River basin management, Bulgarian case study

The master plans for the management of river basins have been elaborated. The territory of Bulgaria is divided into four main hydrological zones - Danube, Black Sea, East and West Mediterranean hydrological zones. The rivers from Danube zone discharged directly to the Danube river, the North boundary of the country. All rivers from the eastern part of Bulgaria discharged directly to the Black Sea. The rivers from East and West Mediterranean hydrological zones discharged to Mediterranean Sea after flowing trough Greece and/or Turkey. The main river basins in Bulgaria were subjects to the evaluation of master plans.During the elaboration of the master plans the following elements have been investigated:

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Demographical characteristics of the stakeholders in the river basin.

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Economical overview of the stakeholders.

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Estimation of surface water availabilities and resources; Water quantity.

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Groundwater overview and estimation of available groundwater resources.

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Water quality of surface and ground water; sediment load.

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Estimation of water use for domestic, irrational, agricultural and industrial water supply.

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Ecosystems in the river basin; Tundja river basin ecosystems.

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Master Plans elaboration for 2010.

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Water balance calculations for 1998 and 2010.

The aim of this paper is to present an overview of Tundja river basin management. Tundja is one of the biggest tributaries of Mariza river and it is join it in the territory of Turkey. The basin belongs to the East Mediterranean hydrological zone. The hydrological investigations and estimations of natural river flow along the main river body and it’s tributaries will be discussed in details. The calculations concern 1961-2004 study period. Long-term assessment has been performed. The characteristics of the monthly, annual, minimum and maximum river discharges have been obtained.     

How can the ISC location procedures be improved?

For many decades the International Seismological Centre (ISC) has used a well defined procedure to locate seismic events using first P-onsets and the Jeffreys-Bullen tables ([Jeffreys, H., Bullen, K.E., 1940. Seismological Tables. British Association for the Advancement of Science, Gray Milne Trust, London, 50 pp]) as the travel-time reference. However, during the last two decades, more accurate spherical Earth models have been published and enhanced computer capabilities make it easier to implement more sophisticated data inversion schemes. Several features that may improve the location procedure at the ISC were systematically tested using the location program HYPOSAT. The investigated features were the influence of

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the usage of the spherical Earth models JB, PREM, IASP91, SP6, and AK135;

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the usage of later onsets;

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travel-time corrections for local crustal structure based on CRUST 5.1;

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different weighting of the residuals;

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reducing the amount of defining data at a late stage of the inversion process.

Application of different combinations of these factors led to a reduction of the location errors for the 156 test events, of which the epicenter is known with an accuracy of less than 5 km. However, no clear rule of common factors to achieve this result could be defined. Most promising is the application of AK135 as model for travel-time calculations, applying crust specific station corrections and corrections for the reflection points of surface reflections, a combined usage of surface and core reflections, and removing data which have large residuals or do not much contribute to the solution for the last iterations.     

Hydrologic effects of a bushfire in a catchment in south-eastern New South Wales

An opportunity to study the effect of a bushfire on the hydrology of a forested catchment was presented when a bushfire burned through an area of approximately 280 square miles in the Snowy Mountains region of south-eastern New South Wales, Australia, in March 1965. The effect of the fire upon the hydrologic characteristics of two catchments for which streamflow records were available before and after the fire was examined and it was shown that:

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(i) there were pronounced changes in the shape of the flood hydrographs of one catchment,