For the purpose of reducing nonpoint-pollution loads, we must first survey the quantity of accumulated load on the road surfaces, and investigate the composition and local distribution of accumulated load, and then examine how these loads are flushed out by rainfall.
In this paper, in the first half, the accumulated load is determined and the characteristics of the accumulation are examined in each area. In the latter half, runoff characteristics of accumulated loads in rainfall are considered by simulating the runoff accumulated load.
The accumulated load on road surfaces is determined in each area. It has become clear that the accumulated load on road surfaces shows large differences among each area and that it is flushed out in great quantities at a comparatively early stage in rainfall. It is concluded that in this way we will be able to simulate the runoff accumulated loads on road surfaces, and we can obtain useful information on the prevention of water quality deterioration.