General considerations
3.5 Automated hydrological data processing in the U.S.S.R
3.5.1 General considerations
The need for hydrological data increases rapidly, concurrently with the development of the national economy. At the present time, the U.S.S.R. is devoting considerable resources for the improvement of existing hydrological information systems. This improvement is directed toward the increased use of automation of data collection and processing systems and includes the use of automatic sensors and devices which transfer data from the field stations to processing centres and prepares the data in a form suitable for computer com- putation and processing. This led to some changes in structure and funct ions of the existing hydrological information system.
3.5.2 Automated data processing
While manual data processing can be accomplished in a decentralized manner (at hydro- logical stations), under automation it seems advisable to concentrate data processing in a limited number of large centres in order to efficiently utilize the modern computing tech- niques being developed in the U.S.S.R.
The development of the technology and the techniques of automated hydrological data processing requires consideration of the following factors : (a) some hydrological observa- tions are made manually, and (b) all hydrological data fall into two kinds: operational data (forecasts) and hydrologic regime (data for long-term characteristics). The first type makes it necessary to develop methods of recording the observations directly on a medium suitable for direct transmission to the processing centre. This has led to the development of new documentation forms. The difference between the technology of operational data processing and that used for hydrologic regime data relates primarily to the transmission requirements.
Operational hydrologic data and other information from automated observation stations goes to the forecasting centres in the form of reports or telegraphic messages.
The data characterize streamflow regime (gauge heights, discharge, water temperature, etc.) and ice conditions at different stations for certain observation times. In winter the report contains snow-survey data added to the regular information. All these data repre- sent initial input for preparing and issuing hydrological forecasts and information reports for the analyses of current hydrologic conditions.
Information transferred by telegrams is encoded for computer processing. The com- puter decodes and reformats the information and then puts it on magnetic tape for storage. The computer processing programme enters the report in the computer memory and produces an operational forecast of the water supply. In addition, the computer programme checks on the accuracy of the data received from the observation stations.
Examples of systems adapied to diffeveni countries
The effectiveness of this programme used by the U.S.S.R. Hydrometeorological Centre is shown by its ability to handle from 2,000 to 3,000 telegraphic messages and reports received daily.
Hydrological regime information is also processed in the large regional and territorial centres, using ‘ Minsk-22’ or ‘ Minsk-32’ computers. The processing of these data follows the following procedures.
Hydrological stations record the observations on special magazines used for handling perforated (punched) tape. These tapes are sent to the processing centre, while the magazine remains at the station. Occasionally the punching is performed at the processing centres. In the latter case, the booklets containing the observational data are sent to the centres for processing. The processing centres automatically perform quality control checks on the data, process the initial data, and also make corrections to the incoming data. The centres print the streamflow or other observations in tabular form and process the data for storage in the computer. At the same time tables listing errors are printed.
The data tables together with the list of errors and the summary of background informa- tion are sent to the Territorial Centres and are used in the guidance of national economic organizations. If errors not picked up by the computer are found at the station or in the Regional Administration of the Hydrometeorological Service, the staff reports them to the processing centre, where the errors are corrected during the processing of the data for publication in the annual reports.
At the end of each year, the tables for annual reports of hydrological data are prepared at processing centres with the help of computers. The final editing and preparation for printing is done with the assistance of specialists of the Territorial Centres who know the peculiarities of the hydrology of the particular region.
In the planning of an automatic processing system for processing hydrologic data, the initial processing phase turned out to be the most difficult. Although computer programmes are available for the automatic processing of most of the observed items (the hydrological items of gauge heights, discharge, water temperature, sediment, and ice, as well as the meteorological items of precipitation, evaporation, air temperature, humidity, etc.), some items still require a certain amount of manual attention to complete the results. For example, at present, only some phases of computations of estimates for periods when normal methods of computation do not work are automated, but an improved programme is being developed. In this programme, certain information (such as depth, velocity, gauge height, thickness of ice) must be furnished. Analytical methods of calculation are used in the new programmes rather than the graphical methods widely used at present.
