https://doi.org/10.1002/hyp.14112

McDonnell, J. J., Gabrielli, C., Ameli, A., Ekanayake, J., Fenicia, F., Freer, J., ... & Woods, R. (2021). The Maimai M8 experimental catchment database: Forty years of process-based research on steep, wet hillslopes. Hydrological Processes, e14112. doi:10.1002/hyp.14112

Many of our legacy research and observation catchments were developed during the First International Hydrological Decade (IHD) (1965-74)—a period of intense catchment gauging/instrumentation and arguably the beginning of serious process hydrology. The IHD helped our science move beyond the era of infiltration (Beven, 2020) and towards an era that recognized subsurface contributions to runoff via subsurface stormflow. The year the IHD ended the Maimai experimental catchment(s) were initiated in New Zealand (Figure 1). These studies investigated originally the hydrological effects of forest harvesting and radiata pine plantations in former native beech and podocarp forest but quickly morphed into a long sequence of runoff process investigations. Maimai has slopes that are short (<30 m) and steep (mean 34O) with local relief on the order of 100-150 m. Maimai showed that subsurface stormflow was by far the major contributor to storm runoff with chronically wet soils, with 156 rain days per year (Rowe & Pearce, 1994). Pearce, Stewart, & Sklash et al. (1986, p.1266) notes that “mean annual gross rainfall is approximately 2600 mm, producing approximately 1550 mm of runoff from 1950 mm of net rainfall [Rowe, 1979]. The catchments are highly responsive to storm rainfall: 1000 mm (65%) of the mean annual runoff is quick flow (QF) as defined by Hewlett and Hibbert’s [1967] separation method [Pearce & McKerchar, 1979]. Quick flow is 39% of annual total rainfall (P).” Here we outline the data that underpins many of the studies from three main field instrumentation and sample collection phases: (1) early M8 catchment-scale research and observations (1974-1988), (2) hillslope scale trenching, forensic analysis and tracing (1993- 2010) and (3) drilling the critical zone with a focus on bedrock groundwater dynamics, tritium age and its relation to streamflow and transport (2014-present). We describe the data series and provide a link to an online repository of these data in Hydroshare at https://www.hydroshare.org/resource/a292cb65a5d24a31a60978b2ab390266/ .

Core Modelling & Forecasting Team

https://doi.org/10.1002/hyp.14112