In some ways, this was a book which could have been written for me personally. I did my PhD on river ecology and the institute where it was partly based later became part of the Centre for Ecology and Hydrology. I also did some research in Aswan, which gets a passing mention. That all gave me a lifelong interest in everything riverine. Having said that, the water analogy is maybe sometimes a little over-used. 'The two of them move in tandem, their shadows blend, like water molecules clinging to each other'. Those sort of metaphors are nice in moderation, but there were a lot of them. I was also not sure what to make of the writing about water memory. What is that all about? It reads like a legitimation of homeopathy, which is rather off-putting. 
There is also quite a lot about living as a migrant in a country where you did not grow up, which also applies to me. "He has even taken English seaside holidays - and yet he is, and always will be, a foreigner". 
The book is nicely written, rather poetic in parts. It uses a rich vocabulary; coruscating, crepuscular and sibilant, were all interesting words. I very much enjoyed the way that the book wove together three stories separated by time and space. That worked very nicely.
What was more difficult to read were the graphic descriptions of massacres. It is, of course, important to remember these events, but that does mean that I might hesitate to recommend the book to some people.
Near to the end of the book she wrote, "there is no better space than literature, especially the novel... within which to freely explore the most complex issues of our time with nuance, depth, care and empathy".  I could not agree more.