Derivation of spatially detailed lentic habitat map and inventory at a basin scale by integrating multispectral Sentinel-2 satellite imagery and USGS Digital Elevation Models

Abstract

Aquatic habitats are essential for aquaculture, agriculture, and municipal water supply. The geographical location and quantitative information about the aquatic habitats are critical for inventorying, monitoring, and managing these valuable resources. This paper presents a novel method that integrates the object-oriented image analysis and DEM-based stream network analysis to map and quantify lentic aquatic habitats, using freely available ESA Sentinel-2 multispectral imagery and USGS DEMs. This integrated method has been applied to the entire Mobile River Basin, USA, and lentic habitats at the basin scale have been delineated and inventoried at the 10-m spatial resolution. The surface water pixels of aquatic habitats are extracted through the Iterative Self-Organizing Data Analysis Technique (ISODATA) unsupervised classification of the Sentinel-2 multispectral images. An object-oriented image analysis approach is then used to group contiguous water pixels to form and map discrete aquatic habitat objects. The stream network in the basin has been hydrologically derived from the USGS DEMs at the 10-m spatial resolution. The combination of the geometric and shape information from the object-oriented image analysis and hydrological information from the DEM-based stream network analysis enables the separation of lotic and lentic habitats. A set of planimetric, geometric, and shape attributes has been numerically derived for each lentic habitat object. The abundance pattern, shape pattern, and spatial distribution pattern of the lentic habitats in the basin have been analyzed. The vast majority of the aquatic habitat objects identified in the Mobile River Basin are lentic habitats. The most striking spatial pattern of lentic habitats is that small, oblong lakes and fish ponds are densely distributed along the Black Prairie Belt in the basin, laying the foundation for the catfish aquacultural industry in the regions of mid-west Alabama and east Mississippi. This research demonstrates that the integration of the recently emerged Sentinel-2A/B satellite multispectral imagery with USGS DEMs represents an effective approach to the inventory and environmental investigation of lentic habitats at a basin scale.