Ball, JE 1987, 'A comparison of the hydraulics in three urban drainage models.'.
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Modelling of urban drainage systems is becoming an increasingly important aspect of the management and operation of drainage systems. An important feature of the modelling process is the techniques used in the modelling of both free surfaces and pressurized flow and the different results which alternative techniques will predict. The predicted hydrographs from three models, i.e. ILSAX, SWMM and PIPENET, are compared for situations where free surface and pressurized flow conditions exist in the network. Also discussed will be the theoretical basis for each of the routing techniques employed by these models.
Ball, JE 1987, 'Importance of dynamic wave components for pipe flows.'.
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Presented are the results of an investigation into the magnitude of the terms in the full dynamic wave equation of motion and the influence of neglecting terms upon the predicted hydrograph propagation. A pipe Froude number is proposed as a criteria for selection of the terms in the equation of motion to be included for accurate prediction of hydrograph propagation.
LOGANATHAN, P & SUTTON, PM 1987, 'PHOSPHORUS FRACTIONS AND AVAILABILITY IN SOILS FORMED ON DIFFERENT GEOLOGICAL DEPOSITS IN THE NIGER-DELTA AREA OF NIGERIA', SOIL SCIENCE, vol. 143, no. 1, pp. 16-25.
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We investigated in phosphorus (P) status of 12 well-drained to moderately well-drained soil profiles along an east-west transect in the Niger Delta area of Nigeria, by determining available P estimated by the methods of Bray and Kurz no. 1, Bray and Kurtz no. 2, Olsen and Truog, and the various P fractions. Total P in the six profiles of soils developed on Coastal Plain sands (CPS) ranged from 281 to 1469 ppm mean, 821), and total P in the four profiles of soils developed on Meander Belt deposits (MBD) and Sombreiro Warri deposits (SWD) ranged from 63 to 293 ppm (mean, 133). The two profiles in the transitional zone between CPS and SWD had total P of 326 to 595 ppm (mean, 441). Organic P ranged from 11 to 338 ppm and constituted 3 to 44% of total P. Inactive inorganic P accounted for 9 to 65% of total P. The relative abundance of the various active inorganic P forms was, in decreasing or der, Fe-P, Al-P, and Ca-P, except in three of the profiles of MBD-SWD region, where Ca-P was nearly equal to or slightly higher than Al-P. The results showed high availability of P in CPS soils, medium availability of P in the transitional zone, and low P in the MBD and SWD regions. The distribution of P fractions indicated a low degree of development of the soils, especially the MBD and SWD soils. Total P was significantly correlated positively with percentage of clay and negatively with pH and percentage of sand. Fe-P and Al-P had significant correlation with total P, percentage of sands, percent-age of clay, and available P extracted by the methods of Bray and Kurtz no. 1, Bray and Kurtz no. 2, and Truog. © 1987 The Williams & Wilkins Co.
LOGANATHAN, P, ISIRIMAH, NO & NWACHUKU, DA 1987, 'PHOSPHORUS SORPTION BY ULTISOLS AND INCEPTISOLS OF THE NIGER DELTA IN SOUTHERN NIGERIA', SOIL SCIENCE, vol. 144, no. 5, pp. 330-338.
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Phosphorus (P) sorption at equilibrium concentrations of 0.1–2 ppm in 0.01 M CaCl2 by 42 samples of highly acidic surface layers of Ultisols and Inceptisols from three major geomorphological regions of the Niger Delta of Nigeria, West Africa, conformed to the Langmuir isotherm. Langmuir sorption maxima and sorption at 0.2 ppm equilibrium P concentration ranged from 100–767 μ P/g soil and 30–240 fig μ P/g soil, respectively, indicating that the soil samples have low to medium P fertilizer requirements. No significant difference in sorption capacities among the soils of the three geomorphological regions or the two soil orders was noticed. Sorption capacities were significantly correlated with percentages of clay and silt, surface area, and different forms of Fe and Al, but not with pH or organic matter. Multiple regression equations relating P sorption to exchangeable Al, amorphous Al, amorphous Fe, and crystalline Fe are presented, and the relative contributions of these factors in the soils of the three geomorphological regions are discussed. © 1987 The Williams and Wilkins.
ROPER, H & BAWEJA, D 1987, 'CARBONATION OF CONCRETE AND ITS PREDICTION - DISCUSSION', CEMENT AND CONCRETE RESEARCH, vol. 17, no. 6, pp. 1003-1004.
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