基于小波随机耦合模型的三江平原年降水量预测

近些年来,由于水田面积迅速增加,导致三江平原井灌水稻区地下水位普遍下降,"吊泵"、局部超采现象时有发生.为解决上述问题,以853农场为例,对实测年降水资料进行差分和标准化处理,采用小波理论和随机水文学方法进行耦合分析,建立了年降小波随机耦合模型,精度检验结果表明,模型有效性和可靠性较高.该模型揭示了区域年降水量的时间变化规律,为853农场乃至整个三江平原充分利用天然降水、合理制定水稻灌溉制度以及地下水资源的恢复和可持续利用提供了科学依据.     

灰色时序组合模型及其在地下水埋深预测中的应用

地下水埋深的变化过程是一个复杂的非线性过程,这种具有复杂的非线性组合特征的序列,使用某一种模型进行预测,结果往往不理想.在分析了灰色GM(1,1)模型、灰色GM(1,1)周期性修正模型和时序AR(n)模型的优点和缺点基础上,提出了一种新的灰色时序组合预报模型.该方法利用了GM预测所需原始数据少、方法简单的优点,用周期修正方法反映其地下水位埋深周期性波动的特征,用AR(n)模型预报其地下水位埋深的随机变化.实例研究表明,这种方法方便简洁实用且预测结果接近于实际观测值,为其它地区的地下水位埋深和相关时间序列的分析研究提供参考与借鉴作用.     

基于混沌粒子群优化算法的灰色GM(1,1)模型在地下水埋深预测中的应用

将混沌优化算法与粒子群优化算法相结合,形成新的混沌粒子群优化算法.利用混沌运动的遍历性,避免陷入局部最优.同时,粒子群算法能加快混沌优化算法的收敛速度,使搜索效率得到提高.用混沌粒子群优化算法优化灰色GM(1,1)模型中的参数,通过横向和纵向比较,优化效果良好,模型预测精度得到了提高.运用该模型对三江平原地下水埋深进行动态预测,预测结果可为有关决策部门提供参考.     

地下水脆弱性风险预警和评估的区间三角模糊多属性决策模型

应用基于逼近理想解排序法的区间三角模糊多属性决策模型,对三江平原六大分区地下水脆弱性进行了风险预警和评估.评估结果与前人吻合,可为有关决策部门采取相应降低环境风险的措施提供参考.实例验证表明,模型具有更高的计算精度和更好的评价效果,为有关环境风险决策部门对地下水风险预警和评估提供了新的思路和方法.     

小波神经网络模型预测二氧化碳+水溶液体系界面张力

二氧化碳+水溶液体系界面张力(IFT)是影响地层中气水两相运移特性的重要参数之一,对二氧化碳捕集、埋存至关重要.为了快速准确地确定二氧化碳+水溶液体系IFT,对已有IFT实验结果进行了统计整理,得到了1 677组样本数据,考虑了压力,温度,气体中甲烷、氮气含量,水溶液中一价阳离子(Na+,K+)浓度、二价阳离子(Ca2+,Mg2+)浓度6个因素对IFT的影响,建立了小波神经网络（WNN）预测模型对二氧化碳+水溶液体系IFT进行预测.模拟结果表明,随机选取839组数据作为训练集样本,得到的小波神经网络结构为6-16-1,该模型预测IFT的平均绝对误差(M_MAE)、平均相对误差(M_MARE)、方差(M_MSE)和相关度(R2)分别为1.23 mN/m,3.30%,2.30 mN2/m2,0.988.与最新提出的多元拟合模型和BP神经网络模型对比结果表明,小波神经网络模型预测精度最高.     

地下水与社会经济的协调发展分析模型及其应用

在我国北方水资源短缺的许多地区,发展用水主要是靠加大地下水超采量来维持的,即通过牺牲后备资源和生态环境,地下水资源对国民经济发展做出了重要贡献.但随着地下水资源的枯竭,可能对区域社会经济带来一定影响.为评价这种影响,提出了一个协调发展模型,简单实用,能够反映客观实际.并在海河流域的典型区域进行了实际应用,结果表明许多地区的地下水环境状况相当不容乐观,在发展经济的同时,也应当注意生态环境的保护.     

基于Kriging模型和提升小波变换的随机模型修正北大核心CSCD

为提高随机模型修正效率,减小计算量,提出了一种基于Kriging模型和提升小波变换的随机模型修正方法.首先,对加速度频响函数进行提升小波变换,提取第5层近似系数代替原频响函数.其次,采用拉丁超立方抽样抽取待修正样本,将其作为Kriging模型的输入,对应的近似系数作为输出,构建Kriging模型.提出了一种引入莱维飞行(Lévy flight)的蝴蝶优化算法(LBOA),并将其应用于Kriging模型相关参数的寻优中,提高Kriging模型的精度.最后,以最小化Wasserstein距离为目标,通过鲸鱼优化算法求解待修正参数的均值.测试函数结果表明,LBOA在寻优能力、收敛精度和稳定性等方面有了很大的提升.数值算例的修正误差均低于0.4%,验证了所提模型修正方法具有较高的修正精度和效率.     

