Translation Series No. 1056

4 .

FISHERIES RESEARCH BOARD OF CANADA Translation Series No. 1056

On a method of making more productive fishery of the Lavers (Porphyra). Engineering ways of improvement and construction

By Takeo Kurakake

Original title: Doboku Koho ni yoru Non i Gyojo no Kairyo Zosei. From: Suisan Zoyoshoku Sosho, No. 3. (Marine culture and propagation.) Published by: Nippon Suisan Shigen Hogo Kyokai (Japan Marine Resources Protection . Association). Tokyo, Japan. Booklet No. 3, pp. 1-52, 1964.

Translated by the Translation Bureau (NO) Foreign Languages Division Department of the Secretary of State of Canada

Fiseeries Research Board of Canada Brôlogical Station, Nanaimo, B. C. 1968

95 pages typescript _4 /! •/ DEniI■ RTMENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT BUREAU FOR TRANSLATIONS BUREAU DES TRADUCTIONS 'IN LANGUAGES DMSÎON DES LANGUES î OREGWVISION ÉTRANGÈRES

• Wi fr:UY ES g ;3 (.1-1 C. A D 0 CA D

NANAIMO, e. L.

TRANSLATED FROM - TRADUCTION DE INTO - X japanese English

SUBJECT - SUJET Seaweed Cultivation Engineering

AUTHOR - AUTEUR Kurakake, Takeo

TITLE IN ENOL101-1 - TITRE ANGLAIS On a Method of Making More Productive Fishery of the Lavers (Porphyre). Engineering Ways of Improvement and Construction.

, TITLE IN FOREIGN LANGUAGE - TITRE LANGUE LTTRANCURE 110 Doboku Koho ni yoru Non i Gyojo no Kairyo Zosei

REFERENCE - RdFÉRENCE (NAME OF BOOK OR RUCLICATION - NOM DU LIVRE OLL PUDLICATION)

Fishery Propagation Series #3

PUBLISHER - LIDITEUR Marine Resources Protection Institution of Japan -- Corporation

CITY - VILLE DATE PAGES .Tokyo March 18, 1964 52

REQUEST RECEIVED FROM OUR NUMBER REQUII PAR Martha Skulski NOTRE DOSSIER N 0 0433

DEPARTMEN TRANSLATOR Noriko Olive MINIST ERE' Fisheries Research Board of Canada TRADUCTEUR

'' YOUF2 NUMBER DATE comPLETrzD May 769-18-14 1 1968• • ie r'IE DOSSIER N 0 REMPLI E L IZ

DATE RECEIVED 1,2112.7.0 L FebruaW22, 1968. f DEIPARTMENT OF THE SECRETARY OF TA SECRÉTARIAT D'h- AT TRANSLATION BUREAU BUREAU DES TRADUCTIONS

01.h FOREIGN LANGUAGES DIVISION DIVISION DES LANGUES ÉTRANGÈRES

YOUR NO. DEPARTMENT DIVISION/0RANC.1 CITY VOTRE N ° MINIST ERE. DIVISION/DIRECTION VILLE 769-18-14 Fisheries

- OUR NO. LANGUAGE TRANSLATOR (IN' TIALS) DATE NOTRE N ° LANGUE TRADUCTEUR III:ITIALES;

0433 Japanese N.O. //,/: •--1."`-e-.--(1

On a Method of Making More Productive Fishery of the Lavers (Porphyra) Engineering Ways of Improvement and Construction

KURAKE Takeo

Introduction 2 1 Features of Shallow Sea Fishing Grounds 2 Wind and Waves and the Situation of Fishing Grounds- Depth -- Water Quality, Turbidity, Amount of Sunlight -- Currents 2 The Construction of Fishing Grounds 4 3 Methodswith Engineering Earthworks 5 The Method of Ground Levering . and Land Readjustment -- Producing Water Courses -- Tilling of Tidal Flats 4 The Construction of Fishing Grounds by Establishing Break Water Fences 22 Waves in Siellow Sea Fishing Grounds and Wave

Breaking -- Establishment of Fences 9 Their Construction ,;;Z

SOS-200-10.-31 ,

and Their Effect -- Stones to be Used to Make Concealed Banks -- Piles to be Used in Pile Rows -- Putting the Construction Work into Operation -- Effect of Work 5 Offshore Culture Conserving Facilities 42 ,Locations in Aichi Prefecture Where Fishing Ground Improvement Construction Work Has Been Carried Out Bibliography 49

Introduction 2

The improvement and construction of fishing grounds ha d been • conducted since &Id-times by the methods of constructing shores, or fish nesting areas, tilling tide flats and cleaning the surface of rocks. After the war, from about 1951 - 1952, this work has been recommenced with Government aid. In Aichi Prefecture, since 1952, by construction work using large construction machines and by establishment of break water fences from 1957 as well as the work of moving stones and making fish nesting areas, the improvement and construction of fishing grounds has been conducted mainly for those fishing grounds with demarcated fishing rights such as laver fisheries, and common fishing grounds such as those for short-necked clams. When attempting this work, if such • fundamental factors as what constitutes good fishing grounds' 3 in shallow sea or a what conditions the fishing grounds should fulfil are not apparent, the methods of construction and improvement cannot be (71termined. Therefore, first of all, our understanding of these factors will be described.

1 Features of Shallow Sea Fishing Grounds

1) Wind and Waves and the Situation of Fishing Grounds When the mixing of water and regeneration of quality .of water in a fishing ground are considered, the more violent the wind and waves are, the better it should be, providing there is no disadvantage such ns the destruction of cultivating facilities by wind and waves. Considering the growth of levers, in a calm water mass the water around the thallus tends to become isolated from other water and this adversely affects the living conditions of the laver. Violent water currents or wind and waves prevent this because they are effective in dispersing the water around the laver. In this regard, the aspect directions of shallow sea fishing grounds are determined naturally. In the case of laver , fishing grounds facing west, north-west and north, which get the winter seasonal wind, are good.

2) Depth

Firstly, as to the sea depth, only the coastal slopes of the continental shelf •rd shallower depths are considered, giving

regard to the range in which earthworking can be done construc- tively. As the sea depth is dependent upon the height of the ground of the sea bed,when cultivating facilities are to be made, and if the species to be cultivated are ones which live in the intertidal zone such as laver, short-necked clams, oysters etc., the height of ground where these will grow in the sea bed is determined naturally. Regarding this, the height of these grounds in shallow sea is determined by tides. In other words, the standards vary from place to place with 5. the local tidel- c/-1,treen*. These are shown in the following table of figures based on Mikawa Bay and standards of the Tide Tables published by the Incorporated Foundation of the Weather Forcasting Association. 0 t G) Nagoya. CD Period of observation: 1949 to. • 0 e JUJ ILU 1 9 1961, 13 years. 5.81 0 ,C) Monthly mean tide level. 1959. 9. 26. 2113356 e Month. eei 0 Last 5 years. 1 1.896m 4. 790 G) Year. (2) Maximum tide level. • 2 1.912 4.264 >t Snherical buoy. C) Weather marker, (a Men level of Aigh water springs.. 3.231 01';131i-if.]•ieli,.liLk CD Mean tide level in last 5 years. CD/lean tide level in Tokyo Bay. Mean level of low water springs. 0 • Tide level table 2. 070 D.L. 7 2.166 (FD Minimum tide level. 0 Hours. L989 -11-U.i,[1 1:3Y Minutes.

10 2. 178 0. 677

11 2. 114 0. 648 D. L. n aom 0. 040 e 1951. 12. 30. 1?,520::.:• • e aom e 0. 000 L 'D. 5

3) Water Quality, Turbidity, Amount of Sunlight The more fertile with nutrient salts the water is, the better its quality. The tolerance levels for chlorine are wide. Unless organic matter is lower than B.O.D. 3.0 p.p.m, it is difficult to say whether the fishing ground will be stable. The turbidity of the water is questionable. Concerning laver, if a gill net suspended vertically from stakes so that it floats in the water, is used for laver culture, laver will not grow on that part of the gill net which is a little lower than the water surface; This depth below the water surface varies according to the location (waves, tide), season, and the turbidity in the fishing ground. Concerning differences in the times cf year, before and after the winter solstice it is best to put laver on the water surface because at that time, the amount of sunlight is the least. Moreover, as the • laver are thought to undergo nutritive propagation until this time of year, the superiority or inferiority of the usual horizontally fixed cultivating grounds alne decided by the turbidity of the water.

4) Currents The current inside shallow sea bays is mainly tidal ont, accompanied by bay and river currents and current due to the weather. Since the tidal current is the main one, this bay current flows with both the ebb tide and the high tide. If the topography of a fishing ground is a wide tidal flat without any obstruction and the sea bed is flat, the 6 current repeats such movements as flowing towards the offing at the time of the ebb tide, and being compressed towards the shore at the time of high tide, as a whole water mass. Therefore, as is shown in Figure 1, especially when the tide movement is small such as the time of a neap tide, each 2 supposed constituent part of the water mass repeats such movements as going out towards the off-shore and compressing towards the coast, whilst they maintain their own relative positions. In other words, in such shallow seas, outwardly the current seems to be flowing considerably, but as they are maintaining the situation of horizontal order, the rate at which the water layers mix together is very low. The degree of stability in this sense -- the horizontal stability e2xJ:DY___ of the water -- varies according to the magnitude of the spring or neap tides as well as the shape of the shallow sea bed, and the type of geographical features. Therefore, it is thought that shallow seas can be divided into the following three classifications. (1) The area where both the high tidal current and ebb tidal current Ï 1 ii., „;;J. • flow in the same direction or only Figure 1. Diagrammatic representation of water one of them flows (the other flows movement in shallow sea 7

very little). (2) The shallow sea where the water mass moves back and forWard at the time of the high and ebb . tides only, and within this range of movement, the current speed varies locally. (3) The flat shallow sea where the slope of the sea bed is gently shelving for some distance ard whose tidal current is generally a uniform back and forth flow, which then has little constant current. There are three classifications as mentioned above, and the shallow seas of (1) and (3) are the objective areas of fishing ground improvements, and also in the case of the construction of fishing grounds, it is thought necessary to make ditches, where the current speed changes, in some parts of the fishing ground, so that the water may exchange well and the productivity may become higher.

2. The Construction of Fishing Grounds

From the above-mentioned factors, the construction of fishing grounds could be divided into three categories: (1) Adjusting the ground height. (2) improving the fishing ground by artificially directing the shallow sea current. (3) In addition, for districts where strong waves are prevalent, establishing combined facilities as countermeasures against natural disasters and for directing water. 8

(1) and (2) are improvement construction5in which earthwork is done with machines of the heavy engineering work type. (3) is the construction of fishing grounds by building such facilities as break water fences or cultivation'conserving facilities.

3 Methods with Engineering Earthworks

1) The Method of Ground Leveling and Land Readjustment (1) Standards for Height of Grounds If the ground which is to be used e.s,a laver culture, . g,Eggcd is too deep, it is corrected by reclaiming or using such facilities as long piles but if it is too high, excavating cannot be avoided. The following is the standard fl-zerhe height to which the ground must be leveled. Figure 2 shows the range of exposed land due to variation in low tide levels inside the Ise Mikawa Bay. The line graphs are joined between either quarter moon days or new and full moon days during the laver season. The heights of the tmo low tides per day were divided into those giving more exposure and those giving less exposure, and for each of these two groups, the quarter moon levels were linked to form one line graph, and the new and full moon levels another. From this Figure, can be seen the height of the tidal range, classi- fied according to the time of tide cycle: A - height which is exposed twice every day, B - twice a day at the time of the

.sPring tide, once a day at the time of the neap tide, C - twice a day at the spring tide, not exposed at the neap tide, D - once a day only at the spring tide.

0 A : • i2t3J3t3J 1, • C : • 7.,4L.17. 4.711; D: If3 iti1li; 0 E: 4-1

, 1 11 2 rz

; ; 1

I ; A ; I • , ; ID ' , ,1 . I e `,1 I 1, \:,•■ I ,4, I I • E \

'2.9 7' S 6 4 ;s 6 3c 6 .3/7 411 0 ; 11112.1 I ; 2 ;Ji 2M

Figuré 2. Tidal range exposure at Mikawa Bay 1 A: tidal range which is exposed twice every day. 2 B: twice a dey at the time of the spring tide, once a day at the time of the neap tide. 3 C: twice a day at the spring tide, not exposed at the neap tide. • 4 D: once a day at the spring tide. 5 E: never exposed. 6 tidal indicator at Nagoya Harbour. 7 laver spore catching level. 8 mean low tide level of neap tides. 9 height of the two daily low tide levels for neap tides. 10 height of the two daily low tide levels for spring tides. 11 mean low tide level of spring tides. 12 day • 13 month 10

The mean tide level is the mean of the laver season, but it does not differ greatly from the mean level of the autumn season alone. And in autumn the level at which the laver spores settle is about 30cm below the mean tide level of the season. If the annual change of mean tide level in autumn is, for con-, venience, supposed to be 20cm (Inside the Ise-Mikawa Bay, the change of tide level is very large.), in the case of Ise-Mikawa Bay, the height of laver fishing groundsis required to be about 70cm lower 27(30 + 20) + 20cm (20cm lower than the laver spore settling level)] than the mean tide level in autumn. Therefore, ground which is high such as that known as alluvion cah be used as laver fishing ground, if .the height of the ground is cut down to that level. .(2) Earthworksin Practice It is necessary to use earthmoving machines such as bulldozers, sand pumping vessels, bucket vessels, properly according to their purpose. Sand pumping vessels and bucket vessels are primarily for use in river3or seas, but bulldozers are made for the purpose of working on land. Therefore, when a bulldozer is used in shallow sea u special consideration must be given to the salt water and to the possibility of sinking intc the mud in the shallow sea bottom. Here is a summary concerning bulldozers.

l. Type of machine used and the time worked: The earthmoving • machines used for the shallow sea in Aichi Prefecture are shown below. 11

Namé-b-f-Fa7r7.17f7Eturer Type Uross Weight Horsepower

Komatsu Manufacturing Co. D-50 8 tons 5 0 Mitsubishi Heavy Industries Co. BBIV 10 " 110 Nippon Special Steel Co. N.T.K -4 6 " 40

Each of these was remodeled for use in shallow sea. Taking soft muddy areas especially into consideration, it was decided to increase the width of the feet of the machine so as to decrease the pressure applied to the earth,and a triangular- shaped shoe called a 'swamp dozer , was devised for the same purpose. Parts such as oil-seals around the feet were also considered. Grease and caps etc. built into the frames were chosen to be of insulator quality, so that those machines could be used in even 60cm of water. The time which can be spent on earth working in the sea is limited according to the size of the tidal range. In the case of Mikawa Bay, the working time is about 4 hours per day at the time of spring tide, and therefore, 40 hours in one tidal period (15 days). 2. Efficiency: The efficiency of earthmoving varies greatly with the distance travelled forward by the dozer in its scraping movement - this distance is termed the stroke l'ecause the machine returns to its starting position. The earthmoving efficiency is gdod if the stroke is about 50m. As work in the

sea is costly, 'it is better to limit the distance of earth • moving to 50m 2 this being efficient. And in the case of earth 12

work in wide tidal flats, it is necessary to use such means as making a deep hole by dredger or sand pumping vessel, and then filling up this hole with soil from the remaining part, thus making the height of the ground lower overall. The quantity of earth extracted per hour within one

50m stroke is 20 - 25 m' when using a 10-ton machine, 15 - 20m 3

by 8-ton machine, 10 - 15m3 by 6-ton machine. Of course, there is some difference according to the geological features and topography of the ground. For a four-hour working day, the

quantity extracted should be about 100m3 with a 10-ton machine,

50m3 with a 6-ton machine.

