Investigation of the Changes of Hydrology Characteristics and the Selections of Sampling Sites under Urbanization in Watershed Scale
| Autor: | Yen-Jen Lee, 李炎任 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 This study focuses on the environmental impacts under the urbanization process. It is divided into two parts, “Urbanization of Rural Areas in Hydrograph Characteristics on Watershed Divisions” and “Selecting Watershed Site to Perform Field Sampling by Spatial Data Mining”. These two parts investigate how to estimate the hydrology characteristics estimate and how to select sites for sampling by using the geostatistics approach or by using the geographic information systems (GIS) in basin scale problems. The first part analyses the changes in hydrograph characteristics of rural statuses to urban statuses on watershed divisions in Taiwan. The main approach is to relate applicable model parameters with the corresponding imperviousness based on calibration and verification by using a semidistributed model and 102 events. The model structure is conceptual linear reservoirs with parallel-type cascaded storages which is represented by overland and channel coefficients. The hourly mean rainfall of the watershed and its divisions are calculated by using the Kriging method. The time-variant rainfall losses are calculated by using the constant percentage method. In calibration, the storage values of 50 events derived by using appropriate parameter bounds and they are more reasonable than those using inappropriate bounds. Based on the optimal interval method, the overland storages display more marked changes than the channel storages in response to imperviousness changes. By contrast, the channel storages are unaffected by the changes in urbanization. The overland storages are related to the imperviousness by using the regression equations for determining their relationships in continuous changes of urbanized divisions. The verification of the regression relationships is based on 52 events. The results indicate that the power linkage is an available selection for linking division parameters with the corresponding imperviousness. Additionally, this study concludes (1) appropriate bounds in parameter calibration which are useful for obtaining significant storage values, and (2) the study results using these suitable storages indicate large changes in imperviousness on the downstream divisions, marked urbanization result in reducing the time to peak at least by 10%, the peak discharge exceeds an increment of 20 to 30%. In the second part, a systematical site selection framework for a wide-range survey is presented. Spatial data mining are used to delimit three classes of pollution potential areas. Moreoever, the results show that, pollution samples highly correlate with the classified potentially contaminated areas. For instance, most of the soil pollution and water pollution appear under the high potentially contaminated area (HPCA). On the other hand, under the low potentially contaminated area (LPCA), no pollution is discovered. This shows that the proposed approach is fairly reliable and can be applied to wide-range areas within a river watershed in order to determine site selections for performing field sampling. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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