Flow partitioning and unstable divergence in fluviokarst evolution in central Kentucky

Abstract

Abstract. In fluviokarst landscapes flow may be partitioned into its surface and subsurface components as well as into diffuse and concentrated flow. The competition among these is hypothesized to be responsible for the divergence of the landscape in a fluviokarst region of central Kentucky into depression-rich, unchannelled karst-rich and channel-poor (KRCP) and strongly fluvially dissected channel-rich karst-poor (CRKP) zones. The interrelationships between diffuse surface runoff, channelized surface flow, diffuse recharge, and point recharge are dynamically unstable and chaotic, implying that small changes in the partitioning are likely to have disproportionately large and long-lived impacts, reflected in geomorphology. In the Kentucky River gorge, rapid Quaternary incision has resulted in local slope changes which should induce instability in the flow partitioning system. A GIS-based landscape classification scheme showed that there is a relationship between slope gradients and the degree of karstification or fluvial dissection. Geomorphic interpretation of landforms in the river gorge area indicates that CRKP and KRCP zones are growing at the expense of other landscape classes. This results in an increase in Kolmogorov entropy, a characteristic of a dynamically, unstable, chaotic system. Results support the hypothesis that divergent landscape evolution is linked to the complex nonlinear dynamics of low partitioning.