Aridity index based on temperature and rainfall data for Kurdistan Region-Iraq

Abstract EN

Aridity index is a numerical indicator of the degree of dryness of the climate at a given location.

Time series of annual precipitation, minimum and maximum temperature records for 22 meteorological stations in Kurdistan region-Iraq were collected from different agencies.

In Kurdistan region-Iraq neither aridity index non it’s trend have been studied, therefore the purpose of this paper is to document the range of an aridity index, called De Martonne’s aridity index (IDM) and to find the trend of aridity index using Mann-Kendal nonparametric test.

Spatial zoning of the region was done using inverse distance weight (IDW) interpolation method by ArcGIS software.

Results showed that different types of climate in the region were appeared however most of the study area falls in the range of semi-arid zone.

Seasonal aridity showed that Kurdistan region-Iraq has extremely humid climate in winter and arid climate in summer.

The De Martonne aridity index, average precipitation and average temperature were drawn for 10, 20 and 30 years according to availability of the data.

Aridity index for 30 years from De Martonne were compared with two other indices and the results were very close.

Trend analyses were performed for precipitation, temperature, and aridity index for the average data of 10, 20, and 30 years.

Results revealed that for 10 year duration Dukan temperature has significant increasing trend at the 95% confidence level.

It can be concluded that the last decade (2006-2015) undergo insignificant increasing in precipitation and temperature.

For 20 year duration Dukan and Hawler temperature showed significant increasing trend at the 95% confidence level.

For 30 year duration all stations temperature increased, Dukan precipitation showed decreasing trend while Dukan aridity index showed increasing trend significantly at the 95% confidence level.

Increased significant trends at the 95% confidence level for temperature appears at both short and long durations (10, 20 and 30 years) while precipitation and aridity index trends appear only in long duration (30 years).