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Kolditz O.,Helmholtz Center for Environmental Research | Bauer S.,University of Kiel | Bilke L.,Helmholtz Center for Environmental Research | Bottcher N.,TU Dresden | And 22 more authors.
Environmental Earth Sciences | Year: 2012

In this paper we describe the OpenGeoSys (OGS) project, which is a scientific open-source initiative for numerical simulation of thermo-hydro-mechanical-chemical processes in porous media. The basic concept is to provide a flexible numerical framework (using primarily the Finite Element Method (FEM)) for solving multifield problems in porous and fractured media for applications in geoscience and hydrology. To this purpose OGS is based on an object-oriented FEM concept including a broad spectrum of interfaces for pre- and postprocessing. The OGS idea has been in development since the mid-eighties. We provide a short historical note about the continuous process of concept and software development having evolved through Fortran, C, and C++ implementations. The idea behind OGS is to provide an open platform to the community, outfitted with professional software-engineering tools such as platform-independent compiling and automated benchmarking. A comprehensive benchmarking book has been prepared for publication. Benchmarking has been proven to be a valuable tool for cooperation between different developer teams, for example, for code comparison and validation purposes (DEVOVALEX and CO 2 BENCH projects). On one hand, object-orientation (OO) provides a suitable framework for distributed code development; however, the parallelization of OO codes still lacks efficiency. High-performance-computing efficiency of OO codes is subject to future research. © 2012 Springer-Verlag.

Chen C.,Helmholtz Center for Environmental Research | Sun F.,Beijing Hydrological Center | Kolditz O.,Helmholtz Center for Environmental Research | Kolditz O.,TU Dresden
Environmental Earth Sciences | Year: 2015

This paper presents the design and integration of a GIS-based data model for the regional hydrologic simulation in the Meijiang watershed, China. Hydrologic systems (HS) require integration of data and models simulating different processes. Here, an object-oriented approach using Unified Modeling Language (UML) is introduced, which supports the development of GIS-based Geodatabase model—GeoHydro/DataBase (GH/DB). Spatial data, such as basins, stream network, and observation stations are stored in the feature classes. The time series and their attributes are included in the tables. Relationship classes are used to link associated objects. The new development within the scientific program OpenGeoSys (OGS) is the integration of GH/DB into the numerical simulations. The graphical user interface is implemented for the pre- and post-processing of the simulation. As for the case study, a regional hydrologic model is developed in the Meijiang watershed area for the understanding of water infiltration from surface into groundwater via soil layer with various time scales. The integration of databases and modeling tool represents the comprehensive hydrosystems and thus it is a useful tool to understand the different processes and interactions between the related hydrological compartments. © 2015, Springer-Verlag Berlin Heidelberg.

Sun F.,Beijing Hydrological Center | Sun F.,Helmholtz Center for Environmental Research | Shao H.,Helmholtz Center for Environmental Research | Wang W.,Helmholtz Center for Environmental Research | And 6 more authors.
Environmental Earth Sciences | Year: 2012

Since the 1980s, high-nitrate concentration in one of the groundwater sampling wells at the Nankou site, northwest of the Beijing Plain, has become a major concern for the local water authority. In a previous study (Sun et al. in Environ Earth Sci 64(5):1323-1333, 2011), a hydrogeological structural model was developed based on the borehole logs of this area and the steady, as well as transient groundwater-flow models, were calibrated using the measured hydraulic heads. In this paper, the potential pollution sources in this area are investigated. The chemical analysis of the groundwater is also presented. The results demonstrate that the most likely pollution source is the untreated wastewater discharge from a nearby fertilizer factory. Furthermore, a mass transport model is developed to reproduce the nitrate transport process in the aquifer at the Nankou site under different pollution sources, i. e., a fertilizer factory, river with wastewater and an agriculture field. The combined effects of the river and agriculture fields present a better understanding of the nitrate transport in the local aquifer. In addition, a pumping scenario is designed to clean up the current nitrate concentration. The pumping rate and the well location are first estimated with 2-D analytical solutions of the type curves method. Then a 3-D numerical model is used to calculate the nitrate-concentration changes after the pumping activities start. In the downstream direction of the regional groundwater flow, three pumping wells are set up for the clean-up strategy. The calculated pumping rate in each well is about 1,500 m 3/day. After 1 year, the nitrate concentration in the observation well recedes to 68 mg/l from the initial value of 72. 9 mg/l, and it will be lower than the limitation value (20 mg/l) after 5,400 days of groundwater extraction. The data assessment and clean-up scenarios reported in this paper are fundamental for the contaminated aquifer management in the future. © 2012 Springer-Verlag.

Sun F.,Helmholtz Center for Environmental Research | Sun F.,TU Dresden | Shao H.,Helmholtz Center for Environmental Research | Kalbacher T.,Helmholtz Center for Environmental Research | And 5 more authors.
Environmental Earth Sciences | Year: 2011

Water shortage and groundwater pollution have become two primary environmental concerns to Beijing since the 1990s. The local aquifers, as the dominant sources for domestic and agricultural water supply, are depleting due to groundwater abstraction and continuous drought in recent years with rapid urbanization and increasing water consumption. Therefore, understanding the hydrogeological system is fundamental for a sustainable water resources management. In this article, the numerical analysis of a 3-D regional groundwater flow model for the Nankou area is presented. The hydrogeological system is reproduced according to sparsely distributed boreholes data. The numerical analysis is carried out using the scientific software OpenGeoSys, which is based on the finite element method. The model calibration and sensitivity analysis are accomplished with inverse methods by applying a model independent parameter estimation system (PEST). The results of the calibrated model show reasonable agreements with observed water levels. The transient groundwater flow simulations reflect the observed drawdown of the last 9 years and show the formation of a depression cone in an intensively pumped area. © 2011 Springer-Verlag.

Sun F.,Beijing Hydrological Center | Yang Z.,Beijing Hydrological Center | Huang Z.,Beijing Hydrological Center
Water Resources Management | Year: 2014

Since the reform and opening-up in 1978, the city of Beijing as the capital of China has been going through a rapid urbanization. Water as the public, fundamental and strategic resources for the social and economic development as well as the survival basis of human and surroundings, is constrained to the urbanization of Beijing. In order to solve the hydrological challenges by urbanization, as the municipal water information service, Beijing Hydrological Center (BHC) is currently focusing on the safe water supply based on the mega-city hydrological development concept and making efforts to deal with new hydrological problems caused by the rapid urbanization. After years of study on theories and practices, the solutions to intense water scarcity, such as new well fields development, South-North water diversion, water resource and quality monitoring networks improvement, reclaimed water usage and so on, have provided strong support for Beijing turning into an international city. In this paper, the current water problems of Beijing are described in details on water shortage, water quality deterioration, drinking water safety and problems concerning water drainage system and flood control. The experiences of hydrometric, water quality and groundwater monitoring networks are provided as measures for water resources management. Additionally, the previous and current research work which provides technical and scientific support for decision-making of water resources management in Beijing is discussed in this paper. © Springer Science+Business

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