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Precipitation concentration index

The precipitation concentration index (PCI), proposed by Oliver (1980) and developed by De Luis and others in 1997. It is an index to analyze the heterogeneity of precipitation and the relationship between variability and monthly precipitation distribution.

The precipitation concentration index (PCI) is a powerful indicator for temporal precipitation distribution and is also very useful for the assessment of seasonal precipitation changes. Change in precipitation patterns and their impact on all life forms is an important climatic problem which needs to be addressed on priority (Davidson, et al., 2003). Markedly, Africa has often shown precipitation variability and associated droughts leading to food shortages (Wood, 1977;Pankhurst & Johnson, 1988;Valli, et al., 2013). It is reported that a 10% deviation of seasonal precipitation from the long-term average precipitation leads to a 4.4% decrease in food production in an area of rain feed Agriculture is common as well as in the area that has backward technology of agriculture.

Usually, the distribution of precipitation is uneven in different month. The large the difference in monthly precipitation, the larger the concentration of precipitation during intra-annual, PCI values that less than 10 indicate a uniform monthly rainfall distribution in the year, whereas values from 11 to 20 denote seasonality of precipitation distribution. Values above 20 correspond to climates with substantial monthly variability in precipitation amounts, therefore, the greater the PCI value, the more variable the monthly precipitation. due to this the calculation and study of precipitation concentration index is very crucial.

accordingly, the classified precipitation concentration index as uniform concentration (PCI < 10), moderate rainfall concentration (11-15), irregular concentration (16-20) and very high concentration (PCI > 20). …

PCI valueClasses
< 10Less precipitation concentration
11 to 15Moderate precipitation concentration
16-20Irregular precipitation distribution
> 20Strong irregular precipitation distribution
Calculation procedure for precipitation concentration index value: suggested by Oliver 1980
Spatial description of PCI

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