Detecting non-stationarity of precipitation across coastal-terrestrial Virginia

Since the industrial revolution, the Earth's ambient temperature has been rising at an accelerating pace, partially due to the release of greenhouse gases (e.g., carbon dioxide) into the atmosphere. Consequently, precipitation may become nonstationary, leading to new patterns of watershed hydrology with more frequent and/or severe floods and droughts. Non-stationarity occurs when one or more of precipitation characteristics exhibit step changes, temporal trends, and/or variance deviations. The objective of this study was to detect historical variations in precipitation characteristics across coastal and terrestrial Virginia, USA. Thirteen indices were selected to represent precipitation characteristics for amount, intensity, spell, maximum, and exceedance. A modified Mann-Kendall technique was applied to detect step changes and/or temporal trends in these indices on an annual basis. The results indicated that most rain gauges showed a statistically significant step change in one or more indices between 1948 and 2019, with more step increases than step decreases. This indicates that precipitation across Virginia has exhibited non-stationarity, which must be considered for water management. This phenomenon is likely true for most coastal regions worldwide.