6 results on '"NDVI"'
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2. Orman Yangın Şiddetinin Google Earth Engine ve Coğrafi Bilgi Sistemleri Kullanarak Analizi: Hatay-Belen Örneği.
- Author
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YILMAZ, Osman Salih, ORUÇ, Mehmet Serdar, ATEŞ, Ali Murat, and GÜLGEN, Fatih
- Subjects
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GEOGRAPHIC information systems , *FOREST fires , *REMOTE-sensing images , *REMOTE sensing , *ALTITUDES , *FOREST fire prevention & control - Abstract
The causes of forest fires in Turkey can be grouped under four main groups such as arson (intentional), carelessness and negligence, natural and unknown fires. Especially the Mediterranean and Aegean regions are the places most affected by these fires. According to the data obtained from the General Directorate of Forestry (OGM), between 1988 and 2019, 4.91 ha forest area was burned per fire only in Hatay. Especially satellite technologies developed in recent years and Remote Sensing (UA) techniques are widely used in the detection of forest fires. In this study, fire severity maps were produced on the Google Earth Engine Platform (GEE) by using the UA method for the forest fire that broke out in the Belen district of Hatay on 09.10.2020. For this purpose, Sentinel-2A (L2A) satellite images dated 04.07.2020 before the fire and 12.10.2020 after the fire were used. The burning severity was graded using the Normalized Differenced Vegetation Index (NDVI), Normalized Burned Ratio (NBR) and NBR differences, Difference Normalized Burned Ratio (dNBR). In addition, elevation, slope, and aspect maps were produced with Geographical Information Systems (GIS) and forest fire was analysed in terms of topographic factors. High burning severity was observed in 50 ha area where the altitude was between 200 - 300 m, in 36 ha area where the slope is more than 30% and in 35 ha area in the eastward. As a result of the analysis, the area with high burning severity in the study area has been calculated as 90.94 ha in total. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Investigation of horizontal vertical and temporal changes of vegetation with NDVI and DEM data (Example of Mardin Savur district)
- Author
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Karadoğan, Sabri, Kavak, Mehmet Tahir, Al, Aladdin, Dicle Üniversitesi, Ziya Gökalp Eğitim Fakültesi, Sosyal Bilimler Bölümü, Karadoğan, Sabri, Kavak, Mehmet Tahir, and Al, Aladdin
- Subjects
Savur ,Vegetation ,Bitki örtüsü ,NDVI ,Coğrafi Bilgi Sistemleri ,Geographic Information Systems ,Remote sensing ,Uzaktan algılama - Abstract
Uzaktan Algılama ile Coğrafi Bilgi Sistemleri teknikleri yeryüzünün doğal özelliklerini, yer ve zamana göre değişiminin gözlemlenmesinde kullanılan yaygın ve güvenilir yöntemlerdendir. Bu yöntemlerin birlikte kullanıldığı en yaygın uygulamalardan biri NDVI (Normalize Edilmiş Fark Bitki Örtüsü İndeksi) analizleridir. NDVI analizi genellikle kuraklığı izlemek, tarımsal verimliliği tahmin etmek veya bölgelere göre bitki örtüsündeki tahribatı belirlemek için yapılan çalışmalarda kullanılır. Böylece doğal döngü açısından önemli bir yere sahip olan bitkilerin ve bitki örtüsünün artış ve azalışının denetlenmesi ve izlenmesi mümkün olabilmektedir. Bu çalışmada, Mardin ili Savur ilçe sınırları içindeki alanı kapsayan 1995-2021 yılları arasındaki 30 m çözünürlüklü Landsat 5, Landsat 8 ve 2000-2021 yılları arasındaki 500 metre çözünürlüklü MODIS (Moderate Resolution Imaging Spectroradiometer) uydu görüntülerinden yararlanılarak NDVI ve DEM (Sayısal Yükselti Modeli) veri katmanları ile sahanın bitki örtüsünün yatay ve dikey yönde dağılımının ve değişiminin belirlenmesi amaçlanmıştır. Bulgular harita ve diyagramlarla değerlendirilmiştir. Remote Sensing and Geographic Information Systems techniques are reliable and common methods that used in examining and observing the natural features of the earth, its change according to place and time. NDVI (Normalized Difference Vegetation Index) analyses are one of the most popular uses of these methods together. Studies that track drought, forecast agricultural output, or identify regional differences in vegetation degradation frequently use NDVI data. As a result, it is feasible to manage and keep track of the growth and decline of vegetation, whichplays a significant role in the natural cycle. In this study, NDVI images were used by utilizing 500-meter-resolution MODIS (Moderate Resolution Imaging Spectroradiometer) satellite images between 2000 and 2021 and 30-meter-resolution Landsat 5, Landsat 8 between 1995 and 2021 to cover the area inside the Savur district of Mardin province. Determining the horizontal and vertical distribution and change of the field's vegetation cover is the goal of DEM (Digital Elevation Model) data layers. Maps and diagrams were used to analyze the findings.
