Identifying long‐term empirical relationships between storm characteristics and episodic groundwater recharge

Abstract

Shallow aquifers are an important source of water resources and provide base flow to streams; yet actual rates of groundwater recharge are difficult to estimate. While climate change is predicted to increase the frequency and magnitude of extreme precipitation events, the resulting impact on groundwater recharge remains poorly understood. We quantify empirical relations between precipitation characteristics and episodic groundwater recharge for a wide variety of geographic and land use types across North Carolina. We extract storm duration, magnitude, average rate, and hourly weighted intensity from long-term precipitation records over periods of 12-35 years at 10 locations. Using time series of water table fluctuations from nearby monitoring wells, we estimate relative recharge to precipitation ratios (RPR) to identify statistical trends. Increased RPR correlates with increased storm duration, whereas RPR decreases with increasing magnitude, average rate, and intensity of precipitation. Agricultural and urban areas exhibit the greatest decrease in RPR due to increasing storm magnitude, average rate, and intensity, while naturally vegetated areas exhibit a larger increase in RPR with increased storm duration. Though RPR is generally higher during the winter than the summer, this seasonal effect is magnified in the Appalachian and Piedmont regions. These statistical trends provide valuable insights into the likely consequences of climate and land use change for water resources in subtropical climates. If, as predicted, growing seasons lengthen and the intensity of storms increases with a warming climate, decreased recharge in Appalachia, the Piedmont, and rapidly growing urban areas of the American Southeast could further limit groundwater availability.

Groundwater recharge amidst focused stormwater infiltration

“…Many of the same factors driving RPR in North Carolina (Tashie et al, ) were found to be important here. Tashie et al () also found a negative correlation between RPR and precipitation magnitude and rate and a positive correlation between RPR and duration, an effect that was more pronounced in developed versus undeveloped areas. The decrease in RPR with larger magnitude events (Figure a) was expected due to greater dominance of overland flow in large magnitude storms (Tashie et al, ).…”

“…Tashie et al () also found a negative correlation between RPR and precipitation magnitude and rate and a positive correlation between RPR and duration, an effect that was more pronounced in developed versus undeveloped areas. The decrease in RPR with larger magnitude events (Figure a) was expected due to greater dominance of overland flow in large magnitude storms (Tashie et al, ). We would expect that in an urban area with infiltration of stormwater, there would be greater RPR at low magnitude events compared with conventionally developed urban watersheds without focused infiltration of stormwater.…”

Impact of climate indicators on continental‐scale potential groundwater recharge in Africa

“…The Spearman's correlation coefficients between PGR and climate-change indicators (temperature and the two extreme rainfall distribution indicators; see Table 3)highlight a general negative correlation between temperature (T) and PGR, with zero effect on the MED, SAH, and HORN regions, with a modest impact on SEQ (-0.20), and with a significant influence on NEQ (-0.48) and SAFR (-0.76) (Tashie et al, 2015). While the relationship between rainfall and temperature is difficult to characterize, the correlation between potential evapotranspiration (ET p ) and temperature is often positive (Kingston and Taylor, 2010).…”

A critical assessment of available ecosystem services data according to the Final Ecosystem Goods and Services framework

“…, Tashie et al. ). Further, landcover is commonly the only spatially explicit data type available over large geographic extents (Ivanov and Eigenraam , Kindu et al.…”