By Natalia Kurakina, Saint Petersburg Electrotechnical University, Russia

A crucial aspect of environmental policy is to review and assess human impacts of all types. GIS plays an important role in achieving this task when monitoring and analyzing the adverse environmental impact on water bodies, such as lakes, rivers, and bays. For example, a GIS can facilitate an evaluation of pollution sources by generating reports and managing data about polluters, results of measurements, reference materials providing classification of hazardous groups, and concentrations of hazardous substances in a specific river or an entire aquatic system. A GIS can also provide the tools to identify the most hazardous contaminants with regard to ecological regulations and contribute to effective decision making to ensure that natural resources are preserved and utilized correctly.

Data translated into charts shows that the Neva River is polluted with petroleum products, nitrites, and iron salts.

Due to the advanced spatial visualization and analysis capabilities of GIS, researchers at Saint Petersburg Electrotechnical University (ETU) in Russia are able to map and study natural water bodies; their polluters; the source, location, and levels of polluting agents; and the content of the pollutants. Their analysis of natural water bodies and industrial enterprises provides the opportunity to predict the level of industrial impact and study various scenarios to make recommendations for rational use of natural water resources.

For the purpose of its water bodies study, ETU's GIS incorporates databases, models, calculation methods, and directives in the form of an integrated information medium for obtaining integrated data. This system design enables researchers to review and perform the following tasks:

• Assess water body quality.
• Review activity of water users.
• Rank water users by the degree of their impact on the environment.
• Evaluate environmental load on a water body taking into account a basin-based approach.
• Produce reports.

The GIS interface is designed by means of ArcView software with spatial and attribute data stored in a local geodatabase.

A Water Body of Investigation

The GIS-based monitoring system was established on part of northwest Russia's Neva River, located in the Kirovsky District of Leningrad Oblast. The Neva River is an integral part of the region's aquatic system, which also includes Onezhskoe Lake, the Svir River, Ladozhskoe Lake, Nevskaya Guba Bay, and the eastern part of Finsky Bay. This entire aquatic system is affected by an industrially developed area that serves as the main source of pollution. The comparative analysis of the values of some chemical parameters of water in Ladozhskoe Lake, Nevskaya Guba Bay, and a northeastern part of Finsky Bay clearly showed that the Neva River is subjected to the greatest load compared with the other water bodies in the aquatic system. The Neva River receives wastewater discharged from municipal wastewater treatment plants, untreated wastewater, and effluents coming from industrial and agricultural enterprises located near its banks.

Information Medium Assessment System

Data from the Neva River findings is stored in a GIS-based information medium assessment system, which is designed to perform hydrochemical analysis of water body quality to assess the adverse impact produced by humans and to set permissible levels of the ecological load on water resources. Its ArcGIS Desktop platform provides integration and use of the distributed information, while enabling users to process the data depending on which sphere (geographic or administrative) it relates to. The information medium consists of a topographic base arranged in the form of GIS layers, a model base of natural bodies and enterprises, databases with the results of monitoring, and analyzing activities and a regulatory framework.

The topographic base of the assessment system is intended for visualization of the results of investigation and spatial analysis. Each GIS layer contains a group of single-type components, such as rivers, lakes, roads, woods, and monitoring checkpoints. These components are arranged in separate folders.

Basis of Models: Natural Water Bodies and Polluters

Depending on their type (rivers, lakes, seas), water bodies are clustered into GIS layers, containing a geographic description of the object and its key characteristics. Smaller rivers are presented as polylines while bigger ones are described as polygonal objects. More sophisticated objects, such as big rivers, are divided into several sections so that one object has several records in the tables with parameters. The information is kept in two files: a graphic description of the object and midchannel areas with major hydrological characteristics (width, depth, and flow velocity).

Databases of ecological control keep data about monitoring stations and the results of measurements performed. The location of monitoring stations is in a shapefile, and the characteristics of the stations are presented in the attributive file, including the name of the station, to what authority it belongs, type of observation network, name of the water body, and other related data. The results of measurements are accumulated in the database in .dbf format and contain the date of measurement, code and name of the observation station, and values for each measured parameter.

Assessment of Water Quality and Industrial Loads

The ArcGIS software-based information medium assessment system enables its users to make analyses in time and space and assess the quality of a water body in different measuring points. For example, a report visualizes average annual values of pollutants in the checkpoints of the Neva River compared with the maximum permissible concentrations (MPC). Another report demonstrates that the river is polluted with petroleum products, nitrites, and iron salts. It is obvious from analyzing the data in each report that the content of harmful substances on the border of the Kirovsky District is higher than that at the river's head.

The tasks of industrial load assessment are to identify key critical substances, define major users who are responsible for these pollutants, and rank the water users in order to give recommendations for making managerial decisions.

To determine critical parameters in the measuring point, the user shall select in the database a number of measured parameters—the results of hydrochemical status control. For each substance from the selected list, it is necessary to calculate the impact coefficient (concentration compared to MPC value). The substances are ranked by the level of the impact. All the substances for which the impact coefficient is more than one are arranged into a group of critical parameters.

For each substance included in the list of critical indexes, the enterprises are identified that discharge this substance, among others, into a water body. Then the extent of the enterprise contribution to the pollution is to be determined. The identified critical water users are then grouped by the different harmful substances they produce. The impact degree of each water user is determined, and the enterprises are ranked by hazard degree of each substance. The results can then be presented in the form of tables and diagrams in an ArcGIS Desktop (ArcMap) interface.

About the Author

Natalia Kurakina is an associate professor in the Information System and Technology Department at Saint Petersburg Electrotechnical University, Russia. In addition to writing more than 90 subject-related papers, Kurakina has written a book titled Measurement System and GIS Technology.

More Information

For more information, contact Natalia Kurakina, St. Petersburg Electrotechnical University (e-mail: nikurakina@eltech.ru), or visit www.eltech.ru/science/unc_gis.