3. 'Size . of fishing ground which may be constructed: In the case of ground height adjustment, the area of fishing ground which can be constructed for a given amount of earth extracted is dependent upon the required height of ground. The size of fishing ground which can be constructed per 1m' of earth

extracted is 10m 4 if the ground is originally 10cm higher, 2 and thus if a 10-ton machine is used the size is 1000m /day.

In a place where it is required to cut 30cm of earth off, an 7 2 area of 3000 - 4000m can be constructed per tide (15 days). Calculating the expenditure, the unit cost of construction becomes 2 approximately Y40 - 50/m . In consideration of the economic efficiency of laver fishing grounds, a place which has to be

cut down by about 60cm may still be an objective area for • constructing a fishing ground. e I 1

1 Before work commenced: Ohsu Misaki Point, Tawara Bay in 1950 2 After commencing work: Ohsu Misaki Point. Tawara Bay in 195â 3 (Laver nets are extensively spread out.) 0 ;til;',`";!:.*J? ri-.1 fa 25

„

;n 33 4',[0[1;ii-, -)(i;;IL:i 0 (11. ! )

(3) Efficiency of the Work Concerning the estimation of the efficiency of constructing fishing grounds by the method of adjusting the ground height, a quotation from 'Fisheries Progation Data No 16 by the Fisheries Branch a Department of Agriculture, Tokyo University is as follows. Incidentally, this fishing ground construction by the means of ground adjusting has been conducted every year in mid summer, without interruption, since 1952 up to the • present, and the topography of Tawara Bay is completely changed. 14 BEGINNING OF QUCTATION "Concerning the Efficiency of Production in the Laver Fishing Grounds Constructed by Adjusting the Ground Height on the Coast of Mikawa Bay

On the coast of Mikawa Bay in Aichi Prefecture, there are quite a few places which cannot be used for laver culture or from which satisfactory products cannot be obtained e because the tidal flat is too high. Construction of new fishing grounds by lowering the height of such places, removing soil with bulldozers, etc. was taken up as an enterprise and has been conducted since 1952. Here let us examine how much the production of laver was increased, by the increased area of fishing ground which was readjusted in height, in a few fishery co-operative associations which gave ctilMe-ratrIy trustworthy records of production. 1) Example: Tawara Fishery Co-operative Association (Atsumi 8 District, Tawara Town) Work of ground adjusting was commenced ex= October e 1952 and the fishing grounds constructed in that year has 1D€en us ed since 1953. The areas adjusted were the spits (see Figure 1) which a6, protruding-into the Tawara Bay as if they would hold the front of the Bay. Although the height of the areas was high, and the quantity of extracted soil was large, the efficiency of work was good, because there were many deep, long and narrow water-routes from which gravel had been removed and were contiguous to the spits and therefore these deep holes 15 were able to be filled up with the extracted earth. From 1953 to 1956 the fishing grounds increased by about 130,000-tsubo* and the earth extracted was about 680,000m3 . The production conditions from 1952 to 1956 are all in the Appendix Table 1. Noteworthy facts are as follows: (a) In the Tawara Fishery Co-operative Association, the method of laver culture was changed Completely in 1953 from the vertical hanging method with bamboo stakes (called hibi*) to the horizontal method with nets. (b) In 1953 the number of nets per horizontal hibi was one net, but it has been increasing by 0.5 net every year. The laver crop condition varies considerably from year to year. In this District there was an abundant harvest in 1952, and in 1954 it was a bad harvest, and in 1953 9 typhoon No. 13 is considered to have exercised an indirect influence. When the increase of production by construction of fishing groundsis analyzed, needless to say one must consider such annual changes of crop condition, and in addition to this, the influence of progress in culturing techniques such as in (a) and (b) cannot be ignored.

Translator's footnotes tsubo: a land measure of about 3.3 square meters. hibi: A description of hibi is given in Fishing News Inter- national, Vol. 2 9 No. 3, July - Sept. 1963. 1 Figure 1. Places in Tawara Oizu area where ground adjusting was carried out. 2 Ohshima. 3 Ohtsushima. 4 Oizu, 5 Mikawa Bay. 6 Ohsu Misaki Point. 7 Tawara Bay. 8 Onizuka. 9 (Tawara) 10 Numbers are years*of operation.

In the case of Tawara Fishery Co-operative Association, as mentioned in (a), from 1953 the vertical hibi production need not be considered, and also since the area used per horizontal hibi is known, the number of hibis built in the fishing ground increased by the construction is easily calculated. Furthermore, the mean number of sheets of laver production per horizontal bibi is known, and if the crop condition for new fishing grounds is not so different from old fishing grounds, thenumber of sheets produced annually can be computed from the area of fishing ground constructed (Table 1). If the output is calculated on the basis of the records of Table 1, using that method, the number of laver

Translator's footnotes • years: Years of the Showa calendar, Showa 30 1955 Shows 31 — 1956, etc. sheet: One sheet is a paper thin 20cm square of dried chopped laver. 17

sheets produced in 1953 in the 30,800-tsubo fishing ground which was constructed in 1952 was about 280,000 sheets, and the revenue was Y2,080,000. As this fishing ground has been used continuously every year, the output produced in four years, from 1953 to 1956 is computed to be about 2,390,000 sheets, the revenue becoming Y10,510,000. The production incomer/per tsubo in this case was Y35.2 in 1953 9 in 1956 it was n59.5 9 and the mean and total incomes for the four years were Y159.5 and .U41.3 respectively. As mentioned above, the reason why the production incOme per tsubo has been increasing continuously since 1953, is thought to be that the number of sheets produced per horizontal hibi is increasing, as is explained in {b) above, and also if the production technique would have been improved from the very beginning of the work of adjusting ground (if the number of sheets produced per horizontal hibi had been more than 1000 sheets every year), the above-mentioned production income would have increased more. Also the relation between the number of nets used per horizontal hibi and the mean number of sheets produced per hibi is shown in Figure 2. As the laver crop condition varies from year to year, this influence has to be borne in mind when considering the scatter of the points. However, the relation becomes an approximate straight line within the range of given conditions. Since in the example of Tawara Fishery Co-operative Association there were no vertical hibi, the calculation was easy, but in order to get the number of sheets produced per

per unit for this case, the increase ratio of sheets produced per horizontal hibi to the sheets produced per vertical hibi has to be computed. However, as there was no useful reference data to enable such a conversion, it was not possible to avoid using the following method after all.

1 ...... -0------(5----- ..,--,,,. - .--,-,y-,,,-,-,--(,5-F„-,,-,-777 ,-,:-. 'le ''.: .',1:fi: ■!..,143 W I bi :,' ',';'. ;.,' i„,,,,,,, „, ;'., •,',., ' _::,_, '''. '' '''' _ P i' n 1.) :11.-.1.2 fle Ifill:. ire, ui v•'''''' ,,,,i, , --"P', 7- .,.. --e-,-- ., - /!: i i•.< .e a . • •

-- `"` - '1-0Z;' , c) A628 '.4wilt ©50 016 (0. 45 277. 20 1083. 85 35. 2 5;l 20 ' 50 616 0. 49 301. 81 2176.27 70.7 27 30 30' 800 40 770 0.91 700. 70 2310.34 76.0 31 .10 770 1.41 i10& S0 4011.08 159.5

23138. 51 10512. 44 341. 3(85. 3) • 29 50 300 0. 19 147.00 1059. 87 70. 7 30 15,000 .10 375 . 0.91 341.25 1139.78 76.0

31 40 375 1. 44 540. 00 2392. 20 159. 5

■;1' 1028. 25 .1591. 85 306. 2(102. 1) 28 1g 30 40 1650 0.01 1501.50 5015.01 76.0 66, 000 29 31 40 1650 1.44 2376.00 10525. 68 150. 5

It! '1 l' 3877. 50 15540, 69 235. 5(117. 7)

30 31 19, 000 40 475 1. 44 1384. 00 3030. 12 159.5

tee. iii- 130, 800 7978. 29 33675. 10 257. 4

Table 1. The output of laver in the newly constructed fishing grounds of Tawara Fishery Co-operetive Association. 1 Year of construction. 2 Year of production. 3 Increased area of fishing grounds. 4 Area used per horizontal bibi. 5 Number of hibis. 6 Mean number of sheets produced per horizontal hibi. 7 Increased output. 8 Number of sheets. 9 Revenue. 10 Mean production revenue per tsubo. 11 Showa. 12 Total 13 Grand total 14 Tsubo. 15 x 1000 sheets 16 Yen. 19

J_ Figure 2. x z 2 x 100 sheets. 3 Number of sheets produced C) per hibi. ir 4 Number of nets used -' • per hibi.

)

q) 1 .; -5 Figure 2.

The area used per horizontal hibi and vertical hibi in 10 each year from 1953 to 1956 may be considered to be about 35 tsubos and 1.2 tEubos respectively. Therefore, if there is no significant difference between the output per tsubo of horizontal hibi and vertical hibi, the_increaseiratio of the production per unit hibi of the former to the latter is 35/1.2 1--; 29 . Incidentally, after 1954, the mean number of nets used per horizontal hibi was 2.5, and in 1953 it was 2 , therefore, if the number of aheets produced per horinzontal hibi when there were two nets was 70% of the number for 2.5 nets, the above- mentioned ratio in 1953 can be estimated to be 29 x 0.7 20. In this way, the number of vertical hibis of Appendix Table 2 is converted into a number of horizontal wi -es, and the mean number of sheets produced per horizontal hibi thus computed is shown in Table 2. Using the mean number of sheets produced per horizontal hibi in Table 2, and doing the same computation as in the above example using Appendix Table 2, the results of 20

Table 3 are obtained. That is, it may be said that by the fisheries construction work of ground adjustment, during the

years 1952 to 1955, the fishing grounds were increased by 1,270,000 tsubos and 16,670,000 laver sheets were produced by this area from 1953 to 1956 and the revenue was Y-70,410,000.

Table 2.

0 CY- ',1 ••-: ,i1: J. ' V- ).;..! ?:_11.17 ..',;;;:1( u„ ,.• 1': D.. ;A x 1000 •)3P. ir( ;-3' 1 9*1; -,1 ; ? 2n

h8128 M 000 4, 600 20 5, 100 8, 112 1. 59 29 300 0,000 20 6,010 7,443 1.24 30 0 6,300 6,300 8,543 1.36 31 0 6,700 6, 700 10, 674 1. 59

1 Year. 2 Number of hibis constructed. 3 Vertical hibi. 4 Horizontal hibi. 5 Conversion i-atio. 6 Converted value of horizontal hibis. 7 Number of sheets produced, x 1000sheets. 8 Mean number of sheets produced per horizontal hibi, x 1000sheets. 9 Showa.

3 ) In Appendix Table 3 the laver output record of the Sugiyama Fishery Co-operative Association is provided, but there was no fisheries construction work of ground adjustment in this Co-operative Association. The change to the horizontal culture method was tried experimentally in 1953, and from 1954, the expansion of the fishing grounds was begun in earnest and by 1956, 90% of the vertical hibis had been changed to horizontal. However, the conditions are not good because the fishing ground 21 is in the Tawara Bay, and the density of nets was too high. A comparison of the annual variation of sheets produced per tsubo for the above-mentioned three fishery co-operative associations (Tawara, Ohsaki, Sugiyem,q) is shown in Figure 3. As in the Tawara Fishery Co-operative Association, not only were more fishing grounds constructed but also, the condition of the fishing grounds was improved by this construction, and since the technique of production is progressing year by year, the output is increasing every year. In the Ohsaki Fishery Co-operative Association, although ground adjusting was clone year, there was no great change in the fishing ground every conditions and as it is thought that their production technique was fairly high from the beginning, it is considered that although there was some increase of production by the increase of fishing grounds, there was no change in the production output per unit area. The annual fluctuation of number of sheets per unit hibi in the Ohsaki and Sugiyama Fishery Co-operative Associations is thought to be due to the crop. variation. The reason that the number of sheets produced by Sugiyama Fishery Co-operative Association is .fewer than that of Ohsaki Fishery Co-operative Association is perhaps the poorer condition of the Sugiyama Fishery Co-operative Association fishing grounds. If the fluctuation of the Ohsaki Fishery Co-operative Association can be generalized, it implies that after 1955, the number of sheets produced by the Sugiyama Fishery Co-operative Association is decreasing slightly this may be said to be the influence of too high a density of nets.

Table 3. Laver output in the newly constructed fishing grounds of the Ohsaki Fish, Co-op. Assoc. C) (I) • 1 "" • 1, i . . 1( 1 P.1'1'.), (!-'i'-) :: x l1 4)0 3, (1 -J) , ( x 10( , )1 ,( .., 1000, ij )(1 .i•i )____ ■ , I , . •-.1C) i i 28 1 D 35 1,850 1.59. 3.18. 2, 9.11. 501 10, 236. 421 ' 158.2 6,1. 7 , 1 • d 29 e 1. 2-0 -1. IS: 2, 29.1. (.:) 1 1..1, r o81 11. r,12 1 1-18. 2 2 7 1 , 0 e e 1. 3 6!1 -1. 00 ;1 2, 516.* * (00. 1 10' 1 1 061 • 001 155.5 31 e e I. 59- -1. SOE :1, 9.11. 50 . I _ i 14, 119 20 _ 218.2 , , (....'D 1- ' 10, 693, 1 1 GO'I 44' 008. 5.1•6`30. ' i ` 2(170. 1) 1 29 35 1,060 1. 24 1 4. 18 1,31.1. 401 5, .19.1. 191 118.5 1 1 :37.0 # # 1.39 4. OR 1, 441. 6O.3. 766. 40: 155. 8, 28 30 1 31 /7 // 1. 591 4. 80 1, 685. 4 0 8, 089. 91I ._ I 1 ..1 218. (i - ; 4, 411. 40: 19, 1 I 3,35Œ5l'5, 003Œ7) l 35 3001 1.36' 4. 00 408. 00, 1, 632. 00 1 155.4 1.30 1 10, 3: ,, , 1 1. 591 4. 80: 477. 00' 2, 289. 601 218. 0 . 1 1 1-- 3, 921. 60 373. 4(186. 7) : _ 30 _ 1 31 ;1 11. 5 1 4101 1. 5( 1 8OE 651. 9OEI 3,129. 11 215. 8 I 126. 1 M, 671. 361 70, 409. 71 1 Year - of construction. 2 Year of production. 3 Increased area of fishing ground (1000-tsubo) 4 Area used per hibi (tsubo). 5 Number of hibis. 6 Mean number of sheets produced per hibi (x 1000). 7 Mean unit price (yen). 8 Increased output. 9 Number of sheets (x 1000). 10 Amount of money (x 1000 yen) 11 Production revenue per tsubo (yen). 12 Showa. 13 Total. 14 Grand total.

1 Figure 3. Figure 3. 2 Number of laver sheets produced per tsubo. 12 3 0 3 Ohsaki, 4 Tawara. SC) 5 Sugiyama. 6 Shows. 7 Year. 8 Fiscal year. ;r( - Q n“,7 I , 11 7-1-0 . 0 4 a 23

Figure 4. Places in Ohsaki-Muro Watarizu ( a part of ) Areas where ground adjusting was carri ed • o ut 1 : Numbers are years of operation. 2 Umedagawa River. 3 ikusegawa River. 4 0:1saki Town. 5 Shinya-Shinden O (Muro - Watarizu). 7 Airport originally. 8 10,000 niz 9 Mikawa;Bay.

