Effect of Water Withdrawal on Hydraulics and Morphology of Pumduang River, Thailand
Abstract The HEC-6 river morphological mathematical model is applied to predict the effect of water withdrawal from the Pumduang River on its water surface and bed profiles. The river is situated in the Surat Thani province in the south of Thailand. The HEC-6 model is calibrated and verified based on field data. After the model calibration and verification, the HEC-6 is applied to predict the effect of water withdrawal on changes in water level and bed level of the river. The predicted changes are compared with the results of a physical movable bed hydraulic model of scale 1:60. The agreement is found to be satisfactory. The equilibrium river bed and water surface profiles are determined for the annual average flow and the 2-, 10-, 25- and 100-year return period floods for the cases with and without water withdrawal. The water withdrawal of 16 percent of the average annual discharge of the Pumduang river is found to have no endangering effect on the flow and morphological condition of the river
Mathematical Modeling of Scour and Deposition
Electronic computers are opening up the field of sedimentation engineering by permitting the analysis of problems which heretofore have required too much time and effort. Movable stream bed profiles are being calculated in addition to water surface profiles. The initial gradation of sediment material in the stream bed may be prescribed to facilitate the calculation of an armor layer. This gradation is continually changed by the computer program in response to sediment particles being deposited on the stream bed and material on the stream bed being removed to satisfy transport capacity. Hydraulic sorting of sediment by grain size is accomodated. The stream bed does not have to be represented by a single grain size. Retardance of motion because of armor layer is calculated.
On Hilbert's thirteenth problem and related questions
Hilbert's thirteenth problem involves the study of solutions of algebraic equations. The object is to obtain a complexity estimate for an algebraic function. As of now, the problem remains open. There are only a few partial algebraic results in this connection, but at the same time the problem has stimulated a series of studies in the theory of functions with their subsequent applications. The most brilliant result in this cycle is Kolmogorov's theorem on superpositions of continuous functions.