Yali Cui

Geostatistical interpolation model selection based on ArcGIS and spatio-temporal variability analysis of groundwater level in piedmont plains, northwest China

Abstract Based on the geo-statistical theory and ArcGIS geo-statistical module, datas of 30 groundwater level observation wells were used to estimate the decline of groundwater level in Beijing piedmont. Seven different interpolation methods (inverse distance weighted interpolation, global polynomial interpolation, local polynomial interpolation, tension spline interpolation, ordinary Kriging interpolation, simple Kriging interpolation and universal Kriging interpolation) were used for interpolating groundwater level between 2001 and 2013. Cross-validation, absolute error and coefficient of determination (R2) was applied to evaluate the accuracy of different methods. The result shows that simple Kriging method gave the best fit. The analysis of spatial and temporal variability suggest that the nugget effects from 2001 to 2013 were increasing, which means the spatial correlation weakened gradually under the influence of human activities. The spatial variability in the middle areas of the alluvial–proluvial fan is relatively higher than area in top and bottom. Since the changes of the land use, groundwater level also has a temporal variation, the average decline rate of groundwater level between 2007 and 2013 increases compared with 2001–2006. Urban development and population growth cause over-exploitation of residential and industrial areas. The decline rate of the groundwater level in residential, industrial and river areas is relatively high, while the decreasing of farmland area and development of water-saving irrigation reduce the quantity of water using by agriculture and decline rate of groundwater level in agricultural area is not significant.

Applicability of artificial recharge of groundwater in the Yongding River alluvial fan in Beijing through numerical simulation

A groundwater transient flow model was developed to evaluate the applicability and effectiveness of artificial recharge scenarios in the middle-upper part of the Yongding River alluvial fan in Beijing. These scenarios were designed by taking into account different types of recharge facilities and their infiltration rate with the Middle Route Project for South-to-North Water Transfer (MRP) as the recharge water source. The simulation results suggest that: (1) the maximum amount of artificial recharge water, for scenario I, would be 127.42×106 m3 with surface infiltration facilities; and would be 243.48×106 m3 for scenario II with surface infiltration and recharge wells under the constraint of the upper limit of groundwater; (2) with preferred pattern of recharge facilities, groundwater levels in both optimized recharge scenarios would not exceed the upper limit within the given recharge period; and (3) implementation of the recharge scenarios would efficiently increase the aquifer replenishment and the groundwater budget will change from −54.11×106 to 70.89×104 and 183.36×104 m3, respectively. In addition, under these two scenarios groundwater level would rise up to 30 and 34 m, respectively, without increasing the amount of evaporation. The simulation results indicate that the proposed recharge scenarios are practically feasible, and artificial recharge can also contribute to an efficient recovery of groundwater storage in Beijing.

Study on the Estimation of Groundwater Withdrawals Based on Groundwater Flow Modeling and Its Application in the North China Plain

The amount of water withdrawn by wells is one of the quantitative variables that can be applied to estimate groundwater resources and further evaluate the human influence on groundwater systems. The accuracy for the calculation of the amount of water withdrawal significantly influences the regional groundwater resource evaluation and management. However, the decentralized groundwater pumping, inefficient management, measurement errors and uncertainties have resulted in considerable errors in the groundwater withdrawal estimation. In this study, to improve the estimation of the groundwater withdrawal, an innovative approach was proposed using an inversion method based on a regional groundwater flow numerical model, and this method was then applied in the North China Plain. The principle of the method was matching the simulated water levels with the observation ones by adjusting the amount of groundwater withdrawal. In addition, uncertainty analysis of hydraulic conductivity and specific yield for the estimation of the groundwater withdrawal was conducted. By using the proposed inversion method, the estimated annual average groundwater withdrawal was approximately 24.92×109 m3 in the North China Plain from 2002 to 2008. The inversion method also significantly improved the simulation results for both hydrograph and the flow field. Results of the uncertainty analysis showed that the hydraulic conductivity was more sensitive to the inversion results than the specific yield.

Development and application of a regional land subsidence model for the plain of Tianjin

In this paper, a coupled numerical groundwater and land subsidence model was developed for the Tianjin Plain. The model was employed to investigate the groundwater resources and their changes over the last decade, and to further predict the changing patterns of the groundwater level and associated land subsidence in future. First, according to the regional hydrogeology, the simulation area was defined with an area of 10.6×103 km2, which was divided into six aquifer units. A coupled groundwater and land subsidence numerical model was built by using Modflow2005 and the land subsidence simulation module SUB (subsidence and aquifer-system compaction), in which the groundwater flow was modeled as three-dimensional unsteady flow and the land subsidence simulation was based on one-dimensional consolidation theory. The model was then calibrated by using the groundwater level contour lines, hydrographs, and land subsidence hydrographs over the period of 1998–2008. In addition, groundwater balance analysis of the simulation period indicated that under multi-year groundwater withdrawal condition the cross-flow recharge, compression release, and lateral boundary inflow contributed 44.43%, 32.14%, and 21.88% to the deep aquifer recharge, respectively. Finally, the model was applied to predict the changing patterns of the groundwater levels and the associated variations in land subsidence under the control of groundwater exploitation after implementation of the south-to-north water diversion project. The simulation results demonstrated that the groundwater level may gradually increase year by year with an decrease in the groundwater withdrawal; and the land in dominated land subsidence regions including the urban area, Dagang, Hangu, Jinghai, Wuqing, and Jinnan, may rebound at an average rate of 2–3 mm/a, and the land subsidence rate in the other regions may decrease.

