Tohru Kanda

On Ditches at the Ancient Capital Cities in Japan

Ditches are constructed at both sides of a street at the ancient capital cities in Japan. As the streets are laid out in a grid pattern, the ancient cities have the network of drainage by ditches. In this paper, the network of drainage in Nagaokakyo and Heiankyo is discussed. The dimensions and the connection of ditches are made clear using historical literature and the archaorogical excavation data. Considering the topography, the flow of drainage are examined. The character of ditches and the plan of storm water drainage between Nagaotakyo and Heiankyo is different from each other.

Urban Runoff Analysis Using the Data Base of Sewer Information

An urban runoff simulation system that utilizes a GIS sewer data base has been developed and applied to a catchment in Kobe. The runoff analysis is based on the Storm Water Management Model (SWMM). The system provides an interface that allows actual sewer network data to be read from the data base and then to be transferred into the link-node format required by SWMM. In addition, the system facilitates the formulation, via computer mapping software, of SWMM-formatted data for drainage catchments which are not included in the data base. The system was applied to a drainage catchment in Kobe and acceptable results were obtained.

Runoff Simulation for Urban Sewer System Using SWMM Combined with Computer Mapping

In this paper, runoff simulation for urban sewer system using SUM combined with computer mapping is discussed. The metho d of input-output data formation for SUM is modified using computer mapping. To reduce the computation time and capacity, the effect of the simplification of sewer system on the results of simulationis examied as for EXTRANof SUM and the comparison of the runoff computation accuracy of RUNOFF with kinematic wave model is carried out as for RUNOFF of SWMM.

Morphological Characteristics of Urban Sewer System

Morphological characteristics of the urban sewer system at Higashinada District in Kobe City are investigated in terms of Hortons Law, Hacks Law, Meltons Law and Fractal dimension. Results of calculation for 25 main sewers show that the maximum order of the sewer system is 1-3 and the Fractal dimension is 1.00-1.33 (ave. 1.10). Hortons Law, Hacks Law and Meltons Law are almost proved with some exceptions. Modified Hacks Law using Fractal dimension gives higher correlation between main sewer length and drainage area compared with the original Hacks Law.