Surface Dryness Index (SDI) is used to quantify precipitation availability over atmospheric water demand. Aridity Index (AI) represents adequacy of the precipitation to satisfy vegetation water demand. AI values are higher for more humid condition and lower for arid condition. A methodology has been developed to generate SDI using INSAT 3D derived daily reference ET and rainfall data. Presently for the generation of SDI daily HE (Hydro-Estimator) rainfall product is used. SDI will be generated for standard meteorological week. The whole procedure has been shown in Figure 1.

The generated SDI will be categorized in four classes:

⋄ Severe Dry: SDI < -75

⋄ Mild Dry: -75 to -0.01

⋄ Mild Wet: -0.01 to 75

⋄ Wet: 75 to 5000

Disclaimer: This is an experimental product and is an indicator dryness and wetness in Rainfed regions of India.