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Installation of lysimeters for measuring recharge to groundwater

Contact: Abigail Lovett

Figure 1

Location of current lysimeter monitoring sites in New Zealand. GNS Science has collaborated with Regional Councils to install sites in the Bay of Plenty, Hawke’s Bay and Southland regions, and some Canterbury sites (pre 2000). 

GNS Science has collaborated with regional councils to install drainage lysimeter sites in the Bay of Plenty, Hawke's Bay, Canterbury, and Southland regions. The primary aim of these lysimeter sites is to determine the proportion of water that infiltrates though the soil, from irrigation and/or rainfall, and contributes to groundwater recharge. The majority of sites (19) are installed on dryland sites, whereas 3 sites have been installed under irrigation to measure combined rainfall and irrigation recharge. The irrigation recharge sites have been installed in collaboration with and the National Institute for Water and Atmospheric Research (NIWA). Data obtained from rainfall recharge monitoring sites is required by Regional Councils and other organisations for water resource management purposes, including calibration of groundwater models and policy development. 

Figure 2

Examples of lysimeter monitoring sites during installations. a) dryland site with a wooden enclosure, installed in a clay soil with wicks, Lower Kaimai, Bay of Plenty; and b) an irrigated site installed on alluvial gravel based soil with a concrete enclosure due to a shallow water table, Five Rivers, Southland.

Site specific characteristics mean that no single installation procedure will be identical, but a general procedure for installation of lysimeters has been used in Bay of Plenty, Hawke’s Bay, Southland, and at recent Canterbury sites (Lovett et al., 2015). The majority of rainfall recharge monitoring sites in New Zealand consists of non-weighing, cylindrical soil monolith lysimeters (i.e., the soil column stays intact). The casings measure 500 mm in diameter by 700 mm deep, and are constructed of galvanised steel. Drainage from the soil base is directed through pipework to an underground enclosure for measurement by tipping bucket rain gauges. A ground-level rain gauge is installed at each site, and soil moisture sensors are installed at single, or multiple depths.

Figure 3

Lysimeter monitoring site at Maraekakaho, Hawke’s Bay, annotated with site components. 

Once a rainfall recharge monitoring site has been running for a minimum period of one year, the dataset can be analysed to better understand rainfall and recharge characteristics (e.g. groundwater recharge period, rainfall to recharge ratio). Ideally, rainfall recharge sites should continue to operate over a period of at least 10 years, with even longer datasets providing considerable information on seasonality. A historic dataset with considerable information existed for rainfall recharge monitoring sites the Canterbury region. This dataset was reviewed for quality assurance and quality control, dataset gaps were filled, and statistical analysis was completed (White et al., 2014). Similar reports are currently being prepared for the Hawke’s Bay and Bay of Plenty regions, and will contribute to the NIWA Waterscape Programme. 

Project Example 1: Bay of Plenty Regional Council (BOPRC)

  • funding source: BOPRC
  • collaborators: GNS Science, BOPRC, landowners
  • 2009 – 2012: GNS Science collaborated with BOPRC to install four dryland rainfall recharge monitoring sites, and to transfer knowledge of the installation method (White et al., 2007; Lovett et al., 2012; Lovett and Harvey, 2012). Subsequently, BOPRC have installed a further three sites in the region.

 Project Example 2: Hawkes’ Bay Regional Council (HBRC)

    • funding source: HBRC and NIWA
    • collaborators: HBRC, NIWA, landowners
    • 2012 – 2013: GNS Science and HBRC collaborated to install three dryland lysimeter sites in the Heretaunga Plains (Lovett and Cameron, 2013)
    • 2014: GNS Science, HBRC and NIWA collaborated to install a paired site (one dryland and one irrigated) in the Ruataniwha Plains (Lovett, 2013; Lovett, 2014).

Project Example 3: Environment Southland (ES)

  • funding source: ES, NIWA
  • collaborators: ES, NIWA, Landcare Research, landowners
  • 2014 - 2015: GNS Science, ES, and NIWA collaborated to install two irrigated lysimeter sites in the Southland Region (Lovett and Payne, 2014; Lovett 2015a)

References

Lovett, A.P.; Gordon, D.; Pearson, L.; Huchby, B.; Mojsilovic, O. 2015 New Zealand lysimeter monitoring site installations. 2 p. IN: NZ Hydrological Society Annual Conference : from data to knowledge, 1 to 4 December 2015, Hamilton : [abstracts]. Wellington: New Zealand Hydrological Society [Link to electronic copy]

Lovett, A., 2015a. Five Rivers lysimeter site installation. GNS Science consultancy report 2015/37LR. 10p.

Lovett, A., 2015b. Arable lysimeter review and design: Part 1. GNS Science consultancy report 2015/146. 19p.

Lovett, A., 2014. Installation of a dryland rainfall recharge lysimeter monitoring site at Ashcott Road, Ruataniwha Plains, Hawke's Bay. GNS Scienceconsultancy report 2013/174. 36p.

Lovett, A., 2013. Ruataniwha Plains rainfall recharge monitoring site installation. GNS Science consultancy report 2013/227LR. 2 p.

Lovett, A.; Cameron, S.G. 2013 Installation of rainfall recharge monitoring sites: Bridge Pa, Maraekakaho and Fernhill, Heretaunga Plains, Hawke's Bay. GNS Science consultancy report 2013/05. 46 p.

Lovett, A.; Cameron, S.G.; Harvey, D. 2012 Installation of a rainfall recharge monitoring site, Lower Kaimai, Bay of Plenty. GNS Science consultancy report 2012/267. 27 p.

Lovett, A.; Harvey, D. 2013 Installation of a rainfall recharge monitoring site, Kaituna, Bay of Plenty. GNS Science consultancy report 2013/104. 35 p.

Lovett, A.; Payne, J. 2014 Installation of the Waipounamu lysimeter monitoring site, Waimea Plains, Southland. GNS Science consultancy report 2014/148. 39 p.

White, P.A.; Moreau-Fournier, M.; Thorpe, H.R.; Lovett, A. 2014 Summary of rainfall recharge measurements with lysimeters and ground-level rainfall observations 1952-1978 and 1997-2011, Canterbury. Lower Hutt, NZ: GNS Science. GNS Science report 2013/10. 26 p. + 1 CD