The Nishiyoge River in Osaka Prefecture is 14 km long with the average width of 7 m. In recent years, water pollution of this river has aggravated while doing a great deal of damage to city water supply and become a serious social problem. A series of investigations have been under way along the whole length of this river since July 1969 and the following is known thus far.
The overall degree of pollution remains essentially the same as it was in 1965 or thereabouts, but migration of pollution sites has apparently occurred when looked at the whole length. The largest source of pollution in 1965 was at station L., 12 km downstream from the riverhead, whereas it is now at station G, 6 km upstream from L.
The largest factor contributing to water pollution is organic waste water discharged from pig farms, followed by waste waters from poultry farms and slaughter houses, domestic sewage, and industrial waste water.
The degree of pollution varies considerably with time of inflow of waste water and also with season.
The electrical conductivity (x) and the residue on evaporation (y) rise and fall as the river flows down and increase 2-to 3-fold at the end of the river. The following relationship is observed between these two.
y=0.767x+18.992 (γ=0.964)
Dissolved matters which increase rapidly with inflow of waste water from pig farms are ammonium nitrogen and phosphorus compounds, and they increase more than 103 times. The values of BOD and COD also rise rapidly and the relationship between the two is expressed by the following equation.
BOD=0.445COD^1.465
Purification of water is possible only by treatment of waste water from domestic animal farms before inflow or by prohibition of inflow itself, and perfection of the sewage system is very much desired. An increase in the flux will assist the purification process.

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The object of this chapter is to examine the abandonment of irrigation reservoirs and the changes in land use in Matsubara City in Osaka, during the period of the rapid economic development in Japan.
These irrigation reservoirs have been abandoned as a result of urbanization and in-dustrilialization. In Matsubara City, 59 irrigation reservoirs were reclaimed in the 24 years from 1958 to 1981, and the reclaimed land reached 68.141ha in area (including reservoirs reclaimed partly.) 54.1 percent of these 68.141ha has been used for public facilities, 17.0 percent for housing, and 9.2 percent for factories. Fields tend to be used much for housing or factory sites, and these reclaimed former reservoir sites are diverted more to public facility sites (Schools, Meeting halls, Playgrounds, Children's parks, etc.)
Matsubara City needed to be supplied with public infrastructure, as urbanization had proceeded without planning, so the irrigation reservoirs were used as building sites. That the rate of use for public facilities was high was due to this unplanned urbanization. Meanwhile the rate of use for housing has been also increasing in recent years, because public infrastructure needs have been virtually met and the financial condition of this city has become worse. The abandonment of irrigation reservoirs should be considered from both these perspectives.
In addition, the disuse of irrigation reservoirs has caused many problems: loss of pool function, financial problems in their disposal by sale, and re-organization of the utilization regulations. Especially the utilization regulations have become increasingly confused. This will be described in the next chapter.

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This is the first comprehensive report on Japanese Gyrosigma spp. with special reference to their taxonomy and distribution. They are very conspicuous in permanent slides because usually they have large valves with characteristic shapes. However they have not been well studied probably because of their paucity in most samples. In total 30 taxa were identified from samples collected from various localities throughout Japan. The following five taxa are newly reported from Japan: G. acuminatum var. curta, G. acuminatum var. lacustre, G. plagiostomum, G. simile, and G. spencerii var. curvula.

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This paper describe the characteristics of the floodways in Japan through the history of their development. The object channels are 327 that the all floodways to be called in Japan today. A research adopts the method that inspects the attribute of the floodway individually in the outlet form, the diversion structure and the development year etc. As the second step, the correlation of each attribute had been considered. As a result, it was found that the Otozu River is oldest in the history of the floodway development, in the channels that discharges only flood that exist.

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