中国北部边疆第四系地下水研究

在中国北部边疆西起天山东端的北山，东至大兴安岭北段的４２００ｋｍ地域内，气候干旱少雨，水资源贫乏，第四系地下水是主要供水源之一。本文首次比较系统地研究了该区第四纪堆积物的分布和地下水的赋存规律。文中依据不同地貌单元、地层岩性及气候条件诸因素将本区第四系地下水划分为枝状沟谷砂砾石层孔隙水、河谷冲积平原砂砾石层孔隙水两种主要类型，并着重对有重要供水意义的河谷冲积平原砂砾石层孔隙水的分布、埋藏条件、富水性及水化学特征进行了论述。

A STUDY ON THE QUATERNARY GROUNDWATER OF THE NORTH BORDER AREA OF CHINA

The water system in the north frontier area of China is not well developed. All the rivers are inland water systems only except the Ergun River. The climate in most of the region is continental monsoon type of temperate zone. It is dry and windy in spring. The summer is short with concentrated precipitation. Topographically the region becomes lower eastwards. There is abundant pore-space water in the loose rocks. Based on various landform units, stratum lithology and climate conditions, the pore-space water can be summarize as follows:1 Pore-space water in Dendritic valley gravel bed The Dendritic type valleys mainly located in the bedrock mountain areas. They were formed by surface water flowing along the various structure lines, and erosion of lithologically soft and hard layers. Generally, they are of dendriform. The water level of pore-space water in Dendritic type valley gravel bed is at 1-4m deep, with mineralization degree of 1.2g /L.2 Pore-space water in river valley alluvial plain gravel bed They are distributed in Ejin, Bayandulan, Ulan Usuhundi, Seyeriji, Ulgai, Hailar and Mordaga rover valleys. The aquifers are mainly composed of the sand and gravel of Holocene and upper Pleistocene, Quaternary. The frontier line in the area is 4200km long, crossing longitude for 28°.Its landform and climate features and also, the hydrogeological conditions, differ greatly from place to place.(1) The western area: The major river valley alluvial plain occurs in the Ejin River valley, which being sourced in the Qilian Mountain, Gansu Province, flows northwards. After entering the inner Mongolia, it runs northeastwards and finally converges into the Juyanhai Lake. The drainage area is large, and the river valley is long and wide with width of 40￣50km. The lithology of aquifers is grit, middle-fine sand and powder-fine sand, with thickness of 10￣80m. The lithology and thickness vary more obviously in crosswise: The lithology of main river course is middle grit and silt with thickness of 50￣80m, and that of both sides are fine silt and powder--fine sand with thickness of 10 ￣ 50m. Therefore, the productive aquifers have been formed along the main river course, its water level is at 2.5m underground, and the water outport of individUal well is more than 1000m3/d. In some areas, the water output of individual well reaches to more than 2 0(Xhn3 /d' It is sodium bicarbonate type water, the mineralization degree is less than lg/L. As the Non-main river course are concerned, the aquifer is fine silt and powder-fine sand with thickness of 10￣50m. Its water level is at 3￣7m underground. The water output of individual well is 100￣1000m3/d. The hydrochemical type is sodium calcium bicarbonate. The mineralization degree is less than 1.5g /L.(2) The Central area: The major river Valley alluvial plains occur in the Bayandulan, Ulan Usuhundi, Seyeriji and Ulgai Rivers.(a) The Bayandulan alluvial river valley plain: It enters into the survey area from the south and streches into Mongolia, covering an area of 540kin2. The groundwater moves from the south to the north. The thickness of the aquifer varies very much in crosswise. The average thickness is 10￣80m, so, the variation of water output per well is between 130 and 3 682m3 /d. (b) The Ulan Usuhundi hiver valley plain: The river is sourced in Mongolia,flows from the northeast to the southwest and finally converges into Qagan Nur Lake.The drainage area is small. The river valley is 70km long and 3 ￣ 6km wide. The lithology of aquifer is gravel, middle grit and middle silt with thickness of 40￣ 60m' The lithology, thickness and granularity vary obviously both crosswise and lengthwise.In crosswise, the lithology of main river course is gravel and middle grit. The thickness is 40 ￣ 60m and becomes thinner to the both sides. The granularity also becomes finer. In lengthwise, from the upper to the lower reaches, the lithologic granularily becomes thinner. The aquifer distributes continuously. Hence, a productive aquifer is formed along the main river course. The water output of indvid