''Some examples for the rainfall induced earthflows in the Western Blacksea Region of Turkey

Regional meteorological anomalies induce different types of mass movements. In May 1998, the Western Black Sea Region of Turkey has experienced such a type of meteorological anomaly. Numerous residential and agricultural areas and, engineering lifelines were buried under the floodwaters. Besides the reactivation of many previously delineated landslides, thousands of smallscale landslides mostly in earthflow type occurred in all over the region. The earthflows were mainly developed in flysch type units, which have already presented high landslide concentrations. In this study, three different catchments namely Agustu, Egerci and Kelemen were selected because these subcatchments have the most landslide prone geological units of the region. The targets of this proceeding are to describe the spatial distributions and statistical assessments of the shallow earthflows triggered. The unique condition units (UCU) were employed during the statistical analyses. The numbers of the unique condition units are 4052 for the Agustu subcatchment, 13241 for the Egerci subcatchment and 12314 for the Kelemen subcatchment. The earthflow intensity is the highest in the Agustu subcatchment (0.038 flow/UCU) while this value is the lowest for the Egerci subcatchment (0.0035 flow/UCU)

''Earthflows in a small catchment from eastern black sea region (Turkey): Conditional (Environmental) factors and susceptibility assessments

Islahiye catchment, covering an area of 37.7 km P2 in the eastern Black Sea region, was heavily suffered from earthflows triggered by heavy rainfall in 1995 and 2002 (on July 23). Earthflows caused 17 causalities, four houses were demolished and some engineering lifeline structures were damaged in the catchment. Total 121 earthflows were recorded in the area. The weathering of the rock units, existence of steep slopes and human interaction can be evaluated as the main factors conditioning of earthflows. The main triggering factor of earthflows in the region is rainfall either intensive or long lasting. The majority of the earthflows were occurred in the weathered zones, which is mainly composed of inorganic and organic silts and silty clays of low plasticity. The slopes having more than 30 degrees constitute approximately 50 % of the entire catchment which varies between 1.5 and 4.0 km in width and 13 km in length. The minimum and maximum elevation values are 150 m and 1970 m, respectively. In order to identify other potential earthflow prone areas in the catchment, earthflow susceptibility assessments were performed using logistic regression analyses. The available raster data such as slope, aspect, curvature and elevation data were produced from digital elevation model (DEM) in GIS environment and were employed during the analyses. Two different mapping units namely pixel and unique condition units were used for performing logistic regression analyses. In addition, a comparison of performance of the earthflow susceptibility maps of Islahiye catchment was carried out. It can be said that the susceptibility map prepared based on unique condition units exhibits slightly better performance than that of pixel unit

Application of Fuzzy Logic and Analytical Hierarchy Process (Ahp) To Landslide Susceptibility Mapping At Haraz Watershed, Iran

The main goal of this study is to produce landslide susceptibility maps of a landslide-prone area (Haraz) in Iran by using both fuzzy logic and analytical hierarchy process (AHP) models. At first, landslide locations were identified by aerial photographs and field surveys, and a total of 78 landslides were mapped from various sources. Then, the landslide inventory was randomly split into a training dataset 70 % (55 landslides) for training the models and the remaining 30 % (23 landslides) was used for validation purpose. Twelve data layers, as the landslide conditioning factors, are exploited to detect the most susceptible areas. These factors are slope degree, aspect, plan curvature, altitude, lithology, land use, distance from rivers, distance from roads, distance from faults, stream power index, slope length, and topographic wetness index. Subsequently, landslide susceptibility maps were produced using fuzzy logic and AHP models. For verification, receiver operating characteristics curve and area under the curve approaches were used. The verification results showed that the fuzzy logic model (89.7 %) performed better than AHP (81.1 %) model for the study area. The produced susceptibility maps can be used for general land use planning and hazard mitigation purpose.Wo