龚咀电站水库塌岸模式研究

利用已运行多年的山区型水库地质勘探、预测评价成果,在掌握库岸防护工程的勘察设计、施工及变形坡体的监测等技术资料的基础上,通过对塌岸及变形的分布、类型及形成条件等方面问题的实测调查,分析塌岸效应的形成机制及模式类型,确定各类岩土体的水下及水上稳定坡角等塌岸参数。     

三峡库区忠县岸段塌岸预测研究

水库塌岸给库区带来了巨大的经济损失。自1935年前苏联科学家提出水库塌岸宽度的问题以后,塌岸预测方法成了众多学者研究的热门,提出了许多塌岸预测理论及方法。通过权衡各种方法的利弊,结合对三峡库区忠县岸段现场调查所取得的具有针对性的地质参数,选取了用卡丘金法来预测土质岸坡塌岸宽度,用经验法来预测岩质岸坡塌岸宽度,并借助于SQLite数据库引擎,使两种预测理论计算机程序化、可视化。对两种预测方法的主要参数取值进行了研究,应用于三峡库区忠县岸段的塌岸预测,取得了良好的效果。     

重庆市巫溪县王家河库岸139段塌岸预测研究

随着三峡工程库水位的不断上升,库区长江支流水位相应增长,不仅造成库区土地淹没和移民问题,而且时刻有发生库岸塌岸的危险。通过采用卡丘金塌岸预测方法,对重庆市巫溪县花台乡王家河库岸进行塌岸预测,其结果是可靠的,为选定工程处理措施提供了科学的依据。     

小浪底库区塌岸对淤积库容的影响分析

塌岸是影响黄土地区水库库容的重要因素。分析库区塌岸及其对淤积库容的影响,可以为水库水土保持综合治理、可持续化管理提供重要支撑。以黄河干流中游末端的小浪底水库为例,在塌岸问题梳理、河段划分基础上,通过实地塌岸痕迹勘察和典型剖面淤积过程对比,初步发现:在275 m库水位时,松散土体岸坡段占库岸总长近20%,可能发生塌岸的地段库面较宽,多为沙土河岸且坡度较陡;塌岸多为局部,对库区地形地貌及淤积库容影响有限,塌方再造岸边与水流挟沙淤积相比对库容影响的比例较小。由于缺乏系统的观测资料,为了准确评价塌岸对淤积库容影响,今后应增加塌岸、滑坡等观测项目,加强库区河岸边坡稳定性监测、预测与模拟。     

三峡工程康家咀滑坡区库岸塌岸预测分析

水库塌岸（岸坡再造）是影响三峡水库移民工程安全的重大地质灾害问题。三峡库区蓄水后，库岸防护问题尤其是城镇库岸防护安全问题变得日益突出，以重庆开县为例，探讨该段岸坡变形破坏的特征及其形成原因，并进行了塌岸预测和提出了治理方法。     

三门峡水库库岸坍塌成因分析与防治措施研究

三门峡水库自1960年9月蓄水运行以来,库岸坍塌现象频繁发生,平均每年塌岸0.5～0.7亿m3.指出了造成库岸坍塌的原因主要是地质环境的影响以及水力条件的变化;不同的地形、地貌、地质结构和岩性特征,表现了不同的塌岸强度,其中黄土塬区为极强塌岸段,黄河Ⅱ级阶地为强烈塌岸段,黄河Ⅰ级阶地为中等强烈塌岸段;分析了引起库岸坍塌的主要水力条件有大气降水、地表水和地下水,并且不同水力条件及其变化特征,对库岸坍塌影响的方式和程度也不同;最后给出了防治库岸坍塌应采用标本兼治的原则,治标是指对塌岸进行必要的加固、支挡、衬砌等;治本就是根据引起塌岸的原因以及不同地质环境条件下的塌岸特征和水力条件,因地制宜,因害设防,从根本上进行综合治理.     

