【作者】 聂振龙；

【导师】 张光辉； 张发旺； 陈宗宇；

【作者基本信息】 中国地质科学院 ， 地质工程， 2005， 博士

【摘要】 地下水循环是陆地水循环的重要水文过程，决定着地下水系统的状态和径流特征；地下水更新速率是衡量地下水系统更新能力的重要指标，也是地下水资源评价的重要依据。因此，研究地下水循环及其更新性具有重要意义。地下水系统是一个复杂的、动态的、开放的系统，地下水系统与外界环境之间以及系统内部各级子系统之间不断进行物质和能量的交换，构成一个具有层次性的完整循环系统。气象、水文、地质、构造、水文地质条件和地表植被以及人类活动等诸多因素影响着地下水循环过程，而地下水水化学和同位素组分的变化蕴涵着丰富的水循环信息，为研究地下水循环和更新性提供了有效手段。本文研究目标是揭示西北内陆盆地地下水循环规律及其更新性，为实现地下水资源可持续利用和科学管理提供依据。为此，以黑河干流中游盆地为重点研究区，主要围绕三个方面的内容开展研究工作：(1)不同水体水化学和同位素特征；(2)地下水循环规律，包括地下水补给、径流和排泄机制；(3)地下水系统更新速率估算。本文以系统理论为指导，以同位素和水化学信息为线索，综合运用水文地质学、水文地球化学、同位素水文学以及相关的数学理论，采用定性判断和定量分析相结合的方法开展研究工作。首先，在总结前人成果的基础上，全面了解了研究区的区域背景，详细分析了盆地地下水系统的空间物理结构和水流特征；然后，详细分析地下水系统与相邻系统之间的输入输出关系，从而阐明地下水循环系统的补给和排泄机制；同时，利用同位素和水化学信息的示踪功能和放射性测年技术，识别出盆地地下水循环系统的径流特征；应用同位素模型，估算了盆地地下水的更新速率；最后根据盆地地下水循环规律及其更新性，提出了地下水合理利用建议。通过上述研究，得到以下成果：1．详细分析了源区水循环特征在中高山带冰雪融水和降水一部分形成地表径流，一部分沿裂隙渗入地下形成地下径流；在向下游径流的过程中，形成两种地下径流子系统：浅部的局部径流子系统和深部的区域径流子系统。局部径流子系统在局部补给区接受冰雪融水和降水补给，地下水中冰雪融水约占24％，降水占约76％，经过短暂的地下径流，就近向河流排泄：区域径流子系统在高山区接受冰雪融水和降水补给，在山前断裂带受阻上升至地表成泉；地表水形成于中高山带的冰雪融水和降水，在向下游径流途中不断接受不同地带的降水和地下水补给，根据同位素模型估算，出山地表水中深层地下水占5～7％，降水、冰雪融水和浅部地下水占93～95％。2．讨论了黑河干流中游盆地的边界特征中游盆地地下水系统在南部与祁连山区水系统主要通过出山河流发生水量交换；高台附近的隐伏基岩隆起构成张掖盆地与酒泉东盆地的天然分界，两地下水系统之间没有大规模的水量交换，高台隐伏隆起是张掖盆地地下水系统的集中排泄区。3．阐明了黑河干流中游盆地地下水补给、径流、排泄特征根据地下水化学和同位素信息以及地下水年龄特征，将盆地地下水径流系统划分为局部径流和区域径流两大子系统，根据区位特征又将局部径流子系统细分为两个次级子系统：山前戈壁带局部径流子系统和细土带局部径流子系统。区域径流子系统地下水以水平运动为主，局部径流子系统地下水以垂向交替为主。盆地地下水系统具有三种主要的补给机制：山前垂直入渗补给、细土带河流侧渗补给和灌溉入渗补给。山前垂直入渗补给主要发生在山前冲洪积扇，出山河水渗漏量占地下水补给的75～90％，当地降水入渗占10～25％，山前垂直入渗是山前戈壁带局部径流子系统和盆地区域地下水流系统的主要补给方式；河流侧渗和灌溉入渗补给主要发生在细土平原带和人工绿洲带，是细土带局部径流子系统的主要补给方式。盆地地下水排泄方式主要有：泉排泄、河床溢流排泄、蒸发蒸腾排泄和人工开采。泉排泄主要发生在溢出带附近，泉排量占地表径流量的20～40％；河床溢流排泄主要出现在盆地北部边缘的黑河河床附近，浅层地下水和深层地下水都有排泄，其中浅层地下水排泄量占地表径流的59％左右，深层地下水占19％左右；蒸发蒸腾和人工开采主要出现在细土平原绿洲带。4．揭示了黑河干流中游盆地地下水循环模式地下水系统在山前戈壁带接受降水和出山河水入渗补给；在向下游径流过程中逐渐分化为浅层局部地下水流和深层区域地下水流；区域地下水流继续向下游水平流动，在细土平原带通过越流、人工开采的形式排泄；由于受地形、岩性和构造控制，由山前到细土带，形成多个局部地下水径流子系统；山前局部地下水径流子系统在向下游径流的过程中不断接受河流的渗漏补给，在溢出带以泉的形式排泄；细土平原局部地下水流子系统，接受河流侧渗和农田灌溉入渗补给，地下水以垂向运动为主，通过河床溢流、开采、蒸发蒸腾等形式排泄。5．估算了黑河干流中游盆地地下水的更新速率张掖盆地浅层地下水的年更新速率在0.01～2.5％之间，由于不同地带地下水的循环条件不同，其更新速率差异较大。总体上山前戈壁带地下水更新能力好于细土带地下水；常年性河流补给的地下水更新能力好于季节性河流补给的地下水；沿河流两侧的地下水更新能力好于远离河流的地下水。在垂向上，随深度的增大，地下水的更新速率减小，40m以上的潜水，地下水更新能力最强，年均更新率大于2％；100m以下的深层承压水，更新能力最差，年均更新速率小于0.8％；40～100m之间的中层地下水，更新能力中等，且变化范围较大，年均更新速率在0.5～2.5％之间。6．提出了地下水合理利用分区建议本文从地下水系统自然规律出发，根据地下水的循环及其更新性能力的区位变化规律，将黑河干流中游盆地划分为4个地下水资源利用分区：民乐地下水资源利用区、张掖．临泽地下水资源利用区、高台地下水资源利用区和高台．正义峡地下水资源利用区。并根据不同地带地下水循环更能力，将民乐地下水资源利用区和张掖-临泽地下水资源利用区进一步划分为6个亚区：民乐山前地下水资源涵养亚区、下游地下水控制利用亚区、张掖-临泽洪积扇中上部地下水资源涵养亚区、洪积扇中下部地下水资源开发利用亚区、细土带地下水资源开发利用亚区和细土带地下水资源控制利用亚区。针对不同分区的地下水循环更新能力，提出了相应的地下水合理利用建议。更多还原

【Abstract】 Groundwater circulation is not only an important part of continental hydrologic cycle, but also the main force to drive the groundwater system to carry out its functions. And groundwater circulation and renewability is essential for improving water resource management. So it is necessary to understand groundwater circulation and renewability.As an opening system, groundwater system is characterized by its complicacy and variability. Groundwater system contacts with its neighbor water systems by mass and energy transfer, which is influenced by many factors, such as the condition of weather, hydrology, geology, tectonics, hydrogeology and vegetation. So it is difficult to study groundwater circulation by using traditional hydrogeological methods, while the chemical and isotopic components in groundwater contain much information of hydrologic cycle, which provides an effective method to trace the process of groundwater circulation.The purpose of present work is to reveal groundwater circulation and renewability in the inland basins of Northwest China, Which is vital to groundwater sustainable development. Taken