T237 Advances in the Science of Wildfire-Related Earth-Surface Processes (Posters)

Wednesday, 12 October 2022
9:00 AM - 1:00 PM
Exhibit Hall F

EFFECT OF SUCCESSIVE RUNOFF EVENTS ON TURBIDITY IN POST-FIRE WATERSHEDS WITHIN VALLES CALDERA NATIONAL PRESERVE

Paper number: T237-9
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

  • Dave Pittenger Presenting Author
    Valles Caldera National Preserve, Jemez Springs, NM
  • Ross Shipley
    Valles Caldera National Preserve, Jemez Springs, NM

Abstract

Changes in soil stability and chemistry resulting from wildland fire can have both immediate and long-lasting effects on downstream water quality. Runoff from burned areas can cause dramatic spikes and dips in measured parameters such as turbidity, dissolved oxygen (DO), pH, and specific conductivity (SpC), which have potential to greatly impact the overall health of the stream and its aquatic communities.

This study was conducted to better understand the behavior and rate by which these parameters’ responses change in magnitude as a result of successive runoff-producing rainfall events on recently burned areas. The effects on water quality were investigated in two streams within Valles Caldera National Preserve, New Mexico whose watersheds were impacted by the 2011 Las Conchas fire. Turbidity, DO, pH, SpC, and discharge were measured during spring-to-fall months at 15-minute intervals between 2006 and 2022, capturing the full record of the fire’s impacts as well as its preceding conditions. The turbidity data were analyzed alongside discharge data to identify, then quantify, the number and magnitude of runoff-related high turbidity events which occurred throughout the watershed recovery process. We also investigated the rate by which DO, pH, and SpC rebounded to baseflow values following each turbidity event.

It was observed that with successive runoff events 7 years post-fire, turbidity spikes reduced in magnitude to values more typical of pre-fire conditions. Other parameters affected by high turbidity events exhibited less dramatic spikes and were able to return to baseflow levels more quickly with subsequent events. While it is widely understood that wildland burn-scars do stabilize to some degree over time, the ability to quantify recovery from an upper watershed perspective is invaluable for post-fire land management practices. Further studies may be able to utilize turbidity-spike trends to model erosion-related watershed recovery timelines.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-378834

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.