The effect of post-wildfire management practices on vegetation recovery: Insights from the Sapadere fire, Antalya, Türkiye

Post-wildfire management actions mainly targeting the removal of salvage logs and burned trees is a common but controversial practice. Although it aims to regain some of the natural and economic value of a forest, it also requires disturbing burned areas, which may have some negative consequences affecting, for instance, the carbon cycle, soil erosion, and vegetation cover. Observations from different geographic settings contribute to this scientific debate, and yet, the spatiotemporal evolution of the post-fire road network developed as part of fire management practices and its influence on vegetation recovery has been rarely examined. Specifically, we still lack observations from Türkiye, though wildfires are a common event. This research examined the evolution of the vegetation cover in relation to post-fire road constructions and the resultant debris materials in areas affected by the 2017 Sapadere fire in Antalya, Türkiye. We used multi-sensor, multi-temporal optical satellite data and monitored the variation in both vegetation cover and road network from the pre-to post-fire periods between 2014 and 2021. Our results showed that fire management practices almost doubled the road network in the post-fire period, from 487 km to 900 km. Overall, 7% of the burned area was affected by these practices. As a result, vegetation cover in those areas shows only ∼50% recovery, whereas undisturbed areas exhibit ∼100% recovery 5 years after the event. Notably, such spatiotemporal analysis carried out for different burned areas would provide a better insight into the most suitable post-fire management practices. Our findings, in particular, show that the current practices need to be revisited as they cause a delay in vegetation recovery

