Analysis of postfire hydrology, water quality, and sediment transport for selected streams in areas of the 2002 Hayman and Hinman fires, Colorado

Stevens, Michael R.

doi:10.3133/sir20125267

Cited by 4 publications

(8 citation statements)

References 30 publications

(56 reference statements)

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“…Furthermore, the annual yields of DOC in 2013-2014 were not appreciably different compared to prefire years ( Figure 7) largely because stream-water concentrations were not elevated during early snowmelt, when most DOC export occurred. Our results contrast with some lower elevation fires in the Front Range where substantial increases in DOC were detected after high-intensity rain storms and where concentrations reached levels that could be problematic for downstream water treatment plants (Stevens, 2013;Murphy et al, 2015). In these studies no difference in postfire DOC was detected during snowmelt runoff or baseflow as was the case for the BTMP.…”

Section: Discussioncontrasting

confidence: 95%

“…The reason for the increase in stream alkalinity during the second year is not clear. Possible wildfire‐related sources of alkalinity include weathering of carbonate minerals in ash (Pereira et al, ) as well as weathering of fresh mineral surfaces exposed by soil heating (Stevens, ). The delayed response might reflect slower reaction rates of carbonate and silicate minerals compared to more highly soluble salt components of ash (Khanna and Raison, ).…”

Section: Discussionmentioning

confidence: 99%

“…These findings are similar to those of Benavides‐Solorio and MacDonald (), who found that 90% of postfire sediment in a lodgepole pine forest was generated from high‐intensity summer rainstorms and only 10% was because of snowmelt, and to Murphy et al (), who found that postfire summer convective storms produced turbidity and sediment concentrations that were an order of magnitude higher than those measured during snowmelt. While the turbidity levels measured at BTMP could pose problems for water‐treatment facilities (Reneau et al, ), they were much smaller than those reported following several larger wildfires in the Colorado Front Range (19 900 NTU following the Hayman Fire and >50 000 NTU following the Fourmile Canyon Fire; Stevens, ; Murphy et al, ). Although there are many factors limiting the amount of postfire erosion, the small size of the Fern Lake Fire (15% of watershed), degree and distribution of burn severity in the watershed, and minimal land disturbance likely were important factors.…”

Section: Discussionmentioning

confidence: 99%

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Water-quality response to a high-elevation wildfire in the Colorado Front Range

et al. 2015

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Abstract:Water quality of the Big Thompson River in the Front Range of Colorado was studied for 2 years following a high-elevation wildfire that started in October 2012 and burned 15% of the watershed. A combination of fixed-interval sampling and continuous water-quality monitors was used to examine the timing and magnitude of water-quality changes caused by the wildfire. Prefire water quality was well characterized because the site has been monitored at least monthly since the early 2000s. Major ions and nitrate showed the largest changes in concentrations; major ion increases were greatest in the first postfire snowmelt period, but nitrate increases were greatest in the second snowmelt period. The delay in nitrate release until the second snowmelt season likely reflected a combination of factors including fire timing, hydrologic regime, and rates of nitrogen transformations. Despite the small size of the fire, annual yields of dissolved constituents from the watershed increased 20-52% in the first 2 years following the fire. Turbidity data from the continuous sensor indicated high-intensity summer rain storms had a much greater effect on sediment transport compared to snowmelt. High-frequency sensor data also revealed that weekly sampling missed the concentration peak during snowmelt and short-duration spikes during rain events, underscoring the challenge of characterizing postfire water-quality response with fixed-interval sampling.

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Section: Discussioncontrasting

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Water-quality response to a high-elevation wildfire in the Colorado Front Range

et al. 2015

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“…As a result, increased water yields or even flash floods/ debris flows commonly originate from burned watersheds during post-fire rainstorms (Mahat et al, 2016;Malvar et al, 2015). Further, bare soil conditions accelerate soil erosion, transporting sediments and nutrients to source waters (Belillas et al, 1993;Lane et al, 2008;Malmon et al, 2007;Sheridan et al, 2007;Stevens, 2013). Additionally, elevated levels of turbidity and suspended solids (Hohner et al, 2017;Mast et al, 2016;Murphy et al, 2012) and metals (Abraham et al, 2017) are frequently reported in the post-wildfire runoff.…”

Section: Introductionmentioning

confidence: 99%

Two years of post-wildfire impacts on dissolved organic matter, nitrogen, and precursors of disinfection by-products in California stream waters

et al. 2020

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We investigated the effects of two California wildfires (Rocky and Wragg Fires, 2015) compared to an unburned reference watershed on water quality, dissolved organic matter (DOM), and precursors of disinfection by-products (DBPs) for two years' post-fire. The two burned watersheds both experienced wildfires but differed in the proportion of burned watershed areas. Burned watersheds showed rapid water quality degradation from elevated levels of turbidity, color, and suspended solids, with greater degradation in the more extensively burned watershed. During the first year's initial flushes, concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), ammonium (NH 4 þ /NH 3), and specific ultraviolet absorbance (SUVA 254) were significantly higher (67 ± 40%, 418 ± 125%, 192 ± 120%, and 31 ± 17%, respectively) in the more extensively burned watershed compared to the reference watershed. These elevated values gradually declined and finally returned to levels like the reference watershed in the second year. Nitrate concentrations were near detection limits (0.01 mg-N/L) in the first year but showed a large increase in fire-impacted streams during the second rainy season, possibly due to delayed nitrification. Changes in DOM composition, especially during the initial storm events, indicated that fires can attenuate humic-like and soluble microbial by-product-like (SMP) DOM while increasing the proportion of fulvic-like, tryptophan-like, and tyrosine-like compounds. Elevated bromide (Br À) concentrations (up to 8.7 mM]) caused a shift in speciation of trihalomethanes (THMs) and haloacetic acids (HAAs) to brominated species for extended periods (up to 2 years). Wildfire also resulted in elevated concentrations of N-nitrosodimethylamine (NDMA) precursors. Such changes in THM, HAA, and NDMA precursors following wildfires pose a potential treatability challenge for drinking water treatment, but the effects are relatively short-term (1 year).

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“…Wildfires, when coupled with precipitation events, can lead to substantial sediment loading in streams (Moody and Martin, 2001), leaving the burned watersheds of the upper Rio Hondo Basin at risk of substantial postfire debris flows and flash floods (Tillery and Matherne, 2013). Wildfires can also have substantial effects on downstream water quality (Neary and others, 2008;Smith and others, 2011;Stevens, 2013). This section of the report compares water quality of streams in burned (Eagle Creek and Rio Bonito) and unburned (Rio Ruidoso) watersheds after the Little Bear Fire of June 2012 in samples collected after postfire monsoon rain events and during periods of stable hydrologic conditions.…”

Section: Postfire Water Qualitymentioning

confidence: 99%