安全监测技术在软基筑坝工程中的应用

在软土地基上修建50m以上的高坝．国内外尚没有先例；云南省务坪水库在软土地基上修建52m高坝的成功经验，为软基筑坝施工提供了科学的依据：安全监测技术的日益成熟和完善，为工程施工、运行提供了可靠的保障。以云南省务坪水库为例，阐述安全监测技术在软基筑坝上的应用和意义。     

张家口市河流筑坝与硬化的生态系统健康影响研究

研究筑坝与硬化对河流生态系统健康的影响,为人工改造河流的生态修复和管理优化提供科学依据。以张家口市清水河—洋河干流5个不同程度筑坝与硬化的河段为研究对象,构建了包括河道结构、河床底质、水文特征、水质参数和水生生物5类指标的河流生态系统健康指数(RHI),评估了筑坝与硬化对河流健康的影响。结果表明,河道轻微疏浚或具拦砂坝河段的生态系统健康等级为好(RHI 30~40),具溢流堰河岸硬化河段为中等健康(RHI 20~30),筑坝和河床河岸全硬化的河段生态系统健康等级为差(RHI 10~20)。筑坝与硬化改变河流物理结构,进而影响河床底质组分和水文特征,其与RHI的变化显著相关(P<0.05),是损害河流生态系统健康的主要原因;此外,总磷、有机质污染及较低的水生生物多样性对河流的健康均有不利影响,仅在夏季植物大量生长和污染物质被稀释时,RHI有所提高。为了改善河流生态系统的健康状况,需要恢复自然的河岸和缓冲带,改善河流水动力,并加强外源污染控制。     

Seasonal and diurnal variation of downstream fish movement at four small-scale hydropower plants

Hydropower structures hinder the movement and migration of fishes, impairing their life cycles. Additionally, downstream moving fish are often at risk of being injured during turbine passage. To improve hydropower production towards more fish-friendly techniques and management, knowledge on timing and extent of natural patterns of fish downstream movement is necessary. So far, migration behaviour of long-distance migrators such as eel or salmon has been well studied, but little is known about seasonal and diurnal movement patterns of nonmigratory species or medium-distance migrators. In this study, movement patterns of 39 fish species captured by stownets while transiting hydropower facilities in four impounded rivers were assessed and compared with the fish community composition directly upstream of the hydropower plants assessed by electrofishing. Strong differences between the fish community composition inhabiting the upstream sides of the dams and the fish detected in downstream passage were evident. In each study river, the downstream moving fish community composition differed significantly between spring and autumn. On average, significantly more fish were caught during the night (2.9 fish/hr) than during the day (1.3 fish/hr). Topmouth gudgeon, European grayling and pike-perch mostly moved downstream during the night, whereas roach, spirlin and bleak were the most frequent downstream moving fish during daytime. Downstream fish movement was positively related with turbidity, water temperature and discharge. The strong differences in seasonal and diurnal fish movement patterns suggest that fish damage can be strongly reduced by adaptive turbine and corridor management, for example by shutting down turbines at peak movements.     

拦河大坝对河流有色溶解有机质赋存特征的影响初探

运用紫外-可见吸收光谱和三维荧光光谱技术,分析了长江三峡大坝上下游河水中有色溶解有机质(CDOM)的含量水平和荧光组分构成及其空间变化。结果表明,自三峡水库支流香溪河河口(回水区)向下游至三峡水库主库区,CDOM的紫外吸收系数(a355从1.30 m-1增至5.21 m-1)和类酪氨酸组分荧光强度及其在荧光组分中所占比例(从25%升至62%)均呈上升趋势,至三峡大坝附近达到全段峰值,而类腐殖质荧光强度及其在荧光组分中所占比例逐步下降;过坝后,CDOM吸收系数在黄陵庙处急剧降至全干流检测段最低(a355=0.95 m-1),但类腐殖质在荧光组分中所占比例达到全段最高(76%);再往下游至葛洲坝库区南津关处,CDOM吸收系数(a355=6.83 m-1)又回升至全段最高,其中类酪氨酸为绝对优势组分。水体类酪氨酸组分的增加主要源自水库浮游生物新生产活动以及微生物转化作用的增强;而CDOM的减少是因为颗粒物的吸附作用。拦河大坝形成的湖泊效应和下泄流过程将对河流有色溶解有机质的赋存特征有显著影响。     

人工坝溃决洪水峰顶流量计算公式应用于滑坡堵江坝的可行性探讨

滑坡堵江事件在山区广泛发育,堵江形成的天然坝的稳定性一般不高,在暴雨、地震等诱发因素的作用下可能发生溃决,溃坝洪水对下游河道及沿江两岸的各种设施及居民生命造成巨大威胁,因此溃坝洪水计算意义重大,而峰顶流量和洪水演进过程中洪峰高度的变化直接决定了溃坝洪水的灾害程度。利用谢任之教授提出的人工坝溃决洪水计算方法,根据滑坡天然坝体溃决的实际情况,合理地分析溃口形态,调整了溃口宽度的取值方法,并将其应用于滑坡堵江天然坝瞬时溃决洪水峰顶流量计算中,经历史溃坝实例验证计算结果可靠,为天然坝溃决洪水峰顶流量计算提供了新的思路和方法,也为溃坝洪水灾害评价提供了重要依据。     

