Optimum experimental design of a monitoring network for parameter identification at riverbank well fields

Abstract

Keywords:Groundwater and surface water interactions Riverbank filtration Riverbed clogging Hydraulic conductivity MODFLOW s u m m a r y A steady-state flow regime in riverbank well fields is often violated by fluctuations in river stages and variations in groundwater extraction. In this study, a criterion of quasi-steady flow during filtration processes at riverbank well fields was introduced. Under the assumption of steady-state flow, an analytical approach for determining the key hydraulic parameters (aquifer transmissivity and riverbed filtration resistance) between a stream and a hydraulically connected aquifer during riverbank filtration was presented. An optimal regular observation network (consisting of the locations of monitoring wells and the observation regime), which is based on the model-oriented approach using an example of a riverbank well field near the Kuybyshev Reservoir, Russia, was designed to minimise the uncertainty in the estimates of hydraulic parameters. The analyses showed that the initial recession in the surface water levels for the simplest constant groundwater withdrawal patterns can be used to determine the key hydraulic parameters; the error in these estimated parameters was less than 7% or 12%, depending on the designed monitoring network. When comparing the two typical monitoring networks, observation line A-A that passes midway through the water supply wells performed better than observation line B-B that passes through the water supply wells when estimating the hydraulic parameters. The results of this study can be used as a reference for designing and optimising a monitoring network that aims to determine the key hydraulic parameters at riverbank well fields.

A semi-analytical generalized Hvorslev formula for estimating riverbed hydraulic conductivity with an open-ended standpipe permeameter

“…Although numerous approaches (e.g., grain-size distribution analysis, Darcy's law-based in-stream tests, environmental tracer experiments, water balance techniques, integrated surfacegroundwater numerical modeling, etc.) have been widely applied to investigate the hydraulic properties of riverbed sediments (Cheong et al, 2008;Kalbus et al, 2006;Wang et al, 2015), the accurate estimation of riverbed K values remains a challenge. One of the challenging aspects of estimating riverbed K is associated with its high spatial and temporal variability across measurement scales due to heterogeneity in the riverbed sediments (Chen et al, 2010), scouring and depositional processes during flooding events (Dunkerley, 2008;Hatch et al, 2010), and diurnal and seasonal changes in stream flow temperature (Constantz, 1998).…”

Numerical Approaches for Estimating Daily River Leakage from Arid Ephemeral Streams

“…As shown in Appendix A, water losses from the river during stationary groundwater flow periods are controlled by two hydraulic parameters expressed in length units. The first parameter, which is the streambed hydraulic resistance length, ΔL, characterizes the additional hydraulic resistance due to the bottom sediments of the river channel [36]. The length ΔL is expressed as follows:…”

Design and Optimization of a Fully-Penetrating Riverbank Filtration Well Scheme at a Fully-Penetrating River Based on Analytical Methods

“…Similar to many other optimizing efforts, the parameters are not independent [39], which makes the optimizing efforts more difficult, especially in the use of analytical methods [40]. The basic hydrogeology tells us that the cone of depression of the groundwater level will continually extend both in the vertical and horizontal dimensions when pumping, unless the aquifer could capture as much as water recharge relative to the water yield [41].…”