Evaluating the effects of forest fire on water balance using fire susceptibility maps

• Published in: Ecological indicators 2020-03, Vol.110, p.105856, Article 105856
• Main Authors: Venkatesh, K., Preethi, K., Ramesh, H.
• Format: Article
• Language: English
• Subjects: Fire susceptibility map; Forest fire; SCS-CN; Stream flow; SWAT; SWAT CUP
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2019.105856

•Secondary satellite datasets were considered for developing fire susceptibility maps.•Usage of Susceptibility maps for estimating effects of fire on water balance was proposed.•Highly susceptible sub basins were analysed for variations in lateral and surface flow.•Around 21.16% increase in burnt area was estimated in 2017 when compared to 2005.•Around 30.83% increase in streamflow between pre and post fire scenarios was observed. Sudden and long term changes in the landscape can be attributed to periodic wildfires which, is a cyclic occurrence at Kudremukh national forest in Western Ghats of India. These land-use changes influence the hydrology of landscape, causing disintegration of soil, loss of biodiversity, changes in stream and flooding. To understand and account for these land-use changes, a new approach was implemented by developing fire susceptibility map from topographic, climatic and human-induced factors and validating it with MODIS (Moderate-resolution Imaging Spectro-radiometer) fire points for discretising accuracy. The fire susceptibility map can be used for studying the long-term (year or more) effects of fire on water balance systems. The fire susceptibility map generated for the years 2005 and 2017 was overlaid with MODIS LULC (Land Use Land Cover) for establishing the post-fire scenario whereas MODIS LULC MCD12Q1 (2005 and 2017) was considered as the no-fire scenario to analyse the intensity of the fire and its effect on streamflow and infiltration. These maps along with historical satellite hydro-climatic datasets, were used to assess the effect of forest fire on hydrological parameters using the SWAT (Soil and Water Assessment Tool) model. No-fire and post-fire conditions were established by modifying SCS-CN (Soil Conservation Service-Curve Number) based on previous works of literature to represent the catchment as unburnt and burnt area. The SWAT model was calibrated (2002–2008) and validated (2009–2012) for establishing a baseline scenario. The sensitive parameters obtained from SUFI-2 (Sequential Uncertainty Fitting) algorithm in SWAT-CUP (Calibration and Uncertainty Programs) were used to simulate stream flows till 2017 due to lack of observed streamflow data for the year 2017. It was inferred that the effect of wildfire on flows in recent years (2017) had increased radically when compared to the flows before a decade (2005), diminishing the rate of infiltration and causing the deficit in groundwater to energise. The methodology c