A Case Study For Urban Atlas Project: Gaziantep City

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2014Gaziantep şehri sanayi, ticaret, turizm gibi farklı sektörlerde yapılan yatırımlar nedeni ile Türkiye genelinde gelişmekte olan şehirlerin başında gelmektedir. Yapılan yatırımların sonucu olarak bölge ekonomisinin gelişmesiyle beraber, aldığı göçler nedeni ile şehrin nüfusu artmaktadır. Gaziantep şehir nüfusunun her yıl yaklaşık olarak 50.000 civarında arttığı ve yıl bazında nüfus sayılarının ise 2010 yılında 1.700.763, 2011 yılında 1.753.596, 2012 yılında ise 1.799.558 olarak görülmektedir. Artan nüfusa paralel olarak hızlı bir şekilde yerleşim ve endüstri alanlarının gelişerek yayıldığı gözlemlenmektedir. Uzaktan algılama, veri ve veri işleme teknikleri, sağladıkları hızlı ve ekonomik çözümler nedeniyle, şehir ve bölge planlama, haritacılık işlemleri, tarım ürünlerinin izlenmesi ve yıllık ürün tahminlerinin yapılması, su alanlarının belirlenmesi gibi pek çok farklı çalışma konularında yaygın olarak kullanılmaktadır. Uzaktan algılama sistemleri, şehirlerin ve ülkelerin arazi kullanımı/örtüsü hakkında bilgiye ulaşılmasında en kısa ve en tercih edilen yöntemlerdendir. Şehir planlaması ve şehirlerin gelişimimin mekânsal ve zamansal olarak tespit edilebilmesi için özellikle yüksek çözünürlüklü uydu verileri önemli bilgiler sağlamaktadır. Uydu teknolojileri, klasik yersel ölçümler ile kıyaslandığında, harita üretimi ve şehir planlama uygulamalarında hız, maliyet ve zaman açısından önemli avantajlar sağlamaktadır. Bu çalışmada, Gaziantep şehri için uydu görüntüleri kullanılarak, şehir planlaması uygulamalarına altlık oluşturması ve yerleşim gelişiminin tespiti için arazi kullanım verisinin üretilmesi hedeflenmiştir. Urban Atlas (Şehir Atlası) projesi, uydu görüntüleri üzerinden yüksek tematik detay içeren arazi kullanımı/örtüsü haritalarının oluşturulması ile düzenli ve hızlı bir şekilde şehir ve bölge planlamalarına katkı sağlamak amacıyla oluşturulan bir çalışmadır. GMES (Global Monitoring for Environment and Security) uygulamalarının bir parçası olan Urban Atlas, ERDF (European Regional Development Fund) ve Avrupa Komisyonu (EC) tarafından finanse edilmiştir. Urban Atlas projesi şu ana kadar Türkiye'de herhangi bir bölgede uygulanmamıştır. Bu tez çalışmasının amacı Urban Atlas projesindeki istekleri karşılayacak şekilde Gaziantep iline ait arazi kullanım haritalarının hazırlanması ve şehir atlası metodojisinin ilk kez Türkiye için seçilmiş pilot bir ilde uygulanabilirliğinin ve doğruluğunun incelenmesidir. Bu amaç doğrultusunda, 2013 yılı ağustos ayına ait Spot-5 2.5 m çözünürlüklü uydu görüntüleri ile nesne tabanlı sınıflandırma işlemi yapılarak Urban Atlas terminolojisindeki alt sınıfları içerecek şekilde sınıflandırma yapılmıştır. Sınıflandırma sırasında, uydu görüntülerine ek olarak, sayısal imar planlarından, şehir haritalarından, yol verilerinden, mekânsal nesneler hakkında öznitelik ve görsel bilgiler sağlayan çevrimiçi haritalardan (Google Earth, OGM Meşçere haritaları vb.) yararlanılmıştır. Gaziantep şehrine ait görüntülerin segmentasyonu ile oluşturulan objeler, Şehir Atlası uygulamasında bulunan arazi kullanım/örtüsü sınıflarına istenilen doğrulukla atanmaları sağlanmıştır. Sınıflandırma sonucu genel sınıflandırma, şehir alanları sınıflandırması ve kırsal alanlar sınıflandırması için doğruluk analizleri yapılmıştır. Doğruluk analizleri sonucunda hesaplanan sınıf doğrulukları ve genel doğruluklar, Şehir Atlası uygulamaları için belirlenen minimum sınıf ve genel doğruluk ölçülerini sağladığı görülmüştür. Gaziantep Şehir Atlası sınıfları haritaları oluşturulmak üzere vektör veriye dönüştürülmüştür. CBS ortamında, sınıflandırılmış vektör veriler düzenlenerek Gaziantep Şehir Atlası oluşturulmuş ve yapılan işlemin doğruluğu ortaya konulmuştur.Gaziantep is one of the world's oldest residential area and it is center of culture and commerce with historic Silk Road. Gaziantep's location, which is an important gateway, is within the Southeast Region of the Mediterranean region. Therefore residential and industrial areas has expanded in this city. Gaziantep, with its investments in varied sectors like industry, commerce and tourism, has risen to the forefront of Turkey's developing cities. The population of the city of Gaziantep has been increasing as a result development of the regional economy due to investments, and influence of immigration. With a population of over 1.000.000, it is the 8th largest city in Turkey. The population of Gaziantep has experienced an annual growth of 50.000 per year, with the numbers counting of 1.700.763 in 2010, 1.753.596 in 2011, and 1.799.558 in 2012. Parallel to the rising population, the rapid spread of residential and industrial areas has been observed. Due to the fast and economic solutions provided by remote sensing data and data processing techniques, these techniques have been used in a variety of disciplines such as; urban and region planning, mapping processes, observation of agricultural yield and yearly yield estimates, and the determination of water surface areas. Remote sensing is one of the fastest and most preferred methods of producing information about the land use/cover of cities and countries. High resolution satellite images are extremly useful to be used for spatio-temporal monitoring of cities, planning and development plants and