南水北调中线干渠生态系统结构与功能分析

为分析和掌握南水北调中线干渠生态系统结构与功能的特征参数,根据2015~2019年中线干渠鱼类资源调查数据及实测的鱼类生物学参数数据,应用Ecopath with Ecosim 6.6软件构建了Ecopath食物网模型.模型由18个功能组组成,包括了初级生产者、初级消费者、主要鱼类和有机碎屑等.结果显示：中线干渠生态系统规模总流量、总生产量和总消耗量分别为19186.330,8947.857和1106.002（t/（km²·a））,食物网主要由4个整合营养级（1.00~3.71）构成,最高营养级为大型肉食性鱼类鱤（3.71）.食物网能量传递主要有两条途径,分别为牧食食物链和碎屑食物链,两者传递的能量相当,但牧食食物链传递效率是碎屑食物链的近两倍.交互营养分析结果表明,捕食者对其饵料生物的影响一般为抑制作用,碎屑生物量的增加对大部分功能组的影响为正效应,小型上层鱼类对浮游动物生物量起抑制作用.从各功能组之间的生态位重叠来看,各功能组间捕食者生态位重叠现象不普遍,重叠指数适中,部分肉食性鱼类的捕食者生态位重叠指数达到1.对生态系统总体特征分析发现,中线干渠生态系统的总初级生产量与总呼吸量的比值（P/R）、总初级生产量与总生物量的比值（P/B）、Finn's循环指数（FCI）和Finn's平均路径长度（FML）都表明该生态系统处于发展的幼态期,抵抗外界干扰的能力差.此外,中线干渠生态系统对初级生产力的利用率很低,导致过多的营养物质未进入更高营养级的食物链中进行循环,造成系统能量流动的滞缓.因此,根据生物操纵理论,可通过优化和完善鱼类群落结构,增强对系统初级生产力的利用效率,促进物质循环和能量流动,维持生态系统稳定.     

Diversion of the Ganges Water at Farakka and Its Effects on Salinity in Bangladesh

/ The Ganges River supplies water to the southwest region of Bangladesh mainly through one of its distributaries-the Gorai River. India commissioned a barrage on the Ganges River at Farakka in April 1975 to divert water and make the Bhagirathi-Hooghly River navigable. The diversion has reduced the dry season discharge of the Ganges and Gorai rivers in Bangladesh. Statistical analyses indicate that the changes in the dry season discharge of these rivers are significant. Reduced discharge in the Gorai River has induced accelerated sedimentation and increased salinity in the southwest region of Bangladesh. Empirical analyses demonstrate the relationship between discharge in the Gorai River and salinity. Analyses also determine the requirement of flow for the Ganges and Gorai rivers to keep salinity at threshold limits. Increased salinity has caused negative effects on agriculture, forestry, industry, and drinking water in the southwest region of Bangladesh.KEY WORDS: Bangladesh; Ganges River; Gorai River; Farakka diversion; Salinity     

MODELING A CONCRETE BLOCK IRRIGATION DIVERSION SYSTEM1

ABSTRACT: Concrete block irrigation diversion systems have been proposed as alternatives to permanent dams of concrete or rock or temporary gravel berms. Permanent dams can cause stream channel instability, bank erosion, sediment pollution, ice flow blockage, and safety problems for recreational floating craft. Temporary berms can require substantial streambed disturbance and can promote sediment pollution, stream bank instability, and bank erosion. A design procedure was developed based on a model of the hydraulic performance of concrete block diversion systems. The procedure was used to model a site on the Gallatin River in Montana. The method relies on HEC-RAS (Hydrologic Engineering Center -River Analysis System) software combined with analytical techniques in an iterative scheme. The hydraulic performance of different diversion configurations (the existing heavy-rock diversion system, concrete blocks oriented parallel to flow, and concrete blocks oriented diagonally) was assessed using the model under a range of flow rates. The minimum diversion dimensions (length, number, and size of blocks) that maintained block stability while diverting the requisite flow were determined for each model run. At the Gallatin River site, the block system oriented parallel to flow required less diversion material than the diagonal orientation. The recommended diversion length was 51.8 m (170 ft). Trapezoidal blocks with a top width of 20.3 cm (8 in), a height of 45.7 cm (18 in), and side slopes of 2 vertical to 1 horizontal were specified. This configuration minimizes the total block mass, diverts the required flow, and has a factor of safety of 2.0 against block displacement.     

内陆湖泊富营养化内源污染治理工程对比研究

湖泊富营养化是重大水环境污染问题,目前我国正在开展富营养化的研究及其综合治理。本文分析了底泥疏浚工程、生态引水工程和水生植物修复三种典型的内陆湖泊内源污染治理工程技术在治理湖泊富营养化过程中的作用,综述了三种工程措施在国内外的运用现状,比较了三种措施在改善湖泊水环境过程中的优点和不足,指出在解决湖泊富营养化问题时单独使用其中一种方法都存在的局限性,在此基础上,以滇池为例,对三种工程措施的治理效果和结合途径进行探讨。     

