The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire
Storms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Col...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2015-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/10/8/084007 |
| _version_ | 1797748782687846400 |
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| author | Sheila F Murphy Jeffrey H Writer R Blaine McCleskey Deborah A Martin |
| author_facet | Sheila F Murphy Jeffrey H Writer R Blaine McCleskey Deborah A Martin |
| author_sort | Sheila F Murphy |
| collection | DOAJ |
| description | Storms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Colorado Front Range and found that for a three-year period, substantial hydrologic and geochemical responses downstream of a burned area were primarily driven by convective storms with a 30 min rainfall intensity >10 mm h ^−1 . These storms, which typically occur several times each year in July–September, are often small in area, short-lived, and highly variable in intensity and geographic distribution. Thus, a rain gage network with high temporal resolution and spatial density, together with high-resolution stream sampling, are required to adequately characterize post-wildfire responses. We measured total suspended sediment, dissolved organic carbon (DOC), nitrate, and manganese concentrations that were 10–156 times higher downstream of a burned area compared to upstream during relatively common (50% annual exceedance probability) rainstorms, and water quality was sufficiently impaired to pose water-treatment concerns. Short-term water-quality impairment was driven primarily by increased surface runoff during higher intensity convective storms that caused erosion in the burned area and transport of sediment and chemical constituents to streams. Annual sediment yields downstream of the burned area were controlled by storm events and subsequent remobilization, whereas DOC yields were closely linked to annual runoff and thus were more dependent on interannual variation in spring runoff. Nitrate yields were highest in the third year post-wildfire. Results from this study quantitatively demonstrate that water quality can be altered for several years after wildfire. Because the southwestern US is prone to wildfires and high-intensity rain storms, the role of storms in post-wildfire water-quality impacts must be considered when assessing water-quality vulnerability. |
| first_indexed | 2024-03-12T16:09:48Z |
| format | Article |
| id | doaj.art-af0eaaf67b6a4347bfcc95064959149b |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T16:09:48Z |
| publishDate | 2015-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-af0eaaf67b6a4347bfcc95064959149b2023-08-09T14:11:26ZengIOP PublishingEnvironmental Research Letters1748-93262015-01-0110808400710.1088/1748-9326/10/8/084007The role of precipitation type, intensity, and spatial distribution in source water quality after wildfireSheila F Murphy0Jeffrey H Writer1R Blaine McCleskey2Deborah A Martin3US Geological Survey, 3215 Marine Street, Boulder , CO 80303, USAUS Geological Survey, 3215 Marine Street, Boulder , CO 80303, USA; University of Colorado , Boulder , CO 80309, USAUS Geological Survey, 3215 Marine Street, Boulder , CO 80303, USAUS Geological Survey, 3215 Marine Street, Boulder , CO 80303, USAStorms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Colorado Front Range and found that for a three-year period, substantial hydrologic and geochemical responses downstream of a burned area were primarily driven by convective storms with a 30 min rainfall intensity >10 mm h ^−1 . These storms, which typically occur several times each year in July–September, are often small in area, short-lived, and highly variable in intensity and geographic distribution. Thus, a rain gage network with high temporal resolution and spatial density, together with high-resolution stream sampling, are required to adequately characterize post-wildfire responses. We measured total suspended sediment, dissolved organic carbon (DOC), nitrate, and manganese concentrations that were 10–156 times higher downstream of a burned area compared to upstream during relatively common (50% annual exceedance probability) rainstorms, and water quality was sufficiently impaired to pose water-treatment concerns. Short-term water-quality impairment was driven primarily by increased surface runoff during higher intensity convective storms that caused erosion in the burned area and transport of sediment and chemical constituents to streams. Annual sediment yields downstream of the burned area were controlled by storm events and subsequent remobilization, whereas DOC yields were closely linked to annual runoff and thus were more dependent on interannual variation in spring runoff. Nitrate yields were highest in the third year post-wildfire. Results from this study quantitatively demonstrate that water quality can be altered for several years after wildfire. Because the southwestern US is prone to wildfires and high-intensity rain storms, the role of storms in post-wildfire water-quality impacts must be considered when assessing water-quality vulnerability.https://doi.org/10.1088/1748-9326/10/8/084007wildfireforestswater qualitylandscape disturbancerainfall intensityclimate change |
| spellingShingle | Sheila F Murphy Jeffrey H Writer R Blaine McCleskey Deborah A Martin The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire Environmental Research Letters wildfire forests water quality landscape disturbance rainfall intensity climate change |
| title | The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire |
| title_full | The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire |
| title_fullStr | The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire |
| title_full_unstemmed | The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire |
| title_short | The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire |
| title_sort | role of precipitation type intensity and spatial distribution in source water quality after wildfire |
| topic | wildfire forests water quality landscape disturbance rainfall intensity climate change |
| url | https://doi.org/10.1088/1748-9326/10/8/084007 |
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