TRANSPORT-BASED SOURCE TRACKING OF COLIFORMS IN A KARST AQUIFER

Identification and localization of contaminants sources is an important task for karst water protection. Chemical source tracking (e.g., by organic micropollutants) and microbial sources tracking (e.g., by host-specific DNA markers) have been proved feasible for this purpose within karst catchments. In this study we present transport-based source tracking as a complementary approach in a small karst catchment located in southwest Germany. To achieve this, we implemented both the 1D advection-dispersion model (ADM) and 1D two-region non-equilibrium model (2RNEM) in GNU octave. The models were employed for quantifying the transport distance based on contaminant breakthrough curves given that transport velocity and input time can be estimated. The applicability of the concept was successfully validated for tracer test data. We further demonstrated its potential for estimating the distance to the contamination source for coliform bacteria in the catchment which was determined to be about 9 km. We propose utilizing a maximum transport distance to account for less permeable, “slower” pathways. The integration of transport-based source tracking alongside existing techniques enables comprehensive and robust contaminant source identification, fostering efficient protection measures for karst systems. The approach is applicable to systems in which 1D transport can be sufficiently well represented with the ADM and 2RNEM.