Coastline Change Monitor

Multi-temporal shoreline change analysis with transect-based rate computation.

Trigger

Use when the user wants to:

• Monitor coastline erosion/accretion over time
• Compute shoreline change rates (EPR/LRR)
• Identify erosion hotspots
• Compare shoreline positions across years

CLI Usage

# Vector shorelines
python scripts/coastline_change_monitor.py \
  --shoreline-files shore_2015.geojson shore_018.geojson shore_2021.geojson \
  --years 2015 2018 2021

# Raster water masks
python scripts/coastline_change_monitor.py \
  --shoreline-files water_2015.tif water_2018.tif water_2021.tif \
  --years 2015 2018 2021 \
  --transect-spacing 50 --transect-length 300

Parameters

Parameter	Default	Description
--shoreline-files	required	Shoreline files (one per year)
--years	auto	Years for each file
--transect-spacing	100	Spacing between transects
--transect-length	500	Length of each transect
--erosion-threshold	-1.0	EPR threshold for hotspots (m/yr)
--output-dir	./coastline-output	Output directory

Output

File	Description
shorelines.geojson	All shorelines with year attribute
transects.geojson	Generated transect lines
change_rates.csv	EPR/LRR per transect
erosion_hotspots.geojson	Significant erosion segments
report.html	HTML summary report
output-manifest.json	Machine-readable manifest

Exit Codes

Code	Meaning
0	Success
2	Argument error
3	Dependency missing
6	Data validation failure
7	Processing failure

数据下载

本 skill 可自动从 Microsoft Planetary Computer 下载数据 (无需 API key):

python coastline_change_monitor.py --bbox 116,39,117,40 --date-range 2024-06-01,2024-06-30 --output-dir <tmp>

• --bbox W,S,E,N: WGS-84 边界框 (西, 南, 东, 北)
• --date-range START,END: 日期范围 (YYYY-MM-DD,YYYY-MM-DD)
• --aoi-file <path.geojson>: 替代 --bbox 的 GeoJSON 多边形
• --cache-dir <path>: 缓存目录 (默认 ~/.geoskill_cache)

当用户只给 --bbox + --date-range (没有 --image) 时，skill 自动下载数据。 当用户给 --image 时，走原文件路径 (向后兼容)。