Sea breeze is considered good for the cultivation of Satsuma oranges. But however, little research on the effect of sea breeze on Satsuma oranges has been reported in the past. Since the thermal environment of Satsuma oranges has a great influence on the quality of the fruits, it is of great practical importance to acquire reliable information on the role of the sea breeze on the envinonment in order to evolve a suitable method of cultivation. An experiment on the effect of sea breeze on Satsuma oranges, from the viewpoint of energy balance was carried out to supply this information. The results are summerized as follows:
1) The annual trend of the air temperature on the land and the water temperature of the adjacent sea were examined and it was found that the difference between them caused a horizontal heat transfer.
2) The air temperature of the area along the shore is strongly affected by the horizontal heat transfer accompanied by the sea breeze.
3) It was proved that a mild air temperature modified by the sea breeze was good for the clultivation of Satsuma oranges by examining the geographical distribution of the fruits with regard to quality (sugar-acid ratio= soluble solid/ acid) in Kagawa prefecture.
4) The geographical distribution of the fruits with regard to quality in Ehime prefecture was examined and it was found out that the distrii) ution was in accordance with the isothermal map which was related to the sea breeze.
5) It may be stated in conclusion that the reason why the sea breeze is good for cultivation of Satsuma oranges is that the sea breeze accompanies heat transfer. Therefore, the existence of this heat transfer must be taken into account in a plan to reclaim undeveloped land.

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Mole drains constructed in the subsoil of poldered paddy fields are often destroyed by the operation of tractors.
To make clear to what extent a mole drain is diminished by the operation of tractors, at first we chose Fordson DEXTA and set it to work right over the mole drain several times, and we could make clear some facts as shown below.
The mole drain chosen for our investigations was constructed 35 cm under the surface of the ground, and the cross-section of its hole was 63.6 cm² (the hole being abouli 9 cm in diameter) under normal conditions, but after the operation of the tractor the 1 st time, 75% of the hole was destroyed and after the 2 nd time, 97% and after the 3 rd time, the hole was completely destroyed.
In an unconfined compression test, q_u of the unremolded soil was 0.71 kg/cm2 after the 2 nd operation, 0.65kg/cm² after t he 3 rd, and 0.54 kg/cm² after the 4 th in the case of the surface soil.
But when the surface soil was remolded, q_u was lowered, that is q_u was 0.19 kg/cm² after the 2 nd operation, 0.21 kg/cm² after the 3 rd and 0.20 kg/cm2 after the 4 th.
As to the subsoil, q_u was 0.4 kg/cm² in the unremolded soil and 0.05 kg/cm² in the remolded soil after the 1st operation, and 0.27 kg/cm² in the unremolded soil and 0.06 kg/cm² in the remolded soil after the 2 nd operation. After three operations, the subsoil was so softened that we could not measure the value of q_u.
On the other hand, as to the sensitivity of subsoil, q_u was ∞ after three operations.
This result led us to conclude that after three operations the subsoil 35 cm under the surface was very much softened and the constructed mole drain was destroyed.

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At the poldered paddy fields in Kojima Bay, water management or habitual water use which is a kind of intermittent irrigation (3 days ponded and 4 days drained) has been put into practice. The results of these studies on subsoil improvement are as follows.
1) It is found that the modified Sugawara Model is very useful for the analytical investigation of the irrigation and drainage of these paddy fields.
2) By the use of this model, the author and his co-worker discovered one method to estimate such unmeasurable values as the percolation of water in the paddy field and that under of through the boarder.
3) It is pointed out that the discharge of underdrainage is linearly proportionate to the difference between the potential in the paddy field and the water level of the drainage canal as the first approximation.
4) From this point of view, it may be a problem that only underdrainage methods have been used for subsoil improvement.
5) And as for subsoil improvement, at the first attempt, it is necessary to control the water level of the drainage canals.