- Published
- 2023
4. Çok Zamanlı Landsat Uydu Görüntülerinin LULC ve NDVI Analizleri ile Ünye İlçesinde Arazi Kullanımı Değişimlerinin Belirlenmesi.
- Author
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KODAY, Saliha and KIZILKAN, Yusuf
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NORMALIZED difference vegetation index , *GEOGRAPHIC information systems , *LAND cover , *LAND use , *VEGETATION dynamics - Abstract
The environment tends to get away from its natural structure due to industrialization and increasing population. The daily activities of human beings continuously change the natural structure of the environment and the process of environmental effects. Agricultural/economical innovations, increasing need of agricultural products and settlement areas cause changes in the vegetation. Detection of these changes was a difficult and time-consuming process in the past. However, with the development of Geographical Information Systems, these changes can be detected more accurately through various methods and analyses today. The most conspicuous ones of these analyses are NDVI and LULC. For determining the land cover changes in Ünye district, the LULC (Land Use Land Cover) "Maximum Likelihood Classifications" and NDVI (Normalized Difference Vegetation Index) analyses were used. Through these analyses and on a multi-time basis, the land cover changes in Ünye district were analyzed between the years 1985-2000-2017. Among the most important causes behind the changes of land use in Ünye district are the wrong land use, increasing population, and increasing need of agricultural lands. The changes in the lands over the years were determined through Remote Sensing and Geographical Information Systems via areal measurement, and subsequently, suggestions were made concerning the sustainability of the land existence. [ABSTRACT FROM AUTHOR]
- Published
- 2019
5. Analysis of multi-year land use/cover change in the Uludag National Park within a GIS
- Author
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Bursa Uludağ Üniversitesi/Ziraat Fakültesi/ Toprak Bilimi ve Bitki Besleme Bölümü. and Özsoy, Gökhan
- Subjects
NDVI ,Land use/cover ,Arazi kullanım/örtü ,Geographic information systems ,Remote sensing ,Uludağ Milli Parkı ,Coğrafi bilgi sistemi ,Uzaktan algılama ,Uludag National Park - Abstract
Bu çalışma ile Türkiye'nin en popüler kayak merkezine ev sahipliği yapan ve doğal güzellikleri bakımından dünyaca tanınan Uludağ Milli Parkı arazilerinin güncel arazi kullanım/örtü durumunun haritalandırılması ve yıllar içindeki olası değişimlerin coğrafi bilgi sistemi içinde tespit edilmesi amaçlanmıştır. Buna yönelik bölgeyi kapsayan, 1985-2019 yılları arası (34 yıllık) çok bantlı uydu verileri kullanılmış, çalışma alanına ait bir veri tabanı kurulmuş ve elde edilen tüm veriler CBS içinde analiz edilmiştir. Sonuçlara göre, Uludağ Milli Parkı sınırları içinde bulunan kayak merkezi ve yakın çevresinde kentleşme ve erozyon izlerinde artış ile beraber vejetasyonda azalma belirlenmiştir. Buna ek olarak zirveye yakın kesimlerde su yüzeylerinde azalma ve çıplak kaya yüzeylerinde artış saptanmıştır. Ayrıca, yıllar içinde şiddetli erozyon yüzeyleri alansal miktarının da arttığı belirlenmiştir. Bu çalışma ile Uludağ Milli Parkı arazilerindeki çıplak kaya, yerleşim ve şiddetli erozyon yüzeylerinin kapladığı alan, 34 yıllık süreçte 1019,6 ha (% 7,8) alandan 1730,7 ha (% 13,3) alana yükseldiği bulunmuştur. Aynı süre içinde, % 18,7 oran ve 2435,2 ha alan kaplayan alpin çayırların ise % 16,6 oran ile 2163,6 ha alana gerilediği tespit edilmiştir. Çalışmanın önemli çıktılarından birisi de doğal ormanlık alanların güncel durumu ile ilgilidir. Bu çalışmada üretilen 1985 yılı verilerine göre, doğal yoğun ormanlar tüm Milli Park arazilerinin % 43,5’ini (5668,1 ha) kaplarken, 2019 yılı için bu oran % 44,2’ye (5759,2 ha) yükselmiştir. Buna ek olarak bazı alanlarda çalı ve fundalık arazilerin de yoğunlaştığı belirlenmiştir. İnsan etkisinin hiç/çok