四川省彭县葛仙山旅游资源的成因分析与开发方式

葛仙山为龙门山脉中段前山一座紧邻川西平原的中山，距成都约６５ｋｍ，山峰海拔１０２０～１６００ｍ，地形险要。有丰富的科学考察型旅游资源和消遣度假型旅游资源。科学考察型旅游资源包括飞来峰构造和飞来峰地貌、第四纪地壳运动、水系变化和喀斯特地貌。彭灌飞来峰群和阿尔卑斯飞来峰群同负盛名，而葛仙山飞来峰为彭灌飞来峰群中逆推距离最远者，碾掩构造的原地系统地层最新，唯有在葛仙山才能了解彭灌飞来峰群形成于新构造运动中的事实。第四纪地壳运动现象明显。水系变化为次生河袭夺了原始顺向河，喀斯特地貌类型众多，形态典型，可准确研究喀斯特发育的起始时间。消遣度假型旅游资源包括林海雪山、药用植物园、奇峰异洞、泉水、佛光和日出、宗教圣地。在开发上应发挥临近成都和资源丰富的优势，发展多种形式、多种内容的观光，吸引１～２日游的游客。种植奇花异草，广泛造林，洞穴内铺路并安装彩灯，修建富有艺术性的配套建筑。     

引黄济青调水沿程氮污染物的迁移转化研究

2011年4—6月在引黄济青工程输水沿程11个采样点进行4次取样,分析氮污染物的迁移转化。结果表明,总氮在沿程呈下降的趋势,但不同月份存在差别;硝酸盐氮是氮污染物的主要存在形式,与总氮呈正相关;氨氮和亚硝酸盐氮质量浓度较低,沿程有一定波动,但变化较小。沉砂池对硝酸盐氮有一定的去除作用,但对总氮的作用在不同月份存在差异。农业面源污染、植物残体分解、泥沙沉积作用、植物同化作用、微生物作用等因素会影响引黄济青沿程氮污染物质量浓度变化。     

调水过程中城市内河含氮污染物负荷变化规律研究

针对我国城市内河污染日益严重的问题,以巢湖市老城区环城河为研究对象,拟定调水方案,进行调水试验。依据沿河水文水质情况,布设6个实时水质监测点,并将环城河概化为5个河段。应用测得的水文水质数据对各河段不同时间点的含氮污染物负荷进行估算,初步研究了各河段NH3-N、TN负荷量的变化规律。通过对比上下游各河段含氮污染物负荷去除效果,分析调水效果的影响因素,总结个别河段调水效果不佳的原因,提出4条优化意见。并结合实际情况,选取其中可行性较强的1条对其有效性进行实验验证。     

INTERBASIN TRANSFER-THE INTERNATIONAL DIMENSION1

ABSTRACT. A number of interbasin transfers are technically possible on an international scale but extremely few have been developed or are in prospect of early development. The institutional constraints are strong and nationalistic reactions to proposals which strongly favor either one of the nations involved have contributed to delays in development. Many of the more striking illustrations of the problems and opportunities relating to international transfers are present in the proposals for Canadian water export to the United States. Some have antagonized Canadians and made further negotiation difficult but phased and sequential transfers are possible and some could complement Canadian development. An important early phase might be the provision of guarantees for replacement supplies in option agreements that would free current surpluses within the United States for more intensive use. It should no longer be assumed that engineering development will provide adequate benefits for the source region. Allowances for opportunity costs, environmental improvements and some profit on sales appear to be needed for upstream areas if transfers are to be made. Many hazards are present but these can be more than offset by the opportunities if both countries strive for mutual benefit through rational study and continuing negotiation.     

MORPHOLOGIC RESPONSE OF SUBALPINE STREAMS TO TRANSBASIN FLOW DIVERSION1

ABSTRACT: Flow has been diverted from Rocky Mountain streams for many years with little documentation of the impacts on physical form and biological function of the losing stream system. This study addresses whether differences in form can be detected in subalpine step-pool, plane bed, or pool-riffle channels and linked to changes in flow regime from diversion. Total annual discharge was reduced between 20 and 60 percent and average annual peak flow was reduced up to 45 percent in the subalpine systems assessed; channels were diverted between 20 and 100 years. Expected impacts include reduced conveyance and changes in vegetation growth patterns because formerly active surfaces are colonized by riparian species, effectuating shrinking channel capacity. In this study, reduced channel width is used as an indicator of morphologic response. Observed reductions in width, ranging from 35 to 50 percent at some sites, resulted not only from vegetation invasion of stable surfaces but also from the development of an inset beside former cut banks. This observation, however, was restricted to wider pool-riffle channels with gravel bars. Outside of these areas, morphologic changes were either subtle or absent. The absence of widespread response is attributed primarily to periodic “flooding” of the diverted channel. During wetter-than-average years when excess water is available, minimal flow is diverted and the hydrograph resembles a free-flowing regime. The release of high flow to the natural channel potentially offsets changes in form incurred during “dry” periods. The stable nature and structure of subalpine channels also contributes to the absence of reduced capacity.     

LAKE MICHIGAN DIVERSION - STREAM QUALITY PLANNING1

ABSTRACT: By United States Supreme Court action, the diversion of water from Lake Michigan and the Lake Michigan Drainage Basin in the Metropolitan Chicago Area is regulated at an annual maximum rate of 3,200 cfs. Approximately 1,700 cfs of this diversion is used for water supply, and the remaining 1,500 cfs consists primarily of stormwater runoff with lesser amounts of direct lake diversion, such as lockage and leakage, navigational makeup water flows, and discretionary diversion needed to maintain water quality standards in the Metropolitan Sanitary District of Greater Chicago's basic waterways. In order to assess the schedule of its discretionary diversion needs, the District, using a computer model of its basic waterway system, has calculated the minimum discretionary diversion requirements for projected water quality conditions as successive elements of the District's water pollution control program are completed. The results of these analyses can be used as a basis for developing plans for future allocations of the limited supply of Lake Michigan water to other uses such as domestic water supply, when and if such supplies become available.