Analytical methods will not only allow automatic calculations of runoff, but will improve the quality of the results. Graphs of the results may be made with an automatic plotter which is part of the computer’s peripheral equipment.
3.5.3 Automatic computation of runoff
The sequence of operations for automatic computation of runoff is as follows.
First, a group of discharge measurements, made under open-water conditions, is assembled and an approximate stage-discharge-relation is calculated from them. If the necessary accuracy of fitting the measured points to the calculated rating is not satisfied, then a more careful analysis of the initial data is made. This analysis might consist of picking out flood periods or determining changes in the channel cross-section during the period. For this study, details of the discharge measurements would be used. As the result of this analysis, new groups of discharge measurements would be picked out, to group together those for specific periods of time or for periods when certain ranges in stage prevailed. Then an attempt would be made to subject the new groups of data to the same analyses. If this new analysis also did not achieve satisfactory results, it would be necessary to calculate the daily discharge values by a method of interpolation. When necessary,
extensions of stage-discharge ratings are made. W h e n the computations of daily discharges are completed, the results are listed in standard tables and the method of calculation, the ratings with their periods of use, and any corrections used, are also shown. If necessary, the ratings are plotted with the points of the discharge measurements and the derived curves. These plottings may be used by a specialist to determine the accuracy of the computer computations.
3.5.4 Data storage and publication
The system of automatic computation developed in the U.S.S.R. includes files of hydro- logical data recorded on media suitable for automatic input to electronic computers.
Creation of these files involved two different projects: (a) the storage of current infor- mation in machine-readable form, and (b) the conversion of older information into machine-readable form. The storage of current records in these files is a part of the regular processing of such current data. The results of the processing of current data are sorted and collected on magnetic tape with subsequent transfer to microfilm. The technique of storage of the data on microfilm and the arrangement of the data was developed in a manner to facilitate the solving of problems expected to be encountered in the future.
Data is stored in groups by time periods and by river basins. The data must be stored in such a manner that any statistical or engineering calculation may be performed on it and so that the information may be arranged for convenient user examination or for periodic or non-periodic publications.
Data for previous years which have already been processed and listed in publications are initially transferred to punched cards for microfilming and for statistical analysis.
This work has only just begun; data for only the most frequently used data has been punched. When the punching of all the back data is completed, some tens of millions of cards willhave to be punched. As such a project cannot be completed in a short time, priorities have been established involving the elements of observation, the type of data and the areas of coverage.
One of the main aims of the development of an automatic data-processing system must be the increased use of data to model the hydrologic environment as well as the develop- ment of new forms of generalization useful to the national economy.
Traditional information sources such as hydrological yearbooks and water-resource reference books include the data, subjected, as a rule, only to initial processing and contain only some long-term parameters (daily discharge, extreme events, etc.) describing the hydrological rCgime. That is why for better utilization of these data it is necessary to carry out in considerable detail conventional hydrological calculations (the establishment of extreme values, for example). The realization of computer storage banks will allow the further development and introduction of new methods of computation and analysis which will provide the hydrologic information required by the national economy. At the same time it is intended to make these data more useful, still more pertinent to the needs of the national economy. The development of the information system willbe realized gradually.
At the first stage of development it is advisable to keep the existing system of hydrological data yearbooks. However, in the future, the demands for published data will decrease and the computerized information system will supply the bulk of the data required by national organizations.
3.5.5 Conclusions
The above methods describe the use of automatic data processing in the U.S.S.R. con- cerned with the traditional methods of data collection (automatized and non-automatized).
However, as the processing system develops, the technical means (communication lines, computers, etc.) willallow the transmission and processing of new data such as the infor-
Examples of systems adapted to different countries
mation received through the use of satellites and radar. In the U.S.S.R. these new types of information will be used in regional and national studies of precipitation, flood forecasts, snow and ice cover, etc.
The U.S.S.R. has given high priority to the development of automated systems for hydrological data collection, processing and distribution. The complete implementation of this system will provide for not only accurate information concerning the hydrologic regime and improved water supply forecasts, but will place us nearer to the solution of the problem of man’s influence on this regime.
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