The territory of Bulgaria is situated in the intermediate belt between Continental and Mediterranean climatic zones. The dividing line is along the ridge of the Balkan Mountain.

The basic geomorphological regions of Bulgaria are the following:
North Bulgaria :
Climate : Moderate-Continental climate,
Vegetation : Forest-steppe zone
Soils : Tchernozems, Grey forest 
Basin : Black sea
Balkan Mountain Region :
Climate : Mountain climate
Vegetation : Forest. High-mountain, grassy
Soils : Brown forest, Rankers
Watershed boundary : Balkan Mountain ridge
South Bulgaria :
Climate : Continental-Mediterranean climate
Vegetation : Dry forests and bushes
Soils : Synemonic, Vertisols
Basin : Mediterranean Basin


2. Networks of observations

NIMH is the principal responsible for the observation and study of the meteorological elements of Atmosphere, Hydrosphere, Biosphere, Pedosphere. The different Departments of NIMH and the corresponding networks of observation and measurement stations are connected by methods, structure and territory in such a way that the result is the integrated characteristics of the environment (the natural resources of our country).

Core elements of NIMH are the Central Body in Sofia and 4 Regional Centres in Pleven, Varna, Plovdiv and Kjustendil, Their structural units are observatories and observing stations ( observing posts ).

The Department of Hydrology in the Institute is responsible for the Hydrological Networks.

NIMH Networks are the following :

2.1. Meteorological Network :

2.2. Hydrological Network : The hydrological stations can be separated into several types :
  1. According to the data transmission frequencies :
  2. According to the equipment available :
  3. According to the type of analyses are :
2.3. Agrometeorological network : 2.4. Air and water pollution network : The networks of the NIMH have been established at the end of the 19-th and the beginning of the 20-th century. The observation time series for all the networks are longer than 40 years period. Systematic hydrological measurements are available since 1920.

3. The NIMH Information System

3.1. General Information

At present the Information System of the NIMH comprises both file systems and relational databases under DOS and UNIX and ORACLE and DBASE used as DBMS. In the eighties a mainframe was in the centre of the Information system. Later it was replaced by the PC-s. Relational Databases have been designed and created for the Meteorology, the Agrometeorology and the Forest Meteorology.

3.2. Hydrological Database

The Hydrological Database in Bulgaria is a file system consisting of data arrays which represent the professional description of the object "Hydrology" and also of program packages for the data processing. The structure of the data concerning the observation elements for stations, river beds, catchment basins and administrative-economical division allows the data migration to a relational database when such one will be created.

Descriptive data exist also in the file system about the hydrological stations and catchments :

  1. hydrographic characteristics
  2. types of observed and measured elements
  3. information about the measurement systems
Observation reports are involved as data flow into the database:*
  1. report of water levels :
  2. report of the water content observations :
  3. The observation data in most of the cases are water levels and water discharges are determined by the corresponding rating curves in the regional centres of the NIMH.(Fig 1). - Annual rating curve for 1995, river Maritza, st. Parvomay and Fig. 2 - Maritza-river cross-section at st. Parvomay, Dec.1994)

    Statistical results from the data processing are :

    1. daily discharges,
    2. monthly discharges,
    3. annual discharges,
    4. multi-annual discharge characteristics
    Statistical results involve : The operational hydrology is concerned with the real time data processing - obtaining temporary rating curves and intermediate discharges from the real time levels, issuing operational bulletins and forecasts. File system is used for the data storage and - programs for the processing of data, no DBMS or GIS are used at present. Visualisation of spatial data is done by the SURFER program for WINDOWS.(Fig 3 Visualisation of groundwater levels at urbanised area NE Bulgaria by WINDOWS SURFER).

    The hydrological time series are stored in files and are used for operational and scientific services.

    Periodicals and scientific publications are issued. FORTRAN and BASIC have been used as programming languages for the development of the program packages for the processing of the hydrological data.

    4. My experience

    My experience involves programming in FORTRAN and PL for the data processing on a mainframe, and C and BASIC - for PC. Later I participated in the designing, construction, maintenance and management of the relational databases in the environment of ORACLE for the Agrometeo-rological and Forest Meteorological databases and as a Database Administrator of the Meteorological, Agrometeorological and Forest Meteoro-logical databases. These databases have been designed and created under RDBMS ORACLE v.4 and later migrated to v.5 and at the end migrated to v.7.

    5. Demonstration

    I would like to propose you a demonstration of several applications, which are part of the Agrometeorological Database in the environment of RDBMS ORACLE v.7.1.

    The applications are the following :

    The database table represents the logical structure of a database . It provides information about the database object - here - the soil moisture, spatial and time characteristics , units of presentation, and so on.
    The structure of this table is integrated as a logical element in the Agrometeorological database structure which is part of the global Information System "Nature Resources".
    Our idea is to express the integrity and the consistency of the DB.

    Fig 4 - Stations and posts in the Agrometeorological Database.

    Fig 5. - Soil moisture in gravimetric %.

    The form for data processing allows basic data manipulation operations - insert, delete, update, query, format, calculate, validate etc.
    The necessary help facilities have been built - references for the tables of : stations, plots, species - they can be called by the corresponding push-buttons or lists of values.
    The data in these and other tables are used for data validation in the course of data input.

    Fig 6. - AMST Soils - humidity in mm/hor and mm/l.

    Fig 7. - AgmetSt - Soils - Agrophysical Properties.

    The Report "Soil humidity in mm/hor and mm/l" represents the information for the primary horizons (in which the soil moisture is determined), and also for the standardised horizons and layers at intervals of 20,50,100 and 200 cm.

    The data represented in the report have been computed by PL/SQL procedures.

    Fig.8. Dynamics of soil moisture for standardised layers

    Fig. 8 is an example of a graphical visualisation of the output data. In this case it is the dynamic of soil moisture for standardised layers.

    The applications have been selected in such a way that they represent schematically the principal elements of a Relational Database.

    I would like to mention that Bulgaria belongs to the few countries in the world which have a network of agrometeorological stations established and situated in accordance to the geomorphological, climatic, soil and agricultural economical regions.

    The observations have been made over a more than 30 years’ period for the basic agricultural species - wheat, maize and alfalfa in all agrometeorological stations (over 30) and for sunflower, vine, tobacco , apple trees and other species in relation to the economical region.

    The observations from the meteorological network (air and soil temperature, rainfall, solar radiation, air humidity, air saturation deficit, evaporation and so on) and the soil moisture - from the agrometeorological network - cover the territory of the country and they are used also for hydrological tasks.

    6. Final part

    Bulgaria is situated in the transitional zone of climate, vegetation, soils and marine watershed basins and also we must add - in geostrate-gical and transportation- communication aspect - between West Europe and Asia.
    Also the Regional Telecommunication Centre of WMO is in Sofia.
    All presented here above in the context of the MED-HYCOS PROJECT can outline the following :

    1. Bulgaria has an established infrastructure for monitoring the environment over its territory and the staff with the necessary qualification including :

    2. The IS in this area is far behind in comparison to the up to date understanding and the possibilities offered by the modern software and hardware technique.

    3. Bulgaria needs very much to be helped for the construction of a up to date National Hydrological Information System.

    4. Bulgaria has all the necessary conditions for establishing a Sub Regional Hydrological Database.

    Fig. 2a. Principle scheme of the data processing activities