MODFLOW在八五三农场地下水数值模拟中的应用

1、MODFLOW在八五三农场地下水数值模拟中的应用        【中文摘要】水是人类赖以生存和发展的重要自然资源,也是自然生态环境重要的制约因素。随着社会经济的迅速发展,水资源供需矛盾日益突出,解决水资源危机已成为世界范围的战略性题目之一。八五三农场位于三江平原,属于热和半湿润农业天气区,其地下水资源较贫乏,地表水资源丰富,但利用程度不高,该地区在1995年前地下水位变化比较平缓,地下水基本处于采补平衡的状态,1995年以后,地下水位开始持续下降,尤其是近几年来,地下水位降幅愈来愈大,假如不加控制,还有继续下降的趋

2、势。鉴于此,本研究基于地下水数值模型,在水资源供需平衡的基础上,提出了两个可能的地下水控制开采方案,运用模型猜测各个开采方案下地下水流场和水位动态变化趋势,优选方案二作为八五三农场未来地下水利用措施。本论文主要由七部分组成:绪论、研究区基本状况、地下水流数值模拟方法及原理、地下水流数学模型的建立、地下水资源需水猜测及水位预告、地下水资源的治理与保护、结论与不足。其中地下水流数学模型的建立是本论文的关键所在。分析水文地质条件,建立水文地质概念模型。通过八五三农场自然地理和区域水文地质,将第四系承压含水层作为数值模拟对象,概化为非均质各向同性平面二维流。采用GIS与Visual MODFLOW软件

3、相结合,利用ArcGIS的数据编辑和图形处理功能,天生可供Visual MODFLOW调用的底图。将整个研究区以800m×800m的正方形网格离散,总共58行,68列,3944个单元。模拟期为2000年11月5日到2001年11月4日,以月为时间段,每五天为一个时间步长。2000年11月5日到2001年4月25日为模拟识别阶段,2001年4月26日到2001年11月4日为模拟验证阶段。结合水文地质条件、地形地貌条件和含水层特征,将研究区承压含水层的渗透系数分为4个区,弹性释水系数分为3个区。对研究区进行水均衡计算,运行模型,通过实测水位和计算水位的拟合,进行模型的参数识别,再对模型进

4、行验证。经过验证所建立的地下水流数值模拟模型是可靠的,可以对八五三农场地下水资源进行现状模拟与未来变化趋势猜测。本文结合八五三农场的社会发展现状及社会经济发展态势,评价了该区水资源量及水资源开发利用现状,制定了两个方案对20062015年的地下水位变化情况进行了预告,分析评价了地下水运动的时空变化规律及趋势,比较得出优选方案,建议减小地下水开采量,充分利用地表水资源,做到地表水与地下水的联合调度。');【Abstract】 Water is the important natural resources for the mankind survival and development,

5、 as well as an important factor for restriction of natural eco-environment. Accompanying the rapid development of economical society, the contradiction between the supply and the requirement of the water resources stands out increasingly, Solving the water resources crisis has been one of the strate

6、gic problems in the world. 853 farm lies in Sanjiang plain, it belongs to warmth and half moist agricultural climate area, it is poor in groundwater resources, and it is rich in su*ce water resources but its utilization degree is not high. Groundwater level changed comparison gentle in this area bef

7、ore 1995, groundwater was basically in the balance of exploitation and supplement of water resources, underground water table has sustained to decline after 1995, especially in recent years the amplitude reduction of underground water level has become more and more large, the groundwater level has t

8、he trend of descending if we don't control. So this * based on the groundwater numerical model and on the basis of balance of water resources supply and demand puts forward two possible plans to control the exploitation of groundwater, and applies the model to predict the trend of groundwater fl

9、ow field and water level dynamic in each exploitation plan, at last optimizes the second plan as the measure to exploit future groundwater in the 853 farm.This * mainly is constitute by seven parts, as follows: Introduction, Basic situation of the study area, The method and principle of groundwater

10、flow numerical simulation, Establishment of the groundwater flow mathematical model, Need water prediction and water level prediction of groundwater resources, Management and protection of groundwater resources, Conclusion and deficiency.The key of this * is the establishment of groundwater flow mat

11、hematical model. Analyze hydro-geological condition, establish the hydro-geology conceptual model, through the analysis of physical geography and hydro-geology in 853 farm, this study makes the quatemary confined aquifer as the object of the numerical simulation, and generalizes to be heterogeneity,

12、 isotropic and plane two dimensional flow. Use the software of GIS combined with Visual MODFLOW, and use the function of date editing and graphic treatment of GIS, generalize the base map that can be call in Visual MODFLOW. The whole study area is discreted by 800×800mm square grids, 58 rows, 6

13、8 columns, and altogether 3944 cells. The simulation stage is from November 5, 2000 to November 4, 2001, each month is one stage, every five days is one step. From November5, 2000 to April 25, 2001 is the stage of model recognition, and from April 26, 2001 to November 4, 2001 is the stage of model v

14、alidation. Combined hydro-geology, landform and topography with the character of the aquifer, the confined aquifer of the whole study is divided into 4 permeability coefficient areas and 3 coefficient of storage areas. At first, this * carries on water equilibrium calculation for the study area, the

15、n operates the model, identifies parameters of the model through measured and calculated water level fitting, at last validates the model. The groundwater numerical simulation model established by verification is reliable, so it can simulate the present situation and predict the trend of future chan

16、ges of groundwater resources in 853 farm.This * combines the present situation and economy situation of society development in 853farm, evaluates the quantity and exploitation present situation of water resources in this area, predicts the change situation of groundwater level from the year 2006 to 2015 with the two plans, analyzes and evaluates the time and space changing rule and the trend of groundwater mot