长江流域泥沙特点及对流域环境的潜在影响

泥沙是流域系统中的一个重要的物理通量,对流域环境具有直接影响。近40年来,长江上游流域的植被覆盖率减少近一半,水土流失扩大了一倍多。金沙江下游干支泥沙80年代较60年代增加了12％－60％,而通过长江宜昌站的泥沙年平均输沙量则没有增加。由水土流失、山地灾害等带给流域系统的泥沙大部分堆积在各支流的中下游河道。50％以上的支流河道出现了严重的泥沙加积,加积速率可达5－20cm/a,部分支流因泥沙过只而呈辫状河特点。支流河道泥沙的过度液积,构成长江环境的巨大隐患。当发展到一定程度或环境突然变化,堆积在支流的泥沙必然会进入主河道。一旦爆发,将严重影响到长江环境的安全。应尽快开展长江流域上游和支流泥沙的运移和淤积现状及规律调研。     

高速公路建设中水土流失预测模式研究

针对山区高速公路建设的特点和可能造成水土流失的影响及其分布特性,根据国内外对水土流失预测的研究现状,选择了位于西南土石山区在建国道108线西攀高速公路路段的黄水互通式立交A匝道开挖边坡和K11 100～K11 210路段左侧的弃渣场上进行了观测试验,通过15次降雨量和水土流失量的实测,经过降雨强度、各时段降雨动能、降雨总能量参数单因子和复合因子与土壤流失量的相关分析,得出试验区的天然降雨雨滴中数直径与雨强的对数关系和单位降雨强度与降雨动能的关系;初步提出适用于高速公路建设土壤流失预测中的降雨侵蚀力的计算公式、土壤可侵蚀因子值;修正了经验法中的加速侵蚀系数A值.     

Fine‐Sediment Loadings to Lake Tahoe1

Abstract: Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine‐grained sediments emanating from upland and channel sources. The overall objective of the research reported here was to determine the amount of fine sediment delivered to Lake Tahoe from each of the 63 contributing watersheds. The research described in this report used combinations of field‐based observations of channel and bank stability with measured and simulated data on fine‐sediment loadings to estimate fine‐sediment loadings from unmonitored basins throughout the Lake Tahoe Basin. Loadings were expressed in the conventional format of mass per unit time but also in the number of particles finer than 20 μm, the latter for future use in a lake‐clarity model. The greatest contributors of fine sediment happened to be those with measured data, not requiring extrapolation. In descending order, they are as follows: Upper Truckee River [1,010 tonnes per year (T/year)], Blackwood Creek (846 T/year), Trout Creek (462 T/year), and Ward Creek (412 T/year). Summing estimated values from the contributing watersheds provided an average, annual estimate of fine‐sediment (<0.063 mm) loadings to the lake of 5,206 T/year. A total of 7.79E + 19 particles in the 5‐20 μm fraction were calculated to enter Lake Tahoe in an average year with the Upper Truckee River accounting for almost 25% of the total. Contributions from Blackwood, Ward, Trout, and Third creeks account for another 23% of these very fine particles. Thus, these five streams making up about 40% of the basin area, account for almost 50% of all fine‐sediment loadings to the lake. Contribution of fine sediment from streambank erosion were estimated by developing empirical relations between measured or simulated bank‐erosion rates with a field‐based measure of the extent of bank instability along given streams. An average, annual fine‐sediment loading from streambank erosion of 1,305 T/year was calculated. This represents about 25% of the average, annual fine‐sediment load delivered to the lake from all sources. The two largest contributors, the Upper Truckee River (639 T/year) and Blackwood Creek (431 T/year), account for slightly more than 80% of all fines emanating from streambanks, representing about 20% of the fine sediment delivered to Lake Tahoe from all sources. Extrapolations of fine‐sediment loadings to the unmonitored watersheds are based on documented empirical relations, yet contain a significant amount of uncertainty. Except for those values derived directly from measured data, reported results should be considered as estimates.     

Predicting the Planform Configuration of the Braided Toklat River,Alaska, With a Suite of Rule‐Based Models1

Abstract: An ensemble of rule‐based models was constructed to assess possible future braided river planform configurations for the Toklat River in Denali National Park and Preserve, Alaska. This approach combined an analysis of large‐scale influences on stability with several reduced‐complexity models to produce the predictions at a practical level for managers concerned about the persistence of bank erosion while acknowledging the great uncertainty in any landscape prediction. First, a model of confluence angles reproduced observed angles of a major confluence, but showed limited susceptibility to a major rearrangement of the channel planform downstream. Second, a probabilistic map of channel locations was created with a two‐parameter channel avulsion model. The predicted channel belt location was concentrated in the same area as the current channel belt. Finally, a suite of valley‐scale channel and braid plain characteristics were extracted from a light detection and ranging (LiDAR)‐derived surface. The characteristics demonstrated large‐scale stabilizing topographic influences on channel planform. The combination of independent analyses increased confidence in the conclusion that the Toklat River braided planform is a dynamically stable system due to large and persistent valley‐scale influences, and that a range of avulsive perturbations are likely to result in a relatively unchanged planform configuration in the short term.     

