阿斯旺大坝的泥沙效应及启示

阿斯旺大坝修建已经３０多年了。本文着重介绍阿斯旺大坝带来的库区泥沙淤积，下游河道演变和河口海岸的变化，以及采取的治理措施。结合我国大型水利工程建设，阐述阿斯旺大坝给我们的启示。

国外典型水利工程建设后上游库区及河道淤积特点分析

以阿斯旺大坝、格伦峡大坝、胡佛大坝、塔贝拉大坝4个世界典型水利工程为例,在淤积量、淤积形态、淤积位置3个方面分析典型水利工程建成后上游库区及河道的淤积过程,并在同一特征指标下对其淤积特点进行横向比较,得出其异同点。

阿斯旺高坝的生态环境问题

:通过对阿斯旺高坝和尼罗河的实际考察和生态环境监测数据的分析 ,介绍了埃及政府相关管理部门的官员和专家对阿斯旺工程的看法 ,对阿斯旺高坝及其生态环境问题进行了评述。认为阿斯旺工程是一个成功的工程 ,它对埃及发挥的巨大影响和积极作用是有目共睹的。它对生态环境的不利影响 ,确被很多批评者盲目地夸大了 ,其中也包含有政治因素。中国在修建水利工程时 ,要对环境的影响作出客观、科学的评价 ,并采取措施把不利影响减少到最小。阿斯旺高坝运行近 30年 ,在生态环境监测方面积累了丰富的数据 ,这些成果和结论对三峡工程具有直接的借鉴和参考价值。

阿斯旺建坝后尼罗河三角洲泻湖重金属污染特征及其环境意义

本研究以尼罗河三角洲泻湖（Manzala、Burullus、Edku）为典型区域，利用6根浅孔并选取Al、Cd、Cr、Fe、Mn、Pb、Cu、Zn等主要重金属元素，探讨了自然和人类活动（建坝）共同作用下河口泻湖湿地环境重金属时空分布及污染来源。研究结果表明，1964年阿斯旺建坝和海岸保护工程实施后，泻湖地区逐渐演变为稳定而封闭的沉积环境。钻孔上层（〈10～15cm）沉积物重金属富集现象反映了建坝后三角洲泻湖环境污染加重。重金属空间分布表现为平原东西部Manzala和Edku湖污染较重，而中部的Burullus湖污染较轻。相关性分析和富集系数（EF）变化进一步揭示Manzala湖特征污染元素为Pb、Cu、Zn和Cd，污染源主要来自开罗石油化工等产业废水；Burullus湖特征污染元素为Mn和Pb，应该与湖区附近农业废水的大量排放有关；Edku湖特征污染元素则为Mn、Pb和Zn，其重金属可能来自邻近的Abu—Qir湾带来的亚历山大工业废水。

埃及Burullus潟湖沉积生源要素变化:百年来人类活动影响

Burullus是尼罗河河口高封闭性潟湖,其生源要素主要来源于尼罗河,是研究Aswan大坝建成以来流域变化如何影响河口湖泊环境的最佳区域。研究通过对Burullus潟湖B1岩芯的210Pb测年、粒度、以及TOC、TN、TP、BSi生源要素的测试分析,结合历史资料,试图揭示Aswan建坝前后河口湖泊营养盐的差异变化,以及这些变化对生态环境的影响。结果表明:1)沉积物中TOC、TN和TP含量自下而上总体增加,表明尽管Aswan大坝导致营养盐通量急剧减少,但由于下游人类排放N、P通量大大增加,导致下游湖泊N、P浓度并没减少;且沉积TN/TP均小于16,表明湖泊仍为P限制。2)但BSi和BSi/TOC自下而上总体呈减少趋势,表明Aswan大坝引起的水沙减少导致湖泊中硅藻的生物量及其总初级生产力占比都在减少,潟湖水体生态环境将趋于恶化。

浅谈水利工程对环境的影响

我国正处于经济高速增长时期,为了支持经济发展,水利工程在发挥发电、防洪、航运、灌溉等优势的同时,对生态环境的影响也受到了空前关注。本文对水利工程所引起的主要环境影响问题进行了全面的分析。

Groundwater Conditions and the Geoenvironmental Impacts of the Recent Development in the South Eastern Part of the Western Desert of Egypt

The area to the southeast of the Western Desert of Egypt has been subjected to considerable development activities over the last few years. The development includes the cultivation of about 2260 km2 of the desert lands “the well-known Toshka Project”. The hydrogeological conditions of the area are subjected to detailed investigation based upon the construction of the water table maps, hydrologeologic cross-sections, pumping tests, aquifer geometry, and recharge-discharge relationship. The study revealed that the Quaternary and the Nubia sediments are the main water bearing layers in the area. The Quaternary aquifer is of limited potential and made of mixed sand with clay deposit ranges in thickness between 5 to 10 m. The Nubia aquifer is the oldest sedimentary formation and the main groundwater resources in the area. It is represented by multilayered of sand and silt exists generally under artesian conditions. It is composed of three water bearing horizons partially separated by two confining horizons and extends in thickness ranges between 70 and 230 meters. The thickness increases away from the high dam lake. The analysis of pumping tests of the aquifer indicated that its potentiality is increasing north of the High Dam Lake (HDL) whereas it decreases in the other direction. This is due to high hydraulic conductivity and aquifer thickness in the area northeast of Khor Toshka and at west of Garf Hussein. The hydraulic conductivity of the aquifer ranges between 12.73 and 0.9 m/day. The review of the changes in groundwater levels in the area showed that there is a drop in ranges between 1 and 14 meters in the last few years indicating that the extraction from the groundwater is much more higher that the replacement rate. Also, the analysis of the fluctuation of water levels of the HDL and the groundwater level indicated that the influence of water on groundwater level in the area is observed only at a distance less than 10 km from the lake shore line. Seepage from the HDL is estimated as 238.13 × 106 m3/year. The geo-environmental impacts of the development on the surface water and groundwater in the area are evaluated.