The Drying Regimes of Non-Perennial Rivers and Streams
Abstract
Lotic system frameworks built around the flow regime are heavily biased toward perennial rivers and streams. However, the global proportion of non-perennial rivers and streams is predicted to increase due to climate change and anthropogenic influences, which indicates a need to extend this paradigm to river and stream drying. Using 894 USGS streamgages, we isolated 25,207 unique drying events from 1979-2018, which include the streamflow peak directly preceding a no-flow event to the eventual re-emergence of flow. We calculated hydrologic signatures of drying that described the timing, duration, magnitude, and rate of change of flow and then using multivariate statistics, clustered these characteristics into four distinct drying regime clusters. These four clusters represented drying regimes characterized by: (1) more frequent drying, (2) longer no-flow duration, (3) drying following low antecedent flows, and (4) seasonal rapid drying. Results showed considerable variability in drying both in time and space across the contiguous U.S. 75% of gages had more than one drying regime occur during the study period and 80% of events belonged to two drying regime clusters. Random forest analysis revealed that land cover/use were more important predictors of a drying regime cluster than watershed physiography or climate. This drying regime framework could be employed to understand how drying characteristics of a particular site compare to the range of drying conditions in time or space. Furthermore, this approach could be used to link observed physical, chemical, and biological functions associated with dominant drying regimes to extend estimates of ecological understanding to unobserved sites.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H41E..02P