SavedAdd your journal

Journals / Erciyes Üniversitesi Fen Bilimleri Enstitüsü Fen Bilimleri Dergisi / 2025 / Cilt: 41 Sayı: 3

Observation of Lake Eğirdir’s Water Surface Level Changes via SWOT Pixel Cloud: Early-Phase Findings (2023–2025)

SWOT Piksel Bulutu Verisiyle Eğirdir Gölü Su Seviyesi Değişimlerinin İzlenmesi: Erken Dönem Bulguları (2023–2025)

Yunus Kaya(HARRAN UNIVERSITY)0000-0003-2319-4998
Pages
856–869
Publication Date
2025-12-31
🏛️Bibliographic metadata and full text access for this article are provided via DergiPark.
DergiPark Record ↗
✨

AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

Preliminary findings indicate a general downward tendency in summer, autumn, winter, and spring relative to the preceding year; these patterns have not been formally tested for statistical significance.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:This study aims to monitor the water-level dynamics of Lake Eğirdir between August 2023 and April 2025 using the SWOT (Surface Water and Ocean Topography) mission’s Level-2 High-Rate Pixel Cloud (L2_HR_PIXC) data product.
📊
Key Findings & Data:A multi-stage quality-filtering workflow—employing classification_qual, interferogram_qual, and geolocation_qual flags—was applied, followed by outlier removal via the Interquartile Range (IQR) method, yielding representative median water-level estimates per overpass.
💡
Conclusion & Impact:Preliminary findings indicate a general downward tendency in summer, autumn, winter, and spring relative to the preceding year; these patterns have not been formally tested for statistical significance.
🔬Design:Araştırma Makalesi
📍Scope:2023 Verileri
⚙️Variables:SWOT · Piksel Bulutu · Eğirdir Gölü

Abstract

This study aims to monitor the water-level dynamics of Lake Eğirdir between August 2023 and April 2025 using the SWOT (Surface Water and Ocean Topography) mission’s Level-2 High-Rate Pixel Cloud (L2_HR_PIXC) data product. Lake boundaries were delineated via a shapefile mask to isolate relevant surface-water measurements. A multi-stage quality-filtering workflow—employing classification_qual, interferogram_qual, and geolocation_qual flags—was applied, followed by outlier removal via the Interquartile Range (IQR) method, yielding representative median water-level estimates per overpass. Ellipsoidal heights from SWOT were corrected for the corresponding geoid undulation to obtain orthometric water levels. Time series constructed from ~36 million filtered point-cloud observations across 150 overpasses were seasonally matched for year-over-year comparison. Preliminary findings indicate a general downward tendency in summer, autumn, winter, and spring relative to the preceding year; these patterns have not been formally tested for statistical significance. A short-lived, opposite-direction uptick is observed in autumn 2024. As an early-phase application, the results suggest that SWOT PIXC data provide meaningful potential—in both spatial and temporal terms—for monitoring mid-sized, morphologically complex inland water bodies, offering supportive capabilities for sustained freshwater observation in the Turkish context.

Özet

Bu çalışma, SWOT (Yüzey Suyu ve Okyanus Topografyası-Surface Water and Ocean Topography) uydusunun L2_HR_PIXC (Seviye-2 Yüksek Oranlı Piksel Bulutu-Level-2 High-Rate Pixel Cloud) veri ürününü kullanarak Eğirdir Gölü’nün 2023 Ağustos – 2025 Nisan dönemi su seviyesi dinamiklerini yüksek doğrulukla izlemeyi amaçlamaktadır. Göl sınırları shapefile ile tanımlanarak yalnızca ilgili su yüzeyinden gelen ölçümler seçilmiş; sınıflama kalitesi, interferogram kalitesi ve konum kalitesi bayrakları ile çok aşamalı filtreleme uygulanmış ve geriye kalan veriler üzerinde çeyrekler açıklığı (IQR) yöntemiyle uç değerler temizlenerek her geçiş için temsilî medyan seviye serileri elde edilmiştir. SWOT’tan sağlanan elipsoidal yükseklikler jeoit ondülasyonu ile düzeltilerek ortometrik su seviyeleri hesaplanmıştır. Analiz edilen 150 geçişten ve yaklaşık 36 milyon piksel bulutu ölçümünden oluşturulan zaman serileri, mevsimsel eşleştirmeyle yıllar arası karşılaştırılmıştır. Ön bulgular, yaz, sonbahar, kış ve ilkbahar dönemlerinde önceki yıla kıyasla genel bir azalış eğilimine işaret etmektedir; ancak bu değerlendirme, resmî istatistiksel anlamlılık testleriyle doğrulanmamıştır. Bununla birlikte, 2024 sonbaharında kısa süreli ve önceki yıla göre ters yönde tekil bir yükseliş gözlenmiştir. Bu erken dönem uygulamanın sonuçları, SWOT PIXC (Piksel Bulutu–Pixel Cloud) verisinin orta ölçekli ve kıyı yapısı karmaşık iç su kütlelerinde, sürdürülebilir su kaynakları izlemeye anlamlı bir potansiyel sunduğunu göstermektedir. Çalışma, Türkiye bağlamında erken dönemli, yüksek nokta yoğunluklu bir SWOT uygulaması olarak özgün bir vaka sunmaktadır.

