开采条件下的地下水溶质运移规律的研究——以山东济宁漏斗区为例

数值模拟方法是评价地下水资源、模拟地下水水流和溶质运移的主要方法和手段之一。本次研究应用Visual MODFLOW建立了研究区地下水三维水流及溶质运移模型,并应用其中的MODPATH模块模拟了地下水中水质点的运移轨迹,分析了由于过量开采而形成地下水水位降落漏斗后,研究区地下水溶质的运移规律,提出了控制和改善地下水水质的方法。     

Modelling qualitative and quantitative parameters of groundwater using a new wavelet conjunction heuristic method: wavelet extreme learning machine versus wavelet neural networks

In recent years, as a result of climate change as well as rainfall reduction in arid and semi‐arid regions, modelling qualitative and quantitative parameters belonging to aquifers has become crucially important. In Iran, as aquifers are treated as the most commonly used drinking water resources, modelling their qualitative and quantitative parameters is enormously important. In this paper, for the first time, values of salinity, total dissolved solids (TDS), groundwater level (GWL) and electrical conductivity (EC) of the Arak Plain, located in Markazi Province, Iran, are simulated by means of four modern artificial intelligence models including extreme learning machine (ELM), wavelet extreme learning machine (WELM), online sequential extreme learning machine (OSELM) and wavelet online sequential extreme learning machine (WOSELM) as well as the MODFLOW software for a 15‐year period monthly. To develop the hybrid artificial intelligence models, the wavelet is employed. First, the effective lags in estimating the qualitative and quantitative parameters of the groundwater are identified using the autocorrelation function (ACF) and the partial autocorrelation function (PACF) analysis. After that, four different models are developed by the selected input combinations and also the ACF and the PACF in the form of different lags for each of ELM, WAELM, OSELM and WOSELM methods. Then, the superior models in simulating the groundwater qualitative and qualitative parameters are detected by conducting a sensitivity analysis. To forecast the electrical conductivity (EC) by the best WOSELM model, the values of the Nash–Sutcliffe efficiency coefficient (NSC), Mean Absolute Error (MAE) and the scatter index (SI) are obtained to be 0.991, 18.005 and 4.28E‐03, respectively. In addition, the most effective lags in estimating these parameters are introduced. Subsequently, the results found by the MODFLOW model are compared with those of the artificial intelligence models and it is concluded that the latter are more accurate. For instance, the scatter index and Nash–Sutcliffe efficiency coefficient values calculated by WOSELM for TDS, respectively, are 5.34E‐03 and 0.991. Finally, an uncertainty analysis is conducted to evaluate the performance of different numerical models. For example, MODFLOW has an underestimated performance in simulating the salinity parameter.     

基于排水沟数值模型的工作面涌水量预测

采煤工作面的涌水量预测是煤矿生产过程中防治水工作开展的基础。通过对煤矿采空区水文地质条件概化研究,结合地下水数值模拟软件Visual MODFLOW中各类源汇项的水文地质模型的分析,提出采空区涌水在数值模拟过程中需将其概化为具有面状排水特征的排水沟边界条件,利用面状排水沟边界和局部水均衡分析,可计算得出工作面回采后采空区涌水量。利用本研究得出的采空区概化方法,对黄陇煤田亭南煤矿303工作面进行涌水量数值模拟预测,结果表明其方法合理可靠,流场刻画和水量预测结果均优于以往采用群孔抽水井的概化模型。     

Visual MODFLOW在郎家水源地供水预测中的应用

为确定郎家水源地20年内地下水水质、水量是否满足供水要求,构建了数学模型并运用Visual MODFLOW进行了模拟预测.模拟预测结果表明,所建立的数学模型能够反映真实的地下水状况,当浑河来水为Ⅲ类水质时,郎家水源地水质能够满足供水要求,但是应合理控制浑河来水,以保持水源地水质.     

Development of a cross-section based streamflow routing package for MODFLOW

It is challenging to simulate stream-aquifer interactions for the wide channel streams with the existing stream routing packages of MODFLOW. To overcome this limitation, a Cross-Section streamflow Routing (CSR) package is developed to simulate the streamflow and the interaction between streams and aquifers for the stream with a width larger than the MODFLOW grid size. In the CSR package, streams are divided into stream segments which are formed by two consecutive cross-sections. A cross-section is described by a number of streambed points that determine the geometry and hydraulic properties of the streambed. The stream water depth and streamflow at the cross-sections are related by the Single Channel method, the Divided Channel method, a data table or a power function. A rapid algorithm is used to compute the submerged area of the MODFLOW grid. The streambed conductance of a grid cell is computed based on its submerged area, streambed hydraulic conductivity and thickness. Stream-aquifer seepage is subsequently estimated as the product of the streambed conductance and difference between the stream stage and groundwater hydraulic head. Stream-aquifer seepage is treated as lateral flow in the streamflow routing computation with the Muskingum-Cunge method or mass conservation method. A hypothetical problem is established to test the capabilities of the CSR package with steady- and transient-state models. The results compare favorably with the SFR2 package and the HEC-RAS model. However, significant difference in flood wave attenuation is observed between the CSR package and the SFR2 package. It proves that the CSR package is capable of simulating the variation of stream-aquifer interactions in both space and time efficiently. The CSR package represents a certain improvement over previous MODFLOW streamflow packages by providing the efficient cross-section based computation and the unique capability of simulating streambed heterogeneity in longitudinal and transverse directions.     

