An Internet-based Groundwater Information System

Transcription

1 1 An Internet-based Groundwater Information System Uwe Rueppel a, Udo F. Meissner a, Thomas Gutzke a, Gerrit Seewald b, Michael Petersen b a Institute for Numerical Methods and Informatics in Civil Engineering Darmstadt University of Technology, Petersenstr. 13, D Darmstadt, Germany b CIP Ingenieurgesellschaft mbh, Robert-Bosch-Str. 7, D Darmstadt, Germany The management of groundwater resources for the supply of German cities and suburban areas has become a matter of public interest during the last years. Negative headlines in the Rhein-Main-Area newspapers dealt with cracks in buildings as well as damaged woodlands and inundated agriculture areas as an effect of varying groundwater levels. The management of groundwater is a difficult and sensitive topic for all involved groups, especially the different water supply companies, the consultant engineers, the scientists and the governmental agencies. On initiative of the Darmstadt University of Technology, these groups co-operate on the development of a network-based information system for an efficient groundwater management. Therefore tools for collection, storage, evaluation and visualisation of groundwater-relevant information using network-based technologies have been analysed and implemented. The actual status of this project can be referred at: 1. Introduction The geographical borders of the area in which this project is located are given by hydrogeological boundary conditions: The river Main in the north, the river Neckar in the south, the river Rhein in the west and the mountain chain Odenwald and the Sprendlinger Horst in the east. The described area which is called Hessisches Ried has a size of about 1238 km 2 (fig. 1). In this area live about people in 36 cities and townships. The Hessisches Ried is a part of the Rheingraben, a 300 km long and about 35 to 40 km wide fosse. Because of its geological genesis the surface is very flat and the soil is predominated by gravel and sand. So this region is an extremly rich groundwater reservoir. Professor Research Assistant

2 2 Infiltration Facilities Wells Kliometers Figure 1: Project area and related water supply companies Due to the growing population and the rapid industrial development in the late sixties, the big cities in the Rhein-Main-area like Frankfurt discovered the Hessisches Ried as their groundwater reservoir. Many wells were built and huge amounts of water were pumped out of this area. The groundwater level sank dramatically in the early seventies.

3 3 Figure 2: Cracks in houses as an effect of low-level groundwater and settlement Cracks in houses as a consequence of settlements (fig. 2), dried out agricultural areas and damaged woodlands were the results. As an effect of these circumstances and by massive protests from the public, the quantity of the convey water was decreased. Furthermore, water-reduce-programs for the public were initiated and infiltration facilities which discharged Rhein-water into several areas of the Hessisches Ried were built. These corrective measures took effect and the groundwater level recovered (fig. 3). Figure 3: Development of the groundwater level, shown as a hydrograph of a groundwater gauging station

4 4 The fluctuations of the groundwater level in the following years were mostly a result of meteorological circumstances. Nonetheless the water consumption declined. Last spring the groundwater level was extremely high, so inundated agriculture areas and overflown basements were a result in many parts of the Hessisches Ried (fig. 4). Figure 4: Inundated Fields as a result of a high-state groundwater level 2. Demands on the Groundwater Information System (GWO) At present a holistic management of groundwater resources suffers from the large number of involved groups and their divergent interests on the one hand and a lack of essential information and the complexity of the geological system on the other. Various hydro-geological, climatic, water-economical, chemical and biological interrelations have to be taken into account. Thus, the traditional approaches in information retrieval and management, e.g. single reports in hardcopy form, isolated data maintenance and hardly automation which are characterised by a high staff and time expenditure, aren t sufficient. Necessary information have to be collected and processed currently. A complete, always actual and verified level of the groundwater is one of the most important aspects. For this purpose a widespread system of wells as well as groundwater and climate points of measurement was developed to guarantee a comprehensive groundwater check. The collected information have to be represented with regard to their master data and their quantity data. The master data itself consists of the actual system properties and historical development. Furthermore, the geological, legal and logical relationships have to be taken into account in one holistic data model. The described aspects of the data model have to be transferred in a relational database model, so that the variety of interrelations can be built up. Furthermore, the consistency of the information collected by different partners can be guaranteed. This consistent hydrogeological database is the base for the subsequent evaluation-, simulation- and visualisation-processes [3].

