岩土工程勘察有关问题探讨     

周相国  聂洪玮 《探矿工程》2006,33(7):1-4

针对国内岩土工程勘察现状，对岩土工程勘察理论与经验、勘察的经济性等有关问题进行了探讨；结合天津地区岩土工程勘察实际特点，对天津地区岩土工程勘察涉及的地基承载力、抗震地段划分等问题进行了探讨。  相似文献   

The use of short‐lived radionuclides to quantify transitional bed material transport in a regulated river     

Nira L. Salant  Carl E. Renshaw  Francis J. Magilligan  James M. Kaste  Keith H. Nislow  Arjun M. Heimsath 《地球表面变化过程与地形》2007,32(4):509-524

We investigate the use of the short‐lived fallout radionuclide beryllium‐7 (⁷Be; t_1/2 = 53·4 days) as a tracer of medium and coarse sand (0·25–2 mm), which transitions between transport in suspension and as bed load, and evaluate the effects of impoundment on seasonal and spatial variations in bed sedimentation. We measure ⁷Be activities in approximately monthly samples from point bar and streambed sediments in one unregulated and one regulated stream. In the regulated stream our sampling spanned an array of flow and management conditions during the annual transition from flood control in the winter and early spring to run‐of‐the‐river operation from late spring to autumn. Sediment stored behind the dam during the winter quickly became depleted in ⁷Be activity. This resulted in a pulse of ‘dead’ sediment released when the dam gates were opened in the spring which could be tracked as it moved downstream. Measured average sediment transport velocities (30–80 metres per day (m d^?1)) exceed those typically reported for bulk bed load transport and are remarkably constant across varied flow regimes, possibly due to corresponding changes in bed sand fraction. Results also show that the length scale of the downstream impact of dam management on sediment transport is short (c. 1 km); beyond this distance the sediment trapped by the dam is replaced by new sediment from tributaries and other downstream sources. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

水库防洪等蓄量优化调度模型及应用          下载免费PDF全文

陈森林  孙亚婷  黄宇昊 《水科学进展》2018,29(3):374-382

等蓄量法是中国水库防洪规划与实时调度中常用的调度方式,其3个参数（等蓄流量、起蓄流量和等蓄历时）一直采用试算方法推求。以等蓄流量为输入参数,引入蓄放水0~1状态变量,定义了逐时段水库蓄水量之和最小的线性目标函数,并设置蓄水状态连续性约束解决等蓄历时的推求,建立了水库防洪等蓄量优化调度的0~1整数线性规划模型（RFEV-ILP）。通过亭子口水库应用表明,该模型算法稳定,与理想补偿调度方式计算的防洪库容相差不足1%。该优化模型不仅可以推求防洪库容、起蓄流量及等蓄历时与等蓄流量之间的数值关系,而且能较好地揭示防洪风险与等蓄流量之间的关系、防洪控制点距离水库的远近对等蓄流量可选范围及相应采取防洪策略的影响。  相似文献   

湿地生态水文学研究综述   总被引：4，自引：0，他引：4       下载免费PDF全文

章光新  武瑶  吴燕锋  刘雪梅 《水科学进展》2018,29(5):737-749

基于湿地生态水文研究文献计量分析,透视国内外有关湿地水文、生态水文和水资源等领域的重大研究计划和重要学术会议,系统总结了湿地生态水文学发展历程,可分为萌芽起步阶段（20世纪50年代至80年代）、研究探索阶段（20世纪90年代）和快速发展阶段（21世纪以后）3个阶段,列举了重要代表性研究成果,并重点阐述了湿地生态水文学研究进展;基于对国际湿地生态水文学发展历程、研究进展及热点的综合分析,未来湿地生态水文学研究主要向基于"多要素、多过程、多尺度"的湿地生态水文相互作用机理及耦合机制、气候变化对湿地生态水文的影响机理及适应性调控、湿地"水文-生态-社会"耦合系统互作机理及互馈机制和基于湿地生态需水与水文服务的流域水资源综合管理等方向发展。最后,以国家重大需求为导向,提出了未来中国湿地生态水文学优先发展方向及建议。  相似文献   

中国粮耕价值比与种植结构时空耦合演化及分区调控     

李欣宇  方斌  李怡  李冬杰  何莎莎 《地理学报》2022,77(11):2721-2737

耕地粮食产出价值与种植结构均深刻影响着国家粮食安全,探讨耕地粮食产出价值与种植结构的时空耦合变化,可理清两者关系,助力粮食安全保障能力的提升。本文以中国省级行政单元为研究对象,在深刻解读粮耕价值比和种植结构内涵的基础上,综合利用Simpson指数、耦合协调度模型和空间自相关等方法,分析2004—2020年中国粮耕价值比和种植结构耦合时空演化,以揭示其时空动态关系。结果表明：① 2004—2020年各省份粮耕价值比空间分布特征表现为“由北向南”和“由西向东”的双重递减态势;② 种植结构空间格局呈现由“胡焕庸线”沿线区域向两侧递减的空间分布形态,东北、华北和华东地区多样性递减明显;③ 粮耕价值比与种植结构耦合协调度介于勉强耦合协调与高度耦合协调之间,表现为规律性空间集聚,中西部及东北地区呈高高集聚,具有“匹配性优势”,东南沿海地区呈低低集聚,有待“匹配性改良”,总体表现为：“东北、中部高,东南部低”的态势。本文认为应依据要素空间集聚和扩散的分异特征,因区施策引导耕地粮食品质化与多元化协同演进,促进粮食结构与效益匹配发展。  相似文献   

