Wetland Mapping Using SAR Data from the Sentinel-1A and TanDEM-X Missions: A Comparative Study in the Biebrza Floodplain (Poland)

Magdalena Mleczko,Marek Mróz

doi:10.3390/rs10010078

Abstract

This research is related to the eco-hydrological problems of the herbaceous wetland drying and biodiversity loss in the floodplain lakes of the Middle Basin of the Biebrza River (Poland). An experiment was set up, with its main goals as follows: (i) mapping the vegetation types and the temporarily or permanently flooded areas, and (ii) comparing the usefulness of the C-band Sentinel-1A (S1A) and X-band TerraSAR-X/TanDEM-X (TSX/TDX) for mapping purposes. The S1A imagery was acquired on a regular basis using the dual polarization VV/VH and the Interferometric Wide Swath Mode. The TSX/TDX data were acquired in quad-pol, a fully polarimetric mode, during the Science Phase. The paper addresses the following aspects: (i) wetland mapping with the S1A multi-temporal series; (ii) wetland mapping with the fully polarimetric TSX/TDX data; (iii) comparing the wetland mapping using dual polarization TSX/TDX subsets, that is, the HH-HV, HH-VV and VV-VH; (iv) comparing wetland mapping using the S1A and TSX/TDX data based on the same polarization (VV-VH); (v) studying the suitability of the Shannon Entropy for wetland mapping; and (vi) assessing the contribution of interferometric coherence for wetland classification. Though the experimental results show the main limitations of the S1A dataset, they also highlight the good accuracy that can be achieved using the TSX/TDX data, especially those taken in fully polarimetric mode. Some practical outcomes significant for the study area management using SAR were also described.

Highlights

As stated in Reference [1], the need for wetland mapping has never been greater as the world’s population continues to increase
The paper addresses the following aspects: (i) wetland mapping with the S1A multi-temporal series; (ii) wetland mapping with the fully polarimetric TSX/TDX data; (iii) comparing the wetland mapping using dual polarization TSX/TDX subsets, that is, the HH-HV, HH-VV and VV-VH; (iv) comparing wetland mapping using the S1A and TSX/TDX data based on the same polarization (VV-VH); (v) studying the suitability of the Shannon Entropy for wetland mapping; and (vi) assessing the contribution of interferometric coherence for wetland classification
Compare wetland mapping using S1A and TSX/TDX data based on the same polarization (VV-VH) and covering the same observation period—enhancing the differences in geometric resolution and its effect on classification accuracy

Summary

Introduction

As stated in Reference [1], the need for wetland mapping has never been greater as the world’s population continues to increase. Positive water balance and longer periods of water stagnation are crucial factors in the wetlands re-naturalization process and conservation. In this area, the problems of soil moisture and biomass estimation have been intensively studied in the past [2,3]. The main hydrological concern in this area is how to retain the water for longer periods from early spring flooding. The deficit of water is a factor influencing the life conditions of the ichthyofauna and avifauna. Further consequences of the water deficit are the unfavorable vegetation succession and the reduction of the quantity of species

Methods

Results

Conclusion