Study of Some Lakes in the North-Eastern Romanian Plain Using the Coherence Image of the Tandem Pair (ERS-1 and ERS-2)

Kamel Hachemi, Marta Jurchescu, Florina Grecu, André Ozer, Mircea Cristian Visan

Geomorphology and Remote Sensing. Geography Institute, Liege University, Liège, Belgium.
Geomorphology-Pedology-Geomatics Department, Faculty of Geography, University of Bucharest, Bucharest, Romania.
LGP (Physical Geography Laboratory), UMR 8591, CNRS-National Centre for Scientific Research, Meudon, France ;University of Paris-Est and University Paris 1 Panthéon-Sorbonne, Paris, France.
Physical Geography Department, Institute of Geography, Bucharest, Romania.

DOI: 10.4236/ars.2014.31003                

Abstract

In radar SAR interferometry (InSAR/DinSAR), a Tandem pair (ERS-1/2) is used for the realization of a DEM or the detection of deformations of a major event (e.g. earthquake) occurring between two acquisitions. The advantage of the Tandem pair is the time interval of 24 hours between the two captures. Generally, there is no temporal decorrelation considering the small difference in time between the acquisitions, which results in a good coherence. The coherence image is used indirectly in radar SAR interferometry as an indicator of the levels of confidence of the interferograms. It can be used in a direct way to identify and delimit the various movement zones which disturb the phase of the radar wave. The objective of this work is to show the utility and the effectiveness of the coherence image in the cartography of lakes and vegetation in a region at the Curvature of the Romanian Carpathians1. Between the two acquisitions dates of May 28 and 29, 1995, there was no geological process involving displacements in direction of the radar. This pair represents the only one among the other pairs which gave a good coherence for the whole scene. In the flat part, one notes a good coherence except for the lakes. They are well represented by very dark colours with zero coherence. In the part of high altitude, especially where there is vegetation, a bad coherence can be clearly seen. Using this image (coherence), one could distinguish the parts with vegetation in great movements due to the effects of the wind, therefore characterised by great heights. The coherence image thus makes it possible to delimit two natural elements in this area, the lakes and the vegetation. The lakes are well delimited, in particular when they are full as in the rain seasons. To show this utility and this effectiveness of the coherence image, we measured the surfaces and dimensions of the lakes based on the Tandem pair and to make a comparison with the existing data and to interpret the results obtained. The three lakes, located in the plain to the East and North-East of the Buza;u town, clearly appear in the coherence image.

