Influence of Seepage Face Obliquity on Discharge of Groundwater and its Pollutant into Lake from A Typical Unconfined Aquifer

Lab experiment and mathematical simulation Modular three dimensional finite difference groundwater (MODFLOW) were performed in a soil tank to simulate the hydrogeochemical interaction between lake and typical unconfined aquifer. Results show that the velocity decreases exponentially with the transect distance on seepage face. The maximal velocity occurs at the top point of seepage face. The obliquity of seepage face has a great influence on the maximum and distribution of seepage velocity. With the increase of the obliquity of seepage face, the maximal velocity decreases quickly and the velocity distribution becomes much more even. Most of groundwater flow and pollutant flux discharges through a narrow portion near the top of seepage face. The flow and mass concentrated in the narrow portion increase with the decrease of the obliquity of seepage face. These will benefit to design a reasonable and economical scenario to manage lakeshore and to control the pollution of lake water near lakeshore.     

新形势下开展退田还湖的思路与措施

湖泊是水资源的重要载体,是生态系统的重要组成部分。高强度的人类活动造成湖泊资源的过度开发,导致湖泊水域空间不断萎缩,并引发一系列的生态环境问题,急需通过退田还湖以恢复湖泊健康。在系统分析我国湖泊现状与问题的基础上,按照新形势下推进河湖休养生息和强化空间用途管制等要求,提出了开展退田还湖的总体思路、关键环节和主要措施,为系统科学推进退田还湖提供思路借鉴。     

水资源保护知识问答(三)

8　江河、湖泊、水库等天然水体的水质特征为什么会产生差异 ?　　江河、湖泊和水库尽管同属地表淡水水体 ,但由于它们的水文条件和环境条件的差异 ,使它们呈现出不同的水质特征。8 1　河流水质特征河流是地面水或地下水由高处往低处流动形成的水流 ,由分散细流汇集成小溪、小河 ,尔后汇集成大河注入海洋或湖泊 ,河流的首要特征是具有连续性的水流。河水流速决定于河床的深度、宽度、坡降和粗糙度 ,并受流量的影响。同一河流在不同河段和不同季节 ,流速常有很大的变化 ,形成急流段和缓流段 ,因而河床沉积物也有差别。河流另一特征是有较大的…     

堰塞湖是如何形成的？怎样应对？

堰塞湖是由火山熔岩流,或由地震活动等原因引起山崩滑坡体等堵截河谷或河床后贮水而形成的湖泊。由火山溶岩流堵截而形成的湖泊又称为熔岩堰塞湖。堰塞湖的堵塞物不是固定永远不变的,它们也会受冲刷、侵蚀、溶解、崩塌等等。一旦堵塞物被破坏,湖水便漫溢而出,倾泻而下,形成洪灾,极其危险。     

适用于发展中国家的湖泊富营养化治理技术(下)

发展中国家防治湖泊和沼泽的富营养化,直接从发达国家引进技术是无效的。重要的是要根据各个国家的实际情况推广节能、低费用和低维护费的技术。介绍了适用于发展中国家湖泊富营养化治理的生物技术。包括水产养殖生态园净化、种植水生植物进行净化、沉水植物净化技术的原理、特点和效果。     

ECO-HYDRAULICS TECHNIQUES FOR CONTROLLING EUTROPHICATION OF SMALL SCENERY LAKES-A CASE STUDY OF LUDAO LAKE IN SHANGHAI

The Ludao Lake with an area of 0.86 km2 and 50% water surface ratio, was taken as an example to study the eco-hydraulics techniques for preventing lake eutrophication. Besides external water inflow and outflow, the term related to internal local flow circulation was added in the continuity equation of two-dimensional horizontal hydrodynamic model, and further the hydrodynamic model was calibrated by the scenario of no water exchange. The velocity of 0.2 m/s was suggested to be the critical velocity of controlling algal bloom. To achieve the critical velocity in the whole lake, three factors were analyzed, which are wind, artificial external inflow augmentation and internal local flow disturbance by pump circulation. It is found that the role of wind can be disregarded. For the eco-hydraulics technique of external lake water inflow augmentation, the water flowing route should be firstly optimized, further, the lake inflow has a critical value under specified water level due to the narrow inlets, so the whole lake is difficult to reach the critical velocity to prevent algal bloom, and a combination of external inflow augmentation and internal local flowing disturbance should be considered. Simulation results show that the combination of external water inflow augmentation and internal local flow disturbance requires less eco-flow to achieve the global critical velocity than the sole internal local flow disturbance, for the Ludao Lake, the former requires total eco-flow of 25 m3/s, which reduces by 50% than the latter requiring total eco-flow of 52 m3/s.     

保定市河湖开发治理保护情况普查审核

河湖开发治理保护情况普查是第一次全国水利普查主要内容之一．其普查的重点为河湖取水口的取水量、地表水水源地的供水量、河流湖泊治理情况及水功能区划情况、人河湖排污口的废污水量等．为做好河湖开发治理保护情况普查工作以及确保普查对象数据质量．对各县上报的河湖开发治理保护情况普查的数据开展了数据审核汇总工作。     

小型湖泊应用于地表水源热泵时的热承载能力分析

分析了小型湖泊应用于地表水源热泵时的两种热承载能力计算方法——水面温度法和均匀混合法,并采用其计算了杭州小型湖泊应用于地表水源热泵时的热承载能力。计算结果表明：水面温度法较客观地反映了实际的排水混合及水温恢复过程,可信度更高。用水面温度法对7个代表性城市小型湖泊热承载能力进行分析的结果表明：夏季热承载能力在23-4—29．5W／m2之间,冬季热承载能力在31．6～45．7W／m2之间;设计这类系统的关键在于满足夏季热承载能力的约束。     

从环境资源法理角度看河湖管理的行政作为

只有将江河湖泊定位为公众共用物,将公众的基本用水与企业的营利性用水区别开来,将天然的江河湖泊与人力加工的水产品(如瓶装矿泉水)区别开来,才能从根本上将水政府管理部门与水商品企业、政府对江河湖泊的管理活动和水国有企业的经营活动、水政府管理行为与水市场行为区别开来,才能使政府对江河湖泊的管理接受法律授权、受到法律制约,才能将政府对江河湖泊管理的权力关进笼子,才能更好地发挥政府在水公众共用物供给方面的主导作用、市场在水商品贸易方面的引导作用。     

《中华人民共和国防洪法》解读

<正>《中华人民共和国防洪法》于1997年8月29日第八届全国人民代表大会常务委员会第二十七次会议通过,1997年8月29日中华人民共和国主席令第88号公布,自1998年1月1日起施行,全文共八章,六十六条。它是我国防治洪水工作的基本法律,是调整防治洪水活动中各种社会关系的强制性规范,为防治洪水,防御、减轻洪涝灾害,维护人民的生命和财产安全、保障社会经济的稳定发展提供了重要的法律