River stage tomography: A new approach for characterizing groundwater basins

Abstract

[1] Data from tomographic surveys make an inverse problem better posed in comparison to the data from a single excitation source. A tomographic survey provides different coverages and perspectives of subsurface heterogeneity: nonfully redundant information of the subsurface. Fusion of these pieces of information expands and enhances the capability of a conventional survey, provides cross validation of inverse solutions, and constrains inherently ill posed field-scale inverse problems. Basin-scale tomography requires energy sources of great strengths. Spatially and temporally varying natural stimuli are ideal energy sources for this purpose. In this study, we explore the possibility of using river stage variations for basin-scale subsurface tomographic surveys. Specifically, we use numerical models to simulate groundwater level changes in response to temporal and spatial variations of the river stage in a hypothetical groundwater basin. We then exploit the relation between temporal and spatial variations of well hydrographs and river stage to image subsurface heterogeneity of the basin. Results of the numerical exercises are encouraging and provide insights into the proposed river stage tomography. Using naturally recurrent stimuli such as river stage variations for characterizing groundwater basins could be the future of geohydrology. However, it calls for implementation of sensor networks that provide long-term and spatially distributed monitoring of excitation as well as response signals on the land surface and in the subsurface.

A novel method to evaluate the effect of a stream restoration on the spatial pattern of hydraulic connection of stream and groundwater

“…With an inverse model the spatial distribution of the hydraulic properties of the aquifer is estimated from the interplay of all the observed hydraulic head series. Up to now most of the non-numerical hydraulic tomography studies aimed to map the small scale variability of the hydraulic properties of the sediments on the lab to plot scale and used artificial pressure pulses (Yeh et al, 2009;Cardiff and Barrash, 2011). Recently there were attempts to extend hydraulic tomography to the groundwater basin scale and to use natural pressure signals, e.g.…”

“…Recently there were attempts to extend hydraulic tomography to the groundwater basin scale and to use natural pressure signals, e.g. river stage fluctuations as signal (Yeh et al, 2009).…”

“…Time series of hydraulic head reflect effects of different causes, like river stage fluctuations, groundwater recharge, precipitation, evapotranspiration, measurement errors, etc. (Yeh et al, 2009). In contrast to the aforementioned approaches we decomposed the hydraulic head series into independent components using a principal component analysis in order to disentangling the different effects.…”

Geostatistical inverse modeling of the transmissivity field of a heterogeneous alluvial aquifer under tidal influence

“…Historically, the transmissivity and storage coefficient were based on pumping test analysis (Theis, 1935). More recently, hydraulic tomography was developed to integrate more information regarding the head fluctuations from both a set of pumping / injection wells plus observations wells, in order to characterize the distribution of these properties in heterogenous aquifers (e.g., Yeh and Liu, 2000;Zhu and Yeh, 2005;Yeh et al, 2009). Usually in alluvial aquifers, the transmissivity can vary over 5-10 orders of magnitude while the storage coefficient varies over one or two orders of magnitude (Younger, 1993).…”

Dynamic river–groundwater exchange in the presence of a saline, semi‐confined aquifer

“…Such heterogeneity in alluvial aquifers has been highlighted in studies such as Yeh et al . (), which characterize aquifer heterogeneity using groundwater responses to river flood events.…”