decision support for city managers and planers. Fast, accurate, cost and time effective map production and urban planning projects could be succesfully using remote sensing technologies. In this study, the aim of project is producing usable land use data for urban planning projects and to determine residential growth with satellite images of Gaziantep. Producing land use/cover maps with high tematic details from satellite images for Urban Atlas Projects, which contibutes urban and regional planning in an orderly and quickly. Urban Atlas is a part of GMES (Global Monitoring for Environment and Security) Projects, which is funded by ERDF (European Regional Development Fund) and the European Commission (EC). Urban Atlas project has never been used in any city of Turkey. The purpose of this thesis study is to produce land use/cover maps belonging the Gaziantep with maps' standards of Urban Atlas Project and examining to feasibility and accuracy of Urban Atlas in a pilot city of Turkey for the first time. Urban Atlas Project includes twenty classes. Four of them are their main classes. Which is artificial surfaces, agricultural, semi-natural and wetland areas, forest areas and water surface areas. Other classes for urban areas are included into artificial surfaces class. These classes describe ratio of urban areas, type of buildings, roads and construction or mineral areas. The surface objects are classified and identified within Urban Atlas land use/cover classes. Data types are determined with surface objects' features and proposed data for using into Urban Atlas Projects. In order to inrease the accuracy and save time in the process chain, the city of Gaziantep was separated into 7 regions. These regions have been determined through the analysis of satellite images, with the consideration of country borders, residential, forests, agricultural and barren areas. Especially, city center includes lots of urban residential details, therefore which region classificaion process is more important than other regions. To fulfill this aim, object based classification method was used applied to Spot-5 2.5m satellite images obtained in August 2013 to create main classes and sub-classes in Urban Atlas terminology. During the classification process, in addition to satellite images, the project has benefitted from digital development plans, city maps, road data, and online maps that provides visual information and features about locational objects (Google Earth, OGM Meşçere maps etc.). The objects created through the segmentation of images belonging to the city of Gaziantep, were assigned correctly to land use/cover classes found in Urban Atlas Project. The unused layers of vector data were expunged and attiribute properties of vector data were edited to be used in the classification process. By comparing satellite images and vector data, their compatibility within limit of error has been controlled. In this study, for visual interpretation, which has benefitted from one of the most well-known and used maps; Google Earth, and other maps such as yandex maps and Spot 6 satellite images belonging to the same region. These data have been used in order to help with the process of classification through interpreting color, tone, shape, shadow, texture, and pattern features. During the process of segmentation on satellite images, the pixels have been grouped according to shape, color, compactness and scale parameters, and have been made to create segments of similar pixels. During the classification process, different parameters and thematic layers have been used for urban city centers and other districts in order to apply different segmentation processes. Used methods of classification processes are nearest neighbor method, fuzy classification method and visual interpretation, these enables the classification of segments on the images. Fuzy classification method is occured from decision trees, which formed from determined functions and indices has been made. Initially, the main classes of water, forested, residential and roads have been determined. During the classification processes, two different decision trees were created for the urban city centers and other districts. Segments are classified with Urban Atlas minimum mapping unit for each classes. Segments' size are determined with function and showed how many pixels are included in segments. Smaller segments than minimum mapping unit are classified with classification rules into Urban Atlas User Guide. As a results of classification process, accuracy assesment for general classification, classifications of urban and rural areas have been made. The general accuracy and class accuracy of these analyses have been observed to meet the minimum standards for class and general accuracy measures required for the Urban Atlas Project. The classes of the Gaziantep Urban Atlas have been transformed into vector data, to create maps. Into GIS software, the classified vector data has been reformed to create the Gaziantep Urban Atlas and the accuracy of the procedure has been shown. Where residential areas, industrial sites, construction sitesi, roads and green surface are showed with high accuracy into Gaziantep Urban Atlas. Gaziantep Urban Atlas has contributed to city and region planning for generate regular city residential areas and industiral sites in future.Yüksek LisansM.Sc

