analyze-site

Site Suitability Analysis

v0.1 status — production-ready for 4 built-in purposes (airport, residential, commercial, public-facility) plus user-supplied custom rulesets. Free public data sources (OSM, SRTM DEM, Natural Earth). No satellite imagery yet — that's a v0.2 candidate.

This skill answers the question "why is this location good (or bad) for purpose X?" by overlaying the candidate location against terrain, infrastructure, exclusion zones, and demographic data, then scoring each criterion in a per-purpose ruleset.

The output is a markdown report a human can read and trust — not a black-box number.

When to Use

Common phrasings that trigger this skill:

• /gis-to-db:analyze-site --location "36.30,33.51" --purpose airport
• /gis-to-db:analyze-site --area parcel.geojson --purpose residential
• "Is this location good for an airport?"
• "Why would site A be better than site B for a hospital?"
• "Score this candidate site for industrial development."
• "Run site suitability on these coordinates for a solar farm."

What It Produces

A markdown report with these sections:

# Site Suitability — <purpose> at <location>

## Verdict: <RECOMMENDED | CONDITIONAL | NOT RECOMMENDED>  (score: 73 / 100)

## Criteria

| Criterion | Weight | Score | Why |
|---|---|---|---|
| Terrain slope | 20% | 92 | Average slope 1.2°; max 2.8°. Within airport limit (<3°). |
| Distance to nearest city | 15% | 80 | 24 km to Damascus center. Acceptable noise buffer. |
| Distance to major road | 15% | 65 | 8 km to M5 highway. Workable but not ideal. |
| Conflict with protected areas | 25% | 100 | No overlap with Natural Earth protected zones. |
| Flood risk | 10% | 90 | Elevation 612m, not in floodplain. |
| Existing airport proximity | 15% | 40 | 38 km to Damascus International — too close, ATC conflict likely. |

## Recommendations
- Re-evaluate with 60+ km separation from existing airports.
- Acquire detailed local flood-zone GIS to refine flood-risk score.

## Data Sources
- OSM (roads, urban areas, airports)
- SRTM 30m DEM (elevation, slope)
- Natural Earth Protected Areas (admin layer)
- User-supplied: <path-to-user-layers>

How It Works

1. Validator agent runs first. Invoke gis-preflight-validator with mode=analyze-site. Confirms Python + geopandas + rasterio (for DEM) availability. Verifies the location/area input is valid.
2. Resolve purpose ruleset. Built-in purposes map to YAML files in assets/rulesets/. Custom purposes look in <data-dir>/.gis-to-db/rulesets/ then ~/.claude/gis-to-db/rulesets/. Each ruleset defines criteria with weights and thresholds.
3. Gather reference data. User-supplied layers first; missing layers fetched from OSM (via Overpass API) and SRTM DEM (via OpenTopography) if --fetch-osm / --fetch-dem are set. Cached to ./.gis-to-db-cache/ for re-runs.
4. Reproject to a common CRS. For local analysis, pick a UTM zone covering the candidate area. For wide-area or unknown, EPSG:4326 with geodesic distances.
5. Score each criterion. The script applies the ruleset: distance calculations (shapely + pyproj), terrain stats (rasterio + numpy on DEM), spatial-overlay checks (geopandas .sjoin).
6. Aggregate score. Weighted average of criterion scores → overall 0-100 score. Verdict thresholds: ≥70 RECOMMENDED, 50-69 CONDITIONAL, <50 NOT RECOMMENDED (configurable in ruleset).
7. Render report. Markdown with table, verdict, recommendations, data-source attribution.

Ruleset Format

Each purpose is a YAML file. Built-in: assets/rulesets/{airport,residential,commercial,public-facility}.yaml. Schema:

name: airport
description: Greenfield commercial airport siting criteria.
verdict_thresholds:
  recommended: 70
  conditional: 50

criteria:
  - name: terrain_slope
    weight: 20
    type: terrain_stat
    stat: max_slope_degrees
    score_curve: linear_decreasing
    bounds: { ideal: 0, acceptable: 2, unacceptable: 5 }

  - name: distance_to_nearest_city
    weight: 15
    type: distance_to_layer
    layer: osm:place=city
    score_curve: bell
    bounds: { min: 15, ideal: 30, max: 80 }  # km — too close = noise, too far = unreachable

  - name: distance_to_major_road
    weight: 15
    type: distance_to_layer
    layer: osm:highway=motorway|trunk
    score_curve: linear_decreasing
    bounds: { ideal: 2, acceptable: 15, unacceptable: 50 }  # km

  - name: protected_area_conflict
    weight: 25
    type: overlap_with_layer
    layer: natural_earth:protected_areas
    score: { no_overlap: 100, partial_overlap: 30, full_overlap: 0 }

  - name: existing_airport_proximity
    weight: 15
    type: distance_to_layer
    layer: osm:aeroway=aerodrome
    score_curve: linear_increasing
    bounds: { unacceptable: 0, acceptable: 30, ideal: 80 }

  - name: flood_risk
    weight: 10
    type: terrain_threshold
    stat: elevation_meters
    score_curve: linear_increasing
    bounds: { unacceptable: 0, acceptable: 100, ideal: 500 }

Adding a custom purpose

User drops a YAML at ~/.claude/gis-to-db/rulesets/<name>.yaml and calls --purpose <name>. The skill picks it up automatically. No code changes needed.

Data Sources (v0.1)

Source	What it provides	Auth needed	Internet
User-supplied GIS layers	Whatever the user has — parcels, ownership, zoning, etc.	No	No
OSM via Overpass	Roads, cities, airports, water, land use	No	Yes (--fetch-osm)
SRTM 30m DEM via OpenTopography	Elevation, slope, aspect	No (free public)	Yes (--fetch-dem)
Natural Earth	Protected areas, country boundaries	No	One-time download cached

Implementation Reference

• scripts/analyze_site.py — main scorer. Reads ruleset YAML, layers, candidate location; produces the report.
• scripts/data_fetchers.py — OSM Overpass query helpers, SRTM tile fetcher, Natural Earth loader.
• references/criteria-types.md — full list of supported criterion types (terrain_stat, distance_to_layer, overlap_with_layer, terrain_threshold, density_count) and how each scores.
• references/scoring-curves.md — linear_increasing, linear_decreasing, bell, step, binary curves with formulas and use cases.
• assets/rulesets/airport.yaml, residential.yaml, commercial.yaml, public-facility.yaml — built-in purpose definitions.
• examples/airport-damascus.md — full worked example (the airport siting case).

Important Constraints

• No black-box scoring. Every criterion produces a number AND a "why" sentence. The report is auditable.
• Rule-based, not ML. No training data, no model weights. Adding a purpose is a YAML file, not a retraining pipeline.
• Free data only in v0.1. No commercial APIs, no satellite imagery. Adding these is v0.2 work.
• Coordinate-order rule applies: all location inputs are lng,lat (longitude first), matching MongoDB/GeoJSON convention.
• Caching is opt-out but on by default. OSM and DEM downloads cache to ./.gis-to-db-cache/. Pass --no-cache to force re-fetch.