Add fire module (#922) (#927)

* Add fire module: burn severity, fire behavior, and KBDI (#922)

Seven per-cell raster functions with numpy/cupy/dask/dask+cupy backends:

Burn severity: dnbr, rdnbr, burn_severity_class (USGS 7-class)
Fire behavior: fireline_intensity (Byram), flame_length, rate_of_spread
  (simplified Rothermel with Anderson 13 fuel model lookup)
Fire danger: kbdi (single time-step Keetch-Byram Drought Index)

Includes 54 tests covering known values, NaN propagation, edge cases,
input validation, cross-backend parity, Dataset support, and accessor
smoke tests. Adds .xrs accessor methods for both DataArray and Dataset.

* Add fire analysis user guide notebook

Beginner-oriented walkthrough of all 7 fire module functions with
synthetic data: dNBR, RdNBR, burn severity classification, fireline
intensity, flame length, rate of spread (with fuel model comparison
and moisture sensitivity), and multi-day KBDI accumulation.

* Add fire section to README feature matrix

* Add fire module to Sphinx docs

- API reference page (docs/source/reference/fire.rst) with autosummary
  directives for all 7 public functions
- User guide notebook (docs/source/user_guide/fire.ipynb) with synthetic
  data examples for burn severity, fire behavior, and KBDI
- Updated reference and user guide toctrees

Author: brendancol

CHANGELOG.md

@@ -10,6 +10,7 @@ connected-component labelling; and broad dask+cupy backend coverage across the
 library.
 
 #### New Features
+- Add fire module: dNBR, RdNBR, burn severity class, fireline intensity, flame length, rate of spread (Rothermel), and KBDI (#922)
 - Add 3D multi-band support to focal functions (#924)
 - Add foundational hydrology tools (#921)
 - Add terrain metrics module: TRI, TPI, and Roughness (#920)

README.md

@@ -163,6 +163,20 @@ In the GIS world, rasters are used for representing continuous phenomena (e.g. e
 
 -------
 
+### **Fire**
+
+| Name | Description | NumPy xr.DataArray | Dask xr.DataArray | CuPy GPU xr.DataArray | Dask GPU xr.DataArray |
+|:----------:|:------------|:----------------------:|:--------------------:|:-------------------:|:------:|
+| [dNBR](xrspatial/fire.py) | Differenced Normalized Burn Ratio (pre minus post NBR) | ✅️ | ✅️ | ✅️ | ✅️ |
+| [RdNBR](xrspatial/fire.py) | Relative dNBR normalized by pre-fire vegetation density | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Burn Severity Class](xrspatial/fire.py) | USGS 7-class burn severity from dNBR thresholds | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Fireline Intensity](xrspatial/fire.py) | Byram's fireline intensity from fuel load and spread rate (kW/m) | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Flame Length](xrspatial/fire.py) | Flame length derived from fireline intensity (m) | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Rate of Spread](xrspatial/fire.py) | Simplified Rothermel spread rate with Anderson 13 fuel models (m/min) | ✅️ | ✅️ | ✅️ | ✅️ |
+| [KBDI](xrspatial/fire.py) | Keetch-Byram Drought Index single time-step update (0-800 mm) | ✅️ | ✅️ | ✅️ | ✅️ |
+
+-------
+
 ### **Multispectral**
 
 | Name | Description | NumPy xr.DataArray | Dask xr.DataArray | CuPy GPU xr.DataArray | Dask GPU xr.DataArray |

docs/source/reference/fire.rst

@@ -0,0 +1,30 @@
+..  _reference.fire:
+
+****
+Fire
+****
+
+Burn Severity
+=============
+.. autosummary::
+   :toctree: _autosummary
+
+   xrspatial.fire.dnbr
+   xrspatial.fire.rdnbr
+   xrspatial.fire.burn_severity_class
+
+Fire Behavior
+=============
+.. autosummary::
+   :toctree: _autosummary
+
+   xrspatial.fire.fireline_intensity
+   xrspatial.fire.flame_length
+   xrspatial.fire.rate_of_spread
+
+Fire Danger
+===========
+.. autosummary::
+   :toctree: _autosummary
+
+   xrspatial.fire.kbdi

docs/source/reference/index.rst

@@ -8,6 +8,7 @@ Reference
    :maxdepth: 2
 
    classification
+   fire
    flood
    focal
    multispectral