Temporal and Spatial Analysis for Precipitation Trend and Homogeneity in Semi-Arid Area, Northwestern Iraq as a Case Study

Abstract

Detecting the trends and homogeneity in precipitation records is fundamental in climate change and hydrological studies. This study investigates the homogeneity and trends of precipitation time series at four stations in north-west Iraq. The analysis encompasses the annual, seasonal, and monthly time scale at a significant level of 5%. Four tests were employed to assess the homogeneity analysis of the precipitation time series: Standard Normal Homogeneity, Buishand, Pettitt, and Von Neumann Ratio. Then two methods were applied to detect the trend from 1970–2020. Sequential Mann- Kendall and Innovative trend tests were employed to track the significant trend changes and to find the magnitude, tendency, and significance of the trend during this period for precipitation. Microsoft Excel was utilized to achieve the concepts of homogeneity and trend for the precipitation time series. The results of the homogeneity test confirmed the suitability and homogeneity of the precipitation for further analysis. The trend analysis showed that there is an annual increasing (positive) trend in precipitation at Duhok and Rabia stations by 14 mm/decade and 0.25 mm/decade, respectively. Conversely, Mosul and Tal-Afer stations exhibited a decreasing (negative) trend by 21 mm/decade and 8.9 mm/decade, respectively. Spring precipitation exhibited a statistically significant decreasing trend in all Northwestern stations. The most substantial value in the Mosul station by 11mm/decade. This study highlights the importance of investigating drought and flood adaptation strategies to address the impact of climate changes impacts at the mentioned area.