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
Prediction of the Effects of a Flood Control Project on a Meandering Stream
Abstract : The Arkansas River between Pueblo, Colorado, and John Martin Dam, a distance of about 125 river miles, is an alluvial, sand-bed river. It meanders between bluffs in a flood plain about one mile in width. During geologic time the downstream (eastern) portion of this reach has been migrating southward due to heavy sediment loads from northern tributaries. A local flood control project is being planned for the town of La Junta, which is in the downstream one-third of this reach. A study was undertaken to evaluate the future performance of various flood control alternatives with regard to channel stability, sediment movement, and project maintenance. The alternatives considered were various channel and levee configurations. Evaluations were based on both long-term (100-year period) and short-term (single flood event) hydrologic scenarios. The primary tool used in this study was the movable boundary mathematical model HEC-6 entitled 'Scour and Deposition in Rivers and Reservoirs.' The hydrologic and sediment regimes of the study reach are complex due to four tributaries and eleven major irrigation diversions. This paper describes development of representative data for the long-term analysis, operation of the model, calibration and simulation strategies employed, interpretation of model results, and computational aspects of this application.
Genetic Effects of Acute and Chronic Ionizing Irradiation on Pinus sylvestrisL. Inhabiting the Chernobyl Meltdown Area
The main results of the 12-year radiation-genetic monitoring of radiobiological, cytogenetic, and genetic parameters in Pinus sylvestrisforest plantation from the Chernobyl meltdown area are presented. The acute ionizing irradiation at doses > 1 Gy was shown to induce formation of morphoses and depressed growth; at doses >2 Gy, the reproductive ability of the trees declined. The radiobiological parameters showed a linear or close to linear dose-dependence relationship. The acute irradiation at a dose of 0.5 Gy induced cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of the mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of cytogenetic analysis of seedlings obtained from seeds annually collected in zones of slight, moderate, and strong damage of Pinus sylvestrisL. are presented.