🔖

Cite This Article

Kaya, Y. (2025). Observation of Lake Eğirdir’s Water Surface Level Changes via SWOT Pixel Cloud: Early-Phase Findings (2023–2025). Erciyes Üniversitesi Fen Bilimleri Enstitüsü Fen Bilimleri Dergisi, Cilt: 41 Sayı: 3, 856–869. https://doi.org/10.65520/erciyesfen.1756182

📄 Full Text PDF Viewer

📄

PDF görüntüleyici hazırlanıyor...

References (40)

  1. Bănăduc, D., Simić, V., Cianfaglione, K., Barinova, S., Afanasyev, S., Öktener, A.,. & Curtean-Bănăduc, A. 2022. Freshwater as a sustainable resource and generator of secondary resources in the 21st century: Stressors, threats, risks, management and protection strategies, and conservation approaches. International Journal of Environmental Research and Public Health, 19(24), 16570.
  2. Bergeron, J., Siles, G., Leconte, R., Trudel, M., Desroches, D., & Peters, D. L. 2020. Assessing the capabilities of the Surface Water and Ocean Topography (SWOT) mission for large lake water surface elevation monitoring under different wind conditions. Hydrology and Earth System Sciences, 24(12), 5985-6000.
  3. Biggs, J., Von Fumetti, S., & Kelly-Quinn, M. 2017. The importance of small waterbodies for biodiversity and ecosystem services: implications for policy makers. Hydrobiologia, 793(1), 3-39.
  4. Crétaux, J. F., & Birkett, C. 2006. Lake studies from satellite radar altimetry. Comptes Rendus Geoscience, 338(14-15), 1098-1112. https://doi.org/10.1016/j.crte.2006.08.002.
  5. Davraz, A., Karaguzel, R., Soyaslan, I., Şener, E., Seyman, F., & Şener, S. 2009. Hydrogeology of karst aquifer systems in SW Turkey and an assessment of water quality and contamination problems. Environmental Geology, 58(5), 973-988.
  6. Feng, Y., & Song, C. 2024. Assessing the impacts of ice penetration on monitoring water levels of high-latitude and -altitude lakes from CryoSat-2 altimetry. Journal of Hydrology, 634, 131147. https://doi.org/10.1016/j.jhydrol.2024.131147.
  7. Girard, F., Kergoat, L., Mainassara, I., Wubda, M., Nikiema, D. E., Touré, A. A.,. & Grippa, M. 2025. Performance of the Surface Water and Ocean Topography (SWOT) Mission for Monitoring Small Lakes in West Africa.IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.
  8. Grippa, M., Rouzies, C., Biancamaria, S., Blumstein, D., Crétaux, J. F., Gal, L.,. & Kergoat, L. 2019. Potential of SWOT for monitoring water volumes in Sahelian ponds and lakes. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(7), 2541-2549.
  9. Kaya, Y. 2025. Evaluation of ICESat-2 Laser Altimetry for Inland Water Level Monitoring: A Case Study of Canadian Lakes. Water, 17(7), 1098.
  10. Kaya, Y., Şanlı, F. B., & Abdikan, S. 2023. Determination of long-term volume change in lakes by integration of UAV and satellite data: the case of Lake Burdur in Türkiye. Environmental Science and Pollution Research, 30(55), 117729-117747.
  11. Kaya, Y., Şanlı, F. B., & Abdikan, S. 2025. Refinement of ICESat-2 derived inland water surface levels with the TG20 local geoid model: In the case of Türkiye lakes. Physics and Chemistry of the Earth, Parts A/B/C, 139, 103900.
  12. Khondoker, M., Mandal, S., Gurav, R., & Hwang, S. 2023. Freshwater shortage, salinity increase, and global food production: A need for sustainable irrigation water desalination—A scoping review. Earth, 4(2), 223-240.
  13. Küçükoğlu, M., & Kaya, Y. (2025). Global evolution of inland water levels: drying-speed analysis using IaCESat-2 ATL13. Journal of Hydrology, 134486.
