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Effect of unsteadiness and stratification on local scour
180
Book
mineral sequence described in the text (p. 25) does not fit Fig. 1.101. In our opinion the book is the single best source of information in an important field of the Earth Sciences, and the applications presented in the book are of general importance. The book will be of considerable interest for all scientists working in clays, as well as in other fields (e.g. environment, hard rocks). The dissemination of books published by the American Mineralogy Society for example, shows that there exists a large market for Earth Science books, if they are inexpensive. Unfortunately, the price of the book (148 DM) is too expensive for students, and will probably prevent the wide scale distribution that this book deserves. T.F. Nlgler, Bern G. Biino, Bern SSDI 0012-8252(95)00043-7
Scouring
R.J. Garde, K.G. Ranga Taju and U.C. Kothyari, 1993. Effect of unsteadiness and stratification on local scour. Inter. Science Publ., New York. Hardcover, XV + 102 pp. Price: 45.00$. ISBN l-88570-25-8. This book is a monograph sponsored by the Central Board of Irrigation and Power in New Delhi. This Board is a rather unique foundation with a wide membership of institutions and individuals. It initiates studies within. the field of interest of its members, and it expresses the opinion that “..this report will be of immense use to engineers..” The value of the book lies in the comparison of previously proposed scour formulas and the development of new formulas for both clear water and live bed scour. Any designer will open a book on scour with the hope that it may, finally, replace a scatter bordering on chaos with reason-
reciews
able order, and thus make life easier. The book does this to a considerable extent and is definitely helpful to the designer. For clear-water scour nine independent variables are cleverly reduced to a four-parameter prediction formula. When tested with both old and new data, the new formula gives less scatter than other formulas. The same formula also holds for nonuniform as well as for stratified sediments when recommended procedures to derive an effective size are used. Somewhat surprisingly, for live-bed scour a formula with only three parameters is recommended. A possible explanation may be a cancellation effect of the use of a bedload formula in the derivation of the scour formula, but this point is not discussed further in the book. This reviewer is credited with a formula proposed by his American namesake, a slip which in itself is not serious, but reveals a somewhat cursory reading of the literature. This impression is strengthened when a formula is proposed for shear stress below the horseshoe vortex at the pier nose giving a maximum value equal to 4 times the bed shear in the approach flow. Actually that amplification is the value for potential flow without a horseshoe vortex, while Hjorth (1975) reported a measured maximum of 11 to at 45 degrees from the stagnation point (the reviewer found scour hole contours near wide cylinders mimicking Hjorth’s isolines for bed shear). These incidental observations may be a warning for anyone reading the book with the hope that the experienced teachers who are the authors, explain local scour in this slim volume. They don’t, but that should not deter the practicing engineer from using the book as the handy guideline it is, and which was its intention. Maybe we can hope for an enlightening textbook from the same authors on the same topic? T. Carstens, Trondheim SSDI 0012.8252(95)00052-6
Book
mineral sequence described in the text (p. 25) does not fit Fig. 1.101. In our opinion the book is the single best source of information in an important field of the Earth Sciences, and the applications presented in the book are of general importance. The book will be of considerable interest for all scientists working in clays, as well as in other fields (e.g. environment, hard rocks). The dissemination of books published by the American Mineralogy Society for example, shows that there exists a large market for Earth Science books, if they are inexpensive. Unfortunately, the price of the book (148 DM) is too expensive for students, and will probably prevent the wide scale distribution that this book deserves. T.F. Nlgler, Bern G. Biino, Bern SSDI 0012-8252(95)00043-7
Scouring
R.J. Garde, K.G. Ranga Taju and U.C. Kothyari, 1993. Effect of unsteadiness and stratification on local scour. Inter. Science Publ., New York. Hardcover, XV + 102 pp. Price: 45.00$. ISBN l-88570-25-8. This book is a monograph sponsored by the Central Board of Irrigation and Power in New Delhi. This Board is a rather unique foundation with a wide membership of institutions and individuals. It initiates studies within. the field of interest of its members, and it expresses the opinion that “..this report will be of immense use to engineers..” The value of the book lies in the comparison of previously proposed scour formulas and the development of new formulas for both clear water and live bed scour. Any designer will open a book on scour with the hope that it may, finally, replace a scatter bordering on chaos with reason-
reciews
able order, and thus make life easier. The book does this to a considerable extent and is definitely helpful to the designer. For clear-water scour nine independent variables are cleverly reduced to a four-parameter prediction formula. When tested with both old and new data, the new formula gives less scatter than other formulas. The same formula also holds for nonuniform as well as for stratified sediments when recommended procedures to derive an effective size are used. Somewhat surprisingly, for live-bed scour a formula with only three parameters is recommended. A possible explanation may be a cancellation effect of the use of a bedload formula in the derivation of the scour formula, but this point is not discussed further in the book. This reviewer is credited with a formula proposed by his American namesake, a slip which in itself is not serious, but reveals a somewhat cursory reading of the literature. This impression is strengthened when a formula is proposed for shear stress below the horseshoe vortex at the pier nose giving a maximum value equal to 4 times the bed shear in the approach flow. Actually that amplification is the value for potential flow without a horseshoe vortex, while Hjorth (1975) reported a measured maximum of 11 to at 45 degrees from the stagnation point (the reviewer found scour hole contours near wide cylinders mimicking Hjorth’s isolines for bed shear). These incidental observations may be a warning for anyone reading the book with the hope that the experienced teachers who are the authors, explain local scour in this slim volume. They don’t, but that should not deter the practicing engineer from using the book as the handy guideline it is, and which was its intention. Maybe we can hope for an enlightening textbook from the same authors on the same topic? T. Carstens, Trondheim SSDI 0012.8252(95)00052-6