1) Tawara Fishery Co-operative Association • 1) () 11. ■ P-1-1 • .É*

• .. [fi ;,< (1,f2) 1.1 ; 0!.!.! ! ioue '1- :1 F. Cpn QD1k (c el. C), 0 1 1 .f- 271 119. 1 4. 09 29. 21 16. 7 250 4. 08 527 40 50.: 2S! 5;12. 73. 91 60. 01.30. 817, 460 1.76 9. 03 1 11 1 p !)c), 733. 8 7. 21 75. 0,15.1 0 11, 010 1. 36 1,500 0.78 1.5 .501, (1t0 - 1 I , 1 30; 3, 199. 03. 31 141. 0 06. 034. 800 1.90 22. 62 2 3, 525; 120 40* 0 - 31 • 5, 737. 5 4..13 160. 0 19. 0 4,930: 3.85 .1, 000,I 33. SG 2. 5 490 165 •-lotr- 1

2) Ohsaki Fishery Co-operative Association

• ;'• e_ Li n I : f. Mrl

. . 0, â M " E*0. , À ; .1, 2862. 24 ■i125. 3, 96912. 79 1 1 ,.26I 4, 21 52. 45 (11i.!eini I I !271 5, 33113. 74 108.3 SO. 0 0. 78 49. 3 490 315 1 . 35* .28 8, 112.3..18 173. 0 61. 7 13, 690 . 4. 73 10. 01. GO 16. 9 2 4Ultr,.1 I e.) 1 3s.q. • , 29! 7, 113!4. 18 210. 0 37. 0 8, 850 4. 18 O. 3 6. 00 35. 4 2. 5 '30) 8, 543!1. GO 220. 5 10. 5 5, 020 2.00 . 6. 30 38. 7 2. 5 1 I .31110, 674'4. 80 235. 0 14. 5 4, 990 2.01 6. 70 45. 4 2. 5 183 I I 353 2 4

3) Sugiyama Fishery Co-operative Association

3) *5 ILI â 1 'nt) UU147 .,0„Ût;1 !:;1 27 .2. 35 48. 0 46. 0 388 230 inn{.)11-1u.„11Q. 1 28 1, 22313. 031 48. 0 22. 8148. 0 25. 5 • J- Kr-t - FH) 1 1 I 29 947 6. 73 70. 3S. 0 1, 170 13. 4 1. 5 ii::•174,;:i 1 1.) 28 If- C) 1 1 30 1, 0673. 43!708 17.0 2, 150 15. 1 2 e II • 25 1 31 1, 1473. 25 70. S 4. 8 3, 000 16. 2 9 337 274 • 22 MI (D 1

1 Year. 2 Laver output. 3 Number of sheets produced. 4 Unit price. 5 Area of fishing ground. 6 Total. 7 Increased portion. 8 Volume of ground adjustment earthwork. 3 9 Ratio of constructed fishing ground area per 1m 10 Number of bibis constructed. 11 . Vertical hibi. 12 Horizontal hibi. 13 Number of sheets produced per tsubo. 14 Number of nets used per horizontal hibi. 15 Composition of Co-operative Association 16 Number of members. 17 Number of households which constructed hibis; 18 Remarks. 19 Shows. 20 sheets. 21 Yen. 22 1000-tsubo, 23 1000-hibi. 24 hibis 25 persons 26 households 27 1000-hibi. 28 one tsubo per vertical hibi. 29 50 tsubos per horizontal bibi. 30 40 tsubos per horizontal hibi. 31 1.1 tsubosper vertical hibi. 32 35 tsubos per horizontal hibi. 33 Slightly over 1 tsubo per vertical hibi. 34 1 tsubo It ST (and so on). 35 28 tsubos per horizontal hibi. 36 25 tsubos " II ST 37 22 tsubos " END OF QUOTATION 2 5

2) Producing Water Courses (Excavation of Channels for 13 Creating Water Movement)

Excavating channels is one of the construction methods for improving fisheries in tidal flats. This is a method of improving water mixing in fishing grounds by guiding the water in tidal flats.

Figure 3. Diagrammatic representation of current in a channel.

cfr c. 1 Vertical Section. 2 Plan View.

_ 0 .------1-Zu.

® Z if :11 ■/* Veeel./ \11 '‘I PAI

It is considered that the movement of water in tidal flats may arise from the tidal fall which is caused by the variation of tidal power exerted in the open sea. And, in places where the water depth is shallow, a frictional resistance operates between the sea bottom and the water s and the flow is obstructed. This frictional resistance is the shear stress which occurs between the sea bottom and water, and moreover, since the sea bottom is rough, if the water depth decreases, this quantity increases rapidly. That the 26

water depth is shallow in a wide, plane tidal flat, means that the diametrical depth of what is called an open water channel is extremely small, and if in this flat there is a channel with a fairly large water depth which is continuous ' from the open sea e the channel current speed naturally becomes faster than in other parts. (1) Carrying Out of Earthwork 1. Water Channels Made in Tidal Flats: A 5 mentioned above, the great majority of water in a tidal flat is only moving with the tidal current,.maintaining the horizontal order. Because of this, the degree of water exchangi-ng-with other regions is low and therefore, its fishery productivity is low. If there

111, is a water channel in such places, the flow of water in the channel is faster than the flow of water around it, and water from the Part of the fishing ground nearer the shore overtakes the water in front of it (when tide is ebbing), àhd the situation of horizontal order of the water mass is diSturbed -- the exchange of water in the fishing ground becoming better -- and the productivity increases. In making this kind of water channel, it is more usual to improve already established fishing grounds, but it is also efficient to make those channels when fishing grounds are constructed by cutting off the earth or earth readjusting. As the construction objective is a fishing ground whose ground is flat and higher than the neap tide mean low water level e the mean low water level of the sprilig tides may be a sufficient 27

channel depth. As for the channel width, it is usual to construct about 20 - -40m in width and this amount of earthwork • can be done easdly using a swamp bulldozer. 2. Canal Channels: In a bay there may be such places inside' • 14 and outside the bay that have a difference of tide time, because the width of the bay mouth is narrow compared with the size of the bay. For this topography, it is possible to Make the water exchange better by canalizing the sand bar which is forming in the bay mouth , thereby making a water channel from inside to outside the bay. The tide time difference may be shortened by this water channel, and thus the quantity of water entering and leaving by tidal motion may increase a little, but the question is not the absolute quantity, rather that the horizontal stability of water from the bay mouth to the inner most part of the bay is changed. (2) Actual Example and Efficdency Concerning water channels to be constructed in a tidal flat, the example quoted.is of channels constructed in Yahagi- Furukawa Delta where the Kinugasaki Fishery Co-operative Association fishing grounds are situated. In making this channel, much consideration was given to making the river water spread extensively into the fishing grounds.

Concerning the canal channel, an example of this in 15 the eastern side of Fukue Bay, Atsumi District (in the Isuzu Fishery Co-operative Association area) is quoted. Figure 4. Construction plan for fishing ground water channel in the mouth of Yahagi River. Left: Plan view. Right: Aerial photograph of the area shown in plan view at loft taken from east of the river mouth - the point of intersection of the two water channels can be seen in the lower right. 1 Plan view. 2 Fishing ground improvement constructionCwater channel . construction work 3 A construction area, B construction area . 4 Mat sukishima. 5 Yahagi-Furukawa River. 6 Sensei Shinden. 7 - Starting point of construction area B p ii ty " A 9 Hole excavated by sand•pumping machine. 10 Terminal point of construction area B. 11 IT TI 17 A. •

1. rater Channel in a Tidal Flat: The work described below was carried out as a part of the Coastal Fishery Development Comprehensive Countermeasure Work of the 33rd Year of Showa (1958) with the aid of the Government and Prefecture, and the Kinugasaki Fishery Co-operative Association was the central 'operating body. The following is an explanation of the work and the itemized statement of costs quoted from the work plan records, and for the effect, data up to 1961 were examined. (1) Ep1anation of Work

0 iTÉ mg

1. :::,11:.:0 5,-7J.),1-1 1 1'1';

1, 000 in

10 m,=1 1-*/- : 7:: 1 m 2.

3. •10, 186. 25m' AIR 5. 185m 13:111 <- 5.001. 25m 3 4-> • ' 1, 215, 000j 1 j AL< 581. 0001;] B:111-_< 634, 0001 1.1 1 11 ,1\ ,k)87À11'; 1 D 0 (J., : 1, 000m

1irox 13 mx 4 0.10H-5,200m 3 (1 À 1 H iâ 61)-0) -- 10 1- - 1 H 4 01 7, ?.f. ,50. 0 D '0 ;41aLL -,1111«?;;1À3ÀÏ..,±',50

(ti"":',1 10 1. *:-/ 1-* - 1 Pin 25m , 40m 1111 25m 3-.;', 4 Sf51 x 5011 =5, 000m 3 5.i-Thii1 :r3i1131 ■1-.: 2 .1)21 FJ AI S1ij34. 3.3 -3.S 511 ■11] ?1'• 4: 3 22 87 À 2; 2 ;134. 3. 18 22 e .2.7i.j 131r UÊ 34, 2. 21 ----D. 2 10 H • lif-H 3 -,"“.7-.124:115] 2.; 2 i.i751131. 3. 17 10 H !!:7 H 2 rE 8 Pip,ij 6, J/jjlj 9 D. 0: fi ! 9 O. 7. 0 "i•Ti'

8. ..11: 0) )9C:n=ifin U z.7_1 .1 9 15, 750, 0001 1] (1.50051 x3, 000JA x1. 51 1 1) - 6. 750 1.-1!.W 51 9 (1, 500 :;«.1 x3. 000),.. x 5 1 1.1) 22, 500:-1= 1 :_i Z=1•:ii1 15, 3 . 53'd

• 30 1 Item. 1. Type of work. 2. Central operating body. 3. Amount of construction work. Cost of construqtion work. 4. Operating method. • 5. Period of operation. b. Objective species. 7. Method of administration following the operation. , E. Effect of work. 9. Plan. 2 Remarks. 3 Water channel construction work. 4 Kinugasaki Fishery Co-op. Assoc., Isshiki 'rown, Harimame District. 5 Yen 6 In construction area A, transported by small boats and porters. 7 In construction area B, soil removed by bulldozer. 8 From Feb 21, 1959 to March 22, 1959. 9 Black laver and green laver. 10 Included in the subdivision program of laver culture ground construction. 11 Possible income from increased laver production Y15,750 9 000. 12 Plan view, vertical section, cross section. • 13 See the plan view in the separate sheet attached, The fishing ground under the jurisdiction of the Kinugasaki Fishery Co-op. Assoc., Offshore •from Sensei-Shinden, Isshiki Town, Harimame District., Length 1,000m, width 10m, mean depth lm. 14 Based in Matsukishima, Isshiki Town, Harimame District, Aichi Prefecture. Head of Association: Hirokichi Kasuya. 15 Construction area A 5,185m3 Construction area B 5 9 001.25m3 " Y581 9 060. " Y6$4,000. 16 Worked with'40 small boats and 87 porters per day, 13 transportations per boat daily, Total number of working days equivalent to 10 days. (note) One boat loaded im'3 of soil on board each time and the soil was jet-L,isoned 1,000m offshore. 1m3 x 13times x 40 boats x 10 days - 5,200r? (6m2 ner day for one person) 17 Working for four hours a day with a 10-ton bulldozer, Total number of days equivalent to 50deys, As assistance, one boat, 3 porters a day,and the total number of days equivalent to 50 days. (note) 25eof soil extracted per hour using a 10-ton bulldozer, the mean distance transported to duMping is 40m, that is, 25mx 4 hours x 50 days = 5,000m3. 18 Area A: The first operation - March 4, 1959 to March 8, 1959 • 5 days. The second operation - March 18, to March 22, 1959 40 boats and 87 men every day.

• 31 18 (Continued) Area B: The first operation - Feb. 21, 1959 to March 2, 1959, -- 10 days. Three bulldozers every day, Total number of bulldozer hours was 12 per day. The second operation - March 9, to March 17, 1959 -- 10 days. '1'wo bulldozers even, day, Total number of bulldozer hours was P per day. 19 The green laver culture ground in the Sensei Shinden offing is to be changed to a black laver culture ground. 20 A 7ink in the chain of the program of District Demarcated Fishery Rights which is excercised by the fishery rights of Kinugasaki Fishery Co-op. Assoc. 21 The laver culture ground with 1,500 horizontal bibis for the production of green laver may be changed to one for the production of black laver, therefore, the present income from the green laver production (1,500 hibis x 3,000 sheets x Y1.5 Y6,750,000) could become the income for black laver production (1,500 bibis x 3,000 sheets x Y5. — Y22,500,000) and the difference is an increase of Y15,750,000. • 22 Separate sheets attached.

(2) Itemized Expenditure

C') 1, 0 0 1: 7.7: H r ri I M1,0001 (:\ f' ;t 0 4\ 400 i!JD 8001 350, 000i n r..7;1 1 Ar..1 1 a À 870 AO 300 261, 000. .x 7.2,k ,]•.';•- •: .,-„t 0 634, 000 (:)( r.Z. os j;) y D 10. 200 2, SOO 500, 000 2 À 1;f:f 45,000 , À li 150 300 0 4 \ 50 SOO 40, 000, 1,•:3.751 1 I 0 1 49, GOO 49, 000 :7"./fr F--Y—iMij 0 1, 215, 0001

1 Process & items. 2 Number. 3 Unit. ,4 Unit cost. 5 Cost. 110 6 Remarks. 7 (Water channel construction work in area A) 32

8 Hiring of small motorboats. 9 Wages of men. 10 (Water channel construction work in area B) 11 Hiring of 10-ton type bulldozers. 12 Miscellaneous. ]" Boat-hours. lL Man-hours. 15 Bulldozer-hours. 16 Set -17 Accompanied by one boatman. 18 Equipped with scoops and dredges. 19 Accompanied by two drivers. 20 Stand for parking bulldozers.

(3) Effect of Work This district has been a producer of green lavers (Monostroma) since old times, and a little black laver had been produced along the channel of the Yahagi Furukawa River. The method of culture had been the vertical brushwood hibi . method. This was changed to the horizontal nets culture method in

1955 - 1956. In 1958, the channel construction work described above was carried out, and at the same tiMe, using various methods such as net spreading for the purpose of black laver culture, changing the laver seeding time and the introduction of special nets for black laver, much effort was made to increase the production of black laver. Since 1959, the laver filament technique has been perfected, and the fishing grounds were expanded very widely offshore, and thus rapid progress such as is shown in the following Table was made. The ratio of area of constructed channels to this large production increase is not distinct, but it can be said that one of the reasons for the large increase of laver

production is that in the past the number of green laver sheets produced was 50 - 60% of the total number of sheets produced in this Co-operative Association, but after 1958 the percentage decreased to 20 - 30 and moreover, in 1961 the total production volume was more than doubled.

Annual laver production volume in Kinugasaki Fishery Co-operative Association

Mt 0 4. /t Vi M, e &Pik eu et) 0 ird 11 in ) 9€:1 9a ha GART4132 586 108. 0 1,396,200 11, 035, 200 16, 064, 700 28, 496, 100 33 601 116.6 11,000 5,548,300 16, 355, 500 5, 981, 900 27, 385, 700 34 630 177.0 14,000 5, 027, 100 27, 129, 800 14, 901, 200 97, 058, 100 35 631 385.0 14,841 19, 073, 600 25, 931, 300 19, 073, 900 63, 578, 300 ; 36 631 300.0 15,000 40, 280,300 7, 863, 100 12, 550, 200 60, 693, 600 . , 2

1 Year. 2 Number of households engaged. 3 Culture. 4 Area. 5 Number of horizontal hibis. 6 Number of processed sheets of different varieties produced. 7 Black laver. 8 Mixed laver, 9 Green laver 10 Total. 11 Showa.