A model of seepage field in the tailings dam considering the chemical clogging process

The radial collector well, an important water drainage construction, has been widely applied to the tailings dam. Chemical clogging frequently occurs around the vertical shaft in radial collector well due to enough dissolved oxygen and some heavy metals in groundwater flow of tailings dam. Considering the contribution of water discharge from both vertical shaft and horizontal screen laterals and chemical clogging occurring around vertical shaft well, a new model was developed on the basis of Multi-Node Well (MNW2) package of MODFLOW. Moreover, two cases were calculated by the newly developed model. The results indicate that the model considering chemical clogging occurring around the vertical shaft well is reasonable. Owing to the decrease in hydraulic conductivity caused by chemical clogging, the groundwater level in dam body increases constantly and water discharge of radial collector well declines by 10-15%. For ordinary vertical well, it decreases by 30%. Therefore, chemical clogging occurring around radial collector well can arouse increases of groundwater level, and influence dambody safety.     

生态脆弱地区适宜节水强度研究

选择宁夏青铜峡引黄灌区为研究对象,根据确保既不发生盐渍化也不发生荒漠化控制地下水埋深的原则,运用MODFLOW软件,构建了研究区的地下水数值模拟模型.采用情景分析方法,在模拟9种节水灌溉方案地下水埋深的生态适宜性基础上,给出了研究区适宜节水强度推荐方案.推荐方案对应的节水规模为全年引黄水量44.71亿m3,与2000年的60.29亿m3引水量相比,节水强度达到了25.8%,此为该灌区的适宜节水强度.     

干旱区微咸水灌溉的水-土环境效应预测研究

本文运用MODFLOW及SWAP模型对微咸水灌溉的水-土环境效应进行了预测.模型参数用2004年的观测资料进行率定,并用2002年的资料对模型的可靠性进行了检验.结果显示,淋洗灌溉定额条件下,不同作物的土壤盐分积累及作物相对减产率分别比正常灌溉定额条件下有所降低;微成水灌溉后土壤盐分的积累随着时间的推移呈递减趋势,大约在10年后盐分达到进出平衡状态,平衡时土壤的含盐量(0.126%)仍属于轻度盐渍土;抽取地下微咸水灌溉后,淋洗灌溉定额条件地下水位的下降幅度及含水层盐分的增加量都比正常灌溉定额条件下有所降低.采用微咸水灌溉,淋洗灌溉比正常灌溉对环境有利.     

INFLUENCE OF SEEPAGE FACE OBLIQUITY ON DISCHARGE OF GROUNDWATER AND ITS POLLUTANT INTO LAKE FROM A TYPICAL UNCONFINED AQUIFER

Lab experiment and mathematical simulation Modular three dimensional finite difference groundwater (MODFLOW) were performed in a soil tank to simulate the hydrogeochemical interaction between lake and typical unconfined aquifer. Results show that the velocity decreases exponentially with the transect distance on seepage face. The maximal velocity occurs at the top point of seepage face. The obliquity of seepage face has a great influence on the maximum and distribution of seepage velocity. With the increase of the obliquity of seepage face, the maximal velocity decreases quickly and the velocity distribution becomes much more even. Most of groundwater flow and pollutant flux discharges through a narrow portion near the top of seepage face. The flow and mass concentrated in the narrow portion increase with the decrease of the obliquity of seepage face. These will benefit to design a reasonable and economical scenario to manage lakeshore and to control the pollution of lake water near lakeshore.     

SWAT与Visual MODFLOW的耦合模型模拟应用与研究

在流域水循环原理基础上,利用改进的地表水SWAT模型与地下水Visual MODFLOW模型的耦合模型进行计算。借助ARCGIS技术实现SWAT模型和Visual MODFLOW模型模拟的最小计算单元水文响应单元(HRU)和网格(CELL)相互转化,并将其应用于石家庄市平山县地下水模拟计算。结果表明,改进的耦合模型能准确模拟和预测研究区的地下水变化以及地表水和地下水之间的相互作用。