Established by UNESCO’s International Hydrological Programme, the International Hydrology Series includes a number of valuable contributions on important topics in water science and management. The book by P.P. Mujumdar and D. Nagesh Kumar, entitled Floods in a changing climate, is a welcome addition to this series.
The subtitle, “hydrologic modeling”, clearly states the focus on the book. The authors are providing a very well-structured overview of the basic applications of hydrological models and their joint use with their now inseverable complement, geographic information systems (GIS) in the context of climate change studies.
As Robert Wilby adequately points out in the foreword to this book, “The scientific community offers the practitioner a bewildering set of methodologies” (ix). This is also true in the more specific field of climate change science. However, in a typical pragmatic engineering approach, the authors of Floods in a changing climate have managed to avoid the pitfalls associated with the intricacies of this still-developing scientific field and provide the practitioners with a clear, step-by-step, path forward.
The book comprises six well-defined chapters, preceded by a list of abbreviations and a short glossary. Following the introduction, the reader is provided with a brief overview of some approaches used in hydrologic modelling, starting with classic flood peak estimation methods such as the Soil Conservation Service (SCS) and Rational methods. Flood routing is then discussed and some commonly used algorithms such as the Muskingum method are described.
“To choose is to renounce. How terrifying...” –Dominique Lévy-Chédeville.
Writing a section on commonly used models is a difficult task because the large number of models available means that the authors must make a choice, and hence bring about frustration for modellers whose model was not selected.
The authors chose to describe three models in greater detail: HEC-HMS, HEC-RAS and SWMM. Some would criticize that all three are American models. The authors try to compensate by providing a table of commonly used models, spanning three pages (!). Statistical hydrologists are not forgotten in this review. A section on empirical models is also provided. However, only two approaches are described: the very popular Artificial Neural Networks, or ANN (yes, the usual figure with circles and arrows showing ANN structure is provided) and fuzzy logic-based models. The description of the latter is limited to implementations in flood routing.
Chapter Three, entitled “Climate change impact assessment”, begins with an explanation of the required coupling between large-scale climate models and hydrologic tools. A brief summary of common greenhouse gas emission scenarios follows. The authors have dedicated a rather large section to statistical downscaling, while dynamical downscaling is summarized in four paragraphs. This perceived bias is likely the result of the need for hydrologists to downscale meteorological information at the basin/local scale, which is most often done using statistical downscaling.
Chapters Four and Five provide information on remote sensing analysis and GIS tools used in conjunction with hydrological models. Basic image processing is first reviewed in Chapter Four, with the inclusion of some examples using Matlab. The chapter describing GIS tools includes two sections on the development of digital elevation models (DEM) and one on the integration of GIS data into hydrologic models. Finally, the last chapter provides case studies from the authors’ country (India).
Each chapter includes examples and exercises, indicating that the authors clearly aim for this textbook to be used in hydrology courses. Most figures are appropriate and of high quality, although it is puzzling to see that a book of this quality was printed with all colour plates grouped together (between pages 18 and 19!).
Recently, Ruddell and Wagener (Citation2013) advocated that the path forward in hydrology education is to aim for the next generation of water scientists to be “T-shaped”, meaning that both depths in a specific area (the vertical bar of the T) and breadth in a multidisciplinary context (the horizontal bar of the T) are required. I believe that the book by Mujumdar and Nagesh Kumar will help some hydrologists to cross their T.
Professor, INRS-ETE
© 2014 Canadian Water Resources Association
http://dx.doi.org/10.1080/07011784.2014.942108
References
- Lévy-Chédeville, D. 1981. L'homme aux passions tristes, edited by P. Tysseyre, 163 pp, Paris.
- Ruddel, B., and T. Wagener. 2013. Grand challenges for hydrology education in the 21st century. Journal of Hydrologic Engineering. Accepted manuscript. doi: 10.1061(ASCE)HE.1943-5584.0000956.