2. Canal Channels: This work was taken up as part of the 38th Year of Showa (1963) Countermeasure Work for the Modernizing Construction Improvement of Coastal Fisheries in Aichi Prefecture, and the Isuzu Fishery Co-operative Association is now working as the central operating body with aid from the Clovernment and Prefecture. Therefore, concerning the effect, at the time of printing they have only

•• 34

finished measuring the volume of water passing through the channels. A summary of the work plan follows:

(1) Purpose of Work -- The number of households in Isuzu

' Fishery Co-operative Association is 146, and the main occupation of all these households is laver culture. However, in recent years, the income from laver culture has decreased rapidly, and they are forced to have the lowest standard of living. This work is being put into operation in order to nake the livelihood of those poor fishery families more secure by making the laver culture income higher.

' (2) Summary of Work -- This work is to canal and dredge to

a'depth of lm over a 35.00m width in the shore of Isuzu District

410 so as to direct the sea water of the Mikawa Bay to the Fukue Bay. After dredging, concrete sheet piles will be driven in

at both sides as a bank protection over a total 78m length, and in order to make this strong, tie rods are to be used over a total 70m length. Also in order to keep back sand and waves, and to direct water, concrete sheet piles are to be established

on both side's thè Tukue and , Mikawa Bays to a total length of 140m.

(3) Effect of Work -- The Isuzu Fishery Co-operative Association

is culturing green laver in the Fukue Bay using 5,000 horizontal

hibis with nets. By doing this work, this'green laver culture ground is expe-cted to be changed to a black laver culture ground. By this means, the total production income is 110 expected to increase by7,000,000 and the mean income of each household to increase by about Y50,000.

(4) Administration of Facilities -- Administration Regula- tions (to be established separately). (5) Details of Work CreifI (peel ED ez) 0 (•1 te- - - • eflak-.1 JIP.K i.", IfI1r..1,1z !_i,'.iii!:_i-,1 yii.,,•s,e,:', z 1-• :Y;, 1,1 lit feu e .,,.!e 8, 617m3 0 e Villij 33, 933m3 Pi- 5 /veM1 0 0} )II i it © euenlitmlue «ten HA: 146) Ji 0> e iin,. iiil v— 1. A4 Jvie Pl W 11 r 140m 6, 600, 000 -aril fil 78m i/ - 1 IM ikie a 111 ilD MI (e 4e, len» mm 1 Type of work. 2 Name of district. . 3 Central operating body. 4 Central administrating body. 5 Number of households which are to receive profit. 6 Amount of work. 7 Unit cost 8 Work expenditure. • 9 Tilling, adjusting ground, dredging, canalling work. 10 Isuzu. 11 Isuzu Fishery Co-operative Association. 12 As left. 13 146 households. 14 Dredging. 15 Canalling. 16 Antisilting'andLwater directing fence. 17 Bank protecting fence. 18 Bank reinforcing (using tic rods) 19 Sheet pile construction work—Y6;600.,000. 20 Sheet pile construction work.

(6) An Estimation of the Quantity of Water Exchange Resulting from this Operation (Fisheries Experimental Station) -- From the results of various observations, it is thought that the preferable plaoe for this operation is a circular area of 2 1,350,000m which is due south of the tip of Yarigasaki Point. Mean quantity of water in this areàl às the mean depth of water is about lm, the quantity of water becomes1,350,000m 3 . 36

Using the following, Mean depth of water in the channel 2.1m Mean width of water in the .channel 35.0m Number of hours during which the water comes and goes 5 hours Mean distance travelled per: second 40cm (As is seen in Figure 5, a fairly large tidal range and a difference of tidal time inside and outside the bay was observed, and the mean speed of water passing through the channel was estimated to be 40cm/sec because of this head.) the quantity of water which enters and leaves during one tide after this operation, is 35.0m x 2.1m x 0.4m x 5 hours '9 5.3 x 105m3 . This is almost 40% of the mean total quantity of water, and this amount of water will be a large exchange compared with the amount of the present time. Along with this, the fishing grounds in this district are going to be improved greatly, and it is considered that they will become high productive capacity fishing grounds. Figure 5 No.1 Location of Channel to be Gonstructed. 1 Mikawa Bay. 2 Kurobe Rock. 3 Location of channel. , 4 Tida3 observation. 5 North of the river. 6 Tidal indicator. 7 Fukue Bay. 8 Location of observation. 9 Flood gate X. 10 Flood gate Y. 11 Kobo Mountain. 12 Oritachi. fg 5 I210 1 Cin,teidEl 13 Furuta. 37

Jle

71.* • 7K

.z7e

/re le ece

$0 é ct 6 7 3 I an au M le a /7 ,3 M5MO2 mmirdmenomelemum (fl(ifflip8A 26 ntammx) • Figure 5 No. 2 Table of the difference of tide levels inside and outside the bay soon after the operation was begun. (Observed August.26, 1961)

60 n-23 4o eis re. 2 Je3 80 2.e.‘ -àejt e / 3ne e • • et 41,z.1 és‘

11-00 jilt

à 4 15 à n 0n103841011 31 6 qL1 ••••19o-h eek. Y1,1$41e.neVef îa 6 121 im Figure 6. Tide table at the time when the water current was measured. (Tidal range lm 70cm) 1 Nagoya Harbour standard surface level. 2 A location on the Mikawa Bay side (Shisaki Point). 3 Tidal indicator at Nagoya Harbour. 4 Oct. 31; 1963, 0900 - 1800 hours. (Made according to the index numbers of Shisaki Point which are quoted from the curve drawn for.Nagoya Harbour).

•

+.•

(7) The Carrying Out of the Work and its Effect -- According to the plan, the operation is still being carried out now in

November, The water channel has already been constructed and sheet piles are now being driven in.

Concerning cana1ling, the water channel width is about 35m, the mean height of ground at the bottom of the channel

is -60cm (Tide Table D.L.), and results of the observation of the quantity of sea water which comes and goes is as follows:

Time: Oct. 31, 1963, 1000:lhours to 1700 hours.

Observation Instrument: T.S. Current Integrating Meter. Results of Observation: _4 _ D pi el --e. , pi ilq-zwi 3-y Mf.31 cm/sec et; iti] lei e 10.30 12 35 0 11. 00 5 16 ti 9PMJ11.1fA1j 11 Pi 00 3). I . 30 8 24 MC) elitifleJ ii WI 20 3). i 12.00 14 40 e 30 24 . 66 e 13.00 22 ' 60 .. 30 24 65 , • 14.00 26 70 , L'el( u — ef v)iiit( -i-, tmitatit 30 22 60 e 15.00 14 • 40 0

30 ' 14 40 . 16.00 12 35 N fiek -+31tIcgliiit 0 30 5 16 ei. o eriupeil 16 fqj 26 *irigiÀef.iezej 50. 1cm/sec ,

1 Time 2 Number of rotations of propeller per minute. 3 Current speed. 4 Direction of current. 5 Remarks. 6 Outward. 7 Time of low tide 11:00 a.m. ' 8 Time of turning 11:20 a.m. • 9 Inward. 10 Dyes (Rodamin) were relensed, Dye colour moved straight ahead. 11 Dyes -- moved eastwards.. 39

12 Time of turning 16:26 hours. 13 Mean speed of the inflowing current through the channel: 50.1cm/sec.

The mean speed of the inflowing current in the channel between 11:30 hours and 16:00 hours is 50.1cm/sec. The mean depth of water in the channel is 2.1m, the channel width is 35m, time of water inflowing is 4.5 hours, therefore integration of the quantity of water flowing in gives

35.0 x 2.1 x 0.50 x (4.5 x 3,600) 1-; 6.0 x 10 5 a little over 600,000m3 , and this is more than the quantity estimated when planning. Incidentally, the tide on the day when these measurements were taken is shown in Figure 6.

Photo of constructed channels (canalled water channel). AboVe andght: Mikawa Bay. AbOVe left : Mouth of Fukue Bay beyond the alluvion.

3) Tilling of Tidal Flats - 20 Tillage of tidal flats using tractors has been conducted for many years for the purpose of the items mentioned below. And, in most.cases, tillage and ground adjusting were carried • same work, without making any distinction between out as the 40

them. This is thought to result from the fact that scraping the soil, which is one of the methods of tillage, was being called adjusting ground. (1) In order to loosen hard-packed subsoil by using a disc harrow etc. and to remove harmful marine species such as Hototogisu and Koamamo (2) In order to oxidize the subsoil in areas in which rotten soil and deoxidized layers are deposited, by doing tillage. For (1), it is possible to loosen the soil down to 150mm by using a discharrow. Using harrow, the surface of of the tidal flat'becomes very loosened, and - this effect is maintained for about two tides (one month). After tilling, • ridges and furrows result, as is seen in the photos, and it is very common that Bacillarieae flourish in the furrows, and they are thought to be very good food for bivalves such as short-necked clams which live in the surface of tidal flats.

• •

— ,

' "..;; -;e2C1.....-..' , A*. 5:: 4 e4.xeieemx>see • Tidal flat tillage Tidal flat tillage by disc harrow. by disc plough. 41

Concerning (2), tillage as a means of oxidizing must vary according to the depth of the reduced layer of soil (the depth from the ground surface). In an inner bay tidal flat which is in the mouth of a river and whose ground is high, the first 5 - 7mm depth from the surface is a clean oxidized layer and under this is a black deoxidized layer. And it is thought that the constituent water of'this bottom layer contains various inorganic salts and other things. If this 21 deoxidizing layer is turned up, it has a beneficial influence on the laver crop condition, even several months after tilling. Thus, as a means of reversing the top and bottom layer, tilling is normally done with a disc harrow, however, in places where the layers are deep, disc ploughs have been used as a practical adaptation. With D loughs, reversing the top and bottom layers can be done down to a depth of 30cm. Regarding the effect of tillage for laver culture grounds, the following quotation, although not recent, is from the R enort of Development Work in Shallow Sea Inner Bays in 1952, by the Aichi Fisheries Experimental Station.

BEGINNING OF OUOTATION "Tests Concerning the Effect of Tillage. The District of Shinya Shinden No. 3, Toyohashi City, Aichi Prefecture has been used since old times as a fishing ground of short-necked clams as well as the place where laver • spores settle. After driving hibis into the mud, it was If 2 usual to transplant all the hibis settled on by laver spores within one or two tides, however there were some people who tried laver culture in this same place after transplanting, but they did not grow very well and it was not successful as • a productive culture ground. On the contrary, in the Oshide fishing grounds in Ohsaki District which is on the opposite coast and is not so different in topography, there were no such troubles. Therefore, it was thought that the No. 3 fishing grounds should be able to be good culture grounds by some means. Tillage of the fishing grounds was carried out as one of those methods.

(1) Condition of Hibis. Settling of spores was very dense this year, and on 2 October 30th, 250 - 300 spores per 1cm of floating hibi were observed. After that, on November 1st, the growth of laver was very good and on the horizontal hibis it appeared that it would be possible to pick them at the time of the next tide. (2) Tillage As it was considered that by tilling, the nutrients for laver such as various salts which are thought to be stocked in the surface of tidal flats might be dissolved out, tillage was put into practice as shown in the next figure.

Total area tilled was 6,700 - 6,800 tsubos and the depth of tillage was 120 - 180mm. While tilling, the odour of hydrogen sulfide and methane was very strong, and there was apprehension 43 that if the tillage were to have been carried out extensively, some harm might have been done by those gases.

(a) Period of Tillage: November 3, 1952 10 p.m. to

November 4, 1952 3 a.m. (b) Order of Tillage: The following figure (a,b,c,d) (c) Area of Tillage: 6,700 - 6,800 tsubos. .

1 Shinya Shinden. ® 2 a. 800 tsubos. 4f, 3 b. 800 tsubos. 4 c. 2,500 tsubos. re 1, ri 4 goolf

5 d. 2,500 tsubos. Jet u 800 • (;) A 2500 • =2500 •

(3) Analysis of Wa t er . As a guide for investigating how the quality of the water mass in the area is changed by tilling, water and mud were sampled in each position A, B, C, D at three times, just prior to tillage, and on each of the next two days, and the increase or decrease of nitrogen content was examined. The water quality was measured by using the Stry chhine Reduction 22 Chromatography method NO 2 NO3 — N. Although it was raining on the third occasion, November when the results in this Table are conSidered it:is deduced

Translator's comment: should be "after 2 days, and after the . next 2-days"-,--see Table. 44 that the N 0 content increased 2 5 four times during the three days following the tillage.

0 11e Jj1 3Ill 11 ®KI 2 IM 11 )1 ri -1;1 3 Iffl 11 j] 7 0 i'M A 0 N2Obing/In 3 N,05 1 Fil k Olt N,C5 1 PI L Olt A 17.3 48.1 B 11.6 17.3 1.60 54.7 4.7 C 9.6 20.5 2.11 42.8 4.4 D 13.5 42.8 3.2 0 314 ei 11.6 18.3 47.1 4.1

1 Position measured. 2 First time. November 3rd. 3 Second time. November 5th. 4 Comparison with the first time. 5 Third time. 6 Average.

(4) Subsequent Results

After November 7, the laver growth was remarkably good, and On November 13th it was possible to pick thém, and they were gathered for four days from the 15th to the 18th.

The results after gathering are as follows: for one net hibi

10 kens in length, the number of sheets harvested was 500 on average, the maximum being 800 sheets, and in one floating hibi 10 kens in length the number of sheets harvested was about 1,000 on average, the maximum being 1,600 sheets. The number Of sheets produced in this fishing grounds for this season attained 1,150,000 and the length of laver hanging down from hibis reached 45cm.

Translator's footnotes. ken: Unit Of length, 1 ken = 1.818m IL 5

(5) Consideration of Results From the results of the above-mentioned tests, it is considered that the various nutrient salts which had been stocked in the tidal flat surface might be dissolved out by tilling, and those salts acted as fertilizers and thus promoted the germination and growth of the laver. Because of this, the area which had been used only for laver spore catching was able to be improved for use as a culture ground. However, it is difficult to comment on the confirmation of the effect of tillage by this test only, it is dependent on research in the future." END OF QUOTATION

In addition to this; concerning the . effect of tillage, you are referred to the following book: The Results of Tillage Tests in the Isuzu Laver Culture Ground of Fukue Bay (Fidièry Propagation Data No.2), written by Yasuo Ohshima, Reijiro Hirano, Yunosuke Saito (Fishery Dept., Tokyo University), Takeo Kurake, Tadao Suzuki (Aichi Fishery EXperimental Station).

4 The Construction of Fishing Grounds by Establishing Break Water Fences.

In such places where the production is reduced due to waves being too strong, it is necessary to protect against 46 the waves and subdue their strength somewhat, and at the same time to promote ourrents and maintain the constant currents in the district. Especially in the case of laver fishing grounds, such places where the waves are too strong due to the winter seasonal wind are questionable, that is, places where the shore faces west or north and the distance to the opposite shore is great. For shores facing east and south, the waves are very strong in the autumn, but they are very calm later in spite of the winter seasonal wind, and in order to use them as a laver fishing ground, effort should be concentrated on water guiding, and the subduing of waves need not be considered.

