MIHAI BRETOTEAN

1. THE DEVELOPMENT OF A MANAGEMENT SYSTEM OF GROUNDWATER RESOURCES OF “FRATESTI AQUIFER LAYERS” IN THE CITY OF BUCHAREST MIHAI BRETOTEAN Head of Groundwater Department - National Institute of Hydrology and Water Management Bucharest, Romania

2. I. THE CURRENT PROBLEMS OF THE EXPLOITATION OF THE “FRATESTI AQUIFER LAYERS” IN THE CITY OF BUCHAREST (1) The depth aquifer system of the “Fratesti Layers” (A, B and C), Romanian - Early Pleistocene in age, represents a strategic source of water supply of the city of Bucharest. Due to the structural rising of “Fratesti Layers”, from North to South, these layers join at South of Bucharest the alluvia from the Neajlov and Arges floodplains, in their confluence area (Fig. 1). The water of the phreatic aquifer layer from alluvia of these rivers is polluted with organic substances, NH4+ and NO2 (Fig. 2).

3. I. THE CURRENT PROBLEMS OF THE EXPLOITATION OF THE “FRATESTI AQUIFER LAYERS” IN THE CITY OF BUCHAREST (2) Fig. 1: Lithological sections in the Bucharest area Fig. 2: Space distribution of the water quality

4. I. THE CURRENT PROBLEMS OF THE EXPLOITATION OF THE “FRATESTI AQUIFER LAYERS” IN THE CITY OF BUCHAREST (3) As a consequence of the over-exploitation of the water of the “Fratesti Layers” aquifer system from Bucharest area, especially of the upper aquifer layer “A”, but also of aquifer layers “B” + “C”, found in hydraulic connection, through about 500 wells, with a total discharge of about 1600 l /sec, there were created large depressionary cones, which determine the attraction of polluted waters from the South part to the exploitation area of Bucharest (Fig. 3 and Fig. 4). This is the reason for which, according to the Water Framework Directive 60 /2000 /EC, in the Bucharest area, the “Fratesti Layers” aquifer system must be considered “at risk” from the quantitative and qualitative point of view.

5. I. THE CURRENT PROBLEMS OF THE EXPLOITATION OF THE “FRATESTI AQUIFER LAYERS” IN THE CITY OF BUCHAREST (4) Fig. 3: The piezometric surface of the A aquifer layer Fig. 4: The piezometric surface of the B + C aquifer unit

6. II. THE POLLUTION RISK ASSESSMENT (1) The pollution risk of the “Fratesti Layers” aquifer system, estimated on the basis of a groundwater dynamic model of double-layer finite element type (the layers A and B + C) in steady state and a pollutant transport model based on the transport equation for the miscible substances in a porous medium as follows (Marsily, 1986): D – seeming dispersion tensor (m2/day ); C – mass concentration of the dissolved substances (kg dissolved substance /kg fluid); V – filtration velocity (m /day); nc – cinematic porosity (undimensional); t – variation span of the mass concentration (days)

7. II. THE POLLUTION RISK ASSESSMENT (2) The filtration velocity results from this relation: K – hydraulic conductivity (K = T /M, where T = Transmissivity and M = aquifer thickness) in m /day; H – piezometric head (m) grad – mathematical operator

8. II. THE POLLUTION RISK ASSESSMENT (3) • The pollution risk, expressed by the calculated evolution of the pollutant relative concentration, considered as an ideal tracer (the pollutant propagation velocity is equal with the water average velocity, in lack of the labeling tests), is presented as follows (Fig. 5 and Fig. 6): • in the case of the layer A, the relative concentration, in the southern part of Bucharest, is 25 % after 5 years, 50 % after 15 years, 75 % after 30 years and 80 % after 60 years when the process can be considered stabilized; in the central area of Bucharest, after 60 years, the pollutant relative concentration is about 30 %; • in the case of the complex B + C, the pollutant transport evolution is much slower, so that after 30 years, when the process can be stabilized, the pollutant relative concentration in the Southern part of Bucharest is only 20 %, without the center of the city being affected by pollution.

9. II. THE POLLUTION RISK ASSESSMENT (4) Fig. 5: Distribution of the relative concentration in aquifer layer A, after 60 years Fig. 6: Distribution of the relative concentration in aquifer unit B + C, after 30 years

10. III. MEASURES FOR CREATING A WATER RESOURCES MANAGEMENT SYSTEM OF THE “FRATESTI AQUIFER LAYERS” IN THE AREA OF BUCHAREST CITY (1) • Ist stage • This stage is in progress and consists of: • - the determination of the present situation of the “Fratesti Layers” in Bucharest area and at South of it: wells inventory, piezometric surfaces, yields, hydrogeological parameters (which will be determined by pumping and labeling tests in existent wells) and water quality; • -  the monitoring wells network settlement, which will include both existent wells and, if it is the case, new wells, as well as possible hydrometric stations in the Neajlov and Arges rivers.

11. III. MEASURES FOR CREATING A WATER RESOURCES MANAGEMENT SYSTEM OF THE “FRATESTI AQUIFER LAYERS” IN THE AREA OF BUCHAREST CITY (2) • IInd stage • In the second stage,there are projected the following actions: • -  the equipment (sensors) obtaining and installing for the water levels automatic measuring, both in the monitoring wells and in the case of the Neajlov and Arges rivers, as well as for water quality ( NH4- , NO2-, NO3- , organic substances); • - a monitoring program settlement and implementation, including a data transmission system, in real time, in a database; - a database creation, including a specific software, for data collection and validation and for supplying some mathematical models of the groundwater dynamic and pollutants transport, coupled with GIS techniques

12. III. MEASURES FOR CREATING A WATER RESOURCES MANAGEMENT SYSTEM OF THE “FRATESTI AQUIFER LAYERS” IN THE AREA OF BUCHAREST CITY (3) IIIrd stage On the basis of the obtained data in the previous stages, there will be achieved the following actions: - - the improvement of the groundwater dynamic and pollutant transport mathematical models, already made, according to those specified in the first chapter, for the Bucharest area and the polluted area situated at the South of it, till the Neajlov and Arges rivers; - - the elaboration of some scenarios based on conceived models for establishing the exploitation optimal solution of the “Fratesti aquiferous Layers” in the city of Bucharest, depending of the groundwater quality evolution South of this city and of attracted yield from the Neajlov and Arges rivers, as well as of some solutions for the surface and groundwater cleaning and protection in the area South to Bucharest; - -  the settlement of a hydrogeological protection perimeter in the join zone of the “Fratesti aquiferous Layers” with alluvia from the Neajlov and Arges floodplains.

13. III. MEASURES FOR CREATING A WATER RESOURCES MANAGEMENT SYSTEM OF THE “FRATESTI AQUIFER LAYERS” IN THE AREA OF BUCHAREST CITY (4) The management system created in this way, concerning the exploitation and pollution control of the “Fratesti aquiferous Layers”, is going to be delivered to the local water management authority, in order to become functional at the end of the project. Thanks for attention!