Rainfall forecasting and a real time hydrologic information system for Bangkok, Thailand | |
| Author | Nguyen Quang Hung |
| Call Number | AIT Diss. no.WM-09-02 |
| Subject(s) | Rain and rainfall--Thailand--Bangkok--Forecasting Hydrologic models--Thailand--Bangkok |
| Note | A dissertation submitted in partial fulfillment the requirements for the degree of Doctoral of Engineering, School of Engineering and Technology, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-09-02 |
| Abstract | Occurrence of flooding in cities has become more frequent due to increased population, rapid urbanization and unplanned development. This inevitable natural phenomenon not only damages lives, natural resources and e nvironment, but also impacts of economy and public health. In urban areas, the flood is caused due to several reasons: rising of water level in river passing through the cities, high tides for coastal cities, inadequate sewer system, poor operation and maintenance of drainage system etc. Flood management requires an understanding of causes and forecasting of floods so that appropriate actions including issuance of wa rning can be taken to reduce the adverse impact of floods. One of the most important prerequisites for a flood forecasting system is the real time information on rainfall amounts and intensities. Integrating flood forecasting and real-time hydrologic system can provide a powerful tool for flood prevention and management. The main objectives of this study are to forecast rainfall in Bangkok, Thailand and to simulate flood situation in a commercial area (Sukhumvit area) of Bangkok. Applications inherited from rainfall a nd flood forecast, e.g. forecasted spatially distributed rainfall map and the flood inundation map, are made public through the Internet and WAP services.Two approaches were applied to forecast ra infall in Bangkok area. The first approach is based on artificial neural networks (ANN) with rainfall and other meteorological parameters as an input, and the second one based on translation method using radar images. To design an appropriate ANN model, six alternative models were set up and tested with different networks, model struct ures, transfer functions, and training data sets. Among the six models analyzed, the ANN model which used generalized feedforward type network and a hyperbolic tangent function and a combination of meteorological parameters (relative humidit y, air pressure, wet bulb temperature and cloudiness), and the rainfall at the point of forecasting and rainfall at the surrounding stations, as an input for training of the model was found most satisfactory. The best model was then employed to derive rainfall forecast from 1 to 6 hour ahead at 75 rain gauge stations, as forecast points, covering th e study area. Results show that the models performed consistently well and provided remarkably acceptable results of rainfall forecast with lead time of 1, 2 and 3 hours. Th e efficiency indices gradually reduced as the forecast lead time increased from 4 or 5 or 6 hours. Although the model performance of 6 hour forecasting was low and the forecasting was not as accurate as expected, the developed model can still be us ed for practical applications such as rainfall forecasting and flood management for the urban areas. In the second approach, the Translation m odel which is developed with both parallel and rotational translation, shearing strain and expansion of the rainfall pattern was applied to form a translation vector field from the consecutive radar images collected from BangNa weather radar station. The translation vectors are created presenting moving trend of rainfall pattern and its gr owth/decay rate, and then the rainfall is forecasted for 1 hour in advance. From the an alysis of results, 10 minutes is considered as the best time interval between two radar images for 1 hour forecast.A MOUSE model, describing flows both in pipe layer and street networks layer, and simulating one-dimensional flow for river a nd canals network, is developed for a sub- iv catchment (Sukhumvit area) in Bangkok. The drainage model was well calibrated and validated with data collected during fieldw ork. Based on the calibration and verification results, it can be concluded that the MOUSE m odel can be used to simulate water flow in the complex drainage system in the Sukhum vit area. Results from the rainfall forecast models are used as an input into the urban drainage model to simulate and predict flood situation. A Digital Elevation Model (DEM) with grid resolution of 5m is prepared and applied in ArcView environment to genera te flood inundation maps and to evaluate results for various alleviation schemes. Making the real time hydrologic data and in formation available to the public was successfully carried out. A computer at the Asian Institute of Technology is dedicated as a server to establish the real time hydrologic information system. This server receives online data (rainfall and meteorological data, and radar images), updates database and presents them on the website. This server re sponds to different request from the public and provides flood warning, real time status of water level in pipes and street and other information. A web site http://www.wap.ait.ac.th for Internet users was established. On this web site users can see a map with the di stribution of rainfall, an online radar picture of the Bangkok area and a real time flood risk map of the study area. A SMS service was developed and the people who sign up fo r the service automatically receive a warning SMS. In addition, people signing up with a WAP-device also automatically receive a SMS and can then look at the maps at http://www.rain.ait.ac.th/pdadims . This real time hydrologic information system is not only helpful to the urban flood control operators in decision making for effi cient urban flood management to minimize flood damages in the city but also for the public in planning activities and avoid traveling to flooded areas. Moreover, the hydr ologic information system designed in the study is generic, so that the concepts can be easily transferred and implemented at other cities in the Asian region. |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-09-02 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Mukand S. Babel; |
| Examination Committee(s) | Nitin Kumar Tripathi ;Sutat Weesakul ;Gupta, Ashim Das; |
| Scholarship Donor(s) | MTERM – DANIDA; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2009 |