5 5 3. The GWO-System In order to manage the collection of the required information the developed groundwater information system consists of different network-based components. For the aggregation of time-dependant groundwater-relevant information, modern technologies of Mobile Computing (e.g. High-End-Notebooks and Personal Digital Assistants) have been analysed in order to provide an integrated approach in the management of large groundwater systems. The collection also requires a capable information exchange between enterprises and authorities, dealing with raw data as well as processed information (fig. 5). The water supply companies work on a replicated database (local database). The input of data is realised by using uniform frontends. Using this tool, data can be stored into the database for example by mobile computers, by logger or manually. The plausibility of the input data can be verified by various control mechanisms. Once the input data are checked, the local database can be synchronised with the server database [2]. Figure 5: Chart of the internet-based groundwater information system The aggregated information are stored within the described distributed hydrogeological database system. Any water supply company has got their own local database and each local database is a replicate of the central server database. The intervals of the synchronisation between the local and the server database can be started manually or using a pre-defined interval. The control layers of the web application assure that the access rights are correct and support the synchronisation process. The control layers also administrate the access rights of all the other groups, who are interested in the stored information. Be-

6 6 cause of the sensibility of the information, the control layers have to guarantee a specified access and view. For instance, the public has just the right to behold the public information. The water supply companies, the governmental agencies and related consultant engineers have extended rights to behold, change and evaluate the information. Particular workflows are implemented as for example the submission of monitoring reports from the water supply agencies to the governmental agencies each month. Furthermore, import and export tools have been accomplished to fill the server database with the existing data of the water supply companies. Figure 6: Graphical user interface of the map server Based on the server database, existing modeling and simulation systems have to be integrated. Traditionally these processes are linked together using the data export and import functionality of the system. Currently a middleware-based concept is analysed in order to obtain a distributed planning instrument for the determination and forecasting of interrelations in the groundwater cultivation. This combination of a present and large-scaled hydrogeological databases with modern planning and simulation programs leads to a holistic system. Furthermore it provides new possibilities in managing groundwater with regard to environmental protection for the water supply companies, the responsible engineers, the scientists and the governmental institutions [1]. For the creation of diagrams, i.e. hydrographs of groundwater gauging stations, several software tools have been analysed. It is possible to generate diagrams and reports by

7 7 preselection of the information and view them in the web browsers or by generating a PDF-document for archiving. The visualisation of geo-scientific databases in the internet, considering their geographic reference, is performed with an internet-based map server (fig. 6). According to the communication between the map server and the underlying geo-scientific database, it is necessary that the requested data can be filtered interactively in an internet browser using chronological and logical criteria. All stages of the groundwater management from the collection of the raw data to the evaluation, prognosis and visualisation of information are realized in an internet portal. In order to generate reports, actual technologies as e.g. XML in connection with XSL are used. The connection to the server database is realized with Active Server Pages (ASP) and the database connection ActiveX Data Objects (ADO). With regard to public use the security aspects within the described distributed system are of major importance. Therefore, security methods for the modelling of access rights in combination with digital signatures have been analysed and implemented in order to provide a secure data exchange and communication between the different partners in the network. 4. Conclusion For the holistic management of all required data the server database of the internet based groundwater information system was designed. Because of the use of modern Internet information technologies the groundwater-relevant data can be accessed in an actual digital form. Standardised tools for pre- and post-processes including interfaces for import and export enable a fast exchange of relevant information between the water supply companies, the enterprises, the governmental agencies and to the public. For these diverse communication relationships detailed access rights have been defined which offer a protection against unauthorized access of the geo-scientific data. Considering these access rights the internet based visualisation of spatial structures and processes, e.g. of plans with groundwater information in map servers, is a new method for decision support and network based co-operation in the area of groundwater monitoring [4].

8 8 REFERENCES 1. L. Laemmer, M. Burghardt, C. Bloemer, C. Koenig: Parallel Parameter Estimation in Groundwater Flow Models. Holz, P. (Hrsg.); Bechteler, W. (Hrsg.); Wang, S. (Hrsg.); Kawahara, M. (Hrsg.): 3rd International Conference on HydroScience and Engineering, (Advances in HydroScience and - Engineering), U. Meissner, J. Diaz, I. Schoenenborn, R. Krueger: Object-oriented Modelling of Three-dimensional Hydro-Geotechnical Systems. XI. Intern. Conf. on Computational Methods in Water Resources, Cancun, Mexico (p. 709 ff.). Aldama & Aparicio & Brebbia & Herrera & Gray & Pinder (edt.), Comp. Mechanics Publications, Southampton, Boston U. Meissner, J. Diaz: Groundwater Management using Hypermedia and WWW-Techniques. XII. Intern. Conf. on Computational Methods in Water Resources, Kreta, Greece (p. 1 ff.). Burganos & Karatzas & Payatakes & Brebbia & Gray & Pinder (edt.), Comp. Mechanics Publications, Southampton, Boston U. Rueppel, U. Meissner Co-operative Structural Engineering in Distributed Systems. Proceeding of the 8th International Conference on Computing in Civil & Building Engineering, S , Stanford University, USA 2000