Tracing water perturbation using NO 3 - , doc, particles size determination, and bacteria: A method development for karst aquifer water quality hazard assessment

Karst systems, as well as springs, are vulnerable to water perturbation brought by infiltration. In this research, sources of water perturbations were examined. The first objective is to provide a method that can determine the origin of the water flowing in the karst outlet. The second objective is to identify the associated water quality hazards caused by the infiltration source. The method relies on these parameters: turbidity, DOC, NO , particle size, and bacteria (E. coli, enterococcus and total coliforms). As the method was applied during flood events, measurement of the water flow is also needed to have a basic knowledge on the hydrodynamic of the water resource. The proposed method is based on a high resolution monitoring of physico chemical parameters of the water flowing during flood events. Using this proposed method, (1) the origin of the water can be identified, (2) the type and nature of water perturbation can be described, and (3) the type of water perturbation that accompanies contaminants such as the one with anthropogenic source (e.g. NO ) and bacterial nature can be determined. In identifying the water origin, this proposed method employed NO and DOC data normalization. Values are projected in the NO _norm = f(DOC_norm) reference frame. These are aligned to the slope. Depending on the obtained slope (α), water origin can be disclosed. If α > 1, the increase of concentration of DOC weighs more, characterizing water from surface runoff. Whereas, if α