1) Waves in Shallow Sea Fishing Grounds and Wave-Breaking

Shallow sea fishing grounds are limited to the continental shelf and the adjacent shallow sea, so that large waves cannot occur in these fishing grounds. Moreover, for waves in laver culture grounds, only the waves made by the seasonal wind which begins to blow towards November have to be considered. The size of waves depends upon the direction of the fishing grounds, the seasonal wind strength and the distance to the opposite shore, and then it varies according to the sea depth in the fishing ground and to the slope (gradient) of the sea bottom towards the offing. In the case of deep seas, the height of waves is determined by wind speed and the distance to the opposite shore, and the formula has 47 been determined empirically as follows:

H = R x f(X) x (m/s) 2 m Hm: the maximum height of waves. • function (6th order) of the distance to the opposite shore ( C).

m/s: wind speed/second.

R: constant.

It is rather difficult to determine the height,of waves. When following one of the wave peaks, one misses it very easily. Normally, the highest wave is taken to be the mean value of 10% of the highest waves. In shallow seas, the wave height is determined by the

water depth. Whenadeep-sea wave, which is not accompanied

. by water'movement, is incident on a place where the water depth becomes shallower suddenly, the frictional resistance of the sea bottom against the wave increases and the water movement of the lower part is obstructed and then the wave is forced

to break. When waves are about to . break, the wave length decreases, the wave height increases, and following this, they become broken waves. At this time the waves move forward in the incident direction being accompanied by water movement. On sea shores, these movements are always repeated. A relative formula between water depth and wave height is as follows:

hb = 1.28 Hb

hb: water depth at the point of wave breaking (m)

Hb: wave height of broken waves. 14.8

For example, in a place where the water depth is 2m, the height of the waves is about 1.56m, and. no higher wave .than this can occur. In this place, when a large wave comes • from the deep open sea, the wave is forced to break and change to this size of wave. That is, the original energy of the wave is dispersed in some way. It becomés the waves according to the water depth, while a part of it changes to the energy of flow of the broken waves, and the rest of it is absorbed into the ground. Therefore, when the seasonal wind becomes strong in winter, irregular and violent flows are produced between the continental shelf and shallow sea fishing grounds, and these.flows together with the rest e of the waves become a power able to destroy equipment. For instance, if a wave with a 10m wave length, lm wave height is broken completely, the speed of falling of the top of the breaking wave becomes . 5 - 6m/sec, and thus a rapid flow is produced in front of it. Therefore, if the water currents made by broken waves can all be guided in a particular direction, it is possible to bring about an improvement in the currents in the district. This wave breaking due to water depth and guiding of water currents are the purposes of establishing break water fences. -

2) Establishment of Fences, Their Construction, and Their Effect.

In Ise Bay, a part where the waves are too rough for laver culture grounds is the southern part of the west coast 49

fg 7l encoeum

Figure 7. Diagrammatic representation of breaking waves. of Chita Peninsula, and in Mikawa the coast of the western part of the Atsumi Peninsula, although laver culture grounds are being built there.

(1) Establishment

First of all, Tokonameri--Noma and vicinity, where fences were established, are quoted. As is seen in the Diagram, the distance from this district to the opposite coast is about

40km beyond Ise Bay, from the eastern part of this district to the coast line of Mie Prefecture, from the northern part to Nagoya Harbour. Therefore, when the winter seasonal wind is violent, the wave height reaches about 2.0m. This sea is shallow for a considerable distance and the distance from the shore to the high and low tide mark (Om of hydrographic chart) is about 100m to 800m, and from this mark to 200 - 700m offshore is the slope of the continental shelf. Before the construction work was done, the fishing ground was situated in a part shallower than the low tide mark, and when the fishing ground was established a little further towards the 5 0 offing than the mark, extensive damage was inflicted on the fishing ground and the losses were too great for the ground to'be economical. Therefore, in order to expand this fishing ground to a depth of -1.0m to -2.0m, breakwater equipment was planned. In this case, the thing which gave particular apprehension was that the length of the area (width x length) of the fishing ground would be too long.and that if laver nets would be laid all over the area, the degree of water exchange becomes poor and the productivity would become low. Therefore, as for the equipment, the direction of the fences was considered in order to subdue the waves by making the water depth locally shallow against the incident waves, and to make the water exchange better by guiding the water currents caused by the broken waves and also if possible, by causing constant currents along the fences.

(2) Construction

The facilities established between Tokonameri and Noma, and in the western part of the Atsumi Peninsula are shown in Figures 8 to 11. As is seen in the plan views and cross sections, concrete piles 30cm in diameter were driven in at 25 locations where the depth of the sea was -1.0m to -4.0m in a single line with a center to center spacing of 1.0m to 2.0m, and along this line 5m3 to 100m3 of granite lumps per lm of fence were thrown in as a concealed bank, each granite lump weighing 100kg to 500kg. As for the standards used for the quantity of stones thrown, stones were piled up to the Om 51

to -0.5m depth of water, making the slope of the incident wave side about 1:1.5 and the slope of the opposite side about 1:1.2, and the top surface was constructed 1.0 to 2.0m wide.

(3) Effect Incident waves from the offshore cause intermittent

. and strong flows in the incident direction from the broken wave line to the fishing groùnd by being broken in succession. Breakwater fences check this flow and it becomes a resistant power against the fence plus a flow along the fence. And the 'waves which come to the fence are further forced to break by the piles and concealed bank and afterwards, they become smaller waves and a flow along the fence. Considering the piles alone, a row of piles is thought to have only a restraining effect proportional to the cross sectional area of piles presented to the incident waveà (only vertical cross section). Moreover, the energy of the waves is shown in the • following formula. E = jog ( Waite' height/2) 2 x X i) : density 27weight (ton) of 1m3 of sea water 7. g: gravitational constant. X: wave length. And since waves which are incident perpendicular to the row of piles have energies before and after passing the piles which differ only in proportion to the restraining area, • then, if the center to center spacing is lm, and the diameter 52

of the piles is 0.3m, they become 1 : (1.0 - 0.3) --- 1 : 0.7 and the energies are: H. 2 N H. 2 s 1/2pg (7.) xA o : (1.0 - 0.3) x 1/2ipg (7t.)

and if >4.-X t , the ratio of wave height: Ho 2 H I 2 1 x (-2-) : 0.7 x (-2—) = 1:1157 = 1 : 0.836

That is, if there is no change in wave length even after passing the piles, the height of the wave decreases only by about 0.84. If the wave length becomes shorter, the decrease is less. Therefore, the wave subduing effect of piles is very little for waves whose lengths are long. However, the incident direction of waves is usually not perpendicular to the row of piles but has some angle. If the energy of waves which are incident perpendicular to the row of piles is restrained in proportion to the diameter of piles (The incident direction for which waves are completely restrained by a row of piles is the direction of the tangent linking the inside and outside of two adjacent piles.), the energy (E) of waves which are incident at some angle (8) is decreased to d E x sin G x (a - --)a 26 as is shown in the following diagram.

And most of the force component(c)in thd.direction'of the row of piles is guided by the concealed bank and row of piles, which are in the same direction as the component , . and a flow is produced there. In addition, short wave • length waves made by wind become very calm due to the piles. 53

Concerning the facilities in

Noma and its vicinity, as the height of 0 ground in the offshore of this place is B , about -2.5m, the sea depth reaches 4.0m .• at the time of high tide, and when the violent, waves of seasonal wind is a:UMM chtiel 2.0m height have occured, but as the top of the breakwater fence is a: Center to center spacing of piles. at the height of + Om, the sea d: Diameter of piles. depth becomes shallow suddenly at 2.5m, so that the waves are forced to break and in the region of the fence the waves become.shorter than 1.5m. And the flows produced by the concealed bank and row of piles combine, and they increase the productivity by becoming a constant current in the fishing ground.

3) Stones to be Used to Make Concealed Banks. Normally in the case of bank construction work, regarding the size of stones, small 'heart' stones are used inside the structure of the bank and large stones are used to cover thèse, making the surface of the slopes smooth. As the top surface of the concealed banks of breakwater fences is in a 0.0m to 0.5m depth of water, the construction work is always conducted underwater. Therefore, it is most difficult to place the covering stones well and to make the slope surface smooth. Even when the work is done by divers, 54

it is considered that if there are some ineffective stones present, the small 'heart' stones would be exposed and scattered by waves, because the bank is concealed and far from the coast. Therefore, rejecting the 'heart' stones and covering stones method, the plan should be designed mthat;eachof the stones can withstand the waves in its . own place.. In the case of the construction work in Tokonameri, only the same sized stones were piled as a concealed bank along the row of piles. However, although several years later bolted concrete blocks were used for repairing parts of the fence top surface which had become lower because of subsidence of stones, and these parts were raised to the correct depth of water, it is thought that the amount of slope surface not removed is a measure of hàw low the water guiding effect is. Th e si ze (weight) of stones which can withstand the waves is proportional to the cube of the wave height and is inversely proportional to the slope (gradient of bank) as is shown in the following formula.

W ks(2a)3 (cosço- sinço) 3 (s

k: Const. 2a: Wave height. s: Specific gravity of stone. tâne= height/length of base. For instance, in the case of natural stone, if s = 2.2, coefficient k = 1.5 (in the case of artifical square stones, , it is 1.9), gradient of slope 17.3% of 300 and height of waves used in the plan 2a = 2m, •• • • 55

1.5 x 2.2 x 2 3 L — 310k (cos- sin g,) 3 (2.2 - 1) .1 g When 2a = 1.5m, stones of about 100kg are required. In the Aichi Prefecture case, as the desigm.WaVe height is 2m, the weight of stones is determined to be 300 to 500kg each. The stones which are thrown in actually becOme as though they were cemented to each other by shellfish such as oysters, etc. sticking to them. Therefore, it is thought that slightly smaller stones may be used, as those stones are not isolated from one another.

4) Piles to be Used in Pile Rows. Although foundation piles of centrifugal force concrete have been used so'far, this.kindlof pile is designed and manufactured in order to safely transfer the vertical load to the ground. In other words, the pile cross section properties such as shape, quality and dimensions, etc. are determined according to the vertical load. On the contrary the piles used in shallow sea construction, especially in breakwater fences,only receive the force due to waves, which is a horizontal load. From this point of view, the dynamic horizontal:. force of the waves acting on the piles operatesrepetitively, and tensile or compressive stresses are generated inside the pile cross section, so that piles which have a bending moment to stand this should be used. 56

The bending moment is determined according to the wave pressure which is generated in the piles. There are formulas for calculating the wave pressure which is generated by the wave height and the depth of water respectively, but in the case of this construction work, it was determined as follows. As the pile bases are held rigidly up to the + Om sea depth by the stone lumps of the concealed bank, in the case of the Ise Mikawa Bay, the water depth of the piles is only 2m even at the time of high tide. Therefore, considering the wave height at the top surface of the concealed bank as 1.5m, the allowable bending moment of the piles was limited to 2.5 x 10 5 kg/cm. Moreover, as is described in the separate section (Effect), it is .possible that this fence will become a large fish nest and become an angling ground, and when many fishing boats up to one ton operate there, they may hit the fence, and soit was preferred that the bending moment be above 3.0 ton/m, if possible. When piles are chosen, the bending moment can be calculated for each respective factor (cross sectional 2nd order moment, cross section factor, etc.) in the table of the efficiency of pile cross section designs. In the marketed designs of foundation piles, there are.three kinds of bending and fracture tests which may be used for this construction • work, which are reprinted here for your reference.

BEGINNING OF QUOTAÏION

”Concerning the Cracking and Breaking Tests of Foundation Piles Made of Centrifugal Force Reinforced Concrete in Which the Steels Used Are of Different Types

I Piles Provided for Comparative Testing e6 steel wire, e9 and e3 mild steel bar are used, three 10m - 300m/m piles being manufactured from each and tested. Details of each pile are as follows:

10-300 (A) 10-300 (B) 10-300 (C)

0 - 0

r0 15cm, ra 9cm rc =15cm, r1 =9cm r0 =15cm, ri -9cm • r=12. 5cm, t -6cm rc =dr.cm, t=-6cm ' r =12cm, t =Ccm

, :..:k n e,6-24*=, 6. 782cm' ,e,:k U.; 09 - 14*. = 8. 907cm 2 °ikl gi; 013-7*=9. 289cm2 ange...m• • . g yp-5, 700kg/cm2 oyp.---2, 800kg/cm2 ay/J- 2, 800kg/cm2 0,:eiee-u, a 0 fe Mir :iPAi le as. .---2, 850kg/cm2 esc =1,.400kg/cm 2 asa =1, 400kg/cmz aYe9-Inmede yeQ-fnmutue e.yv-inimtia - . 0 0 =450kg/cml o0 -.450kg/cm2 • a, =450kg/cm2 e3à1112 c a .—.175kg/cm . a04 -175kdcme 2 occ =175kg/cm*

1 ç46 steel - 24 strands. 2 e9 steel - 14 bars. 3 e3 steel - 7 bars. 4 steel yield point strength per unit area. 5 . steel allowable strength per unit area. 6 concrete breaking strength per unit area. 7 concrete allowable strength per unit area.

410 II Method of Test With regat.d to the bending test, since breaking is not

an object of the normal method provided for in Japanese Institute of Standards (JIS) 3510, a method as shown in the Figure below was taken and a pure bending moment was increased until the piles were broken.

2opon,fi,- '7 5O cm-

• &I 4 e#74 1

III Results of Test These are shown in the following Table. Cracking and breaking strengths per, unit area (mean of three values for each type of pile)

'n :ITC 50 100 150 200 250 200 350 400 450 500 29 0 Kkg) 0 in 3!1 e ..:-.)-- ,Q,1,- .,, >' I. 375 750 1,125 1,500 1,875 2,250 2,625-- 3,000 I, 3,37D- 3,750 .„1',1.1...- -N ,I y 1 M(kg/m) I P "g) M(kg,'411) — - - - — --- ------1 -6—A- 0.03 0.05 0.12 0.18 1(0.20) (0.27) *T-Y.j (9(4n)rn I 003 6,025 B # 0,03 0.05 0.10 (°37) (1 00) ir 0.16 1 • 147 3,175 C i • 0.025 0.06 0.09 0.16 (0.20) 0.30) 560 1,200 ... 1 .1( - -0 •

1 Types. 2 Load. 3 Maximum moment. 4 Breaking. 5 Mean of three. 6 Maximum cracks.

IV Comparison with the Bending Moment Generated by the Bending Test of JIS. In the JIS'test, when 95% of the pile length (except the shoe) is supported as a cross beam; if the cracking for the bending moment Mo produced . in the mid-point of the pile

by the self weight, is within the allowable cracking (0.2mm), it is satisfactory. The following is a comparison of the design cross sectional moment of inertia and the breaking moment

with the above-mentioned Mo . a) Comparison of Mo with the Moment of Inertia Used in Design Calculations.

a) ‘t-J- z) Mo ii.ii- iiii Je; IA J IS—DM 0 0 I P a it I- ' k g/scam2 kg/ acin2 ea cm Mi/N10 ?el. . 0 (kg/cm) (kg/cm) 10-300 2 850 175 12. 5 0. 01501 1. 04285 15, 700 1,609 1,250 L 29 (A) ' 10-300 1, 400 /r 12 0.019682 1. 1025 17, 670 947 * 0.76 ( B) 10-300 (c) " .• 12 0.020533 1.1141 18,285 987 . 0.79

1 Name. 2 Cross sectional moment of inertia. 3 JIS test moment. 4 Safety factor.

Although in the above Table the values of Ms /Mo for 10-300(B), 10-300(C) are less than 1, there is a safety factor

in esa and moreover according to the JIS regulation it is acceptable even if esa is increased by up to 50%, so that M /M <1 s o is acceptable. (At present it is usual in every company to use a value

of osa increased by 30% in production designs.)