Evolution of groundwater major components in the Hebei Plain: Evidences from 30-year monitoring data

Groundwater is the main water source in the Hebei Plain. Evolution of groundwater chemistry can not only provide scientific data for sustainable usage of groundwater resources, but also help us in better understanding hydrogeochemical processes in aquifers. Spatial distribution and temporal evolution were analyzed on basis of monitoring data between 1975 and 2005. Results showed that major components in groundwater had increasing trends since 1970s. Major components in shallow groundwater increased more than those in deep one. In shallow groundwater of piedmont alluvial fan-recharge zone, concentrations of Na+, Ca2+, SO42− had great increasing trends, while other major components increased by less than 30%. There were great increasing trends in Na+, Cl−, SO42− concentrations in deep groundwater of central alluvial plain-intermediate zone, while other major components increased by no more than 20%. Deep groundwater from coast plain-discharge zone and piedmont alluvial fan-recharge zone showed no significant variations in major ion concentrations. In shallow groundwater, dissolution, evaporation and human activities played a major role in the increase in major components. However, groundwater mixture resulting from deep groundwater exploitation was believed to be the major factors for the increases in major components in deep groundwater of central alluvial plain-intermediate zone.

Groundwater circulation and hydrogeochemical evolution in Nomhon of Qaidam Basin, northwest China

In this study, analysis of hydrogeological conditions, as well as hydrochemistry and isotopic tools were used to get an insight into the processes controlling mineralization, recharge conditions, and flow pattern of groundwater in a typical arid alluvial-lacustrine plain in Qaidam Basin, northwest China. Analysis of the dissolved constituents reveals that groundwater evolves from fresh water (TDS =300–1000 mg/l) to saline water (TDS ≥5000 mg/l) along the flow paths, with the water type transiting from HCO 3⋅Cl–Na ⋅Mg to HCO 3⋅Cl–Na, and eventually to Cl–Na. Groundwater chemical evolution is mainly controlled by water–rock interaction and the evaporation–crystallization process. Deuterium and oxygen-18 isotopes in groundwater samples indicate that the recharge of groundwater is happened by meteoric water and glacier melt-water in the Kunlun Mountains, and in three different recharge conditions. Groundwater ages, estimated by the radiogenic (3H and 14C) isotope data, range from present to Holocene (∼28 ka). Based on groundwater residence time, hydrogeochemical characteristics, field investigation, and geological structure distribution, a conceptual groundwater flow pattern affected by uplift structure is proposed, indicating that shallow phreatic water is blocked by the uplift structure and the flow direction is turned to the northwest, while high pressure artesian water is formed in the confined aquifers at the axis of the uplift structure.

Natural and anthropogenic factors affecting the shallow groundwater quality in a typical irrigation area with reclaimed water, North China Plain

In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO3 type in grass land to Ca·Na-Cl (+NO3) type and Na (Ca)-Cl (+NO3+SO4) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO3) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area.

Design of an index system for deep groundwater management efficiency evaluation: A case study in Tianjin City, China

An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators (law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.

Numerical Simulation for Impacts of Mountainous Tunnel Drainage on Groundwater Environment

Mountainous tunnel drainage can cause various negative impacts on the groundwater environment and human life; as a result, it is necessary that the drainage is quantitatively estimated and minimized during the construction period. In this study, a numerical model was conducted to predict the influences of mountainous tunnel drainage on the groundwater environment in northern China. The results show that the drainage would change the groundwater flow field and form drawdown funnels; however, it would not cause regional groundwater drawdown. Besides, the discharge amount of springs was also affected by the tunnel drainage, and the maximum reducing amount was up to 25%. The storage resources of the aquifers were decreased under the effect of tunnel drainage. All negative influences could be gradually eliminated after the strong drainage. This research can provide effective methods to measure and decrease the impacts of tunnel drainage.

