|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1993 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1992 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Accompanying the recent rapid expansion of urban areas and the redevelopment of established urban districts, the impervious areas have increased, and sewer overflow and surface flooding in heavy rains have become frequent occurrences. In this report, on the basis of the observed results in an urbanized research basin consisting of impervious area and pervious area, the characteristics of rainfall runoff are considered, and modeling of runoff system and runoff simulations area performed. Then, the applications of this methodology are investigated on a practical view point.
1. The one of main sewer area (6.16ha) in residential basin in Kobe City was selected as an objective research basin consisting of impervious area and pervious area. Hydrologic observations, field investigations on drainage basin system and measurements of stormwater flow rate have been performed, and then basic data for analysing the characteristics of rainfall runoff were obtained.
2. Data on the stormwater runoff and
the overflow and flooding that occurred in the research basin, especially the overflow and flooding in September 14, 1989, were collected and analyzed. As a result, the characteristics of stormwater runoff and processes of overflow and inundation have been derived.
3. Model parameters of rainfall loss for the research basin were obtained by applying the method of analyzes taking the characteristics of rainfall loss of respective overland flow planes into account. Various overland flow planed were devided into impervious planes and pervious planes, and respective rainfall loss was calculated by taking depression storage into account in the case of impervious (overland flow) planes, and by taking depression storage and infiltration loss into account in the case of pervious (overland flow) planes.
4. The runoff processes and their modeling have been considered, and the runoff simultations were performed. Then, the applicabilities of this method were investigated on a practical view point. Moreover, simplifications of the method of runoff simulation were also considered by applying the method of equivalent drainage basin.
5. The relations between the increase of impervious overland flow planes and the characteristics of stormwater runoff with flooding were investigated applying the runoff simulation model. The results show to be useful for the evaluation of flooding risk.
6. A simplified method for representing the properties of a ground cover was presented by utilizing LANDSAT-TM data. The time for distinguishing the land surfaces is fairly reduced by using this method. Less