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Among the various losses incurred by an irrigation system, losses caused by natural phenomena such as evaporation or seepage can be treated rather easily, and have been made clear. But, operation losses caused by irrigation system operation have been scarcely studied systematically up to the present, because operation losses vary greatly according to the structure of the system and operation methods, or they can not be studied on an experimental basis. However, as operation losses are generally much larger than natural losses, an adequate irrigation plan can not be set up without a study of this subject.
The Aichi Irrigation System, one of the largest modern irrigation systems in Japan, has been operated for some ten years since October 1961.
Reliable and detailed records of its actual operation for this period have been kept. Fully eight years, from May 1962 to April 1970 were taken for our study period. Losses in the main canal, in laterals and in farms were analyzed. Actual operation results of the Makio dam, the main water source of the system, were also studied.
Analyzed records on water management were compared with the initial plan of the project. They will give us some ideas for future plans of new construction projects and for the water management of existing irrigation systems.
The result of the study is summarized as follows.
(1) Operation losses in the irrigation system are much larger than formerly estimated.
(2) Regulation reservoirs adequately established in a canal system are extremely efficient for proper water management, especially for the prevention of operation losses.
(3) A fluctuation of water demand from time to time tends to increase operation losses very much. It is important to keep a constant flow in a canal.
(4) Intermittent irrigation for paddy fields is desirable for better water management, namely, larger effective rainfall, proper distribution of water and protection of water losses as well as better farm management. But without a perfect rotation distribution of water, losses will increase in an upper ditch or canal.
(5) As a result of these considerations, future irrigation systems should be furnished with one or more regulation reservoirs (including farm ponds) of adequate size at proper locations, and a pipe line system should be adopted as much as possible. Automatic control equipment for rotation irrigation should be developed and it is desirable to automate an entire irrigation system from the intake gate to each individual farm.

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Gross efficiency of water use from a head of lateral to consumption of paddy through lateral, sub-lateral and ditch is discussed in this paper.
Discharge record at each head of laterals, unit duty of water and precipitation record are available for the study. But the actual operation of a great number of ponds which work as supplemental water sources is little known, therefore the efficiency of each lateral is calculated at the particular dry period when the most ponds dry up. Effective rainfall and supplemental water sources are studied afterward.
The summary of this study is as follows;
(1) Gross efficiency of paddy field irrigation is about 70 percent. The larger size of lateral tends to show lower efficiency, and a pumping system shows greater efficiency than a gravity system.
(2) Rainfall is effective within the limitation of a little more than the daily duty of water of a paddy field. As a result, one third of the total rainfall in the irrigation season is effective.
(3) Depending rates on each water source are;
Actual operation Plan
Main water source 57% 40%
Supplemental water source 17 29
Effective rainfall 26 31

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Gross efficiency is calculated from the relation between the diversion dischage and the consumptive use of crops on some laterals which serve only for upland field irrigation.
But these laterals irrigate only four percent of all the upland, therefore the whole area is also checked.
Summary of the results are as follows;
(1) Consumptive use of crops is nearly the same as that of the original plan.
(2) Effective rainfall is larger than that of the plan.
(3) Gross efficiency is 35 percent, which is much smaller than the 73 percent of the plan.
(4) Denendinz rates on each water source are;
Actual operation Plan
Main water source 34% 65%
Effective rainfall 66 35

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Among all the facilities in the Aichi Irrigation System, the Makio dam, main water source of the system, the main canal, and its related structures, including the Togo regulating reservoir, are directly managed by the Corporation as the main structures.
These structures are completey furnished with water measurement devices, and their hydrological records have been kept for some ten years.
The eight years' operation records from May 1962 to April 1970 have been analyzed, and the efficiency of each structure has been calculated. So, the results will be usefull for the planning and operation of future projects.
The results are summarized as follows;
(1) The inflow to the Makio dam is larger than that of the original plan by 50 percent.
(2) Effectivity of the discharge from the Makio dam is still low even though it has been improved year after year. There is a possibility of a supplemental supply of water from the dam.
(3) The phase of water use in the benefited area has remarkably changed in comparison with the original plan, namely, irrigation demand has decreased by half, and the water supply for cities and for industries has increased by five times.
(4) Efficiency in the main canal differs much between its upper reach and its lower one. The regulating reservoir is very efficient for preventing conveyance loss in the upper reach. Efficiency in the irrigation season is lower than that of the non-irrigation season, because the flow phase for irrigation is different from that for water supply.
(5) It takes two to three years for a test operation.

