Project Report on Bojana Bay, Montenegro

The Final Report of the AQMOD project is a contribution to the ADRICOSM-STAR programme. The scope of AQMOD was to study the aquifers occurring gin the Bojana Bay of Montenegro. While ADRICOSM-STAR has a wider remit concerning the response of the Adriatic Sea, including monitoring its likely response to forthcoming changes, AQMOD was restricted to a small portion of the overall terrestrial area that influences this part of the Adriatic. The principle aim of AQMOD was to identify those aspects of terrestrial hydrology and their contribution to the overall system function, through capacity development and strengthening institutional cooperation. From this perspective AQMOD has achieved its objective. A 3-D aquifer system model was prepared with high level of inter institutional cooperation and collaboration that extended to review of archive data in the respective agencies, a preliminary conceptual model formulation, a field campaign in which through supporting finances of the Government of Montenegro, exploration drilling was conducted and finally synthesising all of the data into a model. The model provides the agencies with a tool for further assessment of the hydrogeological system, and more importantly it also enables the agencies to apply the methods and techniques in others parts of Montenegro.

The study area is the alluvial plain of the lowermost part of the river Bojana, which is also the international boundary between Montenegro and Albania. Although this landscape forms a part of the hydrographical basin of the lake Skader, with an area of about 5000 km2, the study area is only about 90 km2. The length of the overall all river system is about 180 km, and the section that was focussed in the study was the last 24 km before the river discharges to the Adriatic Sea. As may be surmised from these figures the impact of the study area on the overall hydrology is very small and indeed the modelling has confirmed this. From the study area, the discharge of aquifers to the river system is about 28 M m3/an, while the flow in Bojana is 20 000 M m3/an. Thus any impact of the aquifer discharge is significantly masked by the huge comparative basin wide surface flow system. Transposing these flow figures into nutrient loads again indicates that the loading to the river system from these aquifers may be about 0.1% of that already in the upstream surface rivers system.

The impact of climate change was a factor of concern in the design of the ADRICSOM Programme and consequently this aspect was examined in the Bojana Bay aquifer system. As far as aquifer hydrogeology is concerned the manifestation of climate change will be through a change in the recharge pattern given that all other factors are constant. Assuming that there is no land use change (which can have a much greater and more rapid impact) a reduction in the annual rainfall to 25% of its present value would result in a corresponding reduction in aquifer outflow of nearly 40%. In contrast a 200% increase in annual recharge to the aquifer would result in an increased annual aquifer outflow of 61%. 

The hydrochemical provinces of the study area are very interesting, since combined with the hydrogeology, they enable the identification of several sub ecosystems that each interplays with the other in the following manner. The rim of the study area, the Karstic aqufers are the ecosystem of pristine and good quality water, with abundant storage potential and withdrawal potential, if well managed. The flat alluvial plains which are the agro productive landscape and ecosystem have transitional water quality, from good quality at the contact with the Karst (that feeds into the alluvium) to brackish in the low lying lands at the coastal plain and the section of the Bojana flood plain that is subject to sea water intrusion. Finally there is the coastal plain, which is in fact a low ridge, or coastal dune, created from the accumulation of coastal deposition of marine sands and possibly accumulation of terrestrial sands. Within the alluvial plain subsystem, there are the salt pans, which are a significant feature, but seem to be inactive in terms of the local hydrology, since they consist of fully engineered pond systems. In addition there is the brackish wetland of the Bojana flood plain, which holds a rich variety of flora and fauna. 

The identification of the sub ecosystems as described above enable several management decisions to be made. Firstly, the pristine aquifer system in the karst needs to be better managed and protected, since some over abstraction at Gac is causing quality deterioration, by laterally drawing in alluvial aquifer waters. Secondly the brackish wetlands are a potentially high value eco-landscape, which if managed better, may has the perspective of providing buffering value to the high nutrient loaded water in the channel of the river Bojana itself. This aspect was beyond the scope of the present study so it has not been pursued further except to state its potential. Finally the coastal dune system is fragile and needs careful management, as has already been stated in several previous studies of the area. The forthcoming pressures on the landscape through the construction of recreational resorts will increase the pressures and these should be managed to contain the degree of impact.

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