50. Control of Deteriorating Water Quality in Extracted Boreholes by Flow Systems Definition

Climate change could be blamed on observed water quality decline. This is an undesirable response in any supply project based on groundwater that could produce negative effects as health hazards for the population, undesirable impacts to infrastructure, and increases of maintenance costs for economic activities. Climate change has created recent concern, also the increase in groundwater extraction resulting in enhancement of salinity and/or toxic element content. Results are significant in regions where aquifer thickness is ~1,000 m or more. The objective of this work is to propose the control of groundwater quality in extraction boreholes when the dynamics of the governing flow systems is defined by establishing their hierarchy as proposed by the Groundwater Flow Systems (GFS). Understanding GFS and their role in extracted groundwater provides adequatestrategies for efficient water use and its corresponding planning and management. Usually boreholes response to groundwater extraction is a mixture of flows of different hierarchy. Vertical inflows increase their importance as drawdown progresses with extraction time. Results suggest climatic conditions may affect local flows. A joint groundwater monitoring for adequate managing is highly satisfactory ie. hydraulic data (water-level), physical (temperature) and chemical (specific element) data may be used to monitor expected response due to extraction.