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Needless to say, field density of soil works is one of the most important indices of the soil properties, and gives us useful information directly or indirectly. However, the measured values are incidents not so accurate as compared to its elaborate procedure. So that, we try to use the surface settlement for the judgment of the compaction efforts. Suppose that the sublayer is well compacted and that no lateral displacement generates, the increase of the soil density depends only on the settlement. So we can get eq.(2), where h: thickness of the layer, S: the suface settlement, γd₀ initial density, γdN: the soil density by Nth compactions.
Defining √= γdN/γd₀, √ can be expressed by eq.(4), (11). Soil used for experiments are silty clay (SM GM), sand and fine rock of which the diameter is less than 40 cm. Compaction equipment consists of two tamping rollers (5. 8, 3. 4ton), a pneumatic-tyre roller (25 ton), a bulldozer (11 ton), a vibratory roller (4. 5 ton) and a tamping rammer (60 kg). Experimental results are shown in Fig. 5-6. The empirical equation of the relationship between strain of the layer and √ is eq.(10), which agrees approximately with eq.(11). These values are the average of 9-27 points. It needs only less than 5 minutes to measure those values.

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Using the measured values by a cone-penetrometer (q_c) and by a procter needle (qp), we try to find the compaction efforts of fill-type dams. Beinga kind of the bearing capacity problem, the penetration resistance is a function of c and φ, by which are obtained functions of water contents and soil density (eqs. 16). q_c and qp are measured 2. 5cm belowthe surface.
The relationship between q_c and water content (ω) is an approximately linear curve as parameters which are the kinds of compaction equipment and its number of passes as shown Fig. 1.
The relationship between γd and q_c is expressed by eqs.(14) as shown Fig. 2. If we correct the initial soil density by its gravel contents, the lines expressed eqs.(14) become almost a line, which coincides approximately with the theoretical curve calculated by eqs.(1), where N_c, N_q, N_r are modified Meyorhof's. Fig. 3. Shows the relation qc and the surface settlement (S).
So we find that the penetration resistance is a very usefulprocedure to find the relative compaction efforts. Time required to measure it is less than 10 minutes.

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Nowadays, soil using even an impervious zone of a fill-type dam usually contains gravel. We consider the influence that the gravel might contact an active surface of a tranducer in situ and examine the effect of the variety of the soil around it.
A gravel touching the active surface of a tranducer is considered to be a medium of a concentrated force, which generates a larger strain for tranducer and a smaller strain when the position of the load departs from its center (Fig. 2-3). At the time, the relationship between the diistance from the center a_x and the ratio Δ= δ/δ_c is expressed by eqs.(12), where δ: the deflection at the center loading at distance a_x, δ_c: the deflection at the center loading at the same position. An experimental result, which almost concides with eqs.(12), is shown Fig. 4.
Stress in soil depends upon its variety as shown in Fig. 5-6, where P: surface load, S: surface settlement by compression, σ: stress in the soil 8.5 cm below the surface a t the initial state. Soils for experiments are cohesive soil for core (C_r), sand for filter (F_r), and Masa-soil weathered from granite (M_a). A CBR mould is used for container of the soil. Stress generated in the sand or Masa-soil is greater than in the cohesive soil.

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Compaction equipment generates statical load and dynamic load which is in proportion to the square of its velocity. Considering only the maximum value of strength, we can treat it as a static load, which is defined as the quasistatic load. This load generates horizontal force due to the coefficient of friction μ_f between soil and vehicle.
Suppose that (1) the load is uniform perpendicularly and the roller is shown as Fig. 2, (2) the deformation of soil allowed is vertical only, and (3) no failure of the soil occurs, we can get eqs.(21), (22) where k: a constant depends on soil vehicle properties. However the settlement is shown by eqs.(29), so that depends upon the soil characteristics and the speed of the vehicle. In Fig. 3 is shown the results caluculated by eqs.(21) and (23), (24) for several cases. These show that the larger settlement and the slower speed make the greater μ_f which generates extensive horizontal force on the ground.

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