Assessing uncertainty in best management practice effectiveness under future climate scenarios          下载免费PDF全文

Sean A. Woznicki  A. Pouyan Nejadhashemi 《水文研究》2014,28(4):2550-2566

Uncertainty of best management practice (BMP) performance in future climates is an important consideration for water resources managers. The objective of this study was to quantify the level of uncertainty in performance of seven agricultural BMPs due to climate change in reducing sediment, total nitrogen, and total phosphorus loads. The Soil and Water Assessment Tool coupled with mid‐21^st century climate data from the Community Climate System Model were used to develop climate change scenarios for the Tuttle Creek Lake Watershed of Kansas and Nebraska. Uncertainty level of each BMP was determined using Latin Hypercube Sampling, a constrained Monte Carlo sampling technique. Samples were taken from distributions of several variables (monthly precipitation, temperature, CO₂, and BMP implementation parameters). Cumulative distribution functions were constructed for each BMP, pollutant, and climate scenario combination. Results demonstrated that BMP performance uncertainty is amplified in the extreme climate scenario. Among BMPs, native grass replacement generally had higher uncertainty level but also had the greatest reductions. This study highlights the importance of incorporating uncertainty analysis into mitigation strategies aiming to reduce negative impacts of climate change on water resources. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

上海市东方医院青岛分院钻孔桩施工技术     

李先经 《探矿工程》2018,45(12):64-68

上海市东方医院（同济大学附属东方医院）青岛分院桩基工程,工程量大,工期紧,因上部存在填土、淤泥质土,地层条件较复杂。根据工程实际情况采用了旋挖钻机、冲击钻机、回转钻机成孔工艺,采取加长钢护筒、泥浆护壁等技术措施,有效解决了缩径、孔壁坍塌问题,保质保量按期完成了施工任务,取得了很好的经济和社会效益。  相似文献   

阜阳华纺新天地超长空桩成孔施工控制措施          下载免费PDF全文

邢敏 《探矿工程》2018,45(6):89-91

阜阳华纺新天地桩基工程,原计划基坑底面施工调整为地面施工,增加了近14 m的空桩。为此,工程桩施工质量存在桩位、孔底沉渣厚度、钢筋笼位置、砼质量、砼桩顶标高等方面控制的相关问题。本文介绍了其施工情况,其经验可供类似工程借鉴。  相似文献   

Statistical analyses of Global U-Pb Database 2017     

Stephen J.Puetz  Carlos E.Ganade  Udo Zimmermann  Glenn Borchardt 《地学前缘(英文版)》2018,9(1):121-145

The method of obtaining zircon samples affects estimation of the global U-Pb age distribution.Researchers typically collect zircons via convenience sampling and cluster sampling.When using these techniques,weight adjustments proportional to the areas of the sampled regions improve upon unweighted estimates.Here,grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb ages.Preliminary tests involve two age models.Model-1 uses the most precise U-Pb ages as the best ages.Model-2 uses the~(206)Pb/~(238)U age as the best age if it is less than a1000 Ma cutoff,otherwise it uses the~(207)Pb/~(206)Pb age as the best age.A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both models.However,after applying acceptance criteria to include only the most precise analyses with minimal discordance,a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the1000 Ma cutoff point.Because of the excessive rejection rate for Model-2,we select Model-1 as the preferred model.After eliminating all rejected samples,the remaining analyses use only Model-1 ages for five rock-type subsets of the database:igneous,meta-igneous,sedimentary,meta-sedimentary,and modern sediments.Next,time-series plots,cross-correlation analyses,and spectral analyses determine the degree of alignment among the time-series and their periodicity.For all rock types,the U-Pb age distributions are similar for ages older than 500 Ma,but align poorly for ages younger than 500 Ma.The similarities(500 Ma)and differences(500 Ma)highlight how reductionism from a detailed database enhances understanding of time-dependent sequences,such as erosion,detrital transport mechanisms,lithification,and metamorphism.Time-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of~91-Myr,~273-Myr,and~819-Myr among the various rock types.  相似文献   

固体矿产绿色勘查钻探技术方法探索与实践          下载免费PDF全文

刘蓓  杨可  张晨  顾科伟  皮健伟  段晓 《探矿工程》2021,48(S1):39-46

西安矿产资源调查中心针对现有固体矿产地质调查（勘查）项目,积极探索和实践绿色地质勘查工作技术方法,因地制宜应用全液压履带钻机、便携式模块化钻机实施“一基多孔”,采用背包钻实施“以钻代槽”,通过优选环保型冲洗液,净化处理废弃冲洗液,控制临时占地规模等具体措施。与传统机场规格相比占地面积减少了80%~85%,临时便道修筑减少了60%~65%,工后复垦复绿达到了80%以上。通过绿色勘查成本费用分析,人员、临时用地（青苗）补偿、绿色环保材料及复垦复绿等费用成本总和降低了40%左右。最后探索实践了绿色勘查工作保障措施,对下一步绿色勘查工作提出了建议,为加强绿色勘查工作理念、完善相关的制度法规、激发绿色勘查工作活力提供了积极的导向。  相似文献   

