Demonstrative actions of spring restoration and groundwater protection in rural areas of Abegondo (Galicia, Spain)

摘要

There is an increasing concern about the chemical and microbiological quality of spring waters in Galicia (Spain) due to bacteriological and nitrate contamination. Demonstrative actions of spring restoration and groundwater protection were implemented in five selected springs and fountains in the municipality of Abegondo. These actions include the cleaning and disinfection of the fountains, the restoration of the spring catchments and the definition and the implementation of the spring protection zones. Available topographic, geological, meteorological, hydrological, hydrogeological and hydrochemical data of the area were used to: (1) elaborate the hydrogeological conceptual model of the study area; (2) assess the groundwater chemical and microbial status; and (3) define the spring protection zones with a numerical groundwater flow and solute transport model solved with the CORE~(2D) code. Spring protection zones include: (1) an immediate zone of absolute restrictions around the spring with a radius of 3 m; (2) an intermediate zone of maximum restrictions where potential contamination activities are restricted; this zone has a radius of 30 m and is defined on the basis of a 50 days transit time; and (3) a remote zone which includes the rest of the contributing groundwater basin where restrictions are moderate. The protection zones defined in the project were included in the general development plan of the municipality. The chemical and microbial data of the springs were monitored during 3 years after the restoration actions. The cleaning and disinfection of the fountains and spring catchments were efficient in dropping noticeably the microbiological contamination and reducing mildly the nitrate concentrations (from 10 to 20%). The efficiency of the restoration measures was partially reduced by: (1) the low frequency of the cleaning and disinfection of the fountains; and (2) the lack of actions to enforce the restrictions in the protection zones to prevent the excessive use of manure as fertilizer in the surroundings of some springs.