Connectivity and flow regime direct conservation priorities for pelagophil fishes

1. Dam construction threatens global aquatic biodiversity by fragmenting stream networks and altering flow regimes. The negative effects of dams are exacerbated by increased drought periods and associated water withdrawals, especially in semi-arid regions. Stream fishes are particularly threatened owing to their mobile nature and requirement for multiple habitats to complete their life cycles. An understanding of relationships with fragmentation and flow regimes, particularly as coarse-scale (e.g. catchment) constraints on species distributions, is essential for stream fish conservation strategies.
2. Prairie chub (Macrhybopsis australis) is a small-bodied minnow (Cyprinidae) with poorly understood ecology endemic to the North American Great Plains. Suspected declines in abundance and extirpations have resulted in conservation interest for prairie chub at state and federal levels. Prairie chub is thought to share its reproductive strategy with pelagic-broadcast spawning minnows (pelagophils). Freshwater pelagic-broadcast spawning fishes have been disproportionately affected by fragmentation and streamflow alteration globally.
3. Relationships of prairie chub occurrence with coarse-scale fragmentation and streamflow metrics were examined in the upper Red River catchment. Occurrence probability was modelled using existing survey data, while accounting for variable detection. The modelled relationships were used to project the distribution of prairie chub in both a wet and dry climatic period.
4. The probability of prairie chub occurrence was essentially zero at sites with higher densities of upstream dams, but increased sharply with increases in flow magnitude, downstream open mainstem, and flood duration. The projected distribution of prairie chub was broader than indicated by naïve occurrence, but similar in both climatic periods. The occurrence relationships are consistent with the hypotheses of pelagic broadcast spawning and represent coarse-scale constraints that are useful for identifying areas of the stream network with higher potential for finer-scale prairie chub conservation and recovery efforts. In addition to informing pelagophil conservation, the relationships are also applicable to pelagic-broadcast spawning fishes in marine environments.

     

坡耕地保护性耕作技术模式的保水保土增产效应研究

采用径流小区与田间小区试验相结合的方式,于2011年在黑龙江省北安市红星农场3.坡耕地进行不同保护性耕作技术模式的水土保持和节水增产效应试验研究.通过对不同处理的径流量、土壤侵蚀量、干物质积累、产量、水分利用效率等分析表明,深松、深松+秸秆还田、深松+秸秆还田+垄向区田、深松+垄向区田四种模式均有一定的水土保持与节水增产效果,其中以深松+秸秆还田+垄向区田的效果最好,相对于常规耕作减流量、减沙量分别为95.12％、90.30％,产量、水分利用效率分别提高25.47％、31.91％.     

坡耕地综合治理技术模式的蓄水保土及增产效应

针对松嫩平原北部丘陵漫岗黑土区严重的水土流失、春旱和耕层渍涝并存的问题,采取了垄向区田与鼠道、暗管和明沟4种措施并将其有机集成形成了4个坡耕地综合治理技术模式。于2009和2010年,以黑龙江农垦北安分局红星农场3°坡耕地为研究对象,研究了不同技术模式对大豆生育期土壤水分动态、产量、作物水分利用效率、地表径流和土壤侵蚀的影响。结果表明,4种技术模式均有不同程度的蓄水保土增产和提高作物水分利用效率的作用,其中鼠洞+暗管+明沟+垄向区田措施效果最为明显,与常规耕作相比产量和水分利用效率分别提高了27.3%和23.9%,地表径流量和土壤流失量分别减少了31.3?mm和456?t/?(km2·a)。     

张家口市河流筑坝与硬化的生态系统健康影响

闸坝建设和河道硬化等水利工程措施在河流系统中的广泛应用,改变了河流原有的生态环境状况。本文以张家口市清水河—洋河干流5个不同程度筑坝与硬化的河段为研究对象,构建了包括河道结构、河床底质、水文特征、水质参数和水生生物五类指标的河流生态系统健康指数（RHI）,评估了筑坝与硬化对河流健康的影响。结果表明,河道轻微疏浚或具拦砂坝河段的生态系统健康等级为好（HRI为30~40）,具溢流堰河岸硬化河段为中等健康（HRI为20~30）,筑坝和河床河岸全硬化的河段生态系统健康等级为差（HRI为10~20）。筑坝与硬化改变河流物理结构,进而影响河床底质组分和水文特征,其与RHI的变化显著相关（p < 0.05）,是损害河流生态系统健康的主要原因;此外,总磷和有机质污染,及较低的水生生物多样性对河流的健康均有不利影响,仅在夏季植物大量生长和污染物质被稀释时,5个河段的RHI有所升高。可见,为了改善河流生态系统健康的状况,需要恢复自然的河岸和缓冲带,改善河流水动力,并加强外源污染控制。