Water Body Mapping
Definition
Water body mapping is the extraction and maintenance of water features from imagery, elevation, and field data. Methods include spectral indices (NDWI/MNDWI), SAR thresholding for all-weather detection, object-based segmentation, and change detection across seasons. Hydrologic conditioning ensures connectivity between lakes and streams. Products often include quality flags for clouds, ice, and turbidity.
Application
Drought monitoring tracks shrinking lakes; reservoir operators manage storage; conservationists protect wetlands; and emergency managers assess flood extents in near real time.
FAQ
How can SAR complement optical methods?
SAR detects calm open water regardless of cloud, but rough seas and emergent vegetation complicate classification; combining with optical reduces errors.
What role does elevation play in improving boundaries?
Shorelines align with contour levels; integrating DEMs constrains plausible edges and filters spurious detections on slopes.
How do you communicate confidence to users?
Provide per-pixel quality masks, uncertainty layers, and metadata on sensor dates and thresholds.
What update cadence is reasonable?
For reservoirs and flood response, daily to weekly; for baseline inventories, seasonal or annual composites may suffice.
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