Surprisingly small increase of the sedimentation rate in the floodplain of Morava River in the Strážnice area, Czech Republic, in the last 1300 years T. Matys Grygar a, ⁎, T. Nováková a,b,c , M. Mihaljevič b , L. Strnad b , I. Světlík c , L. Koptíková d , L. Lisá d , R. Brázdil e , Z. Máčka e , Z. Stachoň e , H. Svitavská-Svobodová f , D.S. Wray g a Institute of Inorganic Chemistry ASCR, v.v.i., 250 68 Řež, Czech Republic b Charles University, Albertov 6, 128 43 Prague, Czech Republic c Nuclear Physics Institute ASCR, v.v.i, 250 68 Řež, Czech Republic d Institute of Geology ASCR, v.v.i., Rozvojová 269, 165 00 Prague, Czech Republic e Masaryk University, Institute of Geography, Kotlářská 2, 611 37 Brno, Czech Republic f Institute of Botany AS CR, v.v.i., Zámek 1, 252 43 Průhonice, Czech Republic g University of Greenwich at Medway, Chatham Maritime, Kent, ME4 4TB, UK abstract article info Article history: Received 20 October 2010 Received in revised form 10 March 2011 Accepted 21 April 2011 Keywords: Fluvial archives Environmental change Proxy analyses Anthropogenic impact Floodplain fines Chemostratigraphy Sediment profiles from the floodplain of Morava River in the Czech Republic have been collected from exposed river banks (4–6 m long sections) and cores (2–4 m deep) and investigated using a set of geochemical proxies validated by granulometry and conventional geochemical analysis, outlined in our previous paper. The work was conducted to evaluate the increase in sedimentation rate during Medieval and modern time periods. Correlation of sediments along the current channel belt allows identification of two most important synchronous changes in the channel structure over the past 1300 years: in the 13th century and at the end of the 16th century. These changes could be related to central European climatic extremes rather than to land cover/land use practises. Analysis of the pollen record in peaty deposits at the floodplain edge allows excluded dramatic deforestation in Medieval times. Maps of the area from the last five centuries revealed direct and indirect signs of past avulsions and clearly show how the original multichannel system was transformed into a single meandering channel in the early 20th century. The extrapolated aggradation rate (net vertical accretion of floodplain fines except for levee sediments) increased from 0.2–0.3 cm/year in 700 AD to 0.3–0.4 cm/year in 2000 AD depending on the grain size of the sediment. This is the smallest yet reported enhancement of siliclastic deposition, although Morava River watershed has been intensively used for agriculture and its land cover has changed in a manner similar to west and central European rivers. © 2011 Elsevier B.V. All rights reserved. 1. Introduction In previous paper (Grygar et al., 2010) geochemical tools have been developed for the determination of the sedimentation rate of floodplain fines by Morava River in Strážnice area. We have shown that the sedimentation rate has depended on the actual facies deposited, the study of deposits from erosion banks must be extended by coring the floodplain more distant to the current channel, and that some of the previous interpretations of the sediment profiles by Kadlec et al. (2009) should be reconsidered. The current paper addresses these questions, hand-drilled cores were analysed, historical maps from 17th and 18th centuries were evaluated, one profile of floodplain sediments with pollen record was analysed, and the output of the previous studies is critically discussed in the light of current knowledge on fluvial response to the changing environment. Research on fluvial systems to elucidate human impacts on soil erosion and sedimentation dynamics in European river systems has flourished in the last decade; the works have recently been reviewed by several authors (Dotterweich, 2008; Lewin, 2010; Macklin et al., 2010; Notebaert and Verstraeten, 2010). Investigations of aggrading rivers hoped to trace anthropogenic environmental changes due to early occupation of lowlands and especially river valleys but, unfortunately, the sedimentation dynamics of floodplains significantly obscures that sediment archive whenever lateral erosion is prevalent (Lewin and Macklin, 2003). Dotterweich (2008) reviewed the sediment record of soil erosion and considered fluvial sediments insufficiently straightfor- ward because of their delayed response to catchment changes. The actual transfer mechanism of eroded soil to river floodplains continues to be investigated and modelled. Recent studies have demonstrated that floodplain sedimentation is delayed after land use change due to temporary sinks of eroded soil, such as colluvia and higher order valleys (Dotterweich, 2008; Kalicki et al., 2008; Lang et al., 2003; Notebaert and Verstraeten, 2010; Rommens et al., 2006) whilst further transport from the temporary sinks needs activation by climatic extremes (Lang et al., Catena 86 (2011) 192–207 ⁎ Corresponding author. Tel.: + 420 2 66173113; fax: + 420 2 20941502. E-mail address: grygar@iic.cas.cz (T. Matys Grygar). 0341-8162/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.catena.2011.04.003 Contents lists available at ScienceDirect Catena journal homepage: www.elsevier.com/locate/catena