Wildfire increases the potential connectivity of runoff and sediment throughout watersheds due to greater bare soil, runoff and erosion as compared to pre‐fire conditions. This research examines the connectivity of post‐fire runoff and sediment from hillslopes (
Specific electrical conductivity (SC) is a basic, effective indicator of water quality. The recent increase in SC data collected with high‐frequency sensors has created a strong need for algorithms that can aid interpretation of these data. This study presents an algorithm that finds and quantifies SC temporal patterns and applies that algorithm to a dataset from a 7.5 km2forested catchment in central New Hampshire. During and after rain events, we show three patterns that emerge in SC time series: A solute flush, resulting in an initial increase in SC, followed by a dilution, followed by the SC’s recovery toward pre‐rain conditions. We compared these SC patterns to precipitation amount and intensity, antecedent wetness, and seasonality. Our results indicate that the magnitude of the flush was driven primarily by precipitation intensity and total rainfall during a storm, and secondarily by antecedent moisture conditions. The magnitude of the dilution was driven mainly by the precipitation amount. The rate of SC recovery was driven by precipitation amount and was correlated with dilution. Overall, the algorithm successfully extracted event‐driven characteristics in the SC time series, allowing the development of functional relationships with hydrologic drivers. Applying similar methodologies to more catchments in the future will help identify functional relationships at more sites and use these relationships to identify catchments most sensitive to future precipitation changes.
more » « less- NSF-PAR ID:
- 10275647
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- JAWRA Journal of the American Water Resources Association
- Volume:
- 57
- Issue:
- 5
- ISSN:
- 1093-474X
- Page Range / eLocation ID:
- p. 844-857
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract < 1.5 ha;n = 31) and catchments (< 1000 ha;n = 10) within two watersheds (< 1500 ha) burned by the 2012 High Park Fire in northcentral Colorado, USA. Our objectives were to: (1) identify sources and quantify magnitudes of post‐fire runoff and erosion at nested hillslopes and watersheds for two rain storms with varied duration, intensity and antecedent precipitation; and (2) assess the factors affecting the magnitude and connectivity of runoff and sediment across spatial scales for these two rain storms. The two summer storms that are the focus of this research occurred during the third summer after burning. The first storm had low intensity rainfall over 11 hours (return interval <1–2 years), whereas the second event had high intensity rainfall over 1 hour (return interval <1–10 years). The lower intensity storm was preceded by high antecedent rainfall and led to low hillslope sediment yields and channel incision at most locations, whereas the high intensity storm led to infiltration‐excess overland flow, high sediment yields, in‐stream sediment deposition and channel substrate fining. For both storms, hillslope‐to‐stream sediment delivery ratios and area‐normalised cross‐sectional channel change increased with the percent of catchment that burned at high severity. For the high intensity storm, hillslope‐to‐stream sediment delivery ratios decreased with unconfined channel length (%). The findings quantify post‐fire connectivity and sediment delivery from hillslopes and streams, and highlight how different types of storms can cause varying magnitues and spatial patterns of sediment transport and deposition from hillslopes through stream channel networks. -
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