ALLOCATION MODEL FOR IRRIGATION WATER COST: CASE STUDY OF THE NILE VALLEY IN EGYPT1

ABSTRACT: An allocation model for irrigation water cost, based on the Use of Facilities method, is presented. The model is developed for large-scale irrigation systems which may include multipurpose reservoirs, irrigation control works, pump stations and irrigation canals of various orders. The model accounts for the water conveyance losses as well as the water gains in the irrigation canals, and their effects on irrigation cost. It is applied to the irrigation distribution system of the Nile Valley in Egypt, which contains the High Aswan Dam, 16 irrigation structures, 12 pump stations, and numerous irrigation canals. The irrigation water cost at 29 areas representing the Nile Valley is determined.     

水利工程对水质的影响评价——以麻栗坝水库为例

通过对麻栗坝水库工程的水质进行预测分析,结果表明,麻栗坝水库不会产生富营养化,重金属含量不会明显增加,水利工程对水体质量变化影响较小。     

尾矿坝地质生态环境风险防护措施分析

尾矿坝的环境风险主要是发生溃坝后对生态环境、水环境造成的不良影响.发生溃坝事故的根源是尾矿坝存在隐患,主要原因有先天因素和后天因素两种,先天因素主要有:尾矿坝建设前期工作中,对自然条件了解不够、尾矿坝设计不当、尾矿坝施工质量不良等;后天因素主要是在尾矿坝生产运行中,由不具备专业知识的人员管理,未按设计要求或有关规定执行.因此,预防溃坝的环境风险防护措施,要从防洪设计、增强坝体稳定性及加强管理等方面进行.     

三峡水库对长江,嘉陵江重庆城区段水质影响初探

本文利用已有的研究成果，初步探讨了三峡工程兴建之后，在正常蓄水位时长江，嘉陵江重庆城区段的水文，水力学特征，预测了重庆城区范围２０１０年的污染物排放水平，用二维水质模型对建库后两江城区段的水质进行了模拟，并对建库前后的浓度变化作了大致的比较。     

一种机械化抢堵堤防溃口方法的探讨

根据对溃口处流速的估算及船舶编队后的阻力初步估计,提出用打桩船队打桩作业的方法来抢堵溃口。此法可获巨大的社会效益和经济效益,而投入甚微。所提出的系驳方法,对船队稳性有极大的提高,克服了抢险的危险性。笔者建议进行必要的流体力学试验,使此法在科学、安全的基础上更臻完善。此法以长江水患溃堤事故为例,探讨并提出了一种机械化抢堵堤防溃口的方法,对有溃口可能的江河均有参考价值。     

A Water Quality Index Applied to an International Shared River Basin: The Case of the Douro River

A Water Quality Index (WQI) is a numeric expression used to evaluate the quality of a given water body and to be easily understood by managers. In this study, a modified nine-parameter Scottish WQI was used to assess the monthly water quality of the Douro River during a 10-year period (1992–2001), scaled from zero (lowest) to 100% (highest). The 98,000 km² of the Douro River international watershed is the largest in the Iberian Peninsula, split between upstream Spain (80%) and downstream Portugal (20%). Three locations were surveyed: at the Portuguese–Spanish border, 350 km from the river mouth; 180 km from the mouth, where the river becomes exclusively Portuguese; and 21 km from the mouth. The water received by Portugal from Spain showed the poorest quality (WQI 47.3 ± 0.7%); quality increased steadily downstream, up to 61.7 ± 0.7%. In general, the water quality at all three sites was medium to poor. Seasonally, water quality decreased from winter to summer, but no statistical relationship between quality and discharge rate could be established. Depending on the location, different parameters were responsible for the episodic decline of quality: high conductivity and low oxygen content in the uppermost reservoir, and fecal coliform contamination downstream. This study shows the need to enforce the existing international bilateral agreements and to implement the European Water Quality Directive in order to improve the water quantity and quality received by the downstream country of a shared watershed, especially because two million inhabitants use the water from the last river location as their only source of drinking water.     

