Seasonal flow patterns are getting more dependent on vegetation phenology than snowpack dynamics in New England
Abstract
Although precipitation is relatively abundant and evenly distributed throughout the year in eastern US, runoff generation often shows strong seasonality driven by both vegetation phenology and snowpack dynamics, decoupled from precipitation patterns. This effect of leaf and snow seasonality on runoff regimes has been recently phrased by vernal and autumnal windows, defined as the periods between snowmelt and leaf-out in spring and between litterfall and snowpack development in autumn, respectively. Using long-term remote sensed vegetation and snowpack information over the last four decades, we analyzed the impact of lengthened growing season and shortened snowpack duration on runoff regimes over a gradient of northeastern to southeastern watersheds. Specifically, we fitted 10-day mean daily (low-frequency) streamflow data using either bimodal or unimodal distributions, which further matched with the vernal and autumnal window patterns in New England. Our results showed that the bimodal distributions of streamflow have been shifting into unimodal distributions as in the southern Appalachian region. This study suggests that seasonal flow regimes are getting more dependent on vegetation phenology than snowpack dynamics in New England with vanishing vernal and autumnal windows driven by lengthened growing season and shortened snowpack duration under ongoing warming. This study also emphasizes the importance of understanding ecological responses to climate change to predict future freshwater regimes in forest watersheds.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H21I..07H