中国陆地基本地貌类型及其划分指标探讨

BASIC TERRESTRIAL GEOMORPHOLOGICAL TYPES IN CHINA AND THEIR CIRCUMSCRIPTIONS

平原、台地、丘陵、山地等是地表最基本的地貌形态，这些名称不仅为专业领域广泛引用，也为普通人所知晓。近100年来多种地貌分类方案中都涉及这些地貌类型名称，有的称其为地貌“基本形态”。由于每种地貌形态都不仅包含形态特征，而且还有一定的成因意义，因此应称其为基本地貌类型。通过对已有的基本地貌分类及其划分指标进行系统分析和评估，认为中国陆地基本地貌类型按照起伏高度和海拔高度两个分级指标组合来划分的原则符合起伏复杂、多台阶中国地貌的基本特点。在传统的平原、台地、丘陵和山地分类的基础上，按起伏高度对山地进一步细分，即划分平原、台地、丘陵（〈200m）、小起伏山地（200～500m）、中起伏山地（500～1000m）、大起伏山地（1000～2500m）和极大起伏山地（〉2500m）等7个基本地貌“形态”。本文对前人以现代雪线、多年冻土下线和森林上线高度为依据确定地貌面海拔高度的分级指标进行了全面分析，由于它们的海拔高度在全国各地存在巨大差异，我们认为海拔高度等级指标并不符合中国实际。通过全国重点地区1：500000地形图山地顶面海拔高度分布和1：1000000国家数字高程模型（DTM）数据库编制的中国地面高程分布图进行较系统的分析，我们提出了应以1000m，2000m，4000m和6000m作为划分低海拔（〈1000m）、中海拔（1000～2000m）、亚高海拔（2000～4000m）、高海拔（4000～6000m）和极高海拔（〉6000m）地貌海拔高度分级指标。根据7个地貌起伏高度形态和5个海拔高度等级，将全国组合成从低海拔平原至极大起伏极高山28个基本地貌类型。

In the past one hundred years,the classification of landforms has been discussed considerably. Some authors called the terms like plain, platform, hill and mountain as basic morphologies but we think they are landform types, because these terms are defined not only by their morphological characteristics, but also by their formations. By systemically analyzing and evaluating the existing fundamental geomorphological classification systems,we consider that it is suitable to classify the complicated geomorphological types of China according to two main indicators,i, e., relative relief height and absolute altitude above sea level. The first indicator is used to divide landforms into four types,i, e., plain, platform,hill,and mountain. We here suggest to further divide them into seven types according to the relative relief height. They are plain, platform, hill （ 〈 200m）, low relief mountain （ 200 - 500m）, intermediate relief mountain （ 500 ~ 1000m ）, high relief mountain （ 1000 ~ 2500m ）, and extremely high relief mountain （〉2500m）. The second indicator is actually just the meters above the sea level. We propose to replace the previous classification criteria of modern snowline,lower boundary of permafrost,and upper boundary of forest belt by the elevation above sea level, because the exact heights of modern snowline, lower boundary of permafrost, and upper boundary of forest belt vary remarkably in China. Through observing the distribution pattern of mountain ridges＇ altitudes on topographic maps （ 1 ： 500000 ） of key regions in China and the distribution map of ground elevation （1 ： 1000000）in national digital topography model（DTM） database, we suggest the following criteria： Low altitude（ 〈 1000m ）, intermediate altitude （ 1000 ~ 2000m ）, sub-high altitude （2000 ~ 4000m ）, high altitude （4000 ~ 6000m）, and extremely-high altitude（ 〉 6000m）. Applying the classification system with seven types of the relative relief heights and five types of absolute altitudes, landforms in China can be divided into 28 basic geomorphological types（Table 1 ）,ranging from low altitude plains to extremely high mountains.