Tümay Kadakci Koca

Post‐fire erosion in Mediterranean environments often persists beyond the first year after burning, yet most assessments focus on short‐term responses. This study examines how soil erodibility changes over three post‐fire years in a limestone‐dominated microbasin in southwestern Türkiye. It evaluates whether widely used empirical soil erodibility (K‐factor) equations can represent medium‐term post‐fire erodibility and how satellite‐based surface deformation measurements can assist their interpretation. Soil properties were measured repeatedly across burn severity (BS) classes, slope aspects and slope positions and analysed together with BS indices and Interferometric Synthetic Aperture Radar (InSAR) time series analysis. Unsaturated hydraulic conductivity and shear strength showed strong relationships with K‐factors, indicating that these parameters are closely linked to post‐fire erodibility changes. InSAR‐derived negative vertical displacement rates, interpreted as a proxy for erosion‐related surface deformation, increased by 45% in the first post‐fire year, peaked at 48% in the second year and declined below pre‐fire levels by the third year. These trends indicate delayed soil recovery relative to vegetation regrowth and a gradual reduction in the influence of BS on surface deformation. Among the compared K‐factor equations, the equations of Wischmeier and Smith's equation most effectively captured short‐term spatial differences between BS classes, whereas the equation of Auerswald et al.'s equation better represented interannual surface deformation trends. In addition, BS‐ and year‐based K‐factor multipliers were proposed to estimate the erodibility of burned soils from unburned reference soils. Overall, the results demonstrate that post‐fire erodibility evolves over time rather than remaining static and that InSAR provides valuable complementary information for monitoring medium‐term erosion dynamics in Mediterranean landscapes.

Wildfires initiate a hazard chain that significantly alters landscapes and geohydrological processes. In addition to the extensively documented effects on vegetation, soil erosion, and debris flows, steep and rocky terrains may experience delayed yet persistent slope instabilities. However, post-wildfire hazard assessment frameworks still predominantly use the soil burn severity indicators for any type of mass wasting processes, while the response of rock masses and their contribution to post-fire hazards remain underrepresented.This study addresses this gap by proposing an integrated, rapid assessment approach to evaluate post-wildfire rock slope instability. The motivation of this study is the necessity of cost-effective and timely tools that support emergency response and short- to medium-term risk management in mountainous Mediterranean environments where infrastructure, settlements, and transportation corridors are exposed to post-fire hazards.The proposed methodology combines Sentinel-2 Level-2A multispectral imagery with field-based observations. Burn severity was mapped using the differenced Normalized Burn Ratio (dNBR), and field surveys were conducted to validate spectral classifications and to identify fire-induced rock degradation indicators. In contrast to conventional soil burn severity observations, special attention was given to rock-specific responses. The rock burn severity indicators were semi-quantitatively evaluated and integrated within a GIS-based framework to identify potential slope sectors with increased rockfall susceptibility.Results show that wildfire-induced thermal alteration can significantly weaken carbonate rock surfaces and discontinuities without necessarily leading to rapid slope failures. Wildfire functions as a conditioning mechanism that elevates the susceptibility of rock slopes to subsequent triggers, including rainfall infiltration, runoff concentration, and solar radiation cycles. The study emphasizes the importance of incorporating rock-specific burn severity indicators into post-wildfire rock slope stability assessments. Such an approach supports more comprehensive risk inventories and improves prioritization of mitigation and monitoring strategies. The findings contribute to ongoing efforts to integrate field observations and remote sensing.

Farklı kütle özelliklerine sahip kayaç kütlelerinin taşıma gücünü en doğru şekilde tahmin eden yöntemlerin seçiminde karşılaştırmalı çalışmalar önem kazanmaktadır. Hangi yöntemin daha sağlam sonuçlar verdiği dayandıkları parametrelerle ilişkili olmaktadır. Bu çalışmada, Miyosen yaşlı Kalabak Tepe (İzmir) kireçtaşlarının taşıma gücü incelemesi değişik yöntemler uygulanarak gerçekleştirilmiştir. Kayaç kütle özellikleri Genelleştirilmiş Hoek-Brown yenilme ölçütü dikkate alınarak belirlenmiştir. Taşıma gücü için uygun yöntemlerin belirlenmesinde arazi modeli ve süreksizliklerin konumları dikkate alınmıştır. Kayacın kütle dayanım parametreleriyle birlikte limit analiz veya sonlu elemanlar yöntemlerinin taşıma gücü analizlerinde kullanılması uygun bir yaklaşım olmaktadır. Sonlu elemanlar yöntemiyle kireçtaşlarının nihai taşıma gücü, limit analiz yöntemlerinden elde edilenlerle karşılaştırılmıştır. Sonuç olarak, bazı limit analiz yöntemlerinden elde edilen sonuçlar, sonlu elemanlar ve diğer limit analiz yöntemlerinden elde edilenlerden daha yüksek bulunmuştur. Yöntemler arasındaki bulgu farklılıkları detaylıca tartışılarak yöntemlerin pratik kullanımına ışık tutulmuştur.

Fracture toughness is an important phenomenon to reveal the actual strength of fractured rock materials. It is, therefore, crucial to use the fracture toughness models principally for simulating the performance of fractured rock medium. In this study, the mode-I fracture toughness (KIC) was investigated using several soft computing techniques. For this purpose, an extensive literature survey was carried out to obtain a comprehensive database that includes simple and widely used mechanical rock parameters such as uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS). Several soft computing techniques such as artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), gene expression programming (GEP), and multivariate adaptive regression spline (MARS) were attempted to reveal the availability of these methods to estimate the KIC. Among these techniques, it was determined that ANN presents the best prediction capability. The correlation of determination value (R2) for the proposed ANN model is 0.90, showing its relative success. In this manner, the present study can be declared a case study, indicating the applicability of several soft computing techniques for the evaluation of KIC. However, the number of samples for different rock types should be increased to improve the established predictive models in future studies.

The changes in physical, chemical, and mineralogical properties of topsoil after forest fires and their relevancy with erosion risk have been so far studied for different geographical regions and ecosystems. It is well known that the risk of erosion increases due to the loss of shear strength and the changes in hydraulic properties after the fire. The consistency limits are strongly related to the shear strength of the soil. Nevertheless, a few studies evaluated the consistency limits of naturally burned soils. In addition, determination of the consistency limits of sandy soils can be very challenging owing to their low plasticity. The temperatures produced by the forest fire that occurred on the left flank of an irrigation dam in Muğla, Kozağaç village affected the topsoil. Hence, grain size distribution, soil organic content (SOM), and Atterberg limits of 24 soil specimens collected from the burned and unburned locations were studied. It was found that the grain size distribution of the burned soil did not significantly change whereas clay content and Atterberg limits increased, and SOM decreased. The methodology followed in this study and the results can be served as a base for future studies of fire effects on sandy soils.