Quantifying the impact of drought severity on carbon and nitrogen cycling in streams
Abstract
Droughts are increasing in frequency and severity, with complex and poorly understood impacts on stream biogeochemistry and ecosystem function. The state of New Hampshire, for example, has experienced an increased frequency of drought with two recent extreme droughts (D3 designation; US Drought Monitor) occurring less than five years apart. The impact of these droughts (2016 and 2020) on stream water quality was captured with high temporal resolution by a network of in situ sensors, offering the unique opportunity to compare stream ecosystem response to extreme dryness across multiple sites. Drought threshold was defined using a moving quantile based on the 80th percentile of the flow duration curves from a 30-day moving window. This threshold was then used to determine the start, end, and severity of drought for each site. We calculated the response of nitrate, fluorescent dissolved organic matter (a proxy for concentrations of dissolved organic carbon), and dissolved oxygen to drought using established ecosystem stability metrics including resistance, resilience, recovery, and temporal stability. Preliminary results show variability in drought severity and duration among study sites and years. We found greater variability in metrics of water chemistry during drier than normal conditions and lower daily mean and wider diel cycles of dissolved oxygen during periods of low flow. Results illustrate the effects of drought in freshwater ecosystems in a humid temperate biome.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.B25E1600H