Peoples have had limited participation in climate-change science due to limited access, power imbalances, and differences in worldview. A western science emphasis on facts and an indigenous emphasis on relationships to spiritual and biophysical components indicate important but distinct contributions that each knowledge system can make. Indigenous communities are experiencing widespread thawing of permafrost and coastal erosion exacerbated by loss of protective sea ice. These climate-induced changes threaten village infrastructure, water supplies, health, and safety. Climate-induced habitat changes associated with loss of sea ice and with landscape drying and extensive wildfires interact with northern development to bring both economic opportunities and environmental impacts. A multi-pronged approach to broadening indigenous participation in climate-change research should: 1) engage communities in designing climate-change solutions; 2) create an environment of mutual respect for multiple ways of knowing; 3) directly assist communities in achieving their adaptation goals; 4) promote partnerships that foster effective climate solutions from both western and indigenous perspectives; and 5) foster regional and international networking to share climate solutions.     

Regulatory control of vehicle and power plant emissions: how effective and at what cost?

Passenger vehicles and power plants are major sources of GHG emissions. While economic analyses generally indicate that a broader market-based approach to GHG reduction would be less costly and more effective, regulatory approaches have found greater political success. We evaluate a global regulatory regime that replaces coal with natural gas in the electricity sector and imposes technically achievable improvements in the efficiency of personal transport vehicles. Its performance and cost are compared with other scenarios of future policy development including a no-policy world, achievements under the Copenhagen Accord, and a price-based policy to reduce global emissions by 50% by 2050. The assumed regulations applied globally achieve a global emissions reduction larger than projected for the Copenhagen agreements, but they do not prevent global GHG emissions from continuing to grow. The reduction in emissions is achieved at a high cost compared to a price-based policy. Diagnosis of the reasons for the limited yet high-cost performance reveals influences including the partial coverage of emitting sectors, small or no influence on the demand for emissions-intensive products, leakage when a reduction in fossil use in the covered sectors lowers the price to others, and the partial coverage of GHGs. If these regulatory measures are in part correcting other barriers or behavioural limitations consumers face, the benefits of overcoming these could offset at least some of the costs we estimate. The extent of any efficiency gap – the difference between engineering estimates of best practice and what actually happens – is highly contested, and offers an important avenue for future research.

Policy relevance

While analysts concerned with national cost of GHG control have long advocated a GHG pricing policy, by a cap-and-trade system or a tax, covering all emissions sources and gases, governments more often pursue sectoral policies and technology standards. Given these political realities, the regulations represent a more politically practical approach to GHG reductions, focusing on solutions that are within reach and that do not depend on technological breakthroughs. If regulations are imposed as a way to get started on larger emissions reductions, and then combined with a broader GHG pricing policy pursuing a deep global cut in emissions, its requirements will eventually be overtaken by the pricing policy. The remaining higher costs of the regulatory targets become diluted so that in later years the difference in average cost per ton between a least-cost approach and one preceded by a period of regulatory action becomes very small.     

Impact‐related noncoaxial deformation in the Pułtusk H chondrite inferred from petrofabric analysis

Petrofabrics in chondrites have the potential to yield important information on the impact evolution of chondritic parent asteroids, but studies involving chondritic petrofabrics are scarce. We undertook an analysis of the Pu?tusk H chondrite regolith breccia. Measurements of anisotropy of magnetic susceptibility and quantitative tomographic examination of metal grains are presented here and the results are compared with petrographic observations. The major fabric elements are in Pu?tusk shear fractures cutting the light‐colored chondritic clasts as well as brittly and semibrittly deformed, cataclased fragments in dark matrix of regolith breccia. Cataclasis is accompanied by rotation of silicate grains and frictional melting. Fabric of metal grains in chondrite is well defined and coherently oriented over the breccia, both in the clasts and in the cataclastic matrix. Metal grains have prolate shapes and they are arranged into foliation plane and lineation direction, both of which are spatially related and kinematically compatible to shear‐dominated deformational features. We argue that the fabric of Pu?tusk was formed in response to impact‐related noncoaxial shear strain. Deformation promoted brittle cataclastic processes and shearing of silicates, and, simultaneously, allowed for ductile metal to develop foliation and lineation. We suggest that plastic flow is the most probable mechanism for the deformation of metal grains in the shear‐dominated strain field. The process led also to the formation of large metal nodules and bands in the dark matrix of breccia.     

Experimental Validation of an Method for In Situ Estimation of Hydraulic Conductivity of Water Treatment Granular Materials

Domestic wastewater-treatment system is today a widely held technique. In order to evaluate the efficiency of these systems, it is necessary to determinate the in situ hydraulic conductivity of the water-treatment granular materials constituting them. The in situ measurement of the hydraulic conductivity of soils has proven to be imprecise, take a long time. Empirical equations based on the physical properties of soil have been proposed to overcome these difficulties. In this context, the originality of this paper is to propose an in situ method to obtain reliable input parameters for the predictive equations of Chapuis (Can Geotech J 41(5): 787–795, 2004) and Carrier (J Geotech Geoenviron Eng 129(11): 1054–1056, 2003) by using both a penetrometer and a geoendoscope. This method is described in the first part of this paper. Then, the validation of the method based on laboratory tests performed under controlled conditions for three kinds of soils is presented. Hydraulic conductivity obtained when applying the method is compared to that measured by a Darcy permeameter. The difference between these two hydraulic conductivities is less than 25%. Finally, the precision of the results is discussed.     

Estimation of the Variability of Tailings Dams Properties in Order to Perform Probabilistic Assessment

Dams are often used for storing mine tailings. These structures present failure mechanisms that can lead to major risks for surrounding populations. In view to managing these risks, it is necessary to take a probabilistic approach in predicting their behaviour. The application of such approaches is limited by the difficulty of obtaining experimental data to estimate the variability of the parameters and conditioned by the relevance of the probability models chosen to represent this variability. This article proposes (1) a probabilistic modelling of the index properties of the mine tailings constituting these dams based on statistical analyses and (2) a method using dynamic penetration tests to estimate on site the mine tailings friction angle and its variability. This method, applied to chilean tailings dams proposes a single model for all tailings dams in order to associate a probability law to the effective friction angle (ϕ′). The procedure is illustrated on the probabilistic study of slope stability carried out at the global scale of a dam and also at the local scale of each of its constituent layers.