Observation network design for selecting locations for water supply wells

Abstract

SUMMARYAn observation network design method, which simultaneously minimizes parameter uncertainty and exploration cost, is developed for locating water supply wells. Observation networks combining wells and geophysical measurements are considered for delineating the 'best' areas for wells. An area is considered the 'best' where the sustainable pumping rate and the degree of protection for the well are the possible maximum. The level of protection is measured by the travel time for a fixed radius protection zone around a well. The 'most appropriate' measurement network is selected based on two often conflicting objectives:(1) minimization of the uncertainty in characterizing the spatial distribution of the expected yield and travel time; and (2) minimization of the observation cost. The accuracy of estimation is characterized by the average and maximum kriging variance for yields and travel times calculated from measured hydrogeologic parameters. The parameters to be measured by an observation network for estimating yields and travel times are layer thicknesses, porosity, hydraulic conductivity and volumetric water content. They may be obtained from direct measurements (e.g. well logs, specific capacity test, and pumping tests) or estimated indirectly from geoelectric measurements. The approach combines two common techniques, geostatistics and multi-criterion decision making (MCDM), to determine the 'best' measurement network. Geostatistics are used to determine the spatial distribution of the estimation variance for yield and travel time calculated from different sources of data. MCDM is utilized to evaluate observation network alternatives based on the estimation variances and the costs associated with them. The methodology is illustrated for a study area located near Ashland, Nebraska.

Field layout of a tiltmeter array to monitor micro‐deformation induced by pumping through a horizontal collector well

“…In the context considered here, tiltmeter studies can reveal useful information on the further improvement of the construction of a system of wells, on the needs to protect groundwater intake zones and thus on appropriate urban planning for land use (Ball and Herbert ; Pesti et al . ). When local hydraulic characteristics are to be investigated, strategies to deploy tilt instruments in an efficient way are required.…”

Designing an optimal multivariate geostatistical groundwater quality monitoring network using factorial kriging and genetic algorithms

“…In monitoring network design studies, many researchers have considered geostatistical approaches to designing or adjusting environmental monitoring systems and quantifying the informational value of monitoring data and their variations, for example, Rouhani (1985), Rouhani and Hall (1988), Christakos and Olea (1988), Loaiciga (1989), Hudak and Loaiciga (1993), Benjemaa et al (1994), Pesti et al (1994) and Wang and Qi (1998). Recently, Brus et al (1999) used a geostatistical sampling scheme to discuss sampling size and points for estimating the mean extractable phosphorus concentration of fields.…”