Pump discharge measurements at NGMP bores : December 2009 and March 2010 surveys

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Moreau-Fournier, M. 2010 Pump discharge measurements at NGMP bores : December 2009 and March 2010 surveys Lower Hutt, N.Z.: GNS Science. GNS Science report 2010/46 30 p.

Abstract: Groundwater quality is monitored at the national level through the National Groundwater Monitoring Programme (NGMP), a long-term Foundation for Research, Science and Technology (FRST) funded research programme operated by GNS Science (GNS) in collaboration with all 15 regional authorities. The purpose of the NGMP is to provide a national perspective on groundwater quality and to detect and interpret spatial and temporal trends and relate them to certain causes, such as natural water-rock interaction or anthropogenic factors such as land use. The NGMP network currently consists of 110 monitoring sites around New Zealand which are sampled quarterly by regional authority personnel following a standardised sampling protocol. As part of the NGMP programme, GNS is presently working to determine the source and age of groundwater at each NGMP site. This determination requires the delineation of the capture zone for each NGMP site, which is dependent on the pump discharge rate and the aquifer hydraulic properties. Aquifer properties are usually assessed through aquifer tests. Aquifer pump-test data for NGMP wells have been recently compiled. Pump discharge measurements for NGMP sites have not been previously compiled. GNS in collaboration with the 15 regional authorities conducted a survey of pump discharge measurements at NGMP sites during two consecutive water sampling events. Discharge measurements were taken using either using flow meter readings or via manual flow measurements, when access and measurement conditions permitted. The December 2009 dataset consists of 73 measurements (107 visited NGMP sites) of pump discharge rate, ranging from 0.05 to 90 l/s with a median value of 0.70 l/s. The March 2010 pump discharge dataset consists of 72 measurements (104 visited NGMP sites) ranging from 0.03 to 30 l/s with a median value of 1.07 l/s. This survey added a total of 103 new pump discharge measurements for 52 NGMP bores that did not hold any previous information, and added 44 pump discharge measurements for 23 NGMP bores for which some prior hydrogeological data existed. (auth/DG)