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name: watershed-delineation description: > Automated watershed delineation from DEM. Computes D8 flow direction, flow accumulation, delineates watersheds from outlet points, extracts stream networks, and generates statistics. Use when the user wants to delineate a watershed, compute flow accumulation, extract streams, or analyze hydrological characteristics from a DEM.

Watershed Delineation

Automated watershed analysis from DEM using D8 algorithm.

CLI Usage

python scripts/watershed_delineation.py --dem dem.tif
python scripts/watershed_delineation.py --dem dem.tif --outlet-row 50 --outlet-col 60
python scripts/watershed_delineation.py --dem dem.tif --stream-threshold 50
python scripts/watershed_delineation.py --synthetic --output-dir ./out

数据下载

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

# 自动下载 Copernicus DEM GLO-30
python scripts/watershed_delineation.py \
    --bbox 116.30,39.85,116.45,39.95 \
    --date-range 2020-01-01,2020-12-31 \
    --output-dir ./ws-auto

下载的内容:

• Copernicus DEM GLO-30 (cop-dem-glo-30) — 替换 --dem

下载元数据（data_source, fetched_at, collection, dem_downloaded）会写入 output-manifest.json。

Parameters

Flag	Type	Default	Description
--dem	path	(required, or use --synthetic)	Input DEM raster (GeoTIFF)
--outlet-row	int	None	Outlet row in DEM grid (default: max accumulation)
--outlet-col	int	None	Outlet column in DEM grid (default: max accumulation)
--stream-threshold	int	100	Stream threshold in accumulation pixels
--output-dir / -o	path	watershed-output	Output directory
--synthetic	flag	False	Run with synthetic demo data (no real inputs needed)
--version	flag	-	Show version and exit

Output

File	Description
flow_direction.tif	D8 flow direction raster
flow_accumulation.tif	Flow accumulation raster
watershed.tif	Watershed mask
streams.tif	Stream network
report.html	Statistics report
output-manifest.json	Machine-readable manifest

Exit Codes

Code	Meaning
0	Success
2	Argument error
3	Dependency missing
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 watershed_delineation.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 --dem) 时，skill 自动下载数据。 当用户给 --dem 时，走原文件路径 (向后兼容)。