A Comparison of Air Temperatures at Irrigated and Nonirrigated Sites in Andalucia, Spain

The purpose of this research is to determine how, land use land cover change, irrigation in particular, affects the air temperature recorded by weather stations located on olive farms in the region of Andalucia, Spain. Data were collected from six weather stations located in close proximity to irrigated olive farms and from three non-irrigated locations. The length of the time series is from 2001 through 2015. The data consist of daily minimum and maximum temperatures, which were then used to calculate their respective monthly averages. Data from all six irrigated sites were compared and analyzed against all three non-irrigated sites (pairwise comparison) for the growing season (April-September). These resulted in 36 total pair-wise comparisons (18 for minimum temperatures and 18 for maximum temperatures). These comparisons were completed for each year and for the entire timeseries for each pair. The latter provides average long-term changes. The results suggests that irrigation does impact air temperature, particularly maximum air temperature. It was found that the maximum temperatures at irrigated locations were generally higher than non-irrigated locations but they gradually decline with progression of the growing season due to increased applications of irrigation as crop-water demand increases. The maximum decline typically occurs during the mid-growing season. As irrigation declines towards the end of the growing season, irrigated sites again tend to become warmer than the non-irrigated locations.