••

h) Comparison of M with Actual Breaking o Moment.

b) 5C,ifea• — )tx FizA- - te.) M, oitu

0 , mo ken 'sip. qqm„im. NI„ kg/m 10-300(A) la'/:11.â 6, 025 1, 250 4.82

10-300 (B) #' 3,475 , 2.78

10-300(C) # 4,200 . 3.35

I Name. 2 Breaking moment. 3 JIS test. 4 Safety factor. 5 Remarks. 6 Average.

0 Consideration of Test Data Examining the test data, the required bending moment

of 3 ton/m can easily be obtained within the range of

allowable cracking (0.2mm) regulated by JIS, by selecting

piles or by increasing the quantity of steel. And regarding 30 the breaking moment, 4 — 6 ton/m can possibly be expected." END OF QUOTATION Pile Driving: The pile driving depth is required to be deep enough to withstand the force of the waves and the load of floating objects and accumulated material. As the concealed bank of a break water fence is to be constructed from the sea

bottom up to the height + Om, the pile driving depth is effectively more secure by this fence length than just the depth that the piles are driven into the ground. Some of the • lumps of stone used for the concealed bank are buried in the 61 ground and,they contribute to strengthening the ground surface. In the following Figure, Cri is the supporting power of the ground. In normal shallow sea beds, it is expected to be 10 - 25 tons (1.0 - 2.5kg/cm) per m2 . When a horizontal force E acts from one direction on the inserted pile, (1) The balance of the ground supporting power and this force is, referring to the Diagram:

E ore h ajh 2 2. (2) from the balance of moments acting on the pile:

E(H + h) = ( arh2 x (gyl x _l_h) —r-h) 3 from (1), (2) 1 - (6E(H h) 2- h h

7777

When total pile length (H + h) = 6(m), the inserted length = 2m, E = 2tons, then WI = 19tons, Crz = 17 tons are required. This much ground supporting power is not always available, but since the concealed batik strengthens the ground like a pile foundation stone, this amount of power is thought to be gained. In the Tokonameri District, the pile driving depth was the minimum, this insertion depth being 2m in the design, but since there is a hard clay layer underneath the • 62 ground, this depth may be satisfactory.

5) Putting the Construction Work into Operation

(1) Selecting the Area Although selections are made for sea areas where the wind and waves are violent, it is necessary to consider the efficiency of investment when making a selection. First of all, from the topographical point of view, the following two cases are considered.

1. The Case of a Coastline Lying North - South (Example: Even if the fences are constructed Tokonameri, Noma) in various lengths, their direction as a whole is almost parallel • to the coastline. Consequently, the break water fence fishing ground is the area enclosed by the fence and the coastline, and its size is determined by the distance from the coast to the slope of the continental shelf. In other words, for the

same length of fence, the size of fishing ground varies with 31 the distance from the shore, and the construction expenditure

per unit area vary. In the case of Tokonameri, as is described in the section headed 'Effect', the fence length

was 3,760m, construction work expenditure was . Y46,261,000, 2 the area of fishing ground is 1,100,000m although this includes the former 'ground, and the construction expenditure 2 per unit area becomes Y42. per m . Consequently, Y4,500 -

5,000 per horizontal laver hibi was spent. There is no question about the investment efficiency because of the great increase in production, however the construction expenditure , • 63 per hibi was too high for the work to be undertaken without aid from the Government and Prefecture. In this sense, as is mentioned above, when the area is to be selected, it is thought to be essential to investigate how far from the shore the fence is to be built and then to estimate the efficiency of. investment. 2. Region of Coastline Which Extends East - West (Example: Atsumi District) — As the wind and waves of concern here are incident from the north - west, it is advantageous to establish the break water fence as a whole in a direction which is almost perpendicular to the coastline, and to use it partly . for water guiding. In this case, the length of the fence becomes • the distance from the coastline to the slope of the continental shelf, and the area of fishing ground constructed should be the almost triangular shape enclosed by the extension lines of the fence and the incident direction. As the incident direction which causes a great deal of damage is near the west slightly inclining to the north, this triangular shape can be presumed to be extremely large. However, in the case of Atsumi District, the distance between two fences was made 800m as is shown in the Figures, after considering the water guiding due to the incident waves which corne from the maximum wind direction (north-west). (2) Examples of Work Carried Out • 1. Example of Tokonameri - Noma in Chita District (1) Plan of Work (Actual Results) •• 64-

(i) Purpose of Work: Although the value of this area as a fishing ground has been estimated to be high, an area which it is possible to use as a fishing ground has been largely left alone because of strong wind and waves. By establishing' break water fences in this place, a fishing ground was constructed for the neighbouring boat fishermen, who changed to laver cultivating. • (ii) Summary of Work: As construction work in this area, at a distance of 300 - 700m from the shore, concrete piles (e0.3m, L 7.0 - 7.5m) were driven in at a 2m Spacing, 200 - 500kg of riprap was thrown in to strengthen the ground, and concrete blocks (lm x lm x lm) were established on the riprap. The 32 volume of work was 580m. The operation of the work was based upon the Aichi Prefecture Construction Work Operation Regulations.

gflumaemie weinima_guma

1=1 e 01Mawpi°-

Breakwater fence in the Superstructure of the concealed Noma area. bank in the Noma area. (established parallel to (Stone lump piles are beneath protected coast). the blocks.) 65 2 (iii) Effect of Work: Area constructed 75,400m , number of horizontal hibis used among three fishing grounds engaged 1,314, South Chita area had 496 hibis (37 people). As for the effect of production 1,500 sheets harvested per hibi, unit cost Y8, production revenue Y12,000. Therefore the income Y12,000 x 496 hibis = Y5,952,000 can be expected. (iv) Administration of the Facilities: As per the AdminiStrative Regulations in separate sheets. (2) Details of Plan (i) Explanation of Plan vuutme

:t a ri (?, 9 iffeur,qui Mif...y.cui.r.i;;I, -9i IQ ecuaenicireue: !1;,11,3/ 1-2 1 0 FilJ 600m I')e n I 22, 500, 000 1)G (1--) w:s;21137):::eur»..9euril 0 -'-' iz- 9 — I 300-700m ED .: 4 A, L7m e0. 3m ea: 2m tiiir412■_.7.>)Miz:nriar6j),Vii-ta, 1 :5 0 a e IN.i0)0,1i.-.:= 9 — b Yur „ y (1. om xi. orn xi. om) ed ef.f1 J 600m ,1'. ;:iiiritc, r■ 4 MIIIV■, ez, i'MIT1f-RhIfil -M.2 -cllejtÀ-)etir_. .t .

) 1A rt 7.1 4.- M et

>lià fi. Jill PM Cqiie138 ee 613 1.12ffir.211M38er- 8J) 31 a -c . Ç'I il A. .f,1;. e. eer.là:UWAReiefillii.-se.... ' j a ar e .1 Màleuntaiww_sfAi/.., ma ,iiii:fe-_.-1. CD

1 Type of work. 2 Construction work of laver fishing ground. 3 Place where l'aork is being done. L. Noms area, Mihama Town, Chita District. 5 Amount of work and expenditure. 6 Amount of work. 7 Fence length. 8 Expenditure. 9 Yen.

10 Summary of work. 11 At a distance of 300-700m from the shore of Mihama Town area in Chita District, concrete piles L7m, vf0.3m are driven in at 2m intervals and riprap is used in the foundation for hardening the ground, and concrete blocks (1.0m x 1.0m x 1.0m) are fitted on the top surface of the riprap, so that the break water fence is extended by 600m. The operations of pile purchase, driving and riprap construction work are to be done by public tender. 12 Method of operation. 13 Contract. 14 Period of operation. 15 June 1, 1963 to August 31, 1963. 16 Name of central administrating body. 17 The Federation of the Aichi Prefecture Fishery Co-operative Associations. 18 Name of designer 19 Secretary of the Federation of the Aichï Prefecture . Fishery Co-operative Associations: Yukizo Nakayama. 20 Remarks.

(ii) Itemized Expenditure

(11)i,Y1 !Pt 1)î _ D II. P. tc.t 1 'fi ri :ez Ji t II t fk 3It tri ez .,'m I 0 m-mmimme 22, 500, 000 ■,„2/ -f;v1Afia.■ ,- - , 302CI-2z 3,621, 000 371 16, 224 600, 288 `-li -f A4T3_21.`a . i. n76. a .1 n 7,3S1 1,880 13,876,280 0 Y1 eil 3: Y2 2, 029, 096 . 0 :h. Jig 302'-' 5,528 I, 669, 456 ' el eg , 15 M 16,224 243,360

,., 342 n4 2 340 116,280 a-FelfeJl.,

remmun8 • 1, 121, 437 • 41 e 101, 899 l'.'i? 18.777.10 X 1.21S rWi I Om n n I, 150, 000 U'i: 16.505,664 x 19.5%

22,500,000 0 ill.

1 Type of work or item of expenditure. 2 Number. 3 Unit. 4 Unit cost. 6,7

5 Amount of expenditure. 6 Remarks. 7 Construction expenditure of breakwater fence. 8 Expenditure of manufacturing concrete piles. 9 Construction expenditure of pile driving. ' 10 Construction expenditure of hardening the foundation with riprap. 11 Construction expenditure of artifical square stones. 12 Manufacturing the stones. 13 .Fitting the stones. 14 Leveling the bottom surface. 15 Hiring of boats, machines and tools. 16 Building and repairing expenses. 17 Uther expenses. 18 Total.

- 19 Piles. • 20 Days. 21 Stones. 22 'Within the construction expenditure 18,777 x 1.2%. 23 Within this construction expenditure 16,505,664 x 19.5%

srlif

Figure 8. Breakwater fence in the . Noma area. I Undertaken in the year 1962, 1,198m. • 2 Undertaken in the year 1963, 580m.

0 e'tt?ile 1.-.4... , mi 9./1/1.4. Wei .p. zed .1.. dy.& p..dej. .D. 3 3o10.• //, 1 p• • I". »... p..1.1, At 9./.11e i fr...... t. ,"...l. )4 .- 't7i .11 • • 11 li 4't ilri... ,. ‘11 • 1 .s , -1.,, . i -.,.1,<'e,...,ig. ,evik.1,,,.. ,. ,msi : • . ,- ,..e-,,,,,,,..., ,, i- ,...t.4,..r.,i,., ,,‘ ,., t,-(..:: ,',.,>;...,. ,•...<-4-,, , ....,,,, .,i,- , -r-- j u

.,..1,..,,Axtvtir•O A,* eie". 1.-. lie A,.a.:1-=‘, le.. e/.` A.. , ...t(..i. Ire Ai - .1,-1-,te.i go 4De ,,,•el=m-1•0/le A p. te.,.2-= W1-I I &bee' .

p.jIJ NcD4301., ,4'•/• DI* Au it O. hp I e, 0•11/ fx• P•12,1"' koA D. let l`l'I"N r., s J- I Itas & v. • .44• 31eLL., A.V.t.fteo, nre.:.,-/-ushistoo dieelitLx+1, ,we w . ■Sr7s3r 7,' .L.• =LC'_..1‘.,4 3 ' 04. 0-, ./...l• 673'W ..i.iii,7- i,.1..hilaitt„, .43,._.:13-U-r7.=„ 1, f" C) 31 1 . - hi4/-1,1„ r L,In1 3"3,1* —2 -" 4 — • I. .11 tei..1 ■ i-Œ111. 'r-- , tn, e so ' ,1(.1.,,,,I_L 2).f le »à±-7*-_ ,I. t -1,3,1,.d.st!. t31 ..t.J.,(,,w,,,,1 deri:11-.. ,b, tnt,2,12_ e!.(e..9114.no.7.1k I I:dt i*.e.,?!Illi..11.,g r- 212 • IL „2„.. u., .1'111 1777 —;), ' LiekbOk ' r ' ' -„-,e-, 101-1. 1. t* at" p V.• l. LL_19 iStf,/..../tyl t.e (7• 7) .1;1/4. II 20

01 ttg 9 1 . . . 7 -....11,,Jouilikir.,:-..7.7..V3Iiii..3, ••• Ira il,,,,•,p.11 i • 33. , •.aule ,ij , • 11 km. • :2 •...../up.....,1,1, ,. 1,1. .0.22.11 Mel, ) )1 I:" r. îe 9 21 5;1111.11bCiMnife

Figure 9. Breakwater fence in the Noma area

1 Cross section. 2 Mark, Distance, Cumulated distance, Height of ground. 3 Height of'ground. 4 Distance, Amount of stone. 5 Calculation table of amount of stone. 6 Detailed diagrams of concrete block. 7 Concrete composition ratio - 1:3:6. 8 Calculation of materials. 9 Concrete. 10 Mould. 11 Steel. 12 Volume of pile within stone. 13 Sub total. • 14 Amount of stone necessary. 69

(

Mum.. ekapiiliter ti'‘' /....„

' .:::: 1.... ,,,; ht.,.

1: etco je • -‘,... t,te

s 1 ■ % 1 \

• :-,4-0- 4egd:- . , , fià\ he*

e Zen "' •

El e 11 .1 4 gfs 10 1 ismu) 9 ezwebitizemi

Figure 10. The location of laver breakwater-fences in the Atsumi area. 1 Shore north. 2 Due north. 3 Undertaken in the year 1962. 4 Undertaken in the year 1963. 5 Area 132. 6 Area 131. 7 Kai ga Hama. 8 Base point. Hokumen-Nankira, Ii-Shinden, Nr. Isuzu, Atsumi Town, Atsumi District. 9 Base point. Hokkaku-Mae area, Ii-Shinden, Nr. Isuzu, Atsumi Town, Atsumi District. 10 Aoyama Shinden. 11 Atsumi Town. • 12 Isuzu. 0 es 1.

lb/ 0.1«. d0 3 1, 1à1à1.- 1P/téi-g evitsis, ed.à0s

01J Lai • •• wir,,,Ct" 1,44 - , ; Ji A,,,I=1-1 44 AP' IL.ii2V Wt. ,. ne A e.

■ 0 Y. / "?' e 1411

es Lay. L it • -à • 10 Ltz 011 _Lit e• /*o.e. ;fit *.14 kale - . o 0 2 t I) 2 ID 5-7 • k ± Oratlf 0

e") ffl 2 IJ 1Î1ÎM

/11 17...o./••• floi -1) ./•.•P' »4. PviP./e- fit

• . 1 le t-,41,t"Z'k " JcsAzetwe,-,r7 er;e.e e ' t . lt.11 q,• Leix.1.7f./.›.SPek ef. •al,io,..1 A4. 1 exi.17•JLILI Ai • i'li'u(?&I> ...v.*

. -1 trpc.9111 2S-q 2{,-C.r.t14 xe, -A 1 Vi - • p .---• r.1- >"- e o. L2 à 1" "...Hit tl êti e• /. ) Lise / te .., ,oi sy • n, i-d,ie Li U• 4 f. ,e- --- à 4. I.L.t.P th àle .•-• 1té 18. • 1> ..... à.I3• 0 '' • -L.)b • a te * J . i • c> J - t b.à 6. S . . 0 7, kulitv.- e i C3*'2.a ig 11 [21 1113îi1 30 &V-E9:i11119e.P.Mielaiî

Figure • 11. Breakwater fences in the Atsurili area in 1955. 71 • I Cross Sections for the First Construction Work. 2 The first construction work, Height of ground. 3 Distance from shore, Mark, Distance of riprap top surface, Cumulated distance, Height of ground. 4 The first construction work, Calculation table of amount of stone. 5 Distance, Amount of stone. 6 Volume of pile within stone. 7 Sub total. 8 Amount of stone necessary. • 9 Cross Sections for the Second Construction Work. 10 The second construction work, Height of .ground. 11 The second construction work, Calculation table of amount stone. 12 Total amount of stone necessary. 13 The first construction work. 14 The second construction work. •

Above: Breakwater fence in the Atsumi Town • area. (It is posi- tioned almost perpendicular to the coastline.) Below: Partial view of the same fence as above. (One pile in 5 is taller than the others.)

