Ecological Modelling 468 (2022) 109959 Available online 15 March 2022 0304-3800/© 2022 Elsevier B.V. All rights reserved. Predicting the potential impact of forest fres on runoff and sediment loads using a distributed hydrological modeling approach Rouhollah Nasirzadehdizaji * , Dilek Eren Akyuz Department of Civil Engineering, Engineering Faculty, Istanbul University - Cerrahpasa, Avcilar, Istanbul, 34320 Turkey A R T I C L E INFO Keywords: Wildfre Land use change SWAT hydrological model Erosion Sediment yield Watershed management ABSTRACT Forest fres profoundly affect the nature of watershed responses to precipitation, increases in runoff rate and volume, and post-fre sediment discharge. A post-fre watershed assessment to identify potential trouble spots for soil erosion and fooding can help land managers for decision-making on deploy mitigation, remediation mea- sures, and restoration action plans. Predicting the potential impact of fres on runoff and soil erosion requires distributed hydrological modeling methods. This study used the Soil and Water Assessment Tool (SWAT), a rainfall-runoff model, to investigate the hydrological consequences of forest fres and their impact on sediment load under different burnt scenarios. For the pre-fre (baseline) scenario, the watershed is calibrated by using the measured discharge and suspended sediment concentration data from the weather station during the time step to estimate post-fre changes at the sub-catchment scale. The total water and sediment yield for the selected sub- catchment in the post-fre scenario with the highest spatial distribution of forest fre, due to the excessive sur- face runoff (an increase of 14.5%) increased signifcantly, resulted in 6.5 times increase in sediment yield. The results obtained from the study indicate a signifcant increase in sediment transport into the stream in the post- fre scenario. A large volume of soil losses occurred during the time step. In contrast, due to removing trees and vegetation from the ground, less evapotranspiration and infltration occurred in selected sub-catchment areas after forest fres. In terms of watershed management, understanding the consequences of forest fres on hydro- logical services will be an effective method for sediment budget control. Therefore, applying the rainfall-runoff and erosion models for the watershed with developing plausible forest fre scenarios can be a productive method to deal with the threats and hydrological risks such as soil erosion and sediment transfer to the downstream environment. 1. Introduction Erosion and related issues have always presented signifcant chal- lenges in water resources management and development. Water consistently erodes sediment from the bed and banks of the reaches and carries it downriver through the catchment. Different phenomena such as ground deformations or landslides can also lead to the overrun of sediments in the river system and forming an unexpected build-up of sediments deposition. In addition to the naturally-occurring sediment, the impact of activities such as agriculture, deforestation, mining, ur- banization, and road building on soil erosion rates is inevitable (Amundson et al., 2015; Hassan et al., 2017). A signifcant cause of changes in sedimentation and erosion patterns is through hydrological modifcations in the forests. Forests have a variety of ecological and hydrological benefts, for example, contributing to enhanced infltration and water retention. The fltration process in the soil column helps to improve water quality (Bredemeier, 2010). Furthermore, the combined effects of vegetation, litter cover, and reduced water yield imply decreased erosion rates under forest cover, baseline sedimentation, reducing food hazards, and affecting both the soil quality and the downstream aquatic environments (Farley et al., 2005; Schüler, 2006). Therefore, through the changes in hydrological processes, deforestation and degradation of forests cause signifcant downstream impacts to the freshwater and estuarine environments, increasing the amount of sedi- ment (Iwata et al., 2003; Pattanayak and Wendland 2007). Forest fres are the most common way of degrading forests and their ecosystems. Forest fres seriously affect ecosystems and cause lost totally or partly forests positive effects; i.e., soil erosion protection, enrichment of soil properties (Certini, 2005), decreasing hydrophobicity, enhancing infltration capacity, and decreasing surface runoff (Martin and Moody * Corresponding author. E-mail address: rouhollahn@ogr.iu.edu.tr (R. Nasirzadehdizaji). Contents lists available at ScienceDirect Ecological Modelling journal homepage: www.elsevier.com/locate/ecolmodel https://doi.org/10.1016/j.ecolmodel.2022.109959 Received 27 January 2022; Received in revised form 27 February 2022; Accepted 9 March 2022