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Application of C-band Radar Interferometry for Dune Monitoring in the Curonian Spit

Bielinis, Martynas LU (2025) In Master Thesis in Geographical Information Science GISM01 20251
Dept of Physical Geography and Ecosystem Science
Abstract
The dune regions of the Curonian Spit are undergoing a gradual deflation and transformation towards a vegetated surface as a result of extensive forestation and dune stabilization efforts limiting sand input to the dunes. Current dune monitoring in the Spit relies mostly on field levelling, whereas radar interferometry – used extensively in land surface monitoring elsewhere – is not utilized. This study aims to determine the applicability of radar interferometry for monitoring the deformation of the Curonian Spit dunes. Interferograms are formed from Sentinel-1 C-band radar data covering the period of 2017-2024 using different temporal baselines. The impact of the temporal baseline length on coherence – the measure of interferometric phase... (More)
The dune regions of the Curonian Spit are undergoing a gradual deflation and transformation towards a vegetated surface as a result of extensive forestation and dune stabilization efforts limiting sand input to the dunes. Current dune monitoring in the Spit relies mostly on field levelling, whereas radar interferometry – used extensively in land surface monitoring elsewhere – is not utilized. This study aims to determine the applicability of radar interferometry for monitoring the deformation of the Curonian Spit dunes. Interferograms are formed from Sentinel-1 C-band radar data covering the period of 2017-2024 using different temporal baselines. The impact of the temporal baseline length on coherence – the measure of interferometric phase quality – is evaluated across the surface classes of the dune region. Total column water vapor, surface soil moisture, normalized difference vegetation index, freeze/thaw status and weather station data are evaluated against coherence to determine the impact that environmental condition differences have on interferometric phase. The interferometric network is then used to determine the deformation rates and annual velocity of the open dune region, and the results are validated against field survey data. Results show that coherence in the open dune classes is high at short temporal baselines, and retains higher values compared to other land cover classes. Rebounds of coherence at annual temporal baselines were detected, emphasizing the importance of similarity in soil moisture and vegetation conditions for coherence stability. Total column water vapor, surface soil moisture, relative humidity and vegetation were found to be the most important variables impacting coherence, yet each explains a small amount of the total variance. The calculated deformation rates were found to severely underestimate deformation known from field survey data, highlighting a necessity for continued studies of InSAR data collection and use. (Less)
Abstract (Uncoded languages)
Po ekstensyvaus apželdinimo ir kopų stabilizavimo, smėlio prietėka į kopas buvo sustabdyta, ir Kuršių Nerijos kopos palaipsniui žemėja ir apauga augalija. Dabartiniai kopų stebėsenos metodai daugiausia remiasi lauko matavimais, o interferometrija, plačiai naudojama paviršiaus stebėsenai kitur, nėra išnaudojama. Šiuo tyrimu siekama įvertinti radaro interferometrijos panaudojimo galimybes Kuršių Nerijos kopų deformacijos stebėsenai. Interferogramos buvo suformuotos iš Sentinel-1 C juostos radaro duomenų, aprėpiančių 2017-2024 m. tyrimo laikotarpį skirtingais laiko tarpais (ang. temporal baselines). Laiko tarpų ilgio poveikis interferometrinei koherencijai (ang. coherence) – inteferometrinės fazes kokybės rodikliui – buvo įvertintas naudojant... (More)
Po ekstensyvaus apželdinimo ir kopų stabilizavimo, smėlio prietėka į kopas buvo sustabdyta, ir Kuršių Nerijos kopos palaipsniui žemėja ir apauga augalija. Dabartiniai kopų stebėsenos metodai daugiausia remiasi lauko matavimais, o interferometrija, plačiai naudojama paviršiaus stebėsenai kitur, nėra išnaudojama. Šiuo tyrimu siekama įvertinti radaro interferometrijos panaudojimo galimybes Kuršių Nerijos kopų deformacijos stebėsenai. Interferogramos buvo suformuotos iš Sentinel-1 C juostos radaro duomenų, aprėpiančių 2017-2024 m. tyrimo laikotarpį skirtingais laiko tarpais (ang. temporal baselines). Laiko tarpų ilgio poveikis interferometrinei koherencijai (ang. coherence) – inteferometrinės fazes kokybės rodikliui – buvo įvertintas naudojant kopų regionų paviršiaus klases. Bendras vandens garų kiekis stulpelyje, dirvožemio drėgmės kiekis, normalizuotas augalijos indeksas, paviršiaus užšalimo būsena ir meteorologinės stoties duomenys buvo įvertinti naudojant koherenciją, norint nustatyti aplinkos sąlygų skirtumo poveikį inteferometrinei fazei. Interferogramų tinklas buvo panaudotas nustatyti deformacijos greitį ir metinį paviršiaus judėjimą atvirų kopų regionuose, o gauti rezultatai buvo validuoti naudojant lauko matavimų duomenis. Rezultatai rodo kad atvirose kopose koherencijos vertės yra aukštos naudojant trumpus laiko tarpus, ir šios vertės išlieka aukščiau verčių kitose paviršiaus klasėse. Pastebėtas koherencijos santykinis pakilimas ties metų ilgumo laiko tarpais pabrėžia dirvožemio drėgmės kiekio ir augalijos būklės panašumų svarbą koherencijos stabilumui. Bendras vandens garų kiekis stulpelyje, dirvožemio drėgmės kiekis, santykinis oro drėgnis ir augalija buvo nustatyti kaip svarbiausi išmatuoti kintamieji, darantys didžiausią įtaką koherencijai. Vis dėlto, visi kintamieji paaiškina tik mažą dalį koherencijos variacijos. Nustatytas deformacijos greitis buvo smarkiai mažesnis negu žinoma iš lauko matavimo duomenų, ir tai akcentuoja reikalingumą tęsti interferometrinių duomenų rinkimo ir panaudojimo tyrimus. (Less)
Popular Abstract
The sand dunes of Lithuania’s Curonian Spit region are an important cultural and natural landmark. Historically, the dunes threatened the villages of the Spit by blowing over them, and this led to efforts to stabilize them. The Spit was reforested, and protective seaside dunes were formed to stop sand. Although this stabilized the sand, the unique landmark of the region began to subside due to lack of new sand. Nowadays, researchers are focused on observing this process and measuring the changing elevation of the dunes.
