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1、第 15 卷增刊 湖 泊 科 学 Vol. 15, Suppl 2003 年 12 月 Journal of Lake Sciences Dec. , 2003 Application of the SWAT Model for River Flow Forecasting in Sri Lanka H. A . Prasantha HAPUARACHCHI1 , LI Zhijia1 2: International Water Management Institute, Battaramulla, Sri Lanka) Abstract In the present study, the
2、SWAT model and the Xinanjiang model have been used for daily flow forecasting of the Kalu River upper catchment in Sri Lanka. Kalu River is the second largest river in Sri Lanka and due to heavy rainfalls over the catchment, steep river slopes with narrow valleys in the upper catchment and mild rive
3、rbed slopes with wide and flat plains in the middle and lower catchments, the floods in Kalu River basin have become regular. The SWAT model has been used for daily river flow predictions in the Kalu River, and compared with the results obtained using the Xinanjiang model. In this study, the Xinanji
4、ang model has performed slightly better than the SWAT model for forecasting the daily flow of Kalu River. In fact it might be partly attributable due to the poor quality and inadequate data, since the output of the SWAT (distributed model) strictly depends on the quality of input data. In addition,
5、many people in Sri Lanka use well water for their domestic purposes. When considering a catchment as a whole, normally it is a very large area, and therefore it is not possible to record or count all the individual minor scale water utilizations in detail such as small irrigation, animal husbandry i
6、n minor scale and industrial water utilizations in minor scale. The cumulative value of such water utilizations might be large. The absence of these data may specially affect the distributed models in water balancing. But the conceptual watershed models (e.g. Xinanjiang model) are capable of adjusti
7、ng their parameters while calibrating, according to the situation since most of their parameters have no physical background. As a result conceptual watershed models show better performance than distributed models where the catchment characteristics and model inputs are limited or incomplete. Keywor
8、ds: Xinanjiang model, SWAT model, conceptual watershed models, distributed watershed models, river flow forecasting In the present study, the SWAT model 1 and the Xinanjiang model 2-3 have been used for Supported by the International Water Management Institute (IWMI). Received:2003-08-01;Accepted:20
9、03-12-17. H. A. Prasantha HAPUARACHCHI, male, Ph.D, email: hapuarayamanashi.ac.jp. 148 湖 泊 科 学 15 卷 daily river flow forecasting of the Kalu River upper catchment in Sri Lanka. Kalu River is the second largest river in Sri Lanka. Basically Sri Lanka receives rainfall in two monsoon seasons. Due to i
10、ts geographical location, Kalu river catchment receives rain during both of these monsoon seasons. Average annual rainfall of the overall catchment is around 4000mm and it ranges from 2750mm in coastal areas to 5000mm in mountainous areas. Since the catchment is entirely situated in the wet zone, it
11、 has a high rainfall to runoff response. This high volume of water often discharges as floods. Floods result in damage to houses, property and even lives. Severe environmental problems such as deforestation and soil erosion can be seen in this catchment due to Chena cultivation and gem mining. In no
12、rmal practice of Chena cultivation, farmers destroy a part of forest by burning and cultivate tropical plants. After some years, when the land becomes non-arable, they move to another place and practice the same. Due to Chena cultivation, tree felling on an extensive scale and the periodic replantin
13、g of tea and rubber plantations, the upper slopes of the catchment are not stable and landslides can be seen often. Also Kalu river upper catchment is popular for gem mining. Normally gem-bearing gravels occur in beds or pockets and are found 2-20m beneath the surface. Gem bearing gravels show horiz
14、ontal extensions and therefore horizontal tunneling is resorted to when mining. Some times these tunnels are several kilometers long and a causative factor for land subsidence in later time. Besides this, there are many environmental problems that could be attributed to gem mining. Sedimentation of
15、clay minerals in rivers and tanks, lowering the ground water table, slope instability, limiting the extent of cultivable land and reducing yield due to soluble minerals which are products of gemming such as calcium, magnesium, potassium, and mosquito breading in abandoned pits are some of these prob
16、lems. Considering these factors, it is important to model the Kalu river upper catchment to identify future environmental hazards. In the present study, the SWAT model has been applied to generate daily flows in the Kalu river upper catchment to identify in the catchment hydrological responses. The Xinanjiang model (a conceptual rainfall runoff model) has al
