INFLUENCE FACTOR ANALYSIS IN A RESERVOIR CATCHMENT AREA FOCUSING ON MANGANESE AND TOTAL PHOSPHORUS IN SOILS

Reservoirs are generally closed water area, and largely impacted by inflowing rivers. Sediment in the Ogouchi reservoir has been known to be discharged from soils in catchment area via rainfall. It could be expected that prevention of discharge of manganese and phosphorous in soils would contribute to less manganese concentration in sediment and algal bloom prevention in the reservoir. This study focused on soil components in the reservoir catchment area. Amount of manganese and total phosphorous in soils were measured, and parameters were estimated for those two components by multiple regression analysis. Further, those two components were provided for correlation analysis with vegetations or slope in the catchments. It was found that there is a strong correlation between the amount of total phosphorous in soils and area ratio of a broadleaf tree.