| Summary: | 碩士 === 國立中興大學 === 水土保持學系所 === 100 === Due to the topographical constraints, excavation and soil preparation are necessary during developing a large area of the building, which will cause erosion disaster. As the result, it is necessary to construct a temporary sedimentation pond. According the handbook of soil loose estimantion, the seasonal rainfall distribution is different in vary regions, the annual rainfall erosion is often unable to describe the erosion potential of seasonal rainfall in the region within one year. If we want to base on the seasonal rainfall erosion characteristics within one year, as the development, site preparation and suitable soil and water conservation practice, the monthly rainfall erosion index distribution is necessary.
This study focused on the development of a small area, the soil and water conservation construction period is within three months. The 10 meteorological partition was based on literatures. The rainy season and non-rainy season were also classified. The monthly rainfall erosion index distribution for 10 meteorological regions was constructed. Overlaping the rainy and non-rainy season with monthly rainfall erosion index distribution, we will sort out the best construction period and worest construction period. The soil loss of the whole year, the best construction period, and worst construction period were calculated according the monthly rainfall erosion index distribution and parmeters retrived from Soil Loss Prediction Handbook respectively. The sedimentation yields during the construction period were also calculated. From the results , the rationality of temporary sedimentation pond volumn will be discussed.
The important conclusions of this study are following:
(1) Inappropriate construction period was mainly from June to September, this period is rainy and typhoon season, compared with other months, rainfall and rainfall erosion index are highest .
(2) October to January is non-rainy season mainly in the central and southern region, rainfall erosion index is the least, so it is the most suitable months for construction. December to March has least rainfall in eastern and northern area (Keelung exception), rainfall erosion index characteristics of the partition of the monthly percentage distribution is minimum, therefore this period is most suitable for the construction.
(3)Keelung is affected by the northeast monsoon, resulting in raining throughout the whole year, however, the typhoon brought heavy rain rainfall intensity is greater affected than the northeast monsoon drizzle, the typhoon season monthly rainfall erosion index slightly higher than other month during the northeast monsoon rainfall erosion index, it is not suitable for the construction period from August to October.
(4) USLE was applied to calculate sedimentation yield for the base of temporary sedimentation pond design. If we use the whole year Rm, which will over estimate the soil loss.
(5) If the construction was conducted during the best period, which will reduce the 1/3 soil loss, and the tempery sedimentation pond volumn can be reduced.
|
|---|
