Ramsar Convention (RC) is the first of modern intergovernmental agreement on the conscious use and conservation of natural resources. It provides a platform for contracting parties working together to develop the best available data, advice, and policy recommendations to increase awareness of the benefits of wetlands in nature and society. Turkey became a party of the RC in 1994, and in the years 1994 to 2013, 14 wetlands that reached the Ramsar criteria were recognized as Ramsar sites (RS). With this study, all inland RS in Turkey from 1985 to 2020 were examined, and changes in the water surface areas were evaluated on the GEE cloud computing platform using Landsat satellite images and the NDWI index. The closest meteorological station data to each RS were evaluated and associated with the surface area changes. The reasons for the changes in these areas, besides the meteorological effects, have been scrutinized using management plans and publications. As a result, inland wetlands decreased at different rates from 1985 to 2020, with a total loss of 31.38% and 21571.0 ha for the spring months. Since the designation dates of RS, the total amount of water surface area reduction was 27.35 %, constituting 17,758.90 ha.
Water resources in the world are becoming scarce due to both natural climatic conditions under the effect of climate change and human-induced activities. The population is rising day-by-day leading to a steady decrease in water resources, which in turn, highly disturbs the natural ecological functions of the vulnerable systems. Lakes can be addressed as important water bodies that are under the effect of shrinkage in different parts of the world, and if no remedial measures are taken, they will disappear in the near future. Lake Burdur in Turkey is among such lakes that lose its water volume over time. This study was performed via a group of interdisciplinary scientists to analyze the spatial and temporal changes in the water surface area in the long-term and in the short-term (2016-2020) with the aim of putting forth the areal changes. Remote sensing technology was utilized for this purpose. Landsat imagery and Sentinel 2 images were utilized for the long and short-term assessments, respectively. Meteorological conditions during the inspection terms were obtained from the State Meteorological Service to determine the dominating reason(s) of area changes over time. Natural conditions and anthropogenic activities are linked with the findings. Resultantly, water withdrawals from the dams and reservoirs built in the region and from the streams feeding the lake for irrigation purposes during the dry season representing the human-induced activities dominate over the natural causes of climate change as is the case in most of the water bodies of the world. This outcome was also confirmed by a detailed analysis of the agricultural areas in the basin through satellite images and by field trips made at site.
Remote sensing that is a low cost data source capable of making temporal observations has more advantages than the traditional methods to obtain land-use/cover change maps. In this study, temporal land-use/cover change of surface water bodies in Konya Closed Basin was evaluated via Landsat satellite images for the past 30 years. The basin, located in Central Anatolia Region of Turkey, faces water scarcity problems; however, wet agricultural activities are still favoured and practiced. Therefore, water resources are becoming more important than ever; public complains about long-lasting drought conditions and on lessening of surface water resources. There are 16 surface water bodies, and 3 of them are lakes; whereas the rest are wetlands of importance. Two of them are Ramsar sites. Results indicate that the surface area of the water bodies in Konya Closed Basin declined by approximately 23.5% within the inspection years. One of the important wetlands of the basin named as Akgol Wetland has almost lost its water surface by 96% at the same time interval, and is in danger of extinction. Thus, this vulnerable wetland has been focused on in the study. The decrease of water surface in the wetland is matched with the meteorological conditions.
