(1) National Research Institute for Earth Science and Disaster Prevention,Japan
(3) Hydrology and Water Management Center for Lower Northern Region, Royal Irrigation Department, Thailand
(4) Hydrology and Water Management Center for Upper Northern Region, Royal Irrigation Department, Thailand
In order to study the variation patterns of discharge, rainfall and the evaporation in tropical area, a hydrometric network consisting of five automatic weather stations, an automatic water level station and eight rainfall stations was established in Khuwae Noi River Basin, which is located to the east of Phitsanulok, Thailand, with catchment area of 4,841km2, occupied by forest by about 77 percent. A lot of information has been obtained about the spatial and temporal distribution of the rainfall, the evaporation characters in this tropical area from the observations.
These stations were sited in different topographic region, namely the mountains, hilly land, higher alluvial plain and lower alluvial plain so as to estimate the areal evapotranspiration. Data had been record continuously every 20 minutes since February 1996. Soil moisture had been also measured every month in order to produce the rating curve between the specific heat conductivity and soil moisture. These observations in this tropical area provide accurate, comprehensive information on temporal and spatial distribution of precipitation and other hydrological data. These data show clearly the pattern of seasonal variation and diurnal changes of discharge, rainfall and so on.
The data from observation were compared with those from GAME reanalysis data-set and also those from TMD (Thai Meteorological Department, Thailand) observation data. The evaporation data derived from the GAME data-set are verified to be reliable to some extend, but the rainfall data need to be improved in this area. The study shows that the TMD rainfall data can be interpolated into grid data for regional water balance analyses and the analyses results are in good agreement with observations.
The discharge of this basin was simulated by using the Distributed Tank Model with temporal resolution of 1 hour and spatial resolution of 0.1 degree. The computation of the areal evaporation was also performed in the Distributed Tank Model. In rainy season the calculated evaporation is close to the observed while in dry season it is apart from the observed. These results confirm that the Distributed Tank Model is suitable for regional water balance analyses.
Submittal Information
Name :
Date :
Wenfeng Huang
29-Jul-04-18:19:22
Organization :
Theme :
National Research Institute for Earth Science and Disaster Prevention, Japan