While many tools are currently used in the measuring of this region, this study attempts to apply radar interferometry to observe the dunes. A satellite with a radar system sends microwaves towards the ground and measures... (More)
The sand dunes of Lithuania’s Curonian Spit region are an important cultural and natural landmark. Historically, the dunes threatened the villages of the Spit by blowing over them, and this led to efforts to stabilize them. The Spit was reforested, and protective seaside dunes were formed to stop sand. Although this stabilized the sand, the unique landmark of the region began to subside due to lack of new sand. Nowadays, researchers are focused on observing this process and measuring the changing elevation of the dunes.
While many tools are currently used in the measuring of this region, this study attempts to apply radar interferometry to observe the dunes. A satellite with a radar system sends microwaves towards the ground and measures the energy that comes back to the radar, which allows observation of the surface. The radar also measures the time it takes for the microwave pulse to come back. If the same object is measured from the same location, but at different times, a difference in the time it takes the microwave to come back might mean a change in the surface elevation.
In this study, radar data is used on the two open dune regions in Lithuania’s Curonian Spit in the period of 2017 to 2024. The study is aimed at looking how useful the radar data is over long periods of time, and whether weather or changing conditions in the area can affect the quality of the radar data. Finally, the study attempts to apply radar data and measure how the dunes change in height over time, and how well does radar observe it.
The study found that sand surfaces of the dune regions can be used for radar tasks as they retain good quality radar data over longer periods of time, and also can partially recover that quality even at year-long periods. Looking at various conditions that can affect radar, it was found that four variables are most important for radar data – the water content in the atmosphere, the relative humidity, the moisture of the soil and the level of vegetation. Finally, by applying radar to measure dune height changes, the method was not successful as it could not estimate the level of change known from other studies and data. (Less)
Please use this url to cite or link to this publication:
author
Bielinis, Martynas LU
supervisor
organization
course
GISM01 20251
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Geography, GIS, Synthetic Aperture Radar, Radar Interferometry, dune deformation, Curonian Spit
publication/series
Master Thesis in Geographical Information Science
report number
192
language
English
additional info
External Supervisor: Linas Bevainis, Vilnius University, Department of Cartography and Geoinformatics
id
9204572
date added to LUP
2025-06-23 16:04:29
date last changed
2025-06-23 16:04:29
@misc{9204572,
  abstract     = {{The dune regions of the Curonian Spit are undergoing a gradual deflation and transformation towards a vegetated surface as a result of extensive forestation and dune stabilization efforts limiting sand input to the dunes. Current dune monitoring in the Spit relies mostly on field levelling, whereas radar interferometry – used extensively in land surface monitoring elsewhere – is not utilized. This study aims to determine the applicability of radar interferometry for monitoring the deformation of the Curonian Spit dunes. Interferograms are formed from Sentinel-1 C-band radar data covering the period of 2017-2024 using different temporal baselines. The impact of the temporal baseline length on coherence – the measure of interferometric phase quality – is evaluated across the surface classes of the dune region. Total column water vapor, surface soil moisture, normalized difference vegetation index, freeze/thaw status and weather station data are evaluated against coherence to determine the impact that environmental condition differences have on interferometric phase. The interferometric network is then used to determine the deformation rates and annual velocity of the open dune region, and the results are validated against field survey data. Results show that coherence in the open dune classes is high at short temporal baselines, and retains higher values compared to other land cover classes. Rebounds of coherence at annual temporal baselines were detected, emphasizing the importance of similarity in soil moisture and vegetation conditions for coherence stability. Total column water vapor, surface soil moisture, relative humidity and vegetation were found to be the most important variables impacting coherence, yet each explains a small amount of the total variance. The calculated deformation rates were found to severely underestimate deformation known from field survey data, highlighting a necessity for continued studies of InSAR data collection and use.}},
  author       = {{Bielinis, Martynas}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Master Thesis in Geographical Information Science}},
  title        = {{Application of C-band Radar Interferometry for Dune Monitoring in the Curonian Spit}},
  year         = {{2025}},
}