<p><strong>Abstract.</strong> A flood, one of the most devastating natural disasters in the world, occurs when water inundates land that's normally dry. Although floods can develop in many ways, river floods (i.e. overflow by rivers or river banks) are the most common. Turkey is one of the flood-affected countries with its 20 main basins in 8 regions. One of the most aggrieved basins in Turkey is the Maritsa river basin in in Eastern Balkans, which also contains the natural border regions with Greece and Bulgaria. 65% of the Maritsa River basin, which originates from the Rila Mountains and joins the Arda and Tundzha rivers, is located in Bulgaria. When the melting snow flow or precipitation in the basin increases, the Maritsa River overflows from the slopes to the Edirne Plain and from time to time exceeds the capacity of the bed, causing floods. On the other hand, since the water level in the dams and reservoirs was kept at the highest level for production purposes, the flood repeat interval increased in the region, since 2000s. Today, it is possible to monitor and evaluate the damages of flood by obtaining very reliable information with space technology. Especially, microwave SAR images that can penetrate clouds, are of great importance in flood mapping because they provide immediate information on the extent of inundation and support the evaluation of property and environmental damages. In this study, rapid flood risk assessment in the region was performed using Landsat 8 and Sentinel 2 Normalized Difference Water Index (NDWI) time series images, and calibrated Sentinel 1 SAR images produced on Google Earth Engine (GEE) platform for 2015-2018 period. GEE is a cloud-based platform that facilitates access to high-performance computing resources to handle very large geographic data sets. The results were compared and verified using meteorological data, riverbed flow data, and digital media news. The results showed that the most affected areas were consistent with the highest measured flow rates and the magnitude of flood damages caused by two main causes in the basin (i.e. opening of shutters in Bulgarian dams or local excessive rainfall) was very different (approximately 8 times larger) from each other.</p>
Deltas and lagoons, which contain many flora and fauna, have rich coastal ecological and biological environments, and are wetlands of vital importance for humans. In this study, the current problems in all coastal Ramsar sites in Turkey are summarized, and changes in water surface areas are investigated using Landsat and Sentinel 1/2 satellite images on the Google Earth Engine (GEE) cloud computing platform. Landsat TM and OLI images were used in the long-term analysis, and time series were created by taking annual and July to September averages between 1985 and 2020. In the short-term analysis, monthly averages were determined using Sentinel 2 images between 2016 and 2020. Sentinel-1 Synthetic Aperture Radar (SAR) images were used in the months when optical data were not suitable for use in monthly analysis. The Normalized Difference Water Index (NDWI) was used to extract water surface areas from the optical images. Afterwards, a thresholding process was used for both optical and radar images to determine the changes. The changes were analyzed together with the meteorological data and the information obtained from the management plans and related studies in the literature. Changes in the water surface areas of all coastal Ramsar sites in Turkey were determined from 1985 to 2020 at different rates. There was a decreasing trend in the Goksu and Kızılırmak Deltas, which also have inland wetlands. The decreasing rates from 1985 to 2020 were −24.52% and −2.86%, for annual average water surfaces for the Goksu and Kızılırmak Deltas, respectively, and −21.64% and −6.34% for the dry season averages, respectively. However, Akyatan Lagoon, which also has inland wetlands, showed an increasing trend. Observing the annual average surface area from 1985 to 2020, an increase of 438 ha was seen, corresponding to 7.65%. Every year, there was an increasing trend in the Gediz Delta and Yumurtalık Lagoons, that do not have inland wetlands. The increasing rates from 1985 to 2020 were 46.01% and 17.31% for the annual average surface area, for the Gediz Delta and Yumurtalık Lagoons, respectively, and 38.34% and 21.04% for the dry season average, respectively. The obtained results reveal the importance of using remote sensing methods in formulating strategies for the sustainable management of wetlands.
Advances in remote sensing technology enable monitoring and detection of these vulnerable water bodies that bear numerous functions and ecological services beyond their intended use. As such, valuable data and information may be provided for long and short‐term analyses and stored in a database for future projections. This paper initially grouped 18 natural lakes of the Konya Closed Basin of Turkey according to their salinity level. Freshwater, saline and brackish lakes have then undergone temporal analysis for every 5‐year intervals via Landsat satellite images. Freshwater lake surfaces have not changed noticeably during the inspection period; however, saline waters have decreased in surface area by 32%. Beysehir Lake constituting 94% of the freshwater category and Tuz Lake representing 97% of the saline group were selected for the short‐term analysis that was monthly conducted for years 2017 and 2018 with optical and SAR images to better verify cause and effect relationship.
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