A climatic water balance model 'WatBal' for bio-climatic classification and agro-climatic analysis

摘要

A computer software (WatBal) was developed for estimating climatic water balance components and length of growing period (LGP) for individual stations using overhead climatic data and soil water retention. The program computes various components of water budget (water surplus/deficit, humidity/aridity/moisture indices, bio-climatic type) following the standard methods considering precipitation (P), potential evapotranspiration (PET), and available water holding capacity (AWC) of soils as inputs at either monthly or weekly time steps. The essential inputs for the program are rainfall and evapotranspiration. Mean rainfall is derived from climatic normals and the evapotranspiration is estimated following Penman-Monteith relation based on inputs of normal temperature, humidity, radiation parameters specific to a location. The water-balance program tested for many stations with diverse soil, physiography and climate conditions over India and was found to provide good results. Spatial interpolation techniques in Geographical Information System (GIS) have been adopted for interpretation of geographical variation of the various water budget components. The WatBal software was used in many agriculture research areas in India. A few applications viz., delineation of bio-climatic types, crop growing period, delineation of agro-ecological regions/sub-regions, agricultural drought classification are discussed.