Lovett, A.; Cameron, S.G.; Reeves, R.R.; Meijer, E.; Verhagen, F.; van der Raaij, R.W.; Westerhoff, R.; Moridnejad, M.; Morgenstern, U. 2015 Characterisation of groundwater - surface water interaction at three case study sites within the Upper Waikato River Catchment, using temperature sensing and hydrochemistry techniques. Lower Hutt, N.Z.: GNS Science. GNS Science report 2014/64 74 p.
Abstract: Groundwater in the Upper Waikato River Catchment is an important resource for economic commercial and domestic water supply, and the source of direct inflow to streams, lakes, rivers, and geothermal systems. Groundwater – surface water (GW-SW) interaction occurs throughout the catchment which can influence surface water flow rates and water quality. Increases in groundwater use have occurred throughout the Waikato region, and are predominantly driven by land use intensification. Consequences of intensification include increased groundwater abstraction, which potentially reduces the availably of water to recharge streams, rivers, and lakes (and therefore can effect hydropower generation); and an increase in discharge of nutrients to groundwater and surface water, leading to potential water quality degradation in lakes, waterways, and groundwater. The aim of this project was to use novel techniques to improve the understanding of GW-SW interaction in the Upper Waikato River Catchment, and involved collaboration between Waikato Regional Council and the GNS Science-led Smart Aquifer Characterisation (SAC) research programme. Three case study sites were selected based on pre-existing knowledge that GW-SW interaction processes occur in the local hydrological system, and to represent a range of scales and settings (e.g., lake, river, and stream). These sites included Whangamata and Whakaipo Bays, Lake Taupo; the Aratiatia Dam to Ohaaki reach of the Waikato River; and Torepatutahi Stream, Broadlands. The primary aim of this project was to apply novel temperature sensing techniques from the SAC program, which include satellite thermal infra-red (satellite TIR), airborne thermal infra-red (airborne TIR), fibre optic distributed temperature sensing (FODTS), to test if the methods complimented each other for improved characterisation of GW-SW interaction in the Upper Waikato River Catchment. The specific objectives of the project were to: identify whether satellite TIR can be used in combination with airborne TIR to identify locations of GW-SW interaction to inform placement of FODTS equipment; and identify whether FODTS is a suitable method to determine GW-SW interaction within the large scale hydrological system of the Upper Waikato River Catchment. In addition, water sampling for hydrochemistry and age dating was completed at two sites (Waikato River reach and Torepatutahi Stream), to identify whether hydro-chemical parameters can be used as an age proxy in these systems. (auth)