HR: 0830h
AN: H11G-0944    [PDF]
TI: Temporal Scaling and Numerical Simulations of The Hydraulic Head and River Baseflow
AU: * Li, Z
EM: zhongwei-li@uiowa.edu
AF: University of Iowa, 121 TH Department of Geoscience, Iowa City, IA 52242
AU: Zhang, Y
EM: you-kuan-zhang@uiowa.edu
AF: University of Iowa, 121 TH Department of Geoscience, Iowa City, IA 52242
AB: Spectral analyses were conducted for hourly hydraulic head (h) data observed over a four-year period at seven monitoring wells in the Walnut Creek watershed, Iowa. The log power spectral density of the hydraulic head fluctuations verse log frequency (f) at all seven wells is shown to have a distinct slope, indicating temporal scaling in the time series of water level fluctuations. The fractal dimension (D) of the time series varies from well to well, and the spectrum for the average h over all seven wells has a fractal dimension of 1.55 and Hurst coefficient of 0.45. The log power spectral density of baseflow in the Walnut Creek and other four watersheds verse log f is shown to have two distinct slopes with a break in scaling at about 27 days. It is shown that the groundwater recharge process in a basin can be estimated from a head spectrum based on existing theoretical results. Hydraulic head in an aquifer may fluctuate as a fractal in time in response to either a white-noise or fractal recharge process, depending on how quickly the hydraulic head responds to recharge events and the physical parameters of the aquifer. The recharge process at the Walnut Creek watershed is shown to have a white-noise spectrum. The observed fluctuations of the head and baseflow are simulated numerically with a transient groundwater flow model in which the recharge rate and hydraulic conductivity are treated as a random process and/or field.
DE: 1829 Groundwater hydrology
DE: 1860 Runoff and streamflow
DE: 1869 Stochastic processes
SC: Hydrology [H]
MN: 2003 Fall Meeting