T H_Ete5Y-ri-1" (i: 4 /I, s R•à)

Floating laver culture in the •sam e. constructed fishing • ground as above.

./ 72

2. Example of the Atsumi Town Area in Atsumi District. •

(1) Plan of Work. (i) Purpose of Work: Although the fishing grounds in Fukue Bay have been utilized mainly for green laver for many -

years, the quality had deteriorated remarkably in recent . years due to a shortage of nutrient salts, worse sea conditions, etc. Accordingly, the income of fishery households is very low. Because of this, as one of the improvements of production structure and the improvements of the coastal fishery structure, 39 the latter being a countermeasure for the modernization Of administration, laver fishing ground construction work is

being put. into practice,and the construction of new fishing grounds is intended to raise the productivity and increase the income of fishery households. In accordance with this,

fishing grounds are being constructed in order to change the , boat fishermen's occupation so that the people are able to

begin to work again. • (ii) Summary of Work: As construction work in this area,

a 2,500:11 breakwater fence (concrete piles L7 - 9m, $'0.3m driven •

in at 2m spacing, 300 - 500kg riprap) is to be established.

In the year 1962, a 526m breakwater fence was established,

and this year without interruption a 600m fence, construction

work expenditure '24,600,000, is to be built in the Isuzu area. The operation of this construction work is based on the • Aichi Prefecture Construction Work Operation Regulations. 73 • (iii) Effect of Work: Total area constructed 2,000,000m 2 , 2 120m per hibi, so that about 9,000 hibis will available for

working, 6,000 hibis in the increased fishing ground in the

ares (40 hibis per household, 150 households), 3,500 hibis for freshly engaged workers (administration by co-operative

work, two groups of the Himaga Higashi, Nishi Fishery

Co-operative Association and the Shinojima Fishery Co-operative Association). This year it is possible to install about 2 2 2,400 hibis in 480,000m (120m per hibi.). As for the effect

of production, an inCome of about Y66,500,000 (1,000sheets

X @Y7 = Y7,000) is expected. (iv) Administration of Facilities: Administrative Regulations are to be established separately. (v) Details of Work:

Q I - _ .11-•:'.',U110 112J.K1: «''' :'+''£ 11 f.'z renAl.), .2.-7.-.m-pu -1f-...m.i-t lit/Jai F9 )jr.rn pi 2 , ; 9 ie5ii nt2) 12011) 556m 44, 245 24, 600, 000

i,rillii.k:i: 52 '.Z4 C) e s:' In 5) ii.1:fi-. - (3 fr) G F/ D,G)I v_ 1,3 Ili ',fete .' II al:1411 on 2J'.14110.5 t Pi I 0 i'j I iiVii*,11Zrei f'l 24, 600, 000 0 - 20, 500, 0001 d 4, 100, 0001 3, 236, 000 F.-i'i 0 fi I

1 Type of work. 2 Construction work of laver fishing ground. 3 Name of place. 4 Central operating body. 5 The Federation of the Aichi Prefecture Fishery Co-operative Associations. 6 Central administrating body. 7 As left. 8 Number of households which are to receive profit. 9 120 households. 10 Amount of work. 11 Unit cost, Yen. 12 Expenditure of work. 13 Monetary assistance.

74 14 Other than assistance. ' 15 Classification of work alloted. 16 Prefecture expense. 17 City, town and village expense. 18 hxpense borne by association. 19 Amount of association expense financed by the Agriculture and Forestry Finance Corporation. 20 Method of operation. 21 Contract.

(2) Details of Plan (i) Explanation of Plan

).D.' eq1J'ai: r;i. D e 9 leP;;'e Mf:iee:,,,e..tiai rpio.)::nifil:YesoliiiiiticÉ ja IF,],,,- 550m Pa 5,,,2 I 2,1, 600, 000FICI DiFily2pil{j} 1) - 1, A 4 )t. (1.5, 5-10m {,0. 3m) C) )liill.J111.k.lz: 2m Illi l'i;ji k- 41- 3,7- . ji- 21 tezeaitim ,:ciiic- t, PiaeiiiifelkL1.14 I. 550m ■11,1z: 1: Z›. A 4 MI:4A» . eriA, J'.!)7(711.?1;ititdifi- nol:2`t eqt7 De. fi. 5 e 0 3) D e ir.i• JUJ RI] 0 Il 38 4r. 7 A 15 Lib, 1131-41 38 !■ f- 9 A 30 ri ..-e D 'a 3111 =1:1 ei cl.e.r,Vil.:(Ltleil 11n.;.11./r.. Di-...r.l. .: I- ,Y.i- e. ' PY.b.mutit teiein-Aee... Vlii, r11 III e =----' e

1 Type of work. • 2 Construction work of laver fishing ground. 3 Place where work is being done. 4 Isuzu area, Atsumi Town, Atsumi District. 5 Amount of work and expenditure. 6 Amount of work. 7 Fence length. 8 Expenditure. 9 Yen. 10 Summary of work. 11 In the Isuzu area, Atsumi Town, concrete piles (L5.5 - 10m, çg0.3m) are driven in at 2m intervals, and riprap is used in the foundation for hardening the ground, so that the breakwater fence is extended by 550m. The operations of pile purchase, driving and riprap construction work are all to be done by public tender. 12 Method of operation. 13 Contract. 14 Period of operation. 15 July 15, 1963 to September 30, 1963. 75

16 Name of central administrating body. 17 The Federation of the Aichi Prefecture Fishery Co-operative Associations. J. Name of designer 19. Secretary of the Federation of the Aichi Prefecture Fishery Co-operative Associations: Yukizo Nakayama. 20 Remarks.

(ii) Itemized Expenditure

1Â j:Ij

(g)

) IT- Uj:- k i , n n :U f;I: 1 iitik 11 elri muuinlm 0 111 (LIM

-o 277 .),: 3,292,500

35 liret H 16,224 567,840

e "Li a W 2, 10, 214 ni3 1,850 18, 951, 400

0 .•.U:';IU-Ufii:1 714,84o D ;i- i: J11 9e1 107, 120 21,099, 825 x 12% .1.UVi a ,A, , Q3 i;fl =5. n ,,-r. 066 ' "' l'9, 518, 685x20% JUM e

(3 ) gt. 24, 600, 000 ,

1 Type of work or item of expenditure. 2 Number. 3 Unit. 4 Unit cost. 5 Amount of Expenditure. 6 Remarks. • 7 Construction expenditure of breakwater fence. 8 Expenditure of manufacturing concrete • 9 Construction expenditure of concrete pile driving. 10 Construction expenditure of hardening the foundation with riprap. 11 Hiring of machines and tools. 12 Building and repairing expenses. 13 Other expenses. • 14 Total. 15 Piles. 16 Days. 17 Yen. 18 Within • 1,099,825 x 12%. • 19 Within this construction work expenditure 19,518,685 x 20%. 76

6) Effect of Work The following example of the ïokonameri Fishery Co-operative Association is quoted to show the effect of work. (1) Details of Work At a distance of 400 - 800m from the coast, concrete piles•(length 6-6.5m, diameter 0.3m) are driven in at 1.5 - 2.0m center to center'spacing, almost parallel with the coastline over a 3,760m length. The foundation is strengthened by 200 - 300kg of granite stone riprap. (2) Method and Effect of Work The construction work is to be undertaken by contract. The work is divided into three, purchàse of concrete piles, concrete pile driving, strengthening the foundation with riprap, and each of these were contracted by nominated public tender

- to the manufacturer or builder concerned. . In Tokonameri, the laver fishing ground construction. work was conducted from the fiscal year 1957 to 1960.(until the ena of March, 1961), and how was the effect of work? If shown, it is as follows:

Laver Production by the Construction of Fishing Grounds. 41

iteZerc ÈÉ.n 0 '..1i. (D :1-1: 0 et, 211: â. 5z: r,--.Ù 'd.(1. ,,-.,lit.‘z. ,...... .4--, • e, d: • A A -P. tirt tFr e Tt e 2 * 2 El e ii e . fil .)■ A 4 NO 0 0 l'eilea: i. rt., lim ri.,2 e o 3, 760m 1-1.e" 0' 30m 6m 46, 261''-' ' 39 124 1, 100, ---,36 000 neTn3r2e3 117)J,%135, eç. 8054t,'. MRZ./.. • n K )iii _r• U el: e mi -a 73 400, 000? 1Z324:la flail-1324m • Z 950 1, 717, 9004 77

1 Central operating body. 2 ïokonameri Fishery Co-operative Association. 3 As above. 4 Quantity of work. 5 Standards used. 6 Pile e.30m, 1-1.6m spacing. 7 Expenditure of work. 8 1000 yens. 9 Period Of establishment. 10 1957 to 1961. 11 Prior to carrying out the work. 12 Number of households which are to receive profit. 13 Area of fishing ground. 14 Number of hibis fitted. 15 The year 1960. 16 The year 1957. 17 Sheets. 18 Production volume.

The first breakwater fence construction work in Tokonameri seen from the offshore side. 1 111 1; ;‘ 1 I I 11 sli ■ ••; ".• ,

eenumm1Jrimeteeemfficto

Firstly, the area of fishing ground enlarged is almost three times, as is shown in the Table. A ?though enlarging the fishing ground area has been done gradually since 1955, before this i certain fishing grounds such as parts of No.1 and No.2 fishing grounds and No.3 fishing ground, and also the spore catching grounds of Honjo, Gakkomae, and Jinjamae were used recklessly as laver fishing grounds. Since around 1955 (this year the Tokonameri and Nisfritea Fishery Co-operative 78

Associations were merged), the laver fishing ground has been expanded gradually, and during this process the establish-

ing of breakwater fences was begun in 1957.

fa 12 9 Figure 12. Laver fishing grounds in the Tokonameri area. 1 Tokonameri Harbour. 2 Office of the Fishery Co-op. Assoc. 3 Breakwater fence. 4 Taruki River. 5 Laver spore catching ground. o No.1 7 No.2 8 No.3 9 Research laboratory. 10 School. 11 Honjo. • 12 Karasaki River. 13 Kojo. 14 Sakai River. 15 Kariya Fishery Co-op, Assoc. 16 Border of common fishing grounds, Distance from the shore 2,000m. 79

Secondly, establishment of the.breakwater fences was • useful in preventing laver nets from being washed away. When laver becomes attached to the laver brushwood or laver nets, their resistance to water currents increases, and • formerly often 50 or 60% of the laver hibis were washed away due to the geographical condition in which wind and waves are strong towards the open sea. Due to the establishment of breakwater fences, very few bibis inside the fences have been • washed away, and although in 1958 some fishing grounds were out of range of the breakwater fences and lost about 60% of their bibis, it is said that the loss was about 10 to 20% as a whole. It is considered that this was useful for stabilizing the administration of the laver culture households and for their business development. Thirdly, the breakwater fences raised the quality of the fishing grounds. As is described in the explanatory documents of the Fishery Co-operative Association, strong . tide currents were produced along the inner side of the breakwater, fences, and these helped the flow of sea water and so made the laver quality better. Fourthly, the breakwater fences, especially the riprap for strengthening the foundation, acted as a fish nesting area. It is said that at present a Considerable number 42 of . shrimps and other fish are clustering to the breakwater fences. Originally, fish catching was conducted in a free • villages or allowed fishing ground, and the fishermen from other 80

mainly were fishing in the area where the fences were to be built, and so there was strong opposition to establishing fences mainly from the fishermen of other villages. However, fishing has now emerged which on the contrary makes good use of the fences, and the fences are said to be useful for even those fishermen. It is said that the fishermen near the Shisaki Point (the point of Chita Peninsula) take about 400 kg of Zui, Mugil japonicus, black porgy, etc. (worth Y60,000), by the method of surrounding a fence with_gill nets such as roundhaul nets and tapping the inside of the fence with bamboo poles. It is said that even if this fishing method is continued every other day, a considerable catch of fish is maintained. In any case, the effect of the breakwater fences must be judged by the increase in laver production. As is shown in the Table, the production of laver was indeed increased about seven times. The number of fishery households for this period is as described, and therefore in 1955 the Production per household was 21,700 sheets and this number increased rapidly to 104,000 sheets in 1960. Also a considerably increased number of round clams were caught'during this period. In view of this, it is said that•the laver fishing grounds are acting as a protection for the breeding places of round clams. A certain portion of the laver harvest increase stated above might have been possible without the • breakwater fences. But under such conditions as the economic 81

pressure caused by the washing away of more than half of the laver hibis, and moreover, the instability of production, and that the fishing area was very limited due to wind and waves, the laver production increase would have been extremely limited. Thus the number of laver culture households would not have increased so much. In this sense, the establishment of the breakwater fences should be thought of as providing an important opportunity for the fishermen in Tokonameri to advance to the laver industry, and for establishing the administration of laver fishery households. This is proved by the facts of the increase in the number of laver culture fishery households since 1957 and the rapidly increased laver production both ' as a total amount and as a mean amount per household. However, the breakwater fences which produced such effects were not established without difficulty, especially at the time of the initial organization. First there was the difficulty of reallocating fishing grounds, and secondly the difficulty in raising the amount of the cost which had to be borne by the local inhabitants. Concerning such matters,you are advised to refer to the following book: 'Economical Aspects of Shallow Sea Fishing', published in 1959 by the Fisheries Research Association, Agriculture, Forestry, and Fishery Financial Corporation. • 8 2

5 Offshore Culture Conserving Facilities

In the fiscal year 1962, as one of the undertakings ' for coastal fishery structure improvement, offshore culture conserving facilities were established in the area of the Kinugasaki Fishery Co-operative Association, Chita District, Aichi Prefecture. By establishing these means of support for the laver culture at the further-most offshore part in this district, where wind and waves are violent, they are intended to preserve the culture facilities and to enlarge the fishing crround. 1) Location Established and Structure The facilities were constructed in six places as is shown in Figure 14, in the area of Onigasaki Point on the west coast of the Chita Peninsula. The structure is as shown in the plan view and cross section of Figure 13, piles being driven in at intervals of 12m parallel to the coastline in each place, and three rows of piles spaced 20m apart were established parallel to the coast. In each 12m x 20m rectan- gular area between two pairs of piles in adjacent rows, ten laver nets specially strengthened against the waves were mounted accOrding to the water surface wafting method by means of ropes using the piles for points of support. With three rows of supporting poles, two rows of laver net facilities can be mounted on the offshore side. The reasoning is that by doing thus, the breakage and • 83 damage of normal laver culture facilities (laver hibis) which,

are inside the row can be prevented.

12.$ o

2COX

(ID 951;e2 ,6.r

24.pm

("D 9 9 L. 1,,,g M 13 IZ 01 US 13 M 02

Figure 13. No. 1. Figure 13 No. 2.' 1 Offshore side of fishing ground. 2 Direction of pile continuation on the offshore side. 3 Direction of pile continuation on the coast side. 4 Offshore side-of fishing ground. • 5 Coast side. 6 M.1, surface and temporary name. 7 For this distance N — 3.

