IGAD Food security, Nutrition & Resilience Information System

Pasture & Forage Conditions (Rangeland)

WRSI-based pasture and forage monitoring across 2 seasons (short rains Oct–Jan and long rains Mar–Jul) sourced from USGS FEWS NET.

Overview

The Rangeland module monitors pasture and forage availability for livestock using the Water Requirement Satisfaction Index (WRSI). WRSI measures the ratio of actual evapotranspiration to the water requirement of rangeland grasses, providing a proxy for biomass availability.

Seasons

The module covers 2 seasons for the East Africa rangelands:

Season	Period	FEWS NET Code
Season 1 — Short Rains	October – January	east1
Season 2 — Long Rains	March – July	east2

Data Layers (per dekad, per season)

Current WRSI — Accumulated WRSI value for the season to date.
Forecast WRSI — Projected end-of-season WRSI based on current conditions.
Anomaly — Deviation of current WRSI from the long-term mean for the same dekad.

Data Model

Model	Level	Key Fields
RangelandSeason	Configuration	title, season_start, season_end
RegionRangeland	IGAD Region	dekad, start_date, end_date, season, file_current, file_forecast, file_anomaly
CountryRangeland	Country	country, dekad, season, min, max, mean
AdminRangeland	Admin Unit	admin, dekad, season, min, max, mean

Interpreting WRSI

WRSI Value	Pasture Condition
80 – 100	Good — water requirements fully met
50 – 79	Moderate — partial water stress
20 – 49	Poor — significant water stress, pasture degradation likely
< 20	Failure — severe deficit, high livestock mortality risk

Views Available

Map (/rangeland/map) — Interactive Leaflet map with season and dekad selectors, and data type toggle (Current / Forecast / Anomaly).
Upload (/rangeland/upload/) — Upload three GeoTIFF files (Current, Forecast, Anomaly) for a given season and dekad.

Data Collection

python manage.py collect_rangeland                     # Collect latest dekads (both seasons)
python manage.py collect_rangeland --dry-run           # Preview without saving
python manage.py collect_rangeland --season 1          # Season 1 only (short rains)
python manage.py collect_rangeland --season 2          # Season 2 only (long rains)
python manage.py collect_rangeland --dekad 202605      # Specific dekad
python manage.py collect_rangeland --latest 3          # Last 3 dekads

The command downloads WRSI zip archives from USGS FEWS NET (east1/ and east2/ directories), extracts three TIF files per season, clips to the IGAD boundary, and calculates zonal statistics.

Relevance

This module is critical for pastoral communities in Kenya, Ethiopia, Somalia, and Sudan. Declining WRSI during the main rainy seasons is an early indicator of potential livestock death and subsequent pastoral livelihoods failure.