数学地质工作的回顾与发展方向     

谢文安  谢玲琳 《湖南地质》1993,12(4):272-276

数学地质。作为计算机技术向地质科学领域渗透的一门边缘学科,无论在地质矿产勘查、科研与管理中,都是一项适用的、有效的新技术新方法。本文着重阐述了湖南省地质矿产局系统。在物化探、区调、测绘、水文地质、环境地质、矿床地质、遥感、国土资源调查、地质资料及地质工作管理等领域,取得的一系列数学地质研究成果与计算机实用技术。它们与国内同类成果相比,处于先进水平。  相似文献   

The effect of forestry drainage operations on upland sediment yields: The results of a storm-based study     

T. P. Burt  M. A. Donohoe  A. R. Vann 《地球表面变化过程与地形》1983,8(4):339-346

The effects of pre-afforestation open ditching on the sediment yield of an upland catchment in the Southern Pennines, England are described. Marked increases in the production of suspended sediment following ploughing caused major pollution of a local reservoir. Sediment supply prior to ditching was limited and easily exhausted, but afterwards remained plentiful, allowing sustained erosion during periods of storm runoff. Large volumes of sediment were carried into the reservoir during the winter of 1980–81. More recently, exhaustion of supplies of loose material in the ditches and revegetation have led to a lower rate of sediment output.  相似文献   

The effect of forestry drainage operations on upland sediment yields: A study of two peat-covered catchments     

I. S. Francis  J. A. Taylor 《地球表面变化过程与地形》1989,14(1):73-83

The suspended sediment yields of two adjacent, paired, catchments on blanket peat in mid-Wales were compared before and after preafforestation drainage works. Catchment A was ploughed whilst an adjacent catchment (B) was left unploughed. After eight months Catchment B was also ploughed. The ploughing strategy in both catchments was designed to minimize sediment loss. However, suspended sediment loss increased 2·5 times following ploughing in Catchment A, whilst no such increase occurred at this time in Catchment B. Subsequently, suspended sediment yields in Catchment B increased 4·8 times after it was ploughed. Organic sediment was lost mainly from furrow sides, and erosion pins showed maximum ground recession in summer, due to peat wastage. Summer desiccation prepared sediment for transport, and organic suspended sediment loads were highest in the autumn. Sediment loads were limited by vegetation colonization and some reduction in sediment loss was due to the presence of unploughed strips adjacent to stream courses.  相似文献   

1668年郯城8.5级地震断裂的全新世滑动速率、古地震和强震复发周期          下载免费PDF全文

王华林 《地震工程学报》1995,17(4):1-12,22

本文根据野外考察，实测和开挖资料研究了１６６８年郯城８ １／２级地震断裂上的全新世位移分布，滑动速率，古地震遗迹，古地震期次和强震复发周期以及地震破裂模式。  相似文献   

Seasonal Migrant Labor in the Forest Industry of the Southeastern United States: The Impact of H-2B Employment on Guatemalan Livelihoods     

Arnold Brodbeck  Wayde Morse 《社会与自然资源》2018,31(9):1012-1029

Migrant labor is a global phenomenon and remittances of migrant workers from non-industrial nations can play an important role in improving quality of life at family, community, and national levels. We focus on workers from Guatemala who obtain visas from the United States (US) Department of Immigration’s H-2B program that allow them to spend six or seven months a year planting and maintaining pine plantations in the southeastern US. Forestry is economically important in this region and the industry has come to depend on migrant labor. Our specific interest is how the H-2B program affects livelihood strategies of these workers, their families, and their communities. Based on primary data from 49 interviews conducted in eight Guatemalan communities, we explain motivations to engage in seasonal migration and positive changes brought about by the H-2B program in nutrition, housing, healthcare and long-term investments in agricultural lands, microenterprise development, education, and family stability.  相似文献   

Criteria for effective zero-deforestation commitments     

《Global Environmental Change》2019

Zero-deforestation commitments are a type of voluntary sustainability initiative that companies adopt to signal their intention to reduce or eliminate deforestation associated with commodities that they produce, trade, and/or sell. Because each company defines its own zero-deforestation commitment goals and implementation mechanisms, commitment content varies widely. This creates challenges for the assessment of commitment implementation or effectiveness. Here, we develop criteria to assess the potential effectiveness of zero-deforestation commitments at reducing deforestation within a company supply chain, regionally, and globally. We apply these criteria to evaluate 52 zero-deforestation commitments made by companies identified by Forest 500 as having high deforestation risk. While our assessment indicates that existing commitments converge with several criteria for effectiveness, they fall short in a few key ways. First, they cover just a small share of the global market for deforestation-risk commodities, which means that their global impact is likely to be small. Second, biome-wide implementation is only achieved in the Brazilian Amazon. Outside this region, implementation occurs mainly through certification programs, which are not adopted by all producers and lack third-party near-real time deforestation monitoring. Additionally, around half of all commitments include zero-net deforestation targets and future implementation deadlines, both of which are design elements that may reduce effectiveness. Zero-net targets allow promises of future reforestation to compensate for current forest loss, while future implementation deadlines allow for preemptive clearing. To increase the likelihood that commitments will lead to reduced deforestation across all scales, more companies should adopt zero-gross deforestation targets with immediate implementation deadlines and clear sanction-based implementation mechanisms in biomes with high risk of forest to commodity conversion.  相似文献   

