Using Radon in the ground and stream water interaction analysis at reach scale in the Upper Tusciano river (Southern Italy)

摘要

In this paper, the results of the experimental investigations on the spatial-temporal variations in Radon activity concentration along a reference segment and reaches of the Upper Tusciano river, are illustrated and discussed. The research aims to perform integrate and interdisciplinary hydro-geomorphological approaches in the framework of the best improvement and site adaptation of the EU Water Directive in Mediterranean, complex river basins. The study area is located inside the M.nt Picentini Regional Park (Campania region, southern Italy). Along the river segment, complex interactions and exchanges between surface and groundwater exist. One of the main problem is to detecting river reaches functioning as gaining by spring flows and losing by stream bed infiltration, respectively. As a support to assess these interaction processes, monthly monitoring campaigns in discharge, electrical conductivity and Radon activity concentration measurements have been and are currently carried out. Results show a general, downstream increase in stream flow discharge along the step-and-pool and bedrock river reaches and a local decrease in the alluvial reaches of the river segment. Both electrical conductivity and Radon space-time distribution provide detailed information about a typical behavior of the stream flow in alternating gaining-losing reaches, where the only discharge measurements are not able to detect this functioning.