基于锂离子电池储能技术的便携式钻机研制与应用          下载免费PDF全文

谭春亮  渠洪杰  彭新明  卢倩  张沁瑞  岳永东  苏兴涛  祝强 《探矿工程》2021,48(S1):361-365

锂离子电池作为现代文明中重要的能量载体被广泛且大量地使用。浅层钻探是一种重要的浅表层调查取样手段,将锂离子电池储能技术应用于便携式钻机的研发,可解决山区、林草区等特殊地貌区防火期内调查取样的难题,实现浅钻调查零碳排,助力绿色勘查发展;本文重点介绍了锂电池电动钻机的技术参数、特点及试验情况,该机型具有体积小、质量轻、无噪音、无污染,主要钻进参数可显示、可调控,钻进数据可采集、可存储等特点,锂离子电池储能技术在便携式钻机中的应用为浅钻装备数字化、信息化和智能化发展奠定了基础。  相似文献   

Reply: Bulk sampling of coarse clastic sediments for particle-size analysis     

Stephen J. Gale  Peter G. Hoare 《地球表面变化过程与地形》1994,19(3):263-268

The work of Gale and Hoare (1992) provides a guide to the minimum mass of bulk sample required to obtain a reproducible measure of the complete particle-size distribution of coarse clastic sediments such as till, fluvial gravel and beach gravel. Dunkerley (1994) makes a number of criticisms and misrepresentations of this procedure. These are systematically refuted and corrected here, and further data obtained from till and beach gravel are provided to support the criterion adopted by Gale and Hoare (1992) for sample reliability. The procedure of Gale and Hoare (1992) is confirmed as a practical guide to the mass of bulk sample required to obtain a reliable measure of the particle-size distribution of coarse clastic sediment.  相似文献   

转矩转速传感器及其在钻机功率测试中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

彭忍社 《探矿工程》1994,(1):51-52,54

介绍了一种用于钻机功率测试的转矩转速传感器，论述了该类传感器的基本工作原理、标定装置、校验方法以及测试系统的组成等问题。  相似文献   

Meteorology and haze structure during AGASP-II,Part 1: Alaskan Arctic flights, 2–10 April 1986     

G. A. Herbert  R. C. Schnell  H. A. Bridgman  B. A. Bodhaine  S. J. Oltmans  G. E. Shaw 《Journal of Atmospheric Chemistry》1989,9(1-3):17-48

The second Arctic Gas and Aerosol Sampling Program (AGASP-II) was conducted across the Alaskan and Canadian Arctic in April 1986, to study the in situ aerosol, and the chemical and optical properties of Arctic haze. The NOAA WP-3D aircraft, with special instrumentation added, made six flights during AGASP-II. Measurements of wind, pressure, temperature, ozone, water vapor, condensation nuclei (CN) concentration, and aerosol scattering extinction (b_sp) were used to determine the location of significant haze layers. The measurements made on the first three flights, over the Arctic Ocean north of Barrow and over the Beaufort Sea north of Barter Island, Alaska are discussed in detail in this report of the first phase of AGASP II. In the Alaskan Arctic the WP-3D detected a large and persistent region of haze between 960 and 750 mb, in a thermally stable layer, on 2, 8, and 9 April 1986. At its most dense, the haze contained CN concentrations >10,000 cm^–3 and b_sp of 80×10^–6 m^–1 suggesting active SO₂ to H₂SO₄ gas-to-particle conversion. Calculations based upon observed SO₂ concentrations and ambient relative humidities suggest that 10⁴–10⁵ small H₂SO₄ droplets could have been produced in the haze layers. High concentrations of sub-micron H₂SO₄ droplets were collected in haze. Ozone concentrations were 5–10 ppb higher in the haze layers than in the surrounding troposphere. Outside the regions of haze, CN concentrations ranged from 100 to 400 cm^–3 and b_sp values were about (20–40)×10^–6 m^–1. Air mass trajectories were computed to depict the air flow upwind of regions in which haze was observed. In two cases the back trajectories and ground measurements suggested the source to be in central Europe.  相似文献   

Estimation of soil loss at a regional scale based on plot measurements—some critical considerations     

J. M. Roels 《地球表面变化过程与地形》1985,10(6):587-595

The paper is prompted by apparent deficiencies in the design of plot studies in regional erosion surveys. The principal shortcomings of observational erosion research have been poor sampling design and inadequate analyses of data. The paper identifies various sources of bias which must be taken into account before plot data can be extrapolated to land units in a regional survey. Judging from soil loss data of a case-study in the Ardèche rangelands one may conclude that even accurate plot measurements can still be rather a rough basis for regional erosion assessment. Finally, the paper highlights strategies that might be used to improve erosion sampling.  相似文献