矩形边界越流承压含水层中非完整井稳定流解析解

针对矩形边界越流承压含水层中非完整井抽水引起的复杂地下水流动问题,建立了直角坐标系下越流承压含水层非完整井稳定流数学模型.通过对地下水流动计算模型的有限Fourier变换和有限Fourier变换域降深函数的逆变换,提出了不同类型边界条件下越流承压含水层非完整井三维稳定流降深解析解.在验证降深解析解正确性的基础上,通过降深解析解计算精度的分析,并结合非完整井抽水条件下含水层地下水流动特性,给出了降深解析解满足计算精度要求的计算项数取值.探讨了含水层正交各向异性、抽水井完整性、井位布置等因素对含水层降深和地下水流动的影响规律,并利用工程案例阐明了降深解析解的工程适用性.     

带有随机设计的非参数回归模型的异方差小波检验

该文讨论了带有随机设计的非参数回归模型的异方差小波检验. 首先给出了回归模型的条件方差函数的经验小波系数, 然后证明了它们是渐近独立和正态的. 基于 Fan (1996) 的方法, 构造了异方差检验统计量.最后通过数值模拟,作者检验了该文所提出的方法的有效性.模拟结果表明该文所提出的检验方法在水平和功效方面表现良好.     

基于MCMC的SV模型分钟高频股指波动率研究

利用沪深300股指2018年11月5日-2018年11月12日1分钟数据,基于马尔可夫蒙特卡罗(MCMC)模拟的贝叶斯方法,采用随机波动模型(SV)对我国股市分钟高频数据波动性进行了实证研究,并利用DIC准则进行模型拟合比较.结果表明,沪深300股指收益率序列具有尖峰,厚尾,聚集性等特征,且随机波动模型对于1分钟高频数据的拟合效果优于5分钟数据,标准随机波动模(SV-N)更适合1分钟高频数据.     

孔洞裂隙水二维流数值模拟的广义差分法

研究区地下水主要为玄武岩类孔洞裂隙水,水文地质模型概化为各向异性非均质,根据第四系玄武岩承压含水层中地下水的分布特征及流动规律,建立二维非稳定流数学模型,采用广义差分法对其求解.通过研究区井群对模型进行识别、验证.结果表明,计算模型与实际水文地质条件比较接近;计算水位与实测水位相吻合.为城市地下水可持续性管理提供科学理论依据.     

CONTROLLING GROUNDWATER QUALITY WITH ENDOGENOUS REGULATORY INSTRUMENTS

ABSTRACT. This research presents a competitive dynamic model that endogenously evaluates the economics of regulatory tax-policy options. This model is then applied to an irrigated corn production area west of Kearney, Nebraska, where the average groundwater contamination level from nitrates is reported to be 8.7 parts per million (ppm). Results indicate that no regulatory policies are necessary for maintaining potable groundwater quality with either a surge-flow irrigation system or a sprinkler irrigation system. In areas where conventional furrow irrigation technology is being used, higher net economic benefits result from the adoption of a variable-tax on nitrogen fertilizer use, followed by a constant-unit tax and a pollution tax.     

三江平原湿地非使用价值支付意愿的影响因素

为了更好地保护三江平原湿地生态系统,应用条件价值评估法(CVM)这一当前国际上流行的生态系统经济价值评价方法,对三江平原湿地的非使用价值进行评价.研究中采用实地调研的方式,进行支付意愿问卷调查,共发放支付卡式CVM问卷552份,回收有效问卷513份.得出三江平原湿地2007年人均支付意愿为71.66元/年.通过对问卷数据的描述性统计,得到支付意愿的分布情况和在各单一因素影响下的变化规律.用主成分分析简化影响因素,运用有序多分类Logit模型,得到在所有影响因素中,个人平均年收入、个人受教育程度以及个人环保态度是影响受访者对三江平原湿地非使用价值支付意愿的主要因素.研究结论使得三江平原湿地开发和保护价值比较成为可能,为政府制定相关政策提供理论基础与科学依据.     

Hydrogeochemical modeling for groundwater management in arid and semiarid regions using MODFLOW and MT3DMS: A case study of the Jeffara of Medenine coastal aquifer,South-Eastern Tunisia