  14. Lee, H., Shum, C. K., Yi, Y., Ibaraki, M., Kim, J. W., Braun, A.,. & Lu, Z. 2009. Louisiana wetland water level monitoring using retracked TOPEX/POSEIDON altimetry. Marine Geodesy, 32(3), 284-302. https://doi.org/10.1080/01490410903094767.
  15. Maubant, L., Dodd, L., & Tregoning, P. 2025. Assessing the accuracy of SWOT measurements of water bodies in Australia. Geophysical Research Letters, 52(6), e2024GL114084.
  16. Medina, C. E., Gomez-Enri, J., Alonso, J. J., & Villares, P. 2008. Water level fluctuations derived from ENVISAT Radar Altimeter (RA-2) and in-situ measurements in a subtropical waterbody: Lake Izabal (Guatemala). Remote Sensing of Environment, 112(9), 3604-3617. https://doi.org/10.1016/j.rse.2008.05.001.
  17. Mugunthan, J. S., Duguay, C. R., & Zakharova, E. 2023. Machine learning based classification of lake ice and open water from Sentinel-3 SAR altimetry waveforms. Remote Sensing of Environment, 299, 113891.
  18. Nair, A. S., Kumar, N., Indu, J., & Vivek, B. 2021. Monitoring lake levels from space: preliminary analysis with SWOT.Frontiers in Water, 3, 717852.
  19. Özçelik, H. 2023. Isparta İlinin Önemli Bitki Alanları ve Özellikleri: Important Plant Areas and their Characteristics in Isparta Province. Journal of Protected Areas Research, 2(1), 26-62.
  20. Özseven, A., Akkurt, I., & Günoğlu, K. 2020. Determination of some dosimetric parameters in Eğirdir Lake, Isparta, Turkey. International Journal of Environmental Science and Technology, 17(3), 1503-1510.
  21. Peral, E., Esteban-Fernández, D., Rodríguez, E., McWatters, D., De Bleser, J. W., Ahmed, R.,. & Srinivasan, K.2024. KaRIn, the Ka-band radar interferometer of the SWOT mission: Design and in-flight performance. IEEE Transactions on Geoscience and Remote Sensing, 62, 1-27.
  22. Pujar, G. S., Taori, A., Chakraborty, A., & Mitran, T. 2024. Sensing climate change through earth observations: perspectives at global and National Level. ss 225-280. In Digital agriculture: A solution for sustainable food and nutritional security. Springer International Publishing, Cham.
  23. Sulistioadi, Y. B., Tseng, K. H., Shum, C. K., Hidayat, H., Sumaryono, M., Suhardiman, A.,. & Sunarso, S. 2015. Satellite radar altimetry for monitoring small rivers and lakes in Indonesia. Hydrology and Earth System Sciences, 19(1), 341-359.
  24. SWOT Sci. Data Products User Handbook. 2024. Jet Propulsion Laboratory Internal, document JPL D-109532, Pasadena, CA, USA. [Çevrimiçi]. Available: https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/web-misc/swot_mission_docs/D-109532_SWOT_UserHandbook_20240502.pdf (Erişim Tarihi: 01.08.2025).
  25. Şener, E., & Davraz, A. 2024. Comparison of drought indices in the analysis of temporal and spatial changes of climatic drought events: a case study in the Egirdir Lake basin (Isparta/Turkey). Natural Hazards, 120(14), 12817-12849.
  26. Şenol, H. İ., Şimşek, O., Yiğit, A. Y., & Kartal, V. 2025. Multi-source assessment of drought risk in Lake Eğirdir under climate change. Physics and Chemistry of the Earth, Parts A/B/C, 104030.
  27. Wang, J., & Fu, L. L. 2019. On the long-wavelength validation of the SWOT KaRIn measurement. Journal of Atmospheric and Oceanic Technology, 36(5), 843-848.
