Effects of sinuosity factor on hydrodynamic parameters estimation in karst systems: a dye tracer experiment from the Beyyayla sinkhole (Eskisehir, Turkey)

Environ Earth Sci (2014) 71:39213933 DOI 10.1007/s12665-013-2777-1

ORIGINAL ARTICLE

Effects of sinuosity factor on hydrodynamic parameters estimation in karst systems: a dye tracer experiment from the Beyyayla sinkhole (Eskisehir, Turkey)

Harun Aydin Mehmet Ekmeki Mehmet Evren Soylu

Received: 5 March 2013 / Accepted: 28 August 2013 / Published online: 8 September 2013 Springer-Verlag Berlin Heidelberg 2013

Abstract The sinuosity factor (SF) is a critical value in karst systems in terms of estimating their hydrodynamic parameters including groundwater velocity, coefcient of dispersion, etc., through dye tracer experiments. SF has been used in a number of different dye tracer experiments in karstic systems to estimate a representative ow path. While knowing SF is crucially important in the estimation of hydrodynamic parameters, its calculation is associated with signicant uncertainty due to the complexity of sub-surface karstic features. And yet, only a few studies have discussed its uncertainties, which might lead some errors in estimation of hydrodynamic parameters from dye tracer experiment. In this study, dye tracer experiments were conducted in two consecutive years (2003 and 2004) representing low and high ow conditions in the Beyyayla sinkhole (Eskisehir, Turkey) where the ow path is well known. Uranine was used in experiments as a tracer and QTRACER computer program was used to determine the hydrodynamic properties of the Beyyayla karst system as well as to gain insights into the effects of SF from dye tracer experiments on estimated parameters. The results

showed that the breakthrough curve follows a unimodal and a bimodal distribution in low and high ow conditions, respectively. These different distributions stem from the water transport mechanisms, where velocities were calculated as 58.2 and 93.6 m h-1 during low and high ow conditions observed in a spring emerging from the south side of the studied system. The results also show that the coefcient of dispersion, Reynolds number, and Peclet number increased and longitudinal dispersivity decreased with the higher ow rate. Furthermore, the estimated parameters did not vary with either the ow conditions or the tracer transit time, but they have shown some variations with SF. When SF was increased by 50 %, a change in these parameters was obtained in the range of 50125 %.

Keywords Dye tracing Sinuosity factor

Hydrodynamic parameters Karst hydrogeology

Turkey

Introduction

Karstication processes...