Wetlands are valuable natural complexes that affect the region’s biodiversity and the water cycle. Inventorying the information on wetlands is crucial for their effective management. One parameter worth inventorying is the inundation status of wetlands. Knowing about the inundation regime helps study wetland vegetation’s spatial patterns. Wetland inundation maps can be prepared using remote sensing-based inputs.
Regional scale wetland inundation maps
Satellite sensor-based products such as that from MODIS, Landsat and Sentinel are being used to estimate the extent of inundation, mainly at a regional scale. They have also helped derive seasonal and inter-annual changes in the inundated area.
Large-scale wetland inundation maps
More recently, the focus has been shifted to small-sized wetlands as they are more vulnerable to climate variability. For monitoring smaller wetlands, large-scale mapping is required, where MODIS, Landsat, or Sentinel data offer an insufficient spatial resolution. For this reason, super-resolution mapping has also been tried by many researchers. Forested wetlands pose another challenge to the use of multispectral remote sensing images.
Integrating LiDAR data is proving helpful
Light Detection and Ranging (LiDAR) data are being integrated with multispectral image datasets to overcome the challenges of large-scale mapping. Generally, elevation data are corrected with surface depressions to establish a water flow network continuity seen on a smaller scale. However, surface depressions are one of the wetland landscape features. LiDAR elevation and intensity data help to identify depressions in landscapes. LiDAR data also provide vertical structure information of vegetation which can help distinguish various vegetation species with similar spectral signatures.
For example, mangrove inundation spatial patterns have been studied using LiDAR. Sentinel-2 multispectral data have been tested after combining with Unmanned Aerial Vehicle (UAV) based LiDAR data, which indicates better prospects.
