Drought Classification

DROUGHT TYPOLOGY CLASSIFICATION CODE This R script classifies hydrological drought events into seven distinct types based on their meteorological drivers and seasonal characteristics. The classification system helps identify the dominant processes leading to streamflow deficits. DROUGHT TYPES:1. rain_to_snow - Rainfall deficit transitioning into snow season drought2. rain_def - Classical rainfall deficit driven drought3. wet_to_dry - Seasonal transition from wet to dry conditions4. cold_snow - Cold season drought with snow accumulation potential5. warm_snow - Warm season drought influenced by snowmelt processes6. composite - Multi-factor drought with mixed driving mechanisms7. snowmelt - Drought primarily caused by snowmelt deficit METHODOLOGY:The script processes gridded pentad (5-day) hydro-meteorological data and:- Calculates standardized anomalies for each variable by pentad- Identifies deficit events using threshold-based detection (10th-15th percentile)- Applies event merging rules (maximum inter-event time, minimum duration)- Classifies streamflow drought events using decision tree logic based on: * Antecedent precipitation deficits * Seasonal timing and temperature conditions * Snow accumulation and melt processes INPUT DATA:- Variables: Precipitation (P), Streamflow (Q), Temperature (TAS), Snow Water Equivalent (SWE), Soil Moisture (SM), Potential Evapotranspiration (PET)- Temporal resolution: Pentad (5-day intervals)- Spatial resolution: Gridded data with x,y coordinates- Source: E-OBS derived hydro-meteorological dataset OUTPUT:Individual .fst files for each grid cell containing:- Event ID, start date, end date- Drought type classification- Deficit magnitude (standardized)- Event duration- Grid cell coordinates REQUIREMENTS:- R packages: data.table, fst- Custom function: def.vol_id() for event identification (source: dv.R) USAGE:The code is configured for testing with 20 neighboring grid cells (1971-1980). For full analysis, remove or modify the spatial/temporal subsetting section. AUTHORS: Sadaf NasreenCONTACT: sdfrn2@gmail.com