Estimation of Phosphorus Loading in Rivers during High Flow Periods
| Autor: | Jih-Hung Liu, 劉紀宏 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 The reservoir in Taiwan almost subjected to the problem of eutrophication because of the surplus of nutrient result in the uncontrollable growth of algae. It is the most important topic to control the loading of phosphorus, in order to retain the good water quality of reservoir. Numerous agricultural activities, especially the production of tea or fruit in riparian areas, are conducted in watersheds in the upstream of reservoir. Nutrients from such activities, including phosphorus, are typically flushed into rivers during high flow period, when over 70 to 90 % of the yearly total amount of phosphorous enters reservoirs. Excessive or enhanced soil erosion from rainstorms can dramatically increase the river sediment load and the amount of particulate phosphorus flushed into rivers, at this time, the particulate phosphorus is the dominant form of phosphorus. The study area Da-Lin bridge is located at the Daiyujay Creek watershed, which feeding the Feitsui Reservoir in Taiwan. First, the kinetic of adsorption/ desorption is found that after the water samples preserved over 16 hours the adsorption and desorption of the system approached equilibrium. During the high flow rate periods the Langmuir isotherm performed the best results of the others in the specific adsorption of phosphorus, furthermore, the amounts of TP transported through the river cross section during the June 9 rainstorm and Typhoon Bilis during duration T were accounted for roughly 0.7% and 28.8% of total TP loading during 2006, respectively. It shows that during the high flow rate periods which contributed the most amount of TP loading in a year. During high flow rates periods, the sampling data the of the river always regarded as the average concentration of the river section, which must be confirm first that the nutrient concentration is completely mixed at the sampling section or the estimation of the method may make some error. Besides, river section are classified into several subsections during typhoon Saomai and typhoon Shanshan and the sampling and simulation are excuting by each subsection to identified a more efficiency method for more representative data. The Chiu’s sediment concentration distribution formula performs the suspended solid concentration well. As mention to the dissolved phosphorus, the method is developed by the diffusion theory and then dimensionless concentration profile formula is obtained. According to the result, assume that the major source of the nutrient occurred at the depth of the river with the same opportunities. The results show that as the average concentration could easily pump at the depth between 0.4-0.6D. In addition, as mention to the particulate phosphorus concentration profile, the results found that the most part of the suspended solid could classified as silt or clay, which used to adsorbed more particulate phosphorus than any others. The specific adsorption (=X/m) ranges of water samples in the typhoon Saomai and Shanshan are observed as 79-3,065 mg P/kg SS and 67-13,329 mg P/kg SS, respectively, which almost at the state of desorption. The usage of relation between basic concentration with adsorption coefficients and, whicn simplified the amount of sampling. So that the cost of sampling should be save and further makes the sampling of phosphorus becomes more efficiency and economic. To summarized the results of the research, which could found out the effect of management of land use in watershed by estimation of phosphorus loading during high flow periods and could also used as the references for the management of land use in watershed in future. |
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