“中国地下水质量评价及污染防护分级图”(1:600万)的编制特点

“THE MAP OF UNDERGROUND WATER QUALITY EVALUATION AND POLLUTION PROTECTION GRADING OF CHINA”(1:6 000 000) ITS COMPILATION FEATURES

本文介绍了“中国地下水质量评价及污染防护分级图”的编图指导思想及编图原则，总结了该图在编图内容和表现形式上的4个特点：1）表现地下水质量演变的主要特征和基本态势;2）反映自然因素和人为因素对地下水质量的双重影响和共同作用；3）力求专业性与实用性的统一；4）首次实现了在全国范围内，用最新标准和方法，对最新资料进行各种类型地下水的统一计算，统一分级评价，增强了实用性和可比性。

The Map of Underground Water Quality Evaluation and Pollution Protection Grading of China' is the first nationwide one of such kind. The objective of the compilation is to make a systematical summary of the achievements in underground water research in China, reflect the newest information and the state of the art. Based above some principals were determined in the compilation. They are as following:(1) The underground water quality evaluation was based mainly on undergroundwater hydrochemical data obtained since the 1990s. We examined various water samples, such as porous warer in loose rocks, fissure water in case rocks, porous fissure water in clastic rocks, karstic water in carbonate rocks, and porous fissure water in Permanent frozen grounds. We made generalized grading evaluation for them,with reference to the standard of drinking warer.(2) Stress on representativeness of the data. We made a comprehensive analysisand summarization to all natural factors and human factors which influences underground water quality.(3) Pay attention to influence of engineering and economic activities to underground water quality, and interaction between natural factors and human factors.(4) Strive to organize the contents of the map with professional features and easy to understand. Demonstration should be clear and easy.Based on the above principles, the map boasts of following features on the contents and representation:(1) Revealing major behavior of underground water quality changes. The MaP of Underground Water Quality Evaluation and Pollution Protection Grading of China has three categories: 1) Underground Water Quality According to the newly issuedNational Underground Water Quality Standard (GB/ T 14848－－93) and its stipulated grading method, a generalized grading evaluation has been made for underground water of five genetic types, with a five grading system f excellent very good, good,bad, and very bad. Phreahc warer and pressure water (in exploited layers) have beenevaluated separately for plain areas. 2) Principal pollutant elements and their distribution. A statistical analysis was made on the collected data resulhng 11 warerquality evaluation items. Besides, five representative pollution indexes, which are widely used in China and able tO reflect macro evolution, are shown on the map.Primary pollution and human pollution were separated. 3) Based on data of underground water quality and itS tendency, and extent of influence of natural conditions and human activities on underground water, pollution protection grading was made. The contents of the three categoreis are closely related with the cycles of underground water evolution (genesis－state protection). The aim is not to discussunderground water quality isolately, but to reveal fundamental behavior of undergroundwater quality changes, seeking the truth from surface phenomena.(2) Combination of natural factors and human activity factors. Underground waterquality depends mainly on geological environments, natural conditions and human engineering and economic activities. We tried to combine natural geological factors and human ergineering and economic activity factors and display them synthetically on the map. Based on the classification of pollutant elements, primary pollution was separated from human pollution. Two sets of marks were used for them. Thus readers can get qinckly a conception on different grades of underground water.(3) Striving for unity of professional knowledge and practice. The international geological mapping community is showing preference of practical map than basic map.The purpose of the compilation of the map has determined its value of application.Among its readers there are some non－geologists, such as policy makers, planners and management personal on environoment protection. Thus, we should keep the map rich of professional knowledge, but easy to understand.As shown on the map, water quality evaluation was made to underground water,according to their formation and distributional features. For plain areas, where phreatic