基于CiteSpace的国土空间用途分区研究进展     

朱佩娟  谢雨欣  周国华  张勇  王楠 《热带地理》2022,42(4):519-532

利用CiteSpace文献可视化软件和文献计量分析方法,分析1979—2020年CNKI期刊数据库中国国土空间用途分区研究的662篇相关文献,系统梳理其研究动态和发展脉络。结果发现：1）国土空间用途分区成果不断涌现,发文量总体呈上升趋势。总体可划分为土地用途分区（1992—2006年）、自然生态空间用途分区（2007—2017年）和国土空间用途分区（2018年至今）3个阶段,发文作者之间合作密切,形成具有规模的科研集群,“土地利用”这一关键词具有0.28的高中心性。2）国土空间用途分区研究政策导向性强,内容不断深化。分区理论、分区体系不断优化;研究方法从定性或定量转变为结合现代科学技术的应用;分区管制研究大多集中于现存问题发现、国外经验启示和分区实践研究3个方面。针对已有研究内容较为传统,科学验证研究不深,理论总结升华不够,以及对多学科融合和大数据的运用不足等问题,提出未来研究重点应包括：开展国土空间用途分区相关理论研究,深化生态空间、海洋空间与乡村建设空间用途分区研究,结合国土空间用途管制体系构建需求拓宽国土空间用途分区研究视角,基于多学科交叉融合开展方法与技术的创新应用等4个方面。  相似文献   

Impact of the water-sediment regulation and a rainstorm on nutrient transport in the Huanghe River   总被引：4，自引：0，他引：4  

巩瑶  姚庆祯  于志刚 《中国海洋湖沼学报》2014,32(1):140-147

Dissolved nutrient concentration in the Huanghe(Yellow) River at Lijin was monitored during a water-sediment regulation period and a subsequent rainstorm from 14 June to 19 July, 2005. This study provides detailed information on nutrient concentrations in the Huanghe River during the water-sediment regulation and rainstorm periods, and is of signifi cance for the downstream area of the Huanghe River and the Bohai Sea. The average concentrations of nitrate, nitrite and ammonia were 304.7 μmol/L, 0.19 μmol/L, and 1.10 μmol/L, respectively, while the average concentrations of dissolved inorganic phosphorus(DIP) and dissolved silicate(DSi) were 0.23 μmol/L and 122.9 μmol/L, respectively. Nutrient concentrations during the water-sediment regulation period were mainly infl uenced by the dilution effect, fl oodplain effect and sediment resuspension while dilution and erosion effects were the main factors during the rainstorm. The fl uxes of dissolved inorganic nitrogen(DIN), DIP and DSi during the water-sediment regulation and rainstorm periods accounted for 20.4%, 19.5%, 16.7% and 4.97%, 6.45%, 5.47% of the annual nutrient fl uxes, respectively. Discharge was the main factor infl uencing the fl uxes of nutrients during both the watersediment regulation and the rainstorm periods.  相似文献   

溶藻弧菌双组分调控系统PhoR/PhoB的基因克隆及生物信息学分析     

张燕飞  ;庞欢瑛  ;吴灶和  ;简纪常  ;鲁义善 《广东海洋大学学报》2014,(6):22-30

双组分调控系统（Two-component Regulatory System）在致病菌的生长及毒力调控中起重要作用.克隆溶藻弧菌（Vibrio alginolyticus）HY9901 株组氨酸激酶PhoR 和反应调控因子PhoB 的全长基因,并对其进行生物信息学分析.序列分析结果显示,phoR（GenBank 登录号：KJ958404）全长1 299 bp,共编码432 个氨基酸;phoB（GenBank 登录号：KJ863646）全长690 bp,编码229 个氨基酸.构建PhoR/PhoB 的系统进化树,结果显示,溶藻弧菌PhoR/PhoB 与副溶血弧菌（Vibrio parahaemolyticus）、哈氏弧菌（Vibrio harveyi）有较近亲缘关系.利用SWISS-MODEL 软件,对PhoR/PhoB 中两个相对保守的功能域HATPase_c 和REC 进行同源建模,发现HATPase_c具有1 个ATP 结合位点,REC 具有4 个天冬氨酸活性位点.  相似文献   

An integrated water balance model for assessing water scarcity in a data-sparse interfluve in eastern India     

Shreyashi Santra Mitra  Jim Wright  Abhisek Santra  A.R. Ghosh 《水文科学杂志》2013,58(10):1813-1827

Abstract

The objective of this study is to measure the balance of water demand versus water resource availability in an interfluve of West Bengal, India to support water resource planning, particularly of inter-basin transfers. Surface water availability was modelled using the US Soil Conservation Service curve number (SCS-CN) approach, whilst groundwater availability was modelled based on water-level fluctuations and the rainfall infiltration method. Water use was modelled separately for the agricultural, industrial, and domestic sectors using a predominantly normative approach and water use to availability ratios calculated for different administrative areas within the interfluve. Overall, the approach suggested that the interfluve receives 327 × 10⁶ m³ year^-1 of excess water after satisfying these sectoral demands, but that the eastern part of the study area is in deficit. However, a sensitivity analysis carried on the approach to several assumptions in the model suggested changed circumstances would produce surplus/deficit ranging from ?215 × 10⁶ to 435 × 10⁶ m³ year^-1 . The approach could have potential for localised water balance modelling in other Indian catchments.