Modeling Morphodynamic Processes in Meandering Rivers with UAV-Basedmeasurements

Akay, Semih Sami (Arel Author)Accurate surface models are a crucial component of studies of morphodynamic modeling of rivers and river channel evolution. The high flows that rivers have are caused by changes in flood bed or low canal flow, also it changes river channel morphology. Floods that occur during the spring months cause significant geomorphological changes. In addition to this, low flows during the summer also trigger erosion and superficial accumulation in the ongoing process. Using an accurate, high-resolution, seamless surface models of the river channel and floodplain allows to detect morphological changes of the whole river channel more accurately than using traditional methods. This enables a more comprehensive view of the riverbed evolution. Therefore, high-quality topographical data at different scales are required to study fluvial processes and river dynamics. Nowadays, a combination of photogrammetry and Unmanned Aerial Vehicle (UAV) systems is widely used for various applications, especially for 3D surface modelling and large scale mapping. UAV systems offer many advantages in terms of cost and image resolution when compared to terrestrial photogrammetry and satellite remote sensing systems. In the study, aerial imaging was carried out via UAV to produce very high resolution surface models based on Structure from Motion (SfM) technique. Multi-temporal topographic data were produced and morphodynamic processes in the Buyuk Menderes River were modeled. Thus, UAV-based a fast and practical way to derive volumetric quantity of lost/gained soil was developed

High resolution mapping of urban areas using SPOT-5 images and ancillary data

This research aims to propose new rule sets to be used for object based classification of SPOT-5 images to accurately create detailed urban land cover/use maps. In addition to SPOT-5 satellite images, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) maps, cadastral maps, Openstreet maps, road maps and Land Cover maps, were also integrated into classification to increase the accuracy of resulting maps. Gaziantep city, one of the highly populated cities of Turkey with different landscape patterns was selected as the study area. Different rule sets involving spectral, spatial and geometric characteristics were developed to be used for object based classification of 2.5 m resolution Spot-5 satellite images to automatically create urban map of the region. Twenty different land cover/use classes obtained from European Urban Atlas project were applied and an automatic classification approach was suggested for high resolution urban map creation and updating. Integration of different types of data into the classification decision tree increased the performance and accuracy of the suggested approach. The accuracy assessment results illustrated that with the usage of newly proposed rule set algorithms in object-based classification, urban areas represented with seventeen different sub-classes could be mapped with 94 % or higher overall accuracy

UAV-based evaluation of morphological changes induced by extreme rainfall events in meandering rivers.

Morphological changes, caused by the erosion and deposition processes due to water discharge and sediment flux occur, in the banks along the river channels and in the estuaries. Flow rate is one of the most important factors that can change river morphology. The geometric shapes of the meanders and the river flow parameters are crucial components in the areas where erosion or deposition occurs in the meandering rivers. Extreme precipitation triggers erosion on the slopes, which causes significant morphological changes in large areas during and after the event. The flow and sediment amount observed in a river basin with extreme precipitation increases and exceeds the long-term average value. Hereby, erosion severity can be determined by performing spatial analyses on remotely sensed imagery acquired before and after an extreme precipitation event. Changes of erosion and deposition along the river channels and overspill channels can be examined by comparing multi-temporal Unmanned Aerial Vehicle (UAV) based Digital Surface Model (DSM) data. In this study, morphological changes in the Büyük Menderes River located in the western Turkey, were monitored with pre-flood (June 2018), during flood (January 2019), and post-flood (September 2019) UAV surveys, and the spatial and volumetric changes of eroded/deposited sediment were quantified. For this purpose, the DSAS (Digital Shoreline Analysis System) method and the DEM of Difference (DoD) method were used to determine the changes on the riverbank and to compare the periodic volumetric morphological changes. Hereby, Structure from Motion (SfM) photogrammetry technique was exploited to a low-cost UAV derived imagery to achieve riverbank, areal and volumetric changes following the extreme rainfall events extracted from the time series of Tropical Rainfall Measuring Mission (TRMM) satellite data. The change analyses were performed to figure out the periodic morphodynamic variations and the impact of the flood on the selected meandering structures. In conclusion, although the river water level increased by 0.4-5.9 meters with the flood occurred in January 2019, the sediment deposition areas reformed after the flood event, as the water level decreased. Two-year monitoring revealed that the sinuosity index (SI) values changed during the flood approached the pre-flood values over time. Moreover, it was observed that the amount of the deposited sediments in September 2019 approached that of June 2018