Do we have enough observational data to predict future hydrology? Perspectives from Lakes380

Written by Gebiaw T. Ayele, David P. Hamilton, Bofu Yu…

With rapid environmental change, there is a growing interested in predicting future changes in water quantity and quality. For this purpose, observational data over a set period where monitoring instruments have been deployed (known as the instrumental period) has been used to validate hydrological models which then predict future water resources.

But is this observational data sufficiently representative and robust to confidently predict future changes in water quality and availability

Even in well-gauged and monitored catchments, the instrumental period may be just a few years. When we predict decades into the future, there is uncertainty as to whether this discrete set of observations adequately covers climate and hydrological changes, including floods and droughts that may have long-term impacts on water quality.

Paleolimnology, the reconstruction of the environmental history of lakes from physical, chemical, and biological analyses of lakes, offers the potential to generate historical data sets well beyond the instrumental period. These data can validate hydrological models, which can subsequently be used for hydrological predictions under climate change.

Lakes380 is a five-year paleolimnology research programme that is collecting and analysing lake sediments and water samples, as well as conducting interviews and field visits, to enrich understanding of the environmental, social and cultural histories of about 10% of New Zealand’s 3800 lakes (greater than 1 hectare).

Lakes380 will provide information on the pre-human and post-human condition of New Zealand’s lakes, as well as providing new information how lakes have changed with shifts in climate. The research program is led jointly by the New Zealand organisations, Cawthron Institute and GNS Science.

PhD candidate Gebiaw Ayele is contributing to the Lakes380 program by helping to develop new ways of understanding historical environmental changes using hydrological and lake models, under his supervisor Professor David Hamilton, who has been involved in the Lakes380 program since its outset.

“I’m hoping to develop better predictions for the hydrological impacts of climate change using the last 2,000 years of sedimentation dynamics and climate for selected lakes, together with a chain of models that connect climate, catchment and lake dynamics.”

The sediment cores collected as part of the Lakes380 program will be used to validate the output from this chain of models. Ultimately, his PhD will: (1) assess human impacts on selected lakes associated with land cover changes (e.g., forest clearance); (2) determine whether hydrological models are suitable tools to reproduce paleolimnological records preserved in the sediment core; and (3) predict sedimentation rates over long time periods in a changing climate.

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