【作者】 刘光龙；

【导师】 南忠仁； 张建明；

【作者基本信息】 兰州大学 ， 环境科学， 2012， 硕士

【摘要】 地下水动态研究是认识地下水资源形成、演化以及揭示地下水系统内部状态特征的有效途径。宁夏河东灌区是我国西北内陆干旱区典型的引黄灌溉区域,长期引黄灌溉引发的一系列生态环境问题已成为制约当地社会经济可持续发展的重要瓶颈,因而对该区域地下水进行研究,深刻认识和掌握地下水动态变化特征,并在此基础上进行仿真模拟和预测,对于促进区域地下水问题的解决和合理开发、管理地下水资源具有重要意义。本文通过野外调查和室内资料整理,分析了河东灌区含水层结构和地下水补给、径流、排泄特征；利用收集的长观资料分析了地下水动态的一般特征及其影响因素。根据灌区地下水收支项资料,采用水均衡法对灌区地下水均衡进行了计算和分析。在GIS技术支持下,计算了研究区不同时间尺度地下水位过程线的分维数,运用地统计学方法分析了灌区地下水位的空间变异特征,采用普通克里格法进行了空间插值,得到不同时期地下水位的空间分布图并进行了具体比较分析。在MATLAB平台下,建立了BP-ANN地下水动态仿真模型,并对不同情景下的地下水埋深进行了预测。主要结论如下：(1)地下水动态的一般特征河东灌区浅层地下水动态类型为灌溉-蒸发型,由于受引黄灌溉影响,不同区域地下水位的年际变化存在明显的周期性,年际动态稳定,年内波动较大；引水量、排水量等人为因素是地下水动态的主要影响因子,气象因子如降水量、气温、日照时数等由于时空分布不均,其对地下水位的影响不同区域存在差异；均衡期内河东灌区地下水为正均衡,相对均衡差为1.04%,基本处于均衡状态。(2)地下水位的分形特征与空间变异河东灌区年际地下水位过程线分维数值域在1-1.1之间,年内分维数接近于1,说明研究区地下水位过程线在时空上分配的不规则性和复杂程度均较小。虽存在一定区域差异,但总体来说地下水动态变化并不剧烈。河东灌区地下水位样本近似呈正态分布,在东西方向呈明显的“U”型趋势,在南北方向呈稳定的线性趋势；变异分析表明,结构性因子对地下水位空间变异性的影响在减弱,人类活动如灌溉、地下水开采等影响增强；地下水位具有强烈的空间相关性,地下水埋深越浅,这种相关性就越大；自然状态下地下水位的空间相关性较小,灌溉可以使其显著增强；普通克里格插值表明,灌区2000-2010年间地下水位年际变幅较小,年内变化较大。(3)地下水动态仿真模拟与预测BP-ANN地下水动态仿真模型较全面地反映了地下水位动态变化特征,具有较高的泛化能力,可以用于灌区地下水动态变化预测；模型预测结果表明,在引水量减少和日照时数增加时,地下水位明显下降,但日照时数增加的影响较引水量减少的影响显著；当引水量增加、日照时数减少时,地下水位明显上升,但引水量增加上升的幅度远高于日照时数；引黄水量对河东灌区浅层地下水具有显著的“补源”作用,在未来引黄水量大幅削减的情况下,将直接影响地下水埋深,因此,在未来继续实施水权转换和节水改造过程中,应充分考虑引黄水量对地下水的补给作用,将河东灌区引黄水量保持在年均9亿m3左右可以保证适宜的地下水埋深。更多还原

【Abstract】 The study of groundwater dynamic is an effective way to awareness of groundwater resources in the formation, evolution and reveals the internal state characteristics of the groundwater system. Hedong Irrigation District in Ningxia Hui Autonomous Region is situated in the northwest of China, a typical irrigation area of arid region. Eco-environment issues caused by long-term irrigation have become a restraining factor for social and economic development. In order to address the problem of regional groundwater, exploit reasonably and manage the groundwater resources, it is important to study the regional groundwater regime, understand the dynamic characteristics of groundwater, simulation and forecast groundwater dynamic.In this paper, the author analyzed the structure of groundwater aquifer, characteristics of recharge, runoff and discharge, combined with field survey and second-hand data. Based on long-term monitoring data, the groundwater dynamic and influencing factors were analyzed, and groundwater balance in target area was calculated. Supported by GIS technology, the fractal dimension of groundwater level on different time scale was calculated. Then the spatial variability of groundwater level was analyzed using geostatistics method, and the different period of groundwater level maps were made by ordinary Kriging interpolation. In MATLAB platform, the BP-ANN groundwater dynamic simulation model was established and used to predict the groundwater table under the different scenario. The main conclusions were summarized as follows:(1)General Characteristics of Groundwater DynamicThe dynamic type of shallow groundwater in Hedong Irrigation District is irrigation-evaporation. Due to the effect of irrigation, the change of groundwater level in distinct zone exist obvious periodicity, which steady in inter-annual and fluctuate largely in one year. Man-made factors such as diverted water volume and displacement are the main influence factors for groundwater dynamic. Meteorological factors such as precipitation, temperature, sunshine hours distributed unevenly in area and time, and its affect on groundwater level are distinct in different areas. In Hedong Irrigation District, groundwater dynamic is proper equilibrium during equilibrium period, the relatively balanced deviation is1.04%, and in a state of equilibrium basically.(2)Fractal Characteristics and Spatial Variation of Groundwater LevelFractal dimension of inter-annual groundwater level hydrograph in Hedong Irrigation District was between1and1.1, and it was close to1for the year, which indicated the level of distribution of groundwater irregularities and complexity were small in time and space. The complexity of groundwater dynamic process was difference in unlike regions, but the changes were not severe on the whole.There was a normal distribution of groundwater level sample in Hedong Irrigation District was obviously U trends in the east-west direction, and direction of stable linear trend in the north-south. The result of variability analysis showed that the structural factors influenced on the spatial variability of groundwater level were weakening, and human activities such as irrigation, groundwater exploitation were strengthening. Groundwater level had a strong spatial correlation and the more groundwater depth was shallow, the more correlation was enhanced. Spatial correlation that in natural state was small that was remarkable increased by irrigation. Ordinary Kringing interpolation showed that the inter-annual change of groundwater level was small and was comparatively large for the year in Hedong Irrigation District.(3)Simulation and Prediction of Groundwater DynamicSimulation model of BP-ANN on groundwater dynamic with high generalization capability reflected the characteristics of change about groundwater level dynamic comprehensively, which could be used to predict the change of groundwater dynamic in Hedong Irrigation District. The results of model prediction showed that groundwater level significantly dropped when diverted water volume reduced and sunshine hours increased, but the effect of increase on sunshine hours was more remarkable than increase of diverted water volume. When diverted water volume increased and sunshine hours reduced, groundwater level was significantly increased but the influence of rise range of groundwater level on increase of diverted water volume was much higher than that sunshine hours. It was obvious that diverted water volume had a function of recharge on shallow groundwater in Hedong Irrigation District, which in the future diverted water volume sharply cut would have a directly influence on the groundwater depth. Therefore, to implement the conversion of water rights and water-saving transformation process continually in the future, the effect of diverted water volume to groundwater recharge should be given full consideration, and it is appropriate that diverted water volume from Yellow River keeping in900million m3can ensure appropriate groundwater depth.更多还原