Keywords

Coherence; Buzau; Lakes; Radar; SAR; Tandem Pair; ERS-1; ERS-2

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Askne, J.I.H., Dammert, P.B.G., Fransson, J., Israelsson, H. and Ulander, L.M.H. (1995) Retrieval of Forest Parameters Using Intensity and Repeat Pass Interferometric SAR Information. Symposium International Extraction des Paramètres Bio-Géophysiques à Partir des Données RSO Pour Les Applications Terrestre, Toulouse, 10-13 October 1995, 119-129.
[2]	Askne, J.I.H., Dammert, P.B.G., Ulander, L.M.H. and Smith, G. (1997) C-Band Repeat Pass Interferometric SAR Observations of the Forest. IEEE Transactions on Geoscience and Remote Sensing, 35, 25-35. http://dx.doi.org/10.1109/36.551931
[3]	Luckman, A., Baker, J. and Wegmüller, U. (2000) Repeat-Pass Interferometric Coherence Measurements of Disturbed Tropical Forest from JERS and ERS Satellites. Remote Sensing of Environment, 73, 350-360. http://dx.doi.org/10.1016/S0034-4257(00)00110-3
[4]	Nico, G., Pappalepore, M., Pasquariello, G., Refice, A. and Samarelli, S. (2000) Comparison of SAR Amplitude vs. Coherence Flood Detection Methods—A GIS Application. International Journal of Remote Sensing, 21, 1619-1631. http://dx.doi.org/10.1080/014311600209931
[5]	Fransson, J.E.S., Smith, G., Askne, J. and Olsson, H. (2001) Stem Volume Estimation in Boreal Forests Using ERS-1/2 Coherence and SPOT XS Optical Data. International Journal of Remote Sensing, 22, 2777-2791. http://dx.doi.org/10.1080/01431160010006872
[6]	Hall-Atkinson, C. and Smith, L.C. (2001) Delineation of Delta Ecozones Using Interferometric SAR Phase Coherence Mackenzie River Delta, N.W.T., Canada. Remote Sensing of Environment, 78, 229-238. http://dx.doi.org/10.1016/S0034-4257(01)00221-8
[7]	Stabel, E. and Fischer, P. (2001) Satellite Radar Interferometric Products for the Urban Application Domain. Advances in Environmental Research, 5, 425-433. http://dx.doi.org/10.1016/S1093-0191(01)00094-6
[8]	Gray, A.L., Short, N., Bindschadler, R., Joughin, I., Padman, L., Vornberger, P. and Khananian, A. (2002) RADARSAT Interferometry for Antarctic Grounding-Zone Mapping. Annals of Glaciology, 34, 269-276.
[9]	Wagnera, W., Luckmanb, A., Vietmeiera, J., Tanseyb, K., Balzterc, H., Schmulliusd, C., Davidsone, M., Gaveauc, D., Gluckf, M., Le Toane, T., Quegang, S., Shvidenkof, A., Wiesmannh, A. and Yu, J.J. (2003) Large-Scale Mapping of Boreal Forest in SIBERIA Using ERS Tandem Coherence and JERS Backscatter Data. Remote Sensing of Environment, 85, 125-144. http://dx.doi.org/10.1016/S0034-4257(02)00198-0
[10]	Blaes, X. and Defourny, P. (2003) Retrieving Crop Parameters Based on Tandem ERS 1/2 Interferometric Coherence Images. Remote Sensing of Environment, 88, 374-385. http://dx.doi.org/10.1016/j.rse.2003.08.008
[11]	Hoffmann, J. (2007) Mapping Damage during the Bam (Iran) Earthquake Using Interferometric Coherence. International Journal of Remote Sensing, 28, 1199-1216. http://dx.doi.org/10.1080/01431160600928567
[12]	Drezet, P.M.L. and Quegan, S. (2007) Satellite-Based Radar Mapping of British Forest Age and Net Ecosystem Exchange Using ERS Tandem Coherence. Forest Ecology and Management, 238, 65-80.
[13]	Tanase, M.A., Santoro, M., Wegmüller, U., De La Riva, J. and Pérez-Cabello, F. (2010) Properties of X-, C-and L-Band Repeat-Pass Interferometric SAR Coherence in Mediterranean Pine Forests Affected by Fires. Remote Sensing of Environment, 114, 2182-2194.
[14]	Touzi, R., Lopes, A., Bruniquel, J. and Vachon, P.W. (1999) Coherence Estimation for SAR Imagery. IEEE Transactions on Geoscience & Remote Sensing, 37, 135-149.
[15]	Adragna, F. and Et Nicolas, J.M. (2001) Traitement des images de Radar à Synthèse d’Ouverture (RSO). Sous la Direction de Henri Ma1tre, Hermes Science Europe Publication, Paris, 328.
[16]	Grecu, F., Comanescu, L., Toroimac, G., Dobre, R., Sacrieru, R. and Marculet, C. (2010) Slope Dynamics-Precipitation Interrelation in the Curvature Subcarpathians (Romania). Revista de Geomorfologie, 12, 45-52.
[17]	Hachemi, K. (2009) Apport de l’Interférométrie Radar SAR Pour la Réalisation d’un MNA (Modèle Numérique d’Altitude) sur la Région Subcarpatique de Buzau (Roumanie). Journal Analele Universitatii Bucuresti, Année LVIII, 5-38.
[18]	Gastescu, P. (1963) Lacurile din Romania. Ed.Academiei, Bucuresti, 293p.
[19]	Geografia Romanei, V. (2005) Campia Romana, Dunarea, Podisul Dobrogei, Litoralul Romanesc al Marii Negre si Platforma Continentala. Academia Romana, Institutul de Geografie, Ed. Academiei, Bucharest, 968p.
[20]	Grecu, F. (2010) Geografia Campiilor Romaniei. Ed.Universitatii, Bucuresti, 260p.
[21]	Visan, G.H., Cirstea, A. and Balauta, L. (1973) Unele Aspecte Climatice in Campia Ramnicului. Geografie, Analele Univesitatii Bucuresti, Anul XXII.
[22]	Balteanu, D. (1989) Caracterele Morfostucturale si Modelarea Actuala. Potentialul Mediului din Subcarpatii Judetului Buzau, Institutul de Geografie, Bucuresti, 49-61.