This guide has been elaborated in accordance with the methodology and technical requirements of the safeguarding of vulnerable drinking water resources in operation. Among these requirements, which were determined to specify the tasks of the target program submitted to Hungarian Government by KHVM (Ministry for Transport, Telecommunication and Water) in 1995, the countrywide assessment of the jeopardised, contaminated, damaged areas and the potential and existing pollution sources is of especial importance. An essential tool to further these tasks is remote sensing (taking and processing aerial photos, satellite photos), the effective use of which requires specific knowledge.
Remote sensing methods are primarily used in the diagnostic phases of the protection procedure of drinking water resources, but they can serve as a basis for the planning and preparation of the safeguarding phase, f. e. in the course of the designation of the hydrogeological protection zones, or later as a part of the monitoring and controlling network.
The assessment of the pollution sources damaging drinking water resources and the geological medium is a complex task with wide-ranging goals, and requiring high responsibility. The exploration of damage serves primarily the purpose of planning operative measures aimed at safeguarding and remediation, further it helps to ground and obtain an objective picture of the current status. There is also great demand on the positioning of potential pollution sources, thus serving the detection of hitherto unknown, but existing pollution. Further it enables the determination and tracing of general trends and their changes thus promoting the preparatory tasks laid down in the different pieces of legislation and increasing the efficiency of supervision by expert authorities.
What makes the remote sensing assessment of pollution sources complex is the connection of several data sources that requires the harmonization of tasks having very different methodologies. The main steps of the assessment are: collection of already existing information, evaluation of remote sensing – mainly aerial – photos, field visits, compilation of results in a database and evaluation.
This short methodological description puts the emphasis on those parts of the safeguarding-procedure of drinking water resources that are connected to remote sensing, in particular to the evaluation of aerial photos. This is a kind of thematic interpretation activity having all significant and general characteristics and processing phases of the remote sensing evaluation method, and all advantages of resulting from its application, in particular the improvement of the effectiveness and the acceleration of the thematic activity, and the close relation to representations, data processing and visualisations in maps.
Remote sensing methods are a product, their improvement a consequence of the technical development of the 20th century. The most precise definition of remote sensing is the following: remote sensing is a branch of science dealing with data collection and measurement of surface objects and phenomenons by using recording devices in no direct contact to those. Beyond data collection the expression covers also their evaluation.
Undoubtedly it was military utilisation that induced and determined the direct needs of development: on one hand there was a demand on topographic maps showing the exact locations of the own and the enemy’s territory, on the other military intelligence was in need of a tool for collecting important information. The problem was solved by the union of photography and a new, futuristic tool, the aeroplane. The development of several new fields of research, in particular the interdisciplinary application of space research, microelectronics and computer technologies, provided the frame for the broadening aspects and new possibilities of remote sensing, for the development of simple photo interpretation to remote sensing systems.
Till now there are two main groups of remote sensing applications: topographic mapping for civil and military purposes (photogrammetry) and thematic – f. e. earth science, meteorological, agricultural, hydrological, environmental management, etc. - information collection (interpretation). The letter combines rather different fields of sciences: f. e. methods used in archaeology and methods for the determination of the surface distribution of elements and chemical materials. The development of remote sensing methods is still in progress – it is only the beginning of its improvement into a wide spreading research method we are witnessing. Therefore this handbook describes the basic and standard remote sensing methods and gives only references to concrete solutions elaborated for special problems.