The study of water quality and the quantification of reserves and their variations according to natural and anthropogenic forcing is necessary to establish an adequate management plan for groundwater resources. For this purpose, a modeling approach is a useful tool that allows, after calibration phase and verification of simulation, and under different scenarios of forcing and operational changes, to estimate and control the groundwater quantity and quality. The main objective of this study is to collect all available data in a model that simulates the Jeffara of Medenine coastal aquifer system functioning. To achieve this goal, a conceptual model was constructed based on previous studies and hydrogeological investigations. The regional groundwater numerical flow model for the Jeffara aquifer was developed using MODFLOW working under steady-state and transient conditions. Groundwater elevations measured from the piezometric wells distributed throughout the study area in 1973 were selected as the target water levels for steady state (head) model calibration. A transient simulation was undertaken for the 42 years from 1973 to 2015. The historical transient model calibration was satisfactory, consistent with the continuous piezometric decline in response to the increase in groundwater abstraction. The developed numerical model was used to study the system's behavior over the next 35 years under various constraints. Two scenarios for potential groundwater extraction for the period 2015–2050 are presented. The predictive simulations show the effect of the increase of the exploitation on the piezometric levels. To study the phenomenon of salinization, which is one of the most severe and widespread groundwater contamination problems, especially in coastal regions, a solute transport model has been constructed by using MT3DMS software coupled with the groundwater flow model. The best calibration results are obtained when the connection with the overlying superficial aquifer is considered suggesting that groundwater contamination originates from this aquifer. Recommendations for water resource managers

• The results of this study show that Groundwater resources of Jeffara of Medenine coastal aquifer in Tunisia are under immense pressure from multiple stresses.
• The water resources manager must consider the impact of economic and demographic development in groundwater management to avoid the intrusion of saline water.
• The results obtained presented some reference information that can serve as a basis for water resources planning.
• The model runs to provide information that managers can use to regulate and adequately control the Jeffara of Medenine water resources.

     

Modeling Optimal Allocation of Deficit Irrigation: Application to Crop Production in Saudi Arabia

We develop an integrated dynamic programming—linear programming (LP) model to solve for optimal land exploitation for a given crop. The model applies deficit irrigation in order to increase the irrigated area at the expense of reducing the crop yield per unit area. The dynamic program guarantees that deficit irrigation is considered only when it is economically efficient. Moreover, it provides the best irrigation level for each growth stage of the crop, accounting for the varying impact of water stress overtime. The LP provides the best tradeoff between expanding the irrigated area and decreasing water share per hectare. The model objective is to maximize the total expected crop yield. The model is particularly applicable for regions suffering from irrigation water scarcity, such as Saudi Arabia. The implementation was made for crops in Al-Jouf Region, north of Saudi Arabia     

A decision tool for optimal irrigated crop planning and water resources sustainability

In the present study, the conjunctive use policies of surface and ground water resources are developed for minimizing water shortage in an irrigation district subject to constraints on groundwater withdrawals and crop planning capacities. An integrated soil water balance algorithm is coupled to a non-linear optimization model in order to carry out water allocation planning in complex deficit agricultural water resources systems based on an economic efficiency criterion. Various options of conjunctive use water resources along with current and proposed cropping patterns have been explored by Koohdasht Irrigation District (KID), a semi-arid region in I.R. Iran. The analysis provides various scenarios, which can help managers in decision-making for the optimum allocation plans of water resources within the irrigation area. The results reveal that the proposed model, as a decision tool for optimal irrigated crop planning and water resources sustainability, may be used for maximizing the overall net benefits and global water productivity of an irrigation district considering an allowable annual recharge of groundwater. Findings indicate the importance of the conjunctive water management modeling, which can be easily implemented and would enhance the overall benefits from cropping activities in the study area.     

A multi-objective optimal allocation model for irrigation water resources under multiple uncertainties

This paper proposed a multi-objective optimal water resources allocation model under multiple uncertainties. The proposed model integrated the chance-constrained programming, semi-infinite programming and integer programming into an interval linear programming. Then, the developed model is applied to irrigation water resources optimal allocation system in Minqin’s irrigation areas, Gansu Province, China. In this study, the irrigation areas’ economic benefits, social benefits and ecological benefits are regarded as the optimal objective functions. As a result, the optimal irrigation water resources allocation plans of different water types (surface water and groundwater) under different hydrological years (wet year, normal year and dry year) and probabilities are obtained. The proposed multi-objective model is unique by considering water-saving measures, irrigation water quality impact factors and the dynamic changes of groundwater exploitable quantity in the irrigation water resources optimal allocation system under uncertain environment. The obtained results are valuable for supporting the adjustment of the existing irrigation patterns and identify a desired water-allocation plan for irrigation under multiple uncertainties.     

奇异联络的残数和奇异截影的指数

本文主要分析了内蒙古河套灌区土壤盐碱化的特点;探讨了盐碱地治理的主要措施;指出在气候干燥,蒸发量大,灌溉水盐份高,用量多,排水少,地下水具有地质矿化源和水位浅以及土壤质地较砂等因素的影响下,河套灌区的土壤盐份具有积累快,年中变化大,含量高等特点。由于盐害最严重的时期是从春小麦播种到5月中旬,本文提出河套灌区盐碱地的治理应首先搞好合理灌水和完善排水;同时改进传统耕作方法,采用先进耕作技术和其他措施综合治理。但任何经济有效的措施的设计与实施都需通过对当地盐碱化过程的深入研究,建立关键时期(秋浇、结冻到化冻、春播)的土壤水盐运动模型,进行田间主体工程的定点试验。