Integrated Water Resources Management: Approach to Improve River Water Quality in the Western Bug River Basin

Abstract

The Western Bug is a transboundary river with relevant environmental impact on the Vistula and the Baltic Sea. On entering the EU it must comply with the European Water Framework Directive, which demands an integrated water resources management (IWRM) on river basin scale. In this paper a systematic approach addressing the IWRM principles is proposed and applied for the upper part of the Western Bug. The existing pollution regime in the W.Bug catchment area to the gauge W.Bug – Kamianka Buska is assessed by application of a five step methodology including system screening, compilation of pressures, comparison with biological status, detailed process analysis of relevant interactions, definition of response measures based on a multi-criteria evaluation. Survey of previous studies, analysis of regional monitoring data, MFA modelling with MONERIS tool and carried measurements campaigns have shown, that in a row with extremely high point source input load on a watershed border (Lviv WWTP), such diffuse sources of nutrients as tile drained areas, rural areas without waste water treatment and erosion compose a nutrients input over an entire basin (approx. 2,500 km2) comparable to the mentioned point source. Moreover, the emission patterns partitioning is different for DIN and TP. During the measurements campaign the results of MFA modelling were supported and other deficits, such as extinction of the natural Poltva river ecosystem and nitrate pollution of the uppermost aquifers were found. Therefore, for detailed process analysis two main subsystems have been identified: (i) River Poltva and River Bug downstream from the confluence with the River Poltva, (ii) the uppermost aquifers. Already at this stage of study it was found that water quality formation in W.Bug is subject to acute deficits in the settlements sanitation systems in the basin while diffuse pollution due to agricultural activities is (under the current socio-economic conditions) of lower relevance.