the basin of the middle reaches of Heihe River as the main study area, the present work focus on three problems: (1) the chemical and isotopic characters of different water bodies; (2) the process of groundwater circulation, which includes the patterns of groundwater recharge, groundwater flow and groundwater discharge; (3) estimation of groundwater renewal rate.Taken the system theory as guide and the chemical and isotopic component as information of hydrologic cycle, the present work carries out the research by using hydrogeology, geohydrochemistry, isotope hydrology and relevant mathematics methods. Firstly, based on understanding of the research background in study area, the present work analyzed the physical frame of groundwater system and the groundwater flow character。Secondly, the groundwater recharge, flow and discharge patterns are identified by analysis of the interaction of groundwater system and its neighbor environment. Thirdly, the groundwater renewal rate is estimated by using two isotopic models. At last, based on the understanding of groundwater circulation and renewability in study area, this paper gives a few advices on groundwater sustainable development.The following results are obtained from present study.1. Illustrated the characters of hydrologic cycle in mountain area of Heihe River.In the alpine zone, some precipitation and meltwater infiltrate in subsurface through fissures, and the remainder water forms the surface water flow. There are two kinds of groundwater flow patterns in mountain area: local groundwater flow and regional groundwater flow. The local groundwater flow system gets recharge from meltwater and precipitation at local spot with the proportion of 24% and 76% respectively. The local groundwater discharges to the near stream, with a short flow path. While the regional groundwater system gets recharge from meltwater and precipitation at the high elevation (>3600m) area and discharges to surface as springs at the interface of mountain area and basins, where the fracture belt exists. The surface water is composed of precipitation, meltwater and groundwater. The fractions of various waters in surface water are calculated by using three-component approach. The results show that the proportion of regional groundwater in the surface water is about 5～7%, and the proportion of precipitation, meltwater and local groundwater is about 93～95%.2. Validated the boundary condition of groundwater system in the basin of the Heihe River middle reaches.The water transfer presents between the groundwater system in basin and the water system in mountain area mainly by the river flow systems. The bedrock blowups at Gaotai is the natural boundary of the Zhangye basin and the Jiuquan basin and there is no water exchange between these two basins.3. Revealed the characters of groundwater recharge, flow and discharge in the basin of the Heihe River middle reaches.Based on the groundwater chemical and isotopic characters and groundwater age in basins, the subsurface flow system is classified into local groundwater subsystem and regional groundwater subsystem. And the local groundwater flow subsystem includes the piedmont local groundwater subsystem and the alluvial plain local groundwater subsystem. The local groundwater moves mainly in the vertical direction, while the regional groundwater moves in the horizontal direction.There are tree recharge mechanisms of groundwater system in the basin of the Heihe River middle reaches, namely, piedmont vertical infiltration, riverbed leakage and irrigative water infiltration. The vertical infiltration presents at the piedmont pluvial fan, where about 75～90% of groundwater