The rivers of civilization Mark G. Macklin a, b, * , John Lewin a a Centre for Catchment and Coastal Research and the River Basin Dynamics and Hydrology Research Group, Department of Geography and Earth Sciences, Aberystwyth University, Ceredigion, SY23 3DB, UK b Institute Agriculture and Environment, College of Sciences, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand article info Article history: Received 29 September 2014 Received in revised form 31 January 2015 Accepted 3 February 2015 Available online Keywords: Civilizations Rivers Floodplains Climate Geomorphology Palaeohydrology Channel contraction Avulsion abstract The hydromorphic regimes that underpinned Old World river-based civilizations are reviewed in light of recent research. Notable Holocene climatic changes varied from region to region, whilst the dynamics of floodplain environments were equally diverse, with river channel changes significantly affecting human settlement. There were longer-term trends in Holocene hydroclimate and multi-centennial length ‘flood- rich’ and ‘flood-poor’ episodes. These impacted on five identified flooding and settlement scenarios: (i) alluvial fans and aprons; (ii) laterally mobile rivers; (iii) rivers with well-developed levees and flood basins; (iv) river systems characterised by avulsions and floodouts; and (v) large river-fed wetlands. This gave a range of changes that were either more or less regular or incremental from year-to-year (and thus potentially manageable) or catastrophic. The latter might be sudden during a flood event or a few seasons (acute), or over longer periods extending over many decades or even centuries (chronic). The geomorphic and environmental impacts of these events on riparian societies were very often irreversible. Contrasts are made between allogenic and autogenic mechanism for imposing environmental stress on riverine communities and a distinction is made between channel avulsion and contraction responses. Floods, droughts and river channel changes can precondition as well as trigger environmental crises and societal collapse. The Nile system currently offers the best set of independently dated Holocene fluvial and archaeological records, and the contrasted effects of changing hydromorphological regimes on flood- water farming are examined. The persistence of civilizations depended essentially on the societies that maintained them, but they were also understandably resilient in some environments (Pharaonic Egypt in the Egyptian Nile), appear to have had more limited windows of opportunity in others (the Kerma Kingdom in the Nubian Nile), or required settlement mobility or exceptional engineering response (Huang He, Mesopotamia) to accommodate problems such as river avulsion, desiccation or local salinization. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction The first Old World civilizations, along the Huang He, Indus, Nile, Tigris and Euphrates rivers were almost entirely on alluvium. They were ‘hydraulic’ (cf. Wittfogel, 1957) or ‘potamic’ in the sense that they were in relatively dry environments and farming depended on natural inundation or controlled irrigation from river water. This most commonly involved floodwaters from ‘exotic’ rivers passing into semi-arid or arid environments; discharges were strongly seasonal, and in most cases derived from headwater precipitation regimes often very different to their receiving flood- plains. Floods also brought nutrient-rich sediments. This provided the potential for a prosperous agriculture and for organised soci- eties to develop urban cultures in which deified rulers, writing, and artistic creativity flourished. At the same time, these early civili- zations were vulnerable to both political and environmental stresses, and there has been much debate as to which factors were most significant in contributing to periods of decline and collapse (McAnany and Yoffee, 2010; Butzer, 2012). From the environmental point of view, causes of settlement abandonment are believed to have included prolonged drought (e.g. the Indus; Giosan et al., 2012), channel network contraction and retraction through abrupt reductions in river flow (e.g. Nile in Nubia; Macklin et al., 2013b) destructive floods associated with short-term climate change (e.g. Huang He; Kidder et al., 2012), and long-term soil * Corresponding author. Centre for Catchment and Coastal Research and the River Basin Dynamics and Hydrology Research Group, Department of Geography and Earth Sciences, Aberystwyth University, Ceredigion, SY23 3DB, UK. E-mail address: mvm@aber.ac.uk (M.G. Macklin). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev http://dx.doi.org/10.1016/j.quascirev.2015.02.004 0277-3791/© 2015 Elsevier Ltd. All rights reserved. Quaternary Science Reviews 114 (2015) 228e244