| Title: | Assessing the hydrologic response to wildfires in mountainous regions |
| Authors: | Havel, A., A. Tasdighi and M. Arabi |
| Year: | 2018 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 22 |
| Pages: | 2527-2550 |
| Article ID: | |
| DOI: | 10.5194/hess-22-2527-2018 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | land use change |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | 5,230 km^2 Poudre River, which drains portions of southeast Wyoming and north central Colorado, U.S. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | This study aims to understand the hydrologic responses
to wildfires in mountainous regions at various spatial
scales. The Soil andWater Assessment Tool (SWAT) was
used to evaluate the hydrologic responses of the upper Cache
la Poudre Watershed in Colorado to the 2012 High Park and
Hewlett wildfire events. A baseline SWAT model was established
to simulate the hydrology of the study area between
the years 2000 and 2014. A procedure involving land use
and curve number updating was implemented to assess the
effects of wildfires. Application of the proposed procedure
provides the ability to simulate the hydrologic response to
wildfires seamlessly through mimicking the dynamic of the
changes due to wildfires. The wildfire effects on curve numbers
were determined comparing the probability distribution
of curve numbers after calibrating the model for pre- and
post-wildfire conditions. Daily calibration and testing of the
model produced “very good” results. No-wildfire and wildfire
scenarios were created and compared to quantify changes
in average annual total runoff volume, water budgets, and full
streamflow statistics at different spatial scales. At the watershed
scale, wildfire conditions showed little impact on the
hydrologic responses. However, a runoff increase up to 75%
was observed between the scenarios in sub-watersheds with
high burn intensity. Generally, higher surface runoff and decreased
subsurface flow were observed under post-wildfire
conditions. Flow duration curves developed for burned subwatersheds
using full streamflow statistics showed that less
frequent streamflows become greater in magnitude. A linear
regression model was developed to assess the relationship
between percent burned area and runoff increase in
Cache la Poudre Watershed. A strong (R2 >0.8) and significant
(p <0.001) positive correlation was determined between
runoff increase and percentage of burned area upstream.
This study showed that the effects of wildfires on
hydrology of a watershed are scale-dependent. Also, using
full streamflow statistics through application of flow duration
curves revealed that the wildfires had a higher effect on
peak flows, which may increase the risk of flash floods in
post-wildfire conditions. |
| Language: | English |
| Keywords: | |