三峡水库生态调度的适应性管理研究

三峡水库的生态调度管理是具有世界难度的动态多目标的决策过程。对三峡水库生态调度的复杂性和管理的不确定性进行分析,提出生态调度适应性管理的基本概念,并构建其理论框架。同时,基于其理论框架深入探讨了三峡水库生态调度的适应性管理需求,认为现阶段需求主要集中在中下游综合性生态流量、水生资源保护、库区水环境保护、中下游干旱及低水位补水、湿地保护5个方面。利用适应性的管理模式,通过持续监测、评价与调整,建立各部门及流域利益相关者参与、协商和交流的平台,以发挥水库最大的综合效益。鉴于目前属于三峡水库试验性蓄水期的阶段性特征认识,加之生态环境影响的滞后性,经济发展、社会转型、认知水平的提高和环保意识的觉醒,需要适应性管理目标随生态调度需求的演替进行不断地调整     

Scenario‐Based and Scenario‐Neutral Assessment of Climate Change Impacts on Operational Performance of a Multipurpose Reservoir

Scenario‐based and scenario‐neutral impacts assessment approaches provide complementary information about how climate change‐driven effects on streamflow may change the operational performance of multipurpose dams. Examining a case study of Cougar Dam in Oregon, United States, we simulated current reservoir operations under scenarios of plausible future hydrology. Streamflow projections from the CGCM3.1 general circulation model for the A1B emission scenario were used to generate stochastic reservoir inflows that were then further perturbed to simulate a potentially drier future. These were then used to drive a simple reservoir model. In the scenario‐based analysis, we found reservoir operations are vulnerable to climate change. Increases in fall and winter inflow could lead to more frequent flood storage, reducing flexibility to store incoming flood flows. Uncertainty in spring inflow volume complicates projection of future filling performance. The reservoir may fill more or less often, depending on whether springs are wetter or drier. In the summer, drawdown may occur earlier to meet conservation objectives. From the scenario‐neutral analysis, we identified thresholds of streamflow magnitude that can predict climate change impacts for a wide range of scenarios. Our results highlight projected operational challenges for Cougar Dam and provide an example of how scenario‐based and scenario‐neutral approaches may be applied concurrently to assess climate change impacts.     

Periodically hydrologic alterations decouple the relationships between physicochemical variables and chlorophyll-a in a dam-induced urban lake

Periodically hydrologic alterations driven by seasonal change and water storage capacity management strongly modify physicochemical properties and chlorophyll-a (Chl-a) and their interactions in dam-induced lakes. However, the extent and magnitude of these changes still remain unclear. This study aimed to determine the effects of periodically hydrologic alterations on physicochemical variables and Chl-a in the dam-induced urban Hanfeng Lake, upstream of Three Gorges Reservoir. Shifts in Chl-a and 13 physicochemical variables were recorded monthly in the lake from January 2013 to December 2014. Chl-a was neither seasonal nor inter-annual differences while a few physical variables such as flow velocity (V) exhibited significantly seasonal variabilities, and chemical variables like total nitrogen (TN), nitrate-nitrogen (NO₃-N), total phosphorus (TP), dissolved silica (DSi) were markedly inter-annual differences. Higher TN:TP (40:1) and lower NO₃-N:DSi (0.8:1) relative to balanced stoichiometric ratios suggested changes in composition of phytoplankton communities and potentially increased proportion of diatom in Hanfeng Lake. Chl-a was predicable by combination of dissolved oxygen (DO), TN and DSi in dry season, and by V alone in wet season. During the whole study period, Chl-a was solely negatively correlated with TN:TP, indicating decline in N concentration and increase in P could therefore increase Chl-a. Our results highlight pronounced decoupling of linkages between Chl-a and physicochemical variables affected by periodically hydrologic alterations in dam-induced aquatic systems.     

长江中游大型通江湖泊湿地景观格局演变特征

鄱阳湖和洞庭湖湿地是长江中游仅有的两个天然通江湖泊湿地,具有不可替代自然和人文价值。近年来,尤其是三峡工程运行以后两湖湿地景观格局发生改变,对区域生态系统平衡和社会经济发展产生重要影响。以Landsat 7为数据源,通过决策树分类及高斯回归的方法定量评估了三峡工程运行前后两湖湿地景观格局的演变特征及其差异性,旨在正确认识大型水利工程的生态效应,为湿地保护与重建提供科学依据。结果表明:2000~2014年,洞庭湖枯水期水位变化不明显。从历史演变特征来看,虽然有少部分植被挤占泥滩和水体,但总体上3种湿地景观类型面积变化不大。相比之下,三峡工程运行后鄱阳湖枯水期水位显著下降,水体面积萎缩近14%,植被面积增加约8%。与2000年相比,2014年鄱阳湖植被分布高程下降了1 m多。不同程度的干旱胁迫是形成两湖湿地景观格局差异性演变特征的主要原因。