Drought Index Calculator

Formula

The formula to calculate the Drought Index (DI) is:

\[ DI = \frac{P - E}{P + E} \]

Where:

(DI) is the Drought Index
(P) is the total precipitation received during a specific period (mm)
(E) is the total evapotranspiration during the same period (mm)

What is a Drought Index?

A drought index is a numerical scale used to characterize the severity and impacts of drought conditions over a certain period and area. It integrates various factors such as rainfall, temperature, soil moisture, and evaporation rates to provide a comprehensive understanding of the drought situation. Different drought indices such as the Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), and the U.S. Drought Monitor are used globally to monitor and manage drought conditions.

Example Calculation

Let's assume the following values:

Total Precipitation (P) = 100 mm
Total Evapotranspiration (E) = 50 mm

Using the formula:

\[ DI = \frac{100 - 50}{100 + 50} = \frac{50}{150} \approx 0.33 \]

The Drought Index (DI) is approximately 0.33.