Cost-effective drone monitoring and evaluating toolkits for stream habitat health: development and application

Effective monitoring for stream habitat health is essential for sustainable restoration and management to conserve ecosystem services. Traditional in situ surveying with multi-metric indices is widely used by state and federal agencies but is often labor-intensive and spatially limited. To address these challenges, this study introduces a suite of cost-effective drone-based monitoring toolkits that integrate automated flight-route design, Structure-from-Motion (SfM) image reconstruction, and multi-metric index (MMI) computation. The toolkits form an end-to-end workflow for quantitative habitat evaluation, enabling centimeter-scale mapping and standardized MMI scoring based on Wisconsin DNR and EPA guidelines. The toolkits were examined at Black Earth Creek, Wisconsin, where high- and low-elevation drone images were collected and processed to generate high-resolution (< 1 cm) ortho-photos and terrain maps. The reconstructed terrain achieved horizontal and vertical accuracies of 0.04 m and 0.17 m, respectively, and the UAV-derived MMI results showed strong agreement with field measurements. The entire process-from flight planning to assessment-can be completed by one operator within three hours using an off-the-shelf drone (< USD 1000) and standard photogrammetry software. Beyond improving efficiency, the integrated toolkits provide spatially continuous, repeatable assessments that capture habitat variability and degradation hotspots often missed by conventional transect-based methods. By significantly reducing labor and costs associated with data collection, processing, and assessment, these UAV-based toolkits offer a cost-effective, scalable, and reproducible solution for routine stream habitat monitoring and long-term conservation planning.