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Geoscientist Online

Introducing Large Rivers

large riversRivers are drains – lines connecting the topographic points of lowest potential in a catchment and, thus, along which water flows to get away.  In doing so, they remove the weathering and erosion products. The basic model, followed by all rivers, large, medium and small, has three zones where sediments are generated, transferred and deposited, respectively. There really are no surprises: water flows downhill.

The difference between large rivers and the others is that, because of their relative length and huge drainage areas, large rivers can function in more modes. The underlying geology is a major controller of mode changes. While these basic issues come through in the book, the presentation and development of the deeper detail in the text seem confusing. In part that might be because large rivers are, almost by definition, very diverse within themselves, and so inherently hard to deal with as a group. In this context it certainly helps that the large Arctic rivers are dealt with in their own separate chapter.

The book is intended to help readers new to the field and, on that basis, covers a wide range of disciplines including geomorphology, hydrology, ecology and the anthropogenic environment. Each chapter, apart from those invited from Wolfgang Junk (large river floodplains) and Olav Slaymaker (Arctic rivers) respectively, ends with a set of questions that will help readers reflect on and take in the content of the chapter concerned.

As might be expected in an introductory book, much of the information given is qualitative rather than quantitative. In the context of introductory ideas and information, however, it is unfortunate that assorted quantitative errors have got through the editing. The nominal capacity of Lake Mead, behind Hoover Dam, is given numerical values that differ by three orders of magnitude – 98 million and billion m3, respectively. Many, if not most, readers will recognise and adjust for that slip. More concerning, though, is that the official (notional) capacity is actually around 32 billion m3, so the significand itself is wrong. There are similar issues elsewhere. It is unlikely, for instance, that the capacity of a reservoir on the Missouri or anywhere else approaches 29,500 km3, exceeding that of Lake Baikal. Apart from such corrections, the book needs a glossary, which should include the “local” names used at times in the text. While the Chinese name for the Yangtze transliterates as Chang Jiang, not all readers will know that.

By Jeremy Joseph

Introducing Large Rivers. A Gupta, 2020. Published by: John Wiley & Sons, Chichester, UK.  ISBN: 978-1-118-45140-3. Softback. 288 pp. List Price £31.99 (ebook).