Optimization of groundwater artificial recharge systems using a genetic algorithm: a case study in Beijing, China

An optimization approach is used for the operation of groundwater artificial recharge systems in an alluvial fan in Beijing, China. The optimization model incorporates a transient groundwater flow model, which allows for simulation of the groundwater response to artificial recharge. The facilities’ operation with regard to recharge rates is formulated as a nonlinear programming problem to maximize the volume of surface water recharged into the aquifers under specific constraints. This optimization problem is solved by the parallel genetic algorithm (PGA) based on OpenMP, which could substantially reduce the computation time. To solve the PGA with constraints, the multiplicative penalty method is applied. In addition, the facilities’ locations are implicitly determined on the basis of the results of the recharge-rate optimizations. Two scenarios are optimized and the optimal results indicate that the amount of water recharged into the aquifers will increase without exceeding the upper limits of the groundwater levels. Optimal operation of this artificial recharge system can also contribute to the more effective recovery of the groundwater storage capacity.RésuméUne approche d’optimisation est utilisée pour le fonctionnement de systèmes de recharge artificielle d’eaux souterraines dans le delta alluvial à Pékin, Chine. Le modèle d’optimisation intègre un modèle d’écoulement d’eaux souterraines en régime transitoire, qui permet la simulation de la réponse des eaux souterraines à la recharge artificielle. Le fonctionnement des installations en ce qui concerne les taux de recharge est formulé comme un problème de programmation non linéaire afin de maximiser le volume d’eau de surface utilisée pour recharger les aquifères sous des contraintes spécifiques. Ce problème d’optimisation est résolu à l’aide d’un algorithme génétique parallélisé (AGP) basé sur OpenMP, qui permet de réduire de manière significative le temps de calcul. Pour résoudre l’AGP avec des contraintes, la méthode des pénalités multiplicatives est appliquée. De plus, les localisations des installations sont déterminées de manière implicite sur la base des résultats des optimisations du taux de recharge. Deux scénarios sont optimisés et les résultats optimaux indiquent que la quantité d’eau utilisée pour la recharge des aquifères va augmenter sans dépasser les limites supérieures des niveaux piézométriques. Un fonctionnement optimal d’un système de recharge artificielle peut également contribuer à la récupération plus efficace de la capacité de stockage des eaux souterraines.ResumenSe utiliza un enfoque de optimización para la operación de sistemas de recarga artificial de agua subterránea en un abanico aluvial en Beijing, China. El modelo de optimización incorpora un modelo de flujo transitorio de agua subterránea, que permite la simulación de la respuesta del agua subterránea a la recarga artificial. La operación de las instalaciones con respecto a las tasas de recarga se formula como un problema de programación no lineal para maximizar el volumen de agua superficial recargada en los acuíferos bajo restricciones específicas. Este problema de optimización se resuelve con el algoritmo genético paralelo (PGA) basado en OpenMP, que podría reducir sustancialmente el tiempo de cálculo. Para resolver el PGA con restricciones, se aplica el método de penalización multiplicativa. Además, las ubicaciones de las instalaciones se determinan implícitamente sobre la base de los resultados de las optimizaciones de la tasa de recarga. Se optimizan dos escenarios y los resultados óptimos indican que la cantidad de agua recargada en los acuíferos aumentará sin exceder los límites superiores de los niveles de agua subterránea. La operación óptima de este sistema de recarga artificial también puede contribuir a la recuperación más efectiva de la capacidad de almacenamiento de agua subterránea.摘要利用一种智能优化算法开展了地下水人工补给系统的管理研究,该人工补给系统位于中国北京的一个冲洪积扇。优化模型嵌入了一个非稳定地下水流模型,用来模拟地下水对人工补给的响应。对人工补给设施回灌速率的管理概化为一个非线性规划问题,规划目标是最大化人工补给水量,并满足一定限定条件的约束。优化模型由基于OpenMP的并行遗传算法(PGA)求解,这种求解方法可以大幅度的减少计算时间。采用罚函数方法解决遗传算法中的限定条件问题。另外,根据补给量的优化结果,人工回补设施的位置也可以间接的确定。两种方案的优化结果表明,在不违反限高水位约束条件下,人工补给水量会一定程度上增加。同时,地下水人工补给系统的优化管理可以有效促进地下水储量的恢复。ResumoA otimização na operação de sistemas de recarga artificial de águas subterrâneas em um leque aluvial em Pequim, na China, é abordada. O modelo de otimização incorpora um modelo de fluxo subterrâneo transiente, que permite a simulação da resposta das águas subterrâneas à recarga artificial. A operação das instalações, no que diz respeito às taxas de recarga, é formulada como um problema de programação não-linear para maximizar o volume de recarga dos aquíferos por águas superficiais sob restrições específicas. O problema de otimização é resolvido através de Algoritmo Genético Paralelo (AGP) baseado em OpenMP, o qual poderia reduzir substancialmente o custo computacional. Para resolver o AGP com restrições, é aplicado o método da penalidade multiplicativa. Além disso, as localizações das instalações são determinadas implicitamente com base nos resultados de otimização das taxas de recarga. Dois cenários são otimizados e os resultados ótimos indicam que a quantidade de recarga nos aquíferos irá aumentar sem exceder os limites superiores dos níveis d’água subterrâneos. A operação ótima deste sistema artificial pode também contribuir para uma recuperação mais efetiva da capacidade de armazenamento de água subterrânea.