az olduğu, ulaşılması çok zor olan bazı yüksek ve eğimli bölgelerde veya kontrolün sağlanabildiği ormanlık kısımlarda yer alan bitki örtüsünde, incelenen zaman içinde, vejetasyonda az da olsa yoğunlaşma gerçekleştiği tespit edilmiştir. Bu çalışma sonuçlarına göre, insan etkisi kontrol altına alındığında ve gerekli erozyon önleme faaliyetleri ile Uludağ’da zamanla doğal bitki örtüsünün daha da yoğunlaşacağı ve yeşereceği söylenebilir. The aim of this research is to determine the current land use/cover status of the Uludag National Parklands, which is hosting the most popular ski center of the country and world-renowned for its natural beauty, and to investigate the possible land use/cover changes over the years. For this purpose, a time-series satellite data, between 1985-2019 (34 years), was used, a database belonging to the study area was established, and all data obtained were analyzed in GIS. According to results, urbanization and severe erosion surfaces increased in the ski center and its close surroundings along with a decrease in vegetation. In addition, a reduction of water surfaces and an increase in bare rock surfaces were detected in the areas near the summit. It was computed that the area covered by bare rock, settlement, and severe erosion surfaces in the Uludag National Parklands were increased from 1019.6 ha (7.8%) to 1730.7 ha (13.3%) over a 34-year period. In the same studied period, alpine meadows covering 18.7% and 2435.2 ha of land were declined to 2163.6 ha with 16.6%. One of the critical outputs of the study is related to the current status of natural forest areas. According to 1985 data, while dense natural forests were covered 43.5% (5668.1 ha) of the entire National Parklands, this rate was increased to 44.2% (5759.2 ha) according to 2019 data. Besides, it was discovered that vegetation was becoming slightly dense in some high and sloped areas where there was little / no human impact due to transportation difficulties. According to the results of this study, natural vegetation in Uludag may become denser and greener over time when the social impact is brought under control and with the necessary erosion prevention activities.
- Published
- 2021
6. Tokat Ġli Bitki Yoğunluk Sınıflarının LANDSAT-7 ETM+ Uydu Görüntüleri ve Coğrafi Bilgi Sistemleri ile AraĢtırılması.
- Author
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DOĞAN, Hakan Mete, KILIÇ, Orhan Mete, and YILMAZ, Doğaç Sencer
- Abstract
Indices developed for vegetation hold important place in remote sensing technology and they are commonly used. One of them is Normalized Difference Vegetation Index (NDVI) which is developed for vegetation and accepted in worldwide. In this study, spatial distribution of plant density of Tokat province in 2000 was mapped by using LANDSAT-7 ETM+ images and Normalized Difference Vegetation Index (NDVI). Obtained NDVI map was classified as very weak, weak, moderate and intensive plant density classes for the first time by utilizing Braun Blanquet cover abundance classes (BB) and geographic information systems (GIS). The accuracy assessment of the created classes was performed by utilizing ground truth data collected from 103 points throughout the study area. The overall accuracy of NDVI (plant density) classes was found as 86.45 %. The results of the study indicated that the majority of the Tokat province takes place in the moderate class (47.56 %). This was followed by intense (40.36 %), low (7.57 %) and very weak (4.14 %) plant density classes. The remaining areas were evaluated as water surface (0.37 %). The results concretely demonstrated the high potential of Tokat province in terms of plant biological diversity and agriculture. BB assessments were also found to be usable to classify the NDVI values in a reliable way. Thus, a robust background reference was also formed to monitor vegetation cover change in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
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