Clarification of grain size characteristics of widely extended alluvial plain sediments is a fundamental and important problem in understanding the modes of formation of alluvial plain. In order to relate grain size distribution to various landforms statistically, the author analyzed the surface deposits, particularly fine, muddy deposits, of alluvial plain, which have not been sufficiently studied as regards their geomorphology or sedimentology. The Kiso River alluvial plain is a typical Japanese flood plain with three geomorphic zone (alluvial fan, natural levee and deltaic plain zone) from the upper to the lower course (Fig. 1). Sediment grains coarser than silt size were analyzed by the method of mechanical sieving (1/4 phi interval), and finer silt and clay particles were analyzed by photoextinc-tion-sedimentation method (Moriyama, 1976a).
Statistical parameters of grain size distributions for the surface sediments of this alluvial plain are shown in Tables 1 and 2. The correlation diagram between mean and skewness (Fig. 2) shows clearly several interesting features as follows. The plots of sandy deposits (river sands and eolian dune sands) are clearly distinguished from those of fine, muddy sediments (surface sediments of alluvial fan; IF, natural levee deposits; KN, and back-swamp deposits; KB). Each muddy sediment, however, cannot be distinguished individually: IF, KN and KB overlap one upon the other. Furthermore, each muddy sediment shows a strong negative correlation between mean and skewness.
In order to consider further precise sedimentological meanings, the author drew the cumulative grain size distribution curves on normal probability paper for all samples (Figs. 3_??_8). And furthermore, he separated quantitatively from each curve . some component populations showing normal distribution and calculated their means, standard deviations and mixing proportions of each component population in reference to muddy sediments, according to the method by Inokuchi & Mezaki (1974b). Their distributions of mean, standard deviation and mixing proportions of each component population are shown in Fig. 9. Consequently, almost all deposits are composed of sand and clay populations. Most of the sand populations have 2.0_??_3.5 phi means with small standard deviations, while the clay populations have mostly 6.5-8.5 phi means with large standard deviations. In spite of relatively constant character in means and standard deviations of both populations, the mixing proportions of each population have great variations.
The coarser grained sediments prevail in sand population and finer ones prevail in clay population. The mixing proportions of each component population are thought to be related to hydraulic conditions; the sediments contain high proportions of sand populations under great flow intensisy. Therefore, the surface sediments of alluvial fan with steeper slopes and those of natural levee near the river channel have dominant sand populations, whereas the sediments of backswamps contain high proportions of clay. As the flow velocity, however, practically may vary with such local surface conditions as the micro-landform, artificially constructed facilities, vegetation, and land use, the distinct relation-ships between grain size characteristics and landforms cannot be expected.
Fig. 9 shows that there is no component populations whose mean lies between two popu-lations (i.e., in the range 3.5_??_6.5 phi). To know this reason, the author prepared histo-grams and relative frequency distribution curves (Fig. 10), calculating the average frequency of all size classes for each geomorphic element. Due to experimental errors in the analyzing method, it is meaningless to give serious attention to small “valley” or “peaks”. In comparison with the very narrow and tall, concentrated distribution of KID and KD, the muddy sediments of IF, KN and KB have broad, low ridged distributions on the whole.

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Hitherto, as to the structural composition of farmstead in Tohoku, it has been a general recognition that the relatively bigger main houses without many attached buildings are rather common, and few attempts have been made to ascertain the detailed regionality within Tohoku. The present author tried in this paper to clarify the regional variation in the plan of attached buildings in farmhouse lots in Tohoku by the questionaire methods and field reconnaissances.
The questionaire indicates that there is the regional variation of considerably wide range in average number of buildings per farmhouse (Fig. 1). In the southern part of eastern Tohoku (Pacific side) each farmhouse has commonly many and various kinds of attached buildings whose number per farmhouse averages four to five. In the western Tohoku (Japan Sea side) the number of buildings in a farmhouse lot is comparatively small (one or two in average) and the common attached building is Sagyosha (Workshop or barn). The northern part of the eastern Tohoku has an intermediate nature and the number of attached buildings is three to four in average.
Sagyosha is the most important attached building and is commonly seen anywhere in Tohoku, but more frequently on plains than on mountains. In such districts as central and southern Iwate, Sendai Plain and northern part of Abukiima mountains, the work-shops connected with domaniwa (dirt floored hall formerly used for working and cooking) of main house are popular characteristics in the landscape of rural settlements.
Sotomaya (outdoor stable; for horses or cattles) is distributed mainly in the eastern Tohoku, especially from the central Iwate to the northern Sendai Plain and in and around the Abukuma mountains. The newly-constructed (outaoor stables), especially for dairy, are increasing recently in Iwate Prefecture, but in Miyagi and Fukushima Prefecture the old-fashioned (outdoor stables) are still maintained. In the western Tohoku, on the contrary, Sotomaya is not commonly seen, but Uchimaya (indoor stables) is rather popular. The outdoor toilet and bathroom, housed separately, out side also found with high frequency in the eastern Tohoku.
The composition of attached buildings is closely related to form of main house. In the south of the eastern Tohoku the main house is comparatively small in size and various functions are usually allocated to respective buildings. It is noteworthy in this region that the main house of four-room plan, dominant in southwestern Japan, is mixed with that of hiroma (wide room) plan. In the western Tohoku where attached buildings are small in number, the main house is relatively small in size and its plan is essentially of the hiroma type. In the most of this region, the peculiar traditional house type, chumonzukuri, with Uchimaya was widespread in former times, but now it is rapidly decreasing. The northern part of the eastern Tohoku was the area of distribution for Uchimaya type house such as Nanbumagariya, a traditional L-shaped house, but recently this type of houses are scarcely seen. These changes in main house types have a close relationship with the plan of attached buildings.
In conclusion, three large areas are identified in Tohoku according to the regional variation in the number of buildings. These are namely multi-building area (southern part of the eastern Tohoku), the mono-building area (the western Tohoku) and the inter-mediate area (northern part of the eastern Tohoku). They are divided further into sub-regions by the detailed plans of various types of attached buildings (ref. Fig. 11).

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Stream water pollution due to domestic wastes has been noticed recently with the in crease of residential area in the suburbs. In this paper, some dissolved substances in the drain water were studied, and the daily variation of water concentration and the amount of load per person per day in the domestic drains excluding raw sewage, or human excre ments, were measured in a small residential area near Tokyo.
The discharge of water from the drains shows a maximum peak at 8:00 a. m. and another smaller peak at 8:00 p. m. Electric conductivity is high from 7 to 10 a. m. and from 5 to 9 p. m. Total-nitrogen and ABS have their concentration peaks in the morning, Cl and K⁺ have their concentration peaks in the evening, and Mg²⁺, Ca²⁺ and 4.3 Bxdo not have noticeable daily variations.
Daily variations of the discharge of K⁺, total-nitrogen and ABS are similar to those of concentrations. Only the discharge of Cl^- has its peak in the morning.
The unit load per person per day is revealed to be as follows, K⁺; 0.65g, Cl^-; 3.89g, total-nitrogen; 2.40g, and ABS; 4.46-4.60g.

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