种植制度对地表径流的影响

水库库岸失稳是水利水电工程中常见的边坡变形方式。由于水库蓄水,水位上涨,引起地下水位升高,岩土体内的断层、裂隙和空隙中的水压力发生变化,使岩土体的强度指标弱化,将可能引起古滑坡体复活或促成新的不稳定滑体。初步探讨了对西北地区中小型水库的库岸稳定机理,通过研究分析,提出了库岸稳定预测的计算方法。     

三峡库区仁沱新街库岸塌岸预测研究

三峡水库蓄水运行后,沿江库岸地质环境将发生急剧变化,会引起崩塌、滑坡和塌岸等工程地质问题。根据库岸特征进行分段,采用极限平衡理论和卡丘金图解法对仁沱新街库岸整体稳定性和局部塌岸进行了分析和预测,确定了每段的破坏模式,并结合城市规划及生态环境保护提出了相应的防护建议。     

黄土丘陵库区塌岸危害及其防治途径

黄土丘陵区水库库区塌岸，不仅侵蚀了大片耕地，影响到库区居民住宅的安全和正常的生产，生活，同时，也是水库泥沙淤积的主要来源之一，本文结合我区近年来开展水库库区及其上游水土保持重点治理的实践，在调查塌岸危害，分析塌岸成因的基础上，提出了生物，工程，化学三项措施相结合，以生物措施为主，岸顶，岸坡，坡脚三级综合防治的基本模式，认为实施水土保持综合防治，节约投资、便于实施，效果明显，是目前进行库区塌岸防治最     

界河塌岸及其流域水土流失综合治理措施 --以额尔古纳河和哈拉哈河为例

因界河塌岸使得我国每年流失大量国土。界河塌岸除受到河岸系统和水力作用的影响外 ,同时还受到流域内水土流失的影响。以额尔古纳河和哈拉哈河为例 ,探讨了界河塌岸的原因 ,提出一体化的治理方式 ,并就重点建设项目进行了设计 ,在此基础上探讨了综合治理的措施。     

土壤种子库研究的热点问题及发展趋向

土壤种子库是指存在于土壤上层凋落物和土壤中全部存活种子的总和。土壤种子库是种群定居、生存、繁衍和扩散的基础,也是植被潜在更新能力的重要组成部分,在植被的更新、演替和恢复过程中起着重要的作用。本文总结提出了土壤种子库研究的几个热点问题以及发展趋向,包括土壤种子库的研究方法,入侵植物的土壤种子库,种子雨、种子库与地上植被的关系,种子库在退化生态系统植被恢复和生物多样性保护中的作用,土壤侵蚀对土壤种子库的影响,全球变化对土壤种子库的影响。同时对这些领域的研究进展进行了综述,旨在为进一步推动今后土壤种子库的研究工作提供参考。     

黄土丘陵区撂荒地不同侵蚀带土壤种子库特征

采用野外调查取样和室内实验相结合的方法,研究了黄土丘陵区撂荒地不同侵蚀带土壤种子库的密度、物种组成、物种多样性以及相似性特征。结果表明:各侵蚀带土壤种子库中共发现26个物种,隶属于13科24属,不同侵蚀带物种组成有所差异,菊科与禾本科为主要组成物种;0—10cm土层内土壤种子库密度随着侵蚀带的变化而变化,有明显的先减少再增大而后再急剧减少的趋势;不同侵蚀带土壤种子库物种多样性指数、丰富度指数、均匀度指数和生态优势度存在着差异,但未达到显著相关水平;土壤种子库组成物种相似性系数变化范围为0.40～0.82,相邻侵蚀带之间的土壤种子库物种相似性较高,随着侵蚀带之间距离的增加,其相似性逐渐变小。这说明不同侵蚀带土壤种子库因受坡面径流引起的土壤侵蚀使种子流失、二次迁移和沉积以及植被的拦截而产生再分布。     