贵州省地矿局钻探工程发展回顾与展望          下载免费PDF全文

宋继伟  苏宁  余立新  李奇龙  李勇 《探矿工程》2021,48(3):1-9

贵州省地矿局建局63年以来,钻探工程作为地质找矿的重要技术手段,发展至今已形成门类齐全、设备精良、技术精湛的专业体系。本文在总述贵州省地矿局地质找矿辉煌成就的基础上,从小口径岩心钻探、大口径深井钻探、地下水机井钻探、浅层地温能钻探等几个重点方面详细回顾了钻探工程的发展历程,对未来发展趋势进行了展望,同时提出了相关的建议,以供今后的工作参考。  相似文献   

Rates, timing, and mechanisms of rainfall interception loss in a coastal redwood forest   总被引：2，自引：0，他引：2  

Leslie M. Reid  Jack Lewis 《Journal of Hydrology》2009,375(3-4):459-470

Rainfall, throughfall, and stemflow were monitored at 5-min intervals for 3 years in a 120-year-old forest dominated by redwood (Sequoia sempervirens) and Douglas-fir (Pseudotsuga menziesii) at the Caspar Creek Experimental Watersheds, located in northwest California, USA. About 2.5% of annual rainfall reaches the ground as stemflow at the site, while 22.4% is stored on foliage and stems and evaporates before reaching the ground. Comparison of the timing of rainfall and throughfall indicates that about 46% of the interception loss occurs through post-storm evaporation from foliage and 54% is either evaporated during the storm or enters long-term storage in bark. Until bark storage capacity is saturated, the proportion of rainfall diverted to bark storage would be relatively constant across the range of rainfall intensities encountered, reflecting primarily the proportional incidence of rainfall on surfaces contributing to bark storage. In any case, loss rates remain high—over 15%—even during the highest-intensity storms monitored. Clearcut logging in the area would increase effective annual rainfall by 20–30% due to reduction of interception loss, and most of the increase would occur during large storms, thus potentially influencing peakflows and hillslope pore-pressures during geomorphically significant events.  相似文献   

Agricultural and forestry trade drives large share of tropical deforestation emissions     

《Global Environmental Change》2019

Deforestation, the second largest source of anthropogenic greenhouse gas emissions, is largely driven by expanding forestry and agriculture. However, despite agricultural expansion being increasingly driven by foreign demand, the links between deforestation and foreign demand for agricultural commodities have only been partially mapped. Here we present a pan-tropical quantification of carbon emissions from deforestation associated with the expansion of agriculture and forest plantations, and trace embodied emissions through global supply chains to consumers. We find that in the period 2010–2014, expansion of agriculture and tree plantations into forests across the tropics was associated with net emissions of approximately 2.6 gigatonnes carbon dioxide per year. Cattle and oilseed products account for over half of these emissions. Europe and China are major importers, and for many developed countries, deforestation emissions embodied in imports rival or exceed emissions from domestic agriculture. Depending on the trade model used, 29–39% of deforestation-related emissions were driven by international trade. This is substantially higher than the share of fossil carbon emissions embodied in trade, indicating that efforts to reduce greenhouse gas emissions from land-use change need to consider the role of international demand in driving deforestation. Additionally, we find that deforestation emissions are similar to, or larger than, other emissions in the carbon footprint of key forest-risk commodities. Similarly, deforestation emissions constitute a substantial share (˜15%) of the total carbon footprint of food consumption in EU countries. This highlights the need for consumption-based accounts to include emissions from deforestation, and for the implementation of policy measures that cross these international supply-chains if deforestation emissions are to be effectively reduced.  相似文献   

Making a difference: Forest biodiversity,affective capacities,and the micro-politics of expert fieldwork     

《Geoforum》2015

Protecting biodiversity requires the practice of making nature values present in natural resource use decisions. In this article, such practices are explored from the perspective of affective capacities for expert fieldwork in forestry. Affective capacities are broadly acknowledged in the literature on embodied knowing, and by the practitioners themselves, as a necessary condition for knowing nature. We will extend this discussion to the politics involved. Drawing on a case study in Finland, the article points out that professional foresters’ affective ways of knowing nature are controlled by institutionalised strategies and practices. Thus, power is exercised through fieldwork, determining how nature can and should be known in forestry. The article concludes that since policy implementation takes place through the intensities present in mundane routines, governance studies would benefit from understanding how the various technologies of governance interact with emergent and embodied capacities.  相似文献