2:30 PM - 2:45 PM
[HGG03-04] Landform Classification by Satellite Image Interpretation and Ground Truth: A Case Study of The Central Area in Ratnapura, Sri Lanka
Keywords:satellite image, landform classification, Sri Lanka, land use
In this study, we developed a novel method for interpreting landform using satellite images, confirmed the landform of the study area, and elucidated the relationship between landform and land use. The study area is in the central part of the Ratnapura District in southern part of Sri Lanka. The geology consists of Precambrian metamorphosed sedimentary rock, specifically gneiss. The area can be primarily classified into mountainous areas and lowland areas. The altitude in the lowland area is several tens of meters, while in the mountainous area, it is approximately 500 meters. An anaglyph was created from a pair of stereo images, consisting of forward and backward images captured by WorldView-3. The landform was interpreted by stereoscopic techniques with an anaglyph. In the lowland area, the river channel, abandoned river channel, natural levee, back marsh, and terrace can be classified. In mountainous areas, landslide mass, talus cone, high hill, and low hill could be classified.
Although Sri Lanka is part of Gondwana and possesses ancient geological formations, a lot of landslides have occurred in the mountainous areas, resulting in landslide masses and talus cones. Residential areas are situated on low hills, terraces, and natural levees, while paddy fields are visible in back marshes and abandoned river channels. There are residency restrictions, and many gemstone mines are located in back marshes. Forests and rubber plantations are commonly found in high hills, talus cones, and landslide masses. Residential areas are also located on the marginal zones of talus cones and landslide masses near the terrace height. The urban area of Ratnapura is primarily developed on terraces. It has been confirmed that the average flood level reaches the height of the natural levee, while the extreme flood level reaches the height of the terrace. In conclusion, the classification of landforms based on satellite images clearly reflects the local landform conditions. Residents are mitigating the risk of flooding by adapting land use and housing to such conditions.
We are extremely grateful to all the staff of the Ministry of Health, Government of Sri Lanka, for their kind assistance during our field survey.
Although Sri Lanka is part of Gondwana and possesses ancient geological formations, a lot of landslides have occurred in the mountainous areas, resulting in landslide masses and talus cones. Residential areas are situated on low hills, terraces, and natural levees, while paddy fields are visible in back marshes and abandoned river channels. There are residency restrictions, and many gemstone mines are located in back marshes. Forests and rubber plantations are commonly found in high hills, talus cones, and landslide masses. Residential areas are also located on the marginal zones of talus cones and landslide masses near the terrace height. The urban area of Ratnapura is primarily developed on terraces. It has been confirmed that the average flood level reaches the height of the natural levee, while the extreme flood level reaches the height of the terrace. In conclusion, the classification of landforms based on satellite images clearly reflects the local landform conditions. Residents are mitigating the risk of flooding by adapting land use and housing to such conditions.
We are extremely grateful to all the staff of the Ministry of Health, Government of Sri Lanka, for their kind assistance during our field survey.