土壤生物工程在北京河流生态恢复中的应用研究

为了研究土壤生物工程措施在河流生态修复中效果,选择北京怀九一渡河段裸露坡岸为研究对象,针对该河段坡面存在着溅蚀,面蚀,沟蚀及侧渗侵蚀等土壤侵蚀现象,采用扦插、生物垫和梢捆3种土壤生物工程措施对河流岸坡进行治理,分别对施工4个月、8个月后植物的生长特征、稳固岸坡效果进行了调查观测,结果表明:在不同土壤生物工程措施下,成活金丝柳的生长情况均达到较高水平,但在以水分、覆土过厚等制约因素下,金丝柳的生长表现出明显差异;扦插措施根系扎根深,易成活,对深层土壤的加固作用良好;土壤生物工程施工后河流岸坡植物快速恢复,生物多样性增加。最后总结了北京地区土壤生物工程施工以及后期管理防护中的注意问题,以期为北京地区河流的生态治理提供一定的技术指导和理论支持。     

Preliminary modelling of sediment production and delivery in the Xihanshui River basin, Gansu, China

This paper outlines an analysis of the spatial distribution of sediment production, delivery and yield in the Xihanshui River basin, South Gansu, China, using the modelling tools of SedNet (Prosser et al., 2001). This model can assess the delivery efficiency to downstream locations, as well as identifying locations with high rates of sediment production. Preliminary model experiments assist understanding of the spatial dynamics of these sediment processes and evaluation of the effectiveness of soil conservation practices since the mid-1980s. Three scenario years (dry, average and wet) from the 1983–2005 record are identified and modelled, and land use and management are represented in the model to reflect known changes since the 1980s. Results show hillslope erosion to be a dominant source of sediment supply, causing the latter to decrease ten-fold between 1984 and 1997/2000. Estimated bank erosion and floodplain deposition rates are sensitive to parameter values, but bank erosion appears less sensitive than hillslope supply to rainfall. The model can be used to assess net changes in floodplain storage; for default parameters, floodplain deposition rates are 25–200 times the rates of bank erosion depending on the climate scenario. Comparing simulation results with measured sediment yields at the three gauging stations indicates encouraging agreement in 2000. In 1984 (the wet year), the model under-predicts, suggesting that additional unmodelled sediment production processes, especially mass movement and gully erosion, may be important in wet years. Mass movement inventory data could close the gap between the high yields measured in the wet scenario year and the estimated yield due to hillslope erosion alone. In 1997 (the dry year), the model over-predicts; this suggests that the land use change parameters required to reflect the effects of conservation may not have been sufficient, implying that conservation has been generally effective, and that evidence of declining sediment yield is not simply a reflection of drier conditions.     

Preliminary modelling of sediment production and delivery in the Xihanshui River basin,Gansu, China

This paper outlines an analysis of the spatial distribution of sediment production, delivery and yield in the Xihanshui River basin, South Gansu, China, using the modelling tools of SedNet (Prosser et al., 2001). This model can assess the delivery efficiency to downstream locations, as well as identifying locations with high rates of sediment production. Preliminary model experiments assist understanding of the spatial dynamics of these sediment processes and evaluation of the effectiveness of soil conservation practices since the mid-1980s. Three scenario years (dry, average and wet) from the 1983–2005 record are identified and modelled, and land use and management are represented in the model to reflect known changes since the 1980s. Results show hillslope erosion to be a dominant source of sediment supply, causing the latter to decrease ten-fold between 1984 and 1997/2000. Estimated bank erosion and floodplain deposition rates are sensitive to parameter values, but bank erosion appears less sensitive than hillslope supply to rainfall. The model can be used to assess net changes in floodplain storage; for default parameters, floodplain deposition rates are 25–200 times the rates of bank erosion depending on the climate scenario. Comparing simulation results with measured sediment yields at the three gauging stations indicates encouraging agreement in 2000. In 1984 (the wet year), the model under-predicts, suggesting that additional unmodelled sediment production processes, especially mass movement and gully erosion, may be important in wet years. Mass movement inventory data could close the gap between the high yields measured in the wet scenario year and the estimated yield due to hillslope erosion alone. In 1997 (the dry year), the model over-predicts; this suggests that the land use change parameters required to reflect the effects of conservation may not have been sufficient, implying that conservation has been generally effective, and that evidence of declining sediment yield is not simply a reflection of drier conditions.     