基于UMT模型的幸福河绩效评价及障碍因子诊断

基于马斯洛需求层次理论,建立包含健康之河、平安之河、富民之河、和谐之河、文化之河、宜居之河6个层级的幸福河评价指标体系,结合未确知测度理论(Unascertained measure theory,UMT))与障碍诊断模型,以黄河甘肃段、宁夏段、内蒙古段为例,分析其2015-2019年幸福河建设绩效并分别对阻碍幸福河建...     

稀土废水中高浓度氨氮处理与回收试验研究

为处理稀土分离排放的高浓度NH4 -N废水,采用模拟废水研究了在不同条件下减压蒸馏回收氯化铵对馏出液中NH4 -N浓度变化影响.发现真空度、不同浓度范围及溶液pH对馏出液中NH4 -N浓度有显著影响,在真空度为0.07MPa,溶液pH为3～4条件下蒸馏,可使馏出液中NH4 -N浓度<15 mg/L.实际废水验证试验表明,废水经气浮除油、氨水中和、适量重金属沉淀剂DTCR去除重金属及活性炭吸附微量重金属及油类物质等预处理后,减压蒸馏可获得较高品质氯化铵产品,经分析达到工业级合格产品,馏出液可作为自来水回用于生产.对废水处理成本和收益进行了估算,发现每处理1 m3废水可获得67.1元的经济收入,实现较高的经济效益和生态环境效益.     

40°N以北城市夏季气候舒适度及消夏旅游潜力分析

全球气候变暖导致我国夏季普遍高温,传统的近距离山地避暑,已不能满足大众对凉爽气候环境的需求。论文着眼我国高纬地区消夏旅游,选取212座城市1980—2010年长期气候观测数据,利用温湿指数、风寒指数、衣着指数对40°N以北城市夏季气候舒适度进行定量测评。研究结论如下:1从气候舒适度角度分析,空间上,东北地区适合消夏旅游的地域广阔,内蒙古和新疆北部山地,适合消夏旅游地域较小;时间上,6月气候舒适度最舒适,均值为7.62,8月次之,7月较差,均值仅6.81。2从旅游舒适期长短分析,东北三省以及新疆的阿勒泰消夏期最长,达60多天,而河北北部、内蒙古中部、新疆伊犁消夏期为30~45 d,内蒙古西部、新疆天山谷地最短,小于30 d;时间上,一年中8月舒适期最长,均值25.1 d,7月次之,6月最短,均值为19.9 d。3高纬地区,消夏旅游区划分为6种。在我国更适宜消夏旅游的地区,主要分布在我国高纬地区的中东部,并且以东北三省最具竞争力。研究可为游客消夏旅游目的地选择和相关部门消夏旅游开发及战略制定提供参考。     

不同降雨条件下侵蚀泥沙黏粒含量的变化规律

以2种典型黄土为研究对象,在模拟降雨条件下,研究了不同雨强和坡度条件下侵蚀过程中黏粒含量的变化规律,比较了泥沙侵蚀颗粒(未分散)和泥沙原始颗粒(分散后)大小分布特征,分析了团聚率和富集率.结果表明,泥沙侵蚀黏粒含量随着坡长和雨强的增大而增加,黄绵土变化明显,增加了8.77%和2.43%;而塿土只增加了2.76%和0.4%.随坡度的增大而减小,分别减少了4.91%和3.93%.黏粒团聚率<1,富集率>1,在侵蚀搬运过程中作为黏粒团被搬运,导致黏粒的富集.研究结果有助于深入了解泥沙颗粒在坡面侵蚀过程中的变化规律,深入理解土壤侵蚀机制,也能为面源污染模型的建立提供重要基础.     

区域环境承载力研究方法初探

明确了区域环境承载力的概念,研究对象和研究内容;分析了区域环境承载力与区域环境容量和区域环境规划的区别和联系,提出建立区域环境承载力指标体系的一般原则和指标体系的一般内容;并且建立了各项指标的灰色关联度模型及各项指标变化的灰色预测模型;按照这套理论方法,对上海市浦东新区区域环境承载力进行分析研究,得到新区5个开发小区的区域环境承载力的量值,从而掌握了5个小区的开发程度,为新区经济、社会、文化活动规模的控制及环境保护提供了指导依据。     

黄山、九华山、天柱山风景区的土壤资源保护问题

通过对黄山、九华山、天柱山风景区的土壤资源进行考察,指出三座名山的土壤资源正在耗损和退化,面临着潜在危机。其原因有自然因素和人为因素。后者表现在过度垦殖使土壤侵蚀加剧,建设旅游设施和公路以及游人过多都给景区的土壤和环境带来压力。文章最后提出五项保护景区土壤资源的对策和措施:(1)加速绿化荒山;(2)有节制地利用风景资源;(3)发展景区土壤改良和培肥工作;(4)适度发展当地名优特产;(5)加强邻近地区生态环境保护。