Groundwater‐stream connectivity from minutes to months across United States basins as revealed by spectral analysis

Abstract

Stream corridors are dynamic places where streams and aquifers are connected and interact to various degrees, depending on geology, climate, stream morphology, and water use. Water table fluctuations propagate through the unconfined aquifer and are linked with changes in solute export to streams and biogeochemical transformations in floodplain soils. Through publicly available USGS data, this study aims to better understand the behaviour of stream‐groundwater connectivity and water table fluctuations by analysing continuous time series of water levels from 17 pairs of stream gauges and nearby (<100 m) groundwater monitoring wells. Sites are located within 8 of 18 major hydrologic units (HUC‐2) across the contiguous United States and span a variety of stream sizes, climates, and land use practises. More than 50% of sites have a water table that remains within 3 m of the land surface year‐round. Energy spectral densities and cross‐wavelet transformations generally reveal strong coherence between the water table and stream stage over daily to monthly periods. The transfer function, which describes relative variations between the water table and stream stage, shows that 10 of 17 sites are more stream‐dominated at daily and monthly frequencies, meaning that water level fluctuations are greater in the stream and propagate into the aquifer. Only 1 of 17 sites is more groundwater‐dominated at daily and monthly frequencies, meaning that water level fluctuations are greater in the aquifer. This study shows the utility of frequency‐domain analysis for revealing specific timescales of stream‐aquifer interaction.

Dynamic Response Characteristics of Shallow Groundwater Level to Hydro-Meteorological Factors and Well Irrigation Water Withdrawals under Different Conditions of Groundwater Buried Depth

“…Cui et al [29] applied wavelet analysis to investigate the response relationship of groundwater depth to precipitation based on the monthly time series data and found that the delayed response time ranged from 8 to 14 months in Baotou, China during the period of 2007-2017. Clyne and Sawyer analyzed the lag response time of riparian groundwater level to stream stage at 17 locations distributed in the United States and found that it varied from days to weeks in the spring and summer [30]. Qi studied the dynamic response of karstic water level to precipitation and water stage of the Yellow River in Jinan area of Shandong Province in China during 2007-2018 [31].…”