The use of a new portable erosion measuring device for assessing the erodibility of the surface layers of flood embankments

When a river overtops its flood banks, water running down the landward side of the bank can rapidly erode the soil surface and scour the bank, sometimes leading to breaches and collapse. A covering of living vegetation, particularly grass, can reduce this risk of water erosion. As part of a project to assess the effectiveness of different management regimes on bank vegetation cover, direct measurements were required of the erodibility of the soil surface. A portable erosion measurement device (EMD) was developed by LAB Coastal with the support of the Environment Agency. This could direct water flowing at known velocities across areas of the flood banks, and it was used to test directly the erosion resistance of vegetated grass banks at three sites. The EMD gave a direct measure of the erodibility of a small sample of flood bank. While measurements of soil strength and assessments of vegetation cover were useful, they did not always correctly characterize the stability of the bank surface as measured directly by the EMD. The EMD and its use are described and the results obtained are discussed. The results indicate that flood banks need to be mown at least once a year to make them less vulnerable to erosion.     

Sediment and Phosphorous Fluxes Analysis in Aquia Creek,a Sub-watershed of the Chesapeake Bay Basin,VA, USA

Decline in global surface water quality around the world is closely linked to excess sediment and nutrient inputs. This study examined sediment and phosphorus fluxes in Aquia Creek, a fourth-order sub-watershed of the Chesapeake Bay located in Stafford, Virginia. The Revised Universal Soil Loss Equation (RUSLE), sediment delivery ratio (SDR), field sediment traps, bank erosion pins, and LIDAR data, combined with historical aerial images, were used in quantifying rill and inter-rill erosion from the basin, as well as internally generated sediments. Stream water and stream bank soils were analyzed for phosphorus. RUSLE/SDR modeling estimates a basin total sediment flux of 25,247 tons year^?1. The greatest calculated soil losses were in deciduous forests and cropland areas, whereas medium and high-intensity developed areas had the least soil loss. Cut-bank erosion ranged from 0.2 to 27.4 cm year^?1, and annual bank sediment fluxes were estimated at 1444 Mg, with a corresponding annual mass of phosphorous of 13,760 kg year^?1. The highest bank loss estimates were incurred along reaches draining urban areas. Stream water total phosphorous levels ranged from 0.054 μg g^?1 during low flows to 134.94 μg g^?1 during high discharge periods in autumn and spring. These results show that stormwater management practices in urban areas are limiting runoff water and soil contact, reducing surficial soil loss. However, the runoff acceleration due to expansion of impervious surfaces is progressively increasing the significance of intrinsic sediment and phosphorous sources by exacerbating stream bank erosion and resuspension of internally stored sediments.     

电厂建设项目土壤加速侵蚀系数测算研究

采用实验小区法、类比法、实地调查和地面观测等多种方法对萍乡赣能电厂建设项目的厂区扩建区、施工区、施工临时用地区、厂外公路、临时堆土弃渣场和取料场等区域施工当中的土壤加速侵蚀系数进行测算,结果表明:厂区扩建区和施工临时用地区的土壤加速侵蚀系数为21,施工区的土壤加速侵蚀系数为32;厂外公路路堑边坡土壤加速侵蚀系数为35,路堤边坡土壤加速侵蚀系数为44、路面土壤加速侵蚀系数为21;取料场采挖边坡的土壤加速侵蚀系数为76,采挖台面的土壤加速侵蚀系数为64;临时堆土场、弃渣场的年均流弃比为6.4%。     

基于水蚀预测模型的红壤坡面侵蚀主要影响因素研究

利用229场侵蚀性自然降雨的小区观测数据,率定并验证了典型红壤坡面水蚀预测(WEPP)模型,并对模型的敏感性检验和弹性系数进行了分析。结果表明,红壤坡面土壤侵蚀对降雨量、雨强、细沟可蚀性、临界剪切力、坡长、坡度等6个输入参数的变化具有强敏感性;地表径流量对降雨量具有强敏感性,对雨强、初始饱和导水率、有效水力传导系数等参数存在弱敏感性。这些参数是影响红壤坡面侵蚀产沙产流的主要因素。