Spatial and temporal effects of wildfire on the hydrology of a steep rangeland watershed

Abstract

Abstract:Wildfire is a major ecological process and management issue on western rangelands. The impacts of wildfire on hydrologic processes such as infiltration, runoff, and erosion are not well understood. Small-plot rainfall simulation methods were applied in a rangeland wildfire setting to determine post-fire hydrologic response. Infiltration and interrill erosion processes were measured immediately post-fire and one year following the 1999 34 400 ha Denio fire in northwestern Nevada. Plot-scale spatial and temporal variability in fire impacts was compared with adjacent unburned areas. An index of water repellency was derived and used to quantify the influence of water-repellent soil conditions on infiltration. Results indicate the impact of the fire on infiltration was localized primarily on coppice microsites directly under shrubs characterized by high surface litter accumulations. Coppice microsites had very uniform fireinduced soil water repellency with 29 of 30 plots exhibiting at least a 10% reduction in initial infiltration with an average 28% reduction. Cumulative erosion was nearly four times higher on burned coppices compared with unburned coppices. The impact of the fire on infiltration and erosion was reduced, but still evident, 1 year after fire. Significant temporal variability in infiltration between years was observed on both burned and unburned areas, complicating the interpretation of fire impacts and hydrologic recovery following wildfire. Published in

Hydrology of the Upper Indus Basin Under Potential Climate Change Scenarios

“…103.3) corresponds to field observations and confirms similar descriptions found in other studies (Soler et al 1994;Rubio et al 1997;Inbar et al 1998;Robichaud 2000;Pierson et al 2001Pierson et al , 2002. The gully erosion prone areas (GHPA) in the four different scenario conditions are shown in Fig.…”

Ecohydrology: Processes and Implications for Rangelands

“…Similarly significant strides have been made in quantifying the spatial variability of infiltration at the hillslope scale (Berndtsson and Larson 1987;Seyfried 1991;Pierson et al 1994Pierson et al , 2001Bhark and Small 2003;Daryanto et al 2013). Infiltration capacities are generally higher under shrub canopies than in intercanopy areas, and these differences markedly influence patterns of soil moisture Barnes 1994, 1999).…”

New procedure for sampling infiltration to assess post-fire soil water repellency

“…After forest fires, the potential for flooding and erosion dramatically increases, partially due to decreased infiltration across the burned landscape (Pierson andothers 2001, Robichaud 2000). Combustion of the surface organic material (litter and duff) can create water repellent layers within the mineral soil.…”

“…Estimating the reduced infiltration after a fire is essential for modeling post-fire hydrologic processes (Pierson andothers 2001, Robichaud 2000). Because water repellent soils have a large impact on the soil infiltration characteristics, post-fire assessment of the extent and degree of fire-induced soil water repellency is used to estimate the reduction in infiltration (Robichaud and others 2000).…”