recharged from river water infiltration and 10～25% of groundwater from precipitation infiltration. The vertical infiltration is the main recharge type of the piedmont groundwater subsystem and the regional groundwater subsystem in basin. The riverbed leakage and irrigative water infiltration exist mainly in the alluvial plan.The main discharge modes of groundwater in basin include springs, riparian seepage, evapotranspiration and groundwater pumping. The springs present at the edge of the piedmont pluvial fan, where about 20～40% of surface water from springs. The riparian seepage mainly takes place at the edge of basin, where about 19% of surface water from deep groundwater discharger and 59% from the shallow groundwater discharge. The evapotranspiration and groundwater pumping exist in the alluvial plan.4. Illuminated the groundwater circulation patterns of basin groundwater system in the middle reaches of Heihe River.At the piedmont pluvial fan, the basin groundwater gets recharge from precipitation and river. Along the path of groundwater flow, it forms two types of groundwater flow subsystem: local flow subsystem and regional flow subsystem. The regional groundwater moves toward the alluvial plan and discharges though upward leakage or pumping wells. Controlled by topography, lithology, and tectonics, the local groundwater subsystem in the piedmont pluvial fan discharges as springs at the edge of pluvial fan, and the local groundwater flow subsystem in the alluvial plan gets recharge from river and irrigative water infiltration and discharges by riverbed seepage, pumping wells and evapotranspiration.5. Estimated the mean annual rates of groundwater renewal in the basin at the middle reaches of Heihe River.The shallow groundwater renewal rates range from 0.01% to 2.5% of the aquifer volume. In different zones of the basin, the groundwater renewal rates are variable due to the different groundwater circulation condition. The groundwater renewal rates decrease from the piedmont to the north edge. And the groundwater renewability is better in the riparian zone than that in the zone far from river.In the vertical dimension, the groundwater renewal rates decrease with depth. In the unconfined aquifer with the buried depth not more than 40 meters, the mean annual rates of groundwater renewal is more than 2% of the aquifer volume, while in the deep confined aquifer buried more than 100 meters, the mean annual rates of groundwater is less than 0.8% of the aquifer volume. In the semi-confined aquifer that lies between the unconfined aquifer and the deep confined aquifer, the groundwater renewability is variable in a wide range with the mean annual renewal rates being of 0.5～2.5%.6. Discussed the groundwater sustainable development modes.Based on the understanding of groundwater circulation and the estimation of groundwater renewal rates, the groundwater system is divided into four subareas for groundwater development: the Minle subarea, the Zhangye-Linze subarea, the Gaotai subarea and the Gaotai-Zhengyixia subarea. Further more, the Minle subarea and Zhangye-Linze subarea are divided into six zones, namely, the groundwater conservational zone at the piedmont of Minle, the restricting development zone at the downstream of Minle, the groundwater conservational zone at the piedmont of Zhangye-Linze, the groundwater development zone at the piedmont of Zhangye-Linze, the groundwater development zone in the alluvial plan of Zhangye-Linze, and the restricting development zone in the alluvial plan of Zhangye-Linze. The present work gives the advices on groundwater development according to the groundwater renewability in different subareas and zones.更多还原