As the conserving facilities are situated on the slope of the continental shelf, the incident waves are forced break there and the large force of the breaking waves falls on the laver nets of the facilities. Since this force is opposed by the frictional resistance between the breaking waves and the fixed nets and by the weight of the floating nets (the nets float on the water surface by means of floats), the wave force is reduced by this amount of resistance. However, all of this force acts through the ropes as a horizontal force on the supporting piles. In fact after constructing the facilities, the wave-damping effect was better than any 84

expectations.

Various structures can be devised for supporting the nets but in this case each pile was established as an independ- ent supporting pole, and the nets were fixed to ropes tied

along the rows. The tensile strength of the nets has a considerable action on the piles in addition to the horizontal wave force. The bending moment which is generated at the foot of

the pile due to the total horizontal force is very large. 44 And the location of the facilities is comparatively deep, the depth of water being -3.0 to -5.0m, and the point at which the

horizontal net-supporting force is acting becomes +1.0 to +1.5m, therefore the length from the foot of the pile to the point of action extends to 5.0m. For this situation, as the bending moment required is very large, steel pipes were specially used. In order to examine the strength of steel pipe piles for horizontal forces, a comparison was made between the data'

concerning the piles to be actually used (made by the Yahata Steel Pipe Company Limited) and the bending strength of centrifugal force concrete stated previously, and the results are as follows:

Concerning the steel pipe, the allowable bending

moment which is generated in the pile by a

static horizontal force'P was obtained for the condition of the bottom of the pipe being • fixed, aS is shown in the figure left. The allowable stress . calcuia-tect fràin the value of 8 )

g14 M' iti F.11 Figure 14. Work of establishing the offshore culture conserving facilities. (in the Taya, Kamaike, Nishi-no-Kuchi areas, Tokonameri City,). 1 204m, 54 piles. 2 120m, 33 nues. 3 300m, 78•piles. 4 456m 117 piles. 5 216m, 52 piles. 6 516m,'132.piles. 7 Area No.162. 8 Area No , 133. 9 Area No. 132. 10 Taya. 11 Enohe. 12 Kamaike 13 Nishi-no-Kuchi. 14 Amadagawa River.

c 2 the allowable bending moment was made to be 1,600kg/ m according to STK 41 specified by the Steel Tube Structure Calculation Standards. From the above figure,

The bending moment at the foot of the pile: M - P.1 The edge stress of the cross section: amax----11-L•y--P2-

• cI The allowable load: Pa= 1. y

note: length of pile 1- 10. 0m, E, =2. lx10°Icemz

86 • Concerning the concrete piles, the actual measured values from the previously mentioned cracking and breaking tests are given again.

0 4 5 .. - I t (1;g:cm2) 0 =• F Kg/cm kg "(..,rn, eD 216.x8.0 5. S5 x 571nk 427 4. 27 x 10' 9. 10x105 165. 2 x 6. 5 2. 10 x 10' 195 1. 95 x 103 4. 20x

300. 0 x 60. 0 1. 61 x 10' x 24* 6. 01x103 er-,■ 9 • ç9 X147Z 0. 95 x 10' 3. 48x105

çq3 X 7* 0. 90x105 4. 20x105

1 Type of piles. 2 Bending rigidity. 3. Allowable load. 4 Allowable bending moment. 5 Breaking bending moment. Steel pipe piles. 7 Concrete piles. 8 Steel e6 , 24 strands. 9 $9 x 14 bars. 10 " $13 x 7 bars.

From the Table, the resistance of concrete piles to , bending is far less compared with that of the steel pipe piles. As these piles are the means of support of the facilities, damage to the piles becomes damage to the culture facilities, therefore they have to be within the allowable bending moment. From the Table, it is not possible to avoid using steel pipe piles.

2) Putting the Work into Practice

1. The condition of the incident waves.

Wave height: 1.5m, Wave length: 40m, Cycle: 6sec. • 87 2. The ground and pile driving.

Water depth: - 5.5m. Quality of the sea bottom: soft, weak clay layer, 2 bearing pressure about 0.3kg/cm . Considering that the first rigidly firm point would be . at a depth of 1.5 - 2.0m from the . sea bed surface, the pile driving length was made to be 6.0m. 3. Wave pressure and moment. The wave pressure which the piles themselves receive from the waves and the horizontal force which the nets transmit to the piles through ropes are considered separately. The wave pressure which piles receive and the moment caused by this are shown in the following Table.

L=12, 000 0216. 3X8. 0 L12,000 0165. 2x6. 5

T M. L T i.:1(111) ® O. 50 O. 12 0. 70 T-M 0. 08 0. 50 T-M 1. 50 0.06 0.30 0.05 0.30 2. 50 0.04 0.20 0.03 0.15 3. 50 0.03 0.10 0.03 0.10 4. 50 0.03 0.08 0.02 0.05 1. 90 1. 10

1 Depth from the sea surface (m). 2 Load T. 3 Moment exerted at the M.L. surface. 4 Sub total.

The horizontal force transmitted from the nets and 46 ropes to the piles and the bending moment of this horizontal force: The calculation of the tensile stress in a laver net • 8 8 was made to be 40kg, when raw laver equivalent to 1,000 dried

laver sheets is growing on a standard 4shaku x 10ken laver

net, by making the following inference. That is, in the Noma area which is situated in the south of this district where the waves are more violent, laver culture is carried out, but quite a number of laver nets are damaged. The laver net consists of a net body and cord loops which are fixed to the

bamboo piles in order to hold the net. If 45 Kuremona (#20x

15x3) twine is used for the cord loops, they all snap, but

this will not happen if 90 Kuremona cord (1/20x30x3) is used.

The maximum tensile stress of 45 Kuremonas is 38.5kg, and that

of 90 Kuremonas is about 70kg (the cord loops are on both sides, but the breaks occur one by one.). As the sea of this area is calmer than the sea of the Noma area, the tensile strength per laver loop is thought to be sufficient if it is

40kg.

The piles are linked by silver rope (manufactured

product made of polyethylene) of diameter 10cm and maximum

tensile stress 1,350kg, and 20 laver nets are linked between

these acting as wave subduing nets, so that 400kg stress falls on one pile through the ropes. Therefore, the moment which

this horizontal strength exerts at the M.L. surface becomes T-M 7 x 0.4 ----- 2.8 . The moment on the M.L. surface of the large

T ...m outermost piles is the total value of 1.4 and 2.8 which

are mentioned above, thus becoming 4.21

Translator's footnotes: shaku: unit of length. 1 shaku = 30.3cm.

• 89 The following Table concerns the above-mentioned piles.

• L-12, 000 e.216. 3 x S. 0 - L-12, 000 ç165. 2X6. 5 ildMT f'.11):r( T M. L iiiiÎ ,:lkii;-: T M. L. ill] .-Lz,ktl. (m) k •,e — ® /.1\ rd- 1. 40 1. 10 71711c 2. 80 1.00 C) 4. 20 2. 10 e T..M 9. 10 4. 20

1 Depth from the sea surface (m). 2 Load T. 3 Moment exerted at the M.L. surface. 4 Moment from waves, -Sub total. 5 Moment from nets. 6 Grand total. 7 Breaking moment T-M.

Furthermore, from the work plan, the details of the • work are as follows: (1) Plan of Work

ummgte -Lr 0 -d, „-; 19 1 (-2:e.'1:.(.1::...1=1, ir o n2k .51L 511 G 2, 30019 .) 9 e1111111;11 IC) 7, 000e Î,Z.: 60, 000m2 ?:t• !AI 6 **T.)? 1.1011te I 9 wu à e m 112., 220À 'ietirJed.'llg 5 ê L ô 49, 000, 000P3 -C 9 711:30 {1,14 4, 550, 00011] 14111111;M:L- -c 11-1n-1 brt i r,1.* 63, 193 Ii] 11/1•1 -3-

1 Type of work. 2 Kind of central operating body. 3 Place where work is to be carried out. 4 Effect of work. 5 Purpose Of work and summary. . • 6 Work of establishing the offshore culture conserving facilities. 7 Onigasaki Fishery Co-op. Assoc. 8 six places (Onigasaki ares). 9 Onigasaki. 10 Number of hibis which are to give profit. 11 Laver nets controlled. 90

12 Number of households which are to gmt profit. 13 Number of people engaged who are to ffec., profit. 14 Approximate • production amount. 15 Income increase. 16 Income increase per household. 17 Ry establishing a 60,000m 4 area of offshore culture conserving facilities in Onigasaki, the development of offshore laver culture fishing grounds is to be attempted, and the conserving facilities are also to be used as facilities for laver net control.

(2) Details of Plan (i) Explanation of Plan

U n g).,..r.s.rry„ I PDfriji; " ! dJI 1,512m U..1;2 17, 436, • 7_p; ' Y,r2. • 2.t.1 (4■;":"nn'IMVJ) CD !A j'ij Ci J ' Î1 37 11 n 1 El UVifi3;•1 38 -4e 3J 31 EI z T1' 3-2 ii a2neuiya›m • Ci

1 Type of work. 2 Offshore culture conserving facilities. 3 Place where work is being done. 4 Taya, Enohe, Kamaike, Nishi-no-Kuchi areas in Tokonameri City. 5 Amount of work and expenditure. • 6 Summary of work. 7 Method of operation 8 Period of operation. 9 Title of central administrating body. 10 Name of designer. 11 Remarks. 12 Amount of work for total length extended, Construction work of steel pipe piles 1812m, Expenditure Y17,436,000. 13 As in the 'Remarks' column. 14 Contract (public tender from nominated companies). 15 Commenced Nov. 1, 1962, completed March 31, 1963. 16 Onigasaki Fishery Co-op. Assoc. 17 Public Works Section of Onigasaki Municipal Office. •

1 (- •

The conserving facilities (steel pipe piles) are to be made approximately parallel to the coastline of Onigasaki area, Tokonameri City in a region 2;000 to 4,000m offshore, using a north to south spacing of 12m and east to west spacing of 20m. (ii) Itemized Expenditure (b 0 I. Et Y. a V.t I] ?Lk f.l• lit lo`r 111. iii.,.r, e: et el ::5-

> I e 17, 436, 000 T..niliino .1e 9e )..-4 T. e y2 15, 500, 035 -Fino 2: 9 tip D il 'rf Ilitti 7■ I Ur- . 8, 407, 209 •-....:1-nterizi -Jr- 1. 0 CD 2,301,580 1 0 , 624,150 U■4 À i‘ 4- 1- C Izi —71Rfti7- 230, 580 3,936, 516 Tija pi r„rza) L ,z, t.,e 0 ;f.eliefi]..111.i4 3,754, 524 e 4.'Ul.10Di.tie4 181,992 )2 e e 1,935,965 • D ee 2 fil e 115,965 D i. e; e 420,000 D z C. V2 1, 400, 000

1 Type of work or item of expenditure. 2 Number. 3 Unit. 4 Unit cost. 5 Amount of expenditure. 6 Remarks. 7 Construction work expenditure. 8 This Construction work expenditure. 9 Purchase of steel pipes. 10 Construction work of steel pipe pile driving. 11 Purchase of 'silver' rope. 12 Construction work of fitting bilver'ropes. 13 Hire of machines and tools. 14 Hire of boats. 15 Hire of navigating boats. 16 Miscellaneous expenses. 17 Building and repairs expenses. 18 Miscellaneous construction work expenses. 19 Other expenses. • 20 Set. 4 -

9,2

• below. . 21 As in the items 22 As below. 23 As in the specifications.

Locations in Aichi Prefecture where Fishing n-round Improvement 48 Construction Work has been Carried out. e.

I; (tte) ._\11 ;-/ay

2. Y.

•J.

‘.4 Yd.. &

()g 0

f tr;, 11 C) • _4 '-

1 Umibe Nagoya District i\lagoya,City). 2 Mie Prefecture. 3 Chita District. 4 Onigasaki. 5 Tokonameri. 6 Noma. 7 Tokonameri City. 8 Ise Bay. 9 Aichi Prefecture. 10 Nishi Mikawa District. 11 Isshiki Town. 12 Kinugasaki. 13 Mikawa Bay. 14 Maeshiba. 15 Toyohashi City. 16 Muro. 17 'Toyohashi District. 18 Shizuoka Prefecture. 19 Tawara Bay. • 20 Nishi Mikawa District. 21 Atsumi. 22 Ares where work was•done. r-

4,7 • 93 BIBLIOGRAPHY 4.9

Aichi Prefecture Fisheries Experimental Station Report: 'Report on Development Work for Shallow Sea Inner Bays (1952 )'. Aichi Prefecture Fisheries Experimental Station Report: 'Report on Development Work for Shallow Sea Inner Bays (1953 - 1957 )'. Aichi Prefecture Fisheries Experimental Station Report: 'A Summary of Earthwork Machines for the Development of Shallow Sea Inner Bays in Aichi Prefecture ° (supplement: Earth Scraping, Tillage Efficiency Test) (1954). Fisheries Branch, Agricultural Department, Tokyo University: 'The Results of Tillage Tests in the Isuzu Laver Culture • Ground in Fukue Bay'.(Fisheries Propagation Data No.2). Fisheries Branch, Agricultural Department, Tokyo University: 'The Production Efficiency in Laver Fishing Grounds Constructed by Adjusting the Ground Height on the Coast of Mikawa Bay' (Fisheries Propagation Data No.16). (quoted in this text.) Fisheries Branch, Department of Fisheries, Commerce and Industry of Chiba Prefecture: 'Concerning the Construction Work of Laver Fishing Grounds' (1958). Chiba Prefecture Inner Bay Fisheries Experimental Station: 'Report on the Investigation of Protected Water Surfaces and Construction of Fishing Grounds' (1959). V. 4 94

Fisheries Research Association, Agriculture, Forestry and Fishery Financial Corporation: 'Economical Aspects of the Shallow Sea Propagation and Culture Fishing.' . F. Matsumoto: 'Research on the Environment for the Growth of Laver, Especially Concerning the Influence of Water Currents'. Japan Shipping :Casualty Prevention Association, compiled by Yokohama Local Meteorological Observatory: 'Waves in Tokyo Bay' Development Investigation Secretariat 13ranch, Hokkaido Board

4 of Development: 'Investigation of a Fundamental Plan of Fishing Ground Construction - Research on Breakwater Fences.' Nippon Cement Technical .Association Pamphlet No.48: 'Centrifugal Force Reinforced Concrete Piles.' Tokai Concrete Industry Company Limited: 'Concerning the Comparison of Foundation Piles of Centrifugal Force Reinforced Concrete in Which the Steels Used are of Different Types.' (Author's name is not written for this book.) 'Comparison Between Steel Pipe Piles and Concrete Piles.' Yahata Steel Pipe Company Limited: 'Steel Pipe Piles for the Break Water Fences of Onigasaki • Fishery Co-operative Association. Calculation of Strength per Unit Area.' 17.

Nippon Steel Pipe Company Limited: 'Technical Data on Pipe Piles.' Agricultural Civil Engineering Experimental Station: 'Concerning the Hydrographie Experiments of Recent Marine Engineering Work.' Fisheries Branch of Aichi Prefecture: 'Mehl_ Marine Report No.86.! T. Ishiwara, J. Homma: /Applied Hydrography, Volume I.' T. Iijima: 'Coastline, Harbour and bay Measurements.' M. Yokoi: • 'Harbour Construction Engineering.'

Takeo Kurakake Graduated from the regular course of the Culture Branch, the Fisheries Training College of the Ministry of Agriculture and Forestry in 1935. Worked for the Experimental Station of Fisheries in Ohkaido, Zenra-nando of old Korea. Entered the Aichi Prefecture Libvernment in 1950, at present is chief of the Investigation. and Research Branch of the Aichi Prefecture Fisheries Experimental Station. •