Electrical Resistance Tomography for Suspended Sediment Measurements in Open Channel Flows Using a Novel Sensor Design H. Inaki Schlaberg*, Jaco H. Baas**, Mi Wang*, Jim L. Best**, Richard A. Williams*, Jeff Peakall** (Received: 14 November 2005; accepted: 24 January 2006) DOI: 10.1002/ppsc.200601062 1 Introduction Electrical Resistance tomography (ERT) has been pre- viously employed to measure sediment concentrations in liquids (Bolton et al. [1], James et al. [2], Qiu et al. [3]), and linear sensors were the first type of sensor em- ployed in previous tomographic applications (Qiu et al. [4]). However, ERT has mostly been used in cylindrical vessels or pipes with a circular sensor around the area of interest. Such sensors would thus disturb the flow when attempting to measure solids concentration in an open channel flow with a free upper surface. The present study is part of a larger project that is inves- tigating the fluid dynamics of water flows that have a be- haviour transitional between laminar and turbulent (J. Baas et al. [5]). In order to quantify the fluid dy- namics of such flows, the use and development of ERT is investigated to allow real-time quantification of solids concentration and stratification. This paper explores the feasibility of using ERT methods for measuring sus- pended sediment concentrations and estimation of the thickness of layers of deposited sediment. The research reported herein focuses mainly on the sensor design with limited efforts expended on hardware and software development. Part. Part. Syst. Charact. 23 (2006) 313–320 313 * Dr. H. I. Schlaberg, Dr. M. Wang, Prof. R. A. Williams, Insti- tute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (UK). E-mail: h.i.schlaberg@leeds.ac.uk ** Dr. J. H. Baas, Prof. J. L. Best, Dr. J. Peakall, Earth & Bio- sphere Institute, School of Earth & Environment, University of Leeds, Leeds LS2 9JT (UK). Abstract Understanding the transport and deposition of sediment (such as sand and clay) is essential to allow the model- ling and prediction of sediment dispersal, and the devel- opment of depositional morphology, within modern en- vironments and ancient sedimentary basins. Electrical Resistance Tomography (ERT) has previously been used to provide a measure of particle concentration within moving suspensions. ERT measurements nor- mally employ electrodes around a circular boundary of a container that allows measurement of multiple projec- tions. However, measuring the concentration of a flow in a rectangular channel without disturbing the flow can- not use these well-established sensor rings. This paper investigates the use of a linear sensor array in the chan- nel bed, and a U-shaped sensor array in the channel bed and walls, to measure spatial and temporal gradients in sediment concentration/conductivity of a channellised flow. To overcome the problems with the effect of sedi- ment-covered electrodes and the limited number of pro- jection angles of a linear sensor configuration, the prop- erties of a U-shaped sensor are explored. Due to the additional projection angles in a U-shaped sensor, im- proved reconstructions are obtained. This paper pre- sents the first measurements of suspended sediment concentration and sediment deposition and test objects using linear and U-shaped tomographic sensors. Keywords: channel flow, suspended sediment, tomography © 2006 WILEY-VCH Verlag GmbH & Co. KGaA,Weinheim http://www.ppsc-journal.com