Hi there,
Scientific efforts in post-fire hydro-geomorphology seem to agree on the dominating importance of the hydro-climatic regime (i.e. precipitation type and timing) on the response of a watershed after a fire. Although variability exists according to scale, fire severity, or soil nature, it appears that post-fire heavy rain or snowmelt can be associated with higher runoff and erosion and eventually higher water and sediment yield.
However, I'm wondering how much topographical settings of a watershed, or of the burned area, can also act as a control of post-fire hydrogeomorphic response, i.e. runoff and erosion? By topographical settings, I mean elevation, ruggedness, slope steepness, curvature, and length, aspect, shape of the watershed or of the burned area...or any metric you could think of to describe a terrain.
To my knowledge, it is something that has hardly been addressed, and only a few papers seem to mention this (I'd be willing to read any reference you may share with me). It also seems that papers focusing on post-fire changes in water or sediment yield, or debris flow, tend to focus on locations displaying a certain level of topographical complexity.
I guess it draws 2 other questions, rather provocative, beside my introductory one:
- Is post-fire hydro-geomorphology "biased" toward complex terrains, especially steeper terrains, because a response is more likely according to general runoff and erosion processes?
- Can we generalize current scientific knowledge and argue that complex terrains, especially those displaying steep slopes, are more likely to experience greater post-fire changes in their hydrogeomorphic regime?
The US FOREST SERVICE may have models on burn intensity and response based on slope, aspect, soils, etc. They use them to assess watershed sensitivity to fire. Fire planning and a prescribed burning program is sometimes used to address fuel buildup and reduce severity. You might have some interest in the post fire plot study in my research gate beginning with Hazel Pistol ... in SW Oregon after severe burning after logging in the late 1970s.
Thanks William, I'll check that.
The USFS/USGS definetely have such models (GeoWEPP is dedicated to post-fire hydrology), and it seems obvious, as runoff-erosion processes are related to topography, that it is the same in burned areas. I think the point of my question here is to either gather papers that include topography as one their post-fire hydro-geomorphologic assessment or/and if general laws of post-fire erosion can be drawn using topographical features and their role in catchment/watershed/basin response.
I think that William has identified the basic source of some long studied activity in fire events. One of the issues I have been interested in has been the disable nature of sediment (soil) when subject to intense heat and how that might increase their instability in both wind and water erosion. There is a quantifiable relationship but I have not seen extensive research with respect to the friability. I suspect that the type of vegetation and root regime would have a role that is fire specific and not a general rule of thumb.
Hi Henry. I agree that the reference given by William is probably one of the oldest. As far as I recall, there are also a few old ones from South-Africa as well.
Specifically related to your interest, you might find this paper by Jorge Mataix-Solera interesting.
Article Fire effects on soil aggregation: A review
I also agree on the fact that trying to draw general laws is rather provocative, especially since post-fire hydrology seems to be fairly limited when comparing the location of many studies to the diversity of world biogeographic biodiversity (i.e. data remain fairly rare and clustered in space), but I think agreeing on a few rules of thumbs could be possible.
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