Analysis of temporal and spatial distribution and change-points for annual precipitation in Kansas, USA

Precipitation directly impacts agricultural production, water resources management, and recreational activities, all of which significantly affect a state's economy. As the human population increases, demand for water escalates due to its crucial role in human health and food production. The question then becomes, can current water management strategies ensure sustainable access to clean water, maintain food supplies, and permit industrial uses given a changing climate? Developing a solid understanding of rainfall patterns and trends is vital, particularly for regions like Kansas with high spatial and temporal climate variability. In this study, three statistical methods were used to analyse annual rainfall trends in Kansas using daily rainfall data from 1890 through 2011: (1) a linear regression model, (2) the Mann-Kendall test, and (3) the Spearman test. A gradual increase in total annual rainfall was noted for 21 of 23 stations, including eight statistically significant upward trends. The 23 station period of record average slope for Kansas was 6.8 mm per 10 year with a minimum value of -8.5 mm per 10 year for Saint Francis in the northwest and a maximum value of 20.1 mm per 10 year for Independence in the southeast. In addition, sudden change analyses were conducted using cumulative sum and Pettitt tests. At 12 stations, significant change-points were detected as early as 1940 and as recently as 1980. The increasing trend, particularly after the significant change-points, is useful in updating water management plans. Total annual rainfall correlates with available water in soil, lakes, streams, and reservoirs and can assist with agricultural production decisions such as crop selection and new plant variety development when combined with rainfall distribution analysis throughout the year.