  28. Wang, J., Pottier, C., Cazals, C., Battude, M., Sheng, Y., Song, C.,. & Pavelsky, T. M. 2025. The Surface Water and Ocean Topography mission (SWOT) prior lake database (PLD): Lake Mask and operational auxiliaries. Water Resources Research, 61(3), e2023WR036896.
  29. Woolway, R. I., Kraemer, B. M., Lenters, J. D., Merchant, C. J., O’Reilly, C. M., & Sharma, S. 2020. Global lake responses to climate change. Nature Reviews Earth & Environment, 1(8), 388-403.
  30. Yücel, A., Markovic, M., Atilgan, A., Rolbiecki, R., Ertop, H., Jagosz, B.,. & Jakubowski, T. 2022. Investigation of annual lake water levels and water volumes with Şen Innovation and Mann-Kendall rank correlation trend tests: example of Lake Eğirdir, Turkey. Water, 14(15), 2374.
  31. Zakharova, E. A., Krylenko, I. N., & Kouraev, A. V. 2019. Use of non-polar orbiting satellite radar altimeters of the Jason series for estimation of river input to the Arctic Ocean. Journal of Hydrology, 568, 322-333. https://doi.org/10.1016/j.jhydrol.2018.10.068.
  32. Zhu, C., Guo, J., Ya, S., Li, W., Gao, J., & Qiu, L. 2025. Moving Geoid Gradient Method for High-Precision and High-Resolution Gravity Recovery From SWOT Wide-Swath Data. IEEE Transactions on Geoscience and Remote Sensing, 63.
  33. Bănăduc, D., Simić, V., Cianfaglione, K., Barinova, S., Afanasyev, S., Öktener, A.,. & Curtean-Bănăduc, A. 2022. Freshwater as a sustainable resource and generator of secondary resources in the 21st century: Stressors, threats, risks, management and protection strategies, and conservation approaches. International Journal of Environmental Research and Public Health, 19(24), 16570.
  34. Girard, F., Kergoat, L., Mainassara, I., Wubda, M., Nikiema, D. E., Touré, A. A.,. & Grippa, M. 2025. Performance of the Surface Water and Ocean Topography (SWOT) Mission for Monitoring Small Lakes in West Africa.IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.
  35. Grippa, M., Rouzies, C., Biancamaria, S., Blumstein, D., Crétaux, J. F., Gal, L.,. & Kergoat, L. 2019. Potential of SWOT for monitoring water volumes in Sahelian ponds and lakes. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(7), 2541-2549.
  36. Lee, H., Shum, C. K., Yi, Y., Ibaraki, M., Kim, J. W., Braun, A.,. & Lu, Z. 2009. Louisiana wetland water level monitoring using retracked TOPEX/POSEIDON altimetry. Marine Geodesy, 32(3), 284-302. https://doi.org/10.1080/01490410903094767.
  37. Peral, E., Esteban-Fernández, D., Rodríguez, E., McWatters, D., De Bleser, J. W., Ahmed, R.,. & Srinivasan, K.2024. KaRIn, the Ka-band radar interferometer of the SWOT mission: Design and in-flight performance. IEEE Transactions on Geoscience and Remote Sensing, 62, 1-27.
  38. Sulistioadi, Y. B., Tseng, K. H., Shum, C. K., Hidayat, H., Sumaryono, M., Suhardiman, A.,. & Sunarso, S. 2015. Satellite radar altimetry for monitoring small rivers and lakes in Indonesia. Hydrology and Earth System Sciences, 19(1), 341-359.
  39. Wang, J., Pottier, C., Cazals, C., Battude, M., Sheng, Y., Song, C.,. & Pavelsky, T. M. 2025. The Surface Water and Ocean Topography mission (SWOT) prior lake database (PLD): Lake Mask and operational auxiliaries. Water Resources Research, 61(3), e2023WR036896.
  40. Yücel, A., Markovic, M., Atilgan, A., Rolbiecki, R., Ertop, H., Jagosz, B.,. & Jakubowski, T. 2022. Investigation of annual lake water levels and water volumes with Şen Innovation and Mann-Kendall rank correlation trend tests: example of Lake Eğirdir, Turkey. Water, 14(15), 2374.