地球環境研究,Vol.6(2004)

The Techniques and Tools of the Kazusabori Well-boring
Hiroki TAKAMURA＊
Keyword: boring technology, lower Pleistocene system, traditional, a thin strip of bamboo
. Introduction

Making

much

of

that

opportunity,

Hisahiro

Ishiwatari (Risshop University) and the author car-Kazusabori, a well-boring technology developed in theried out studies on the details of the technical aspect,area now called Kimitsu-gun, Chiba Prefecture, has

tools and history of Kazusabori.

contributed to construction of numerous flowing (artesian) wells for non-commercial and farming watersupply, since its birth during the Bunka period (18041818) in the Edo era. In 1892, this method was em-

. Geological considerations on the history ofKazusabori

ployed even in oil well development in Niigata and

The Kazusa district occupies the central part of Chiba

Akita Prefectures. It was also introduced to the inter-

Prefecture, bordering on the Shimousa district on thenational community, to India, in particular, as thenorth, on Awa on the south, facing Tokyo Bay on the

Kazusa System. It was Japan's most advanced well-

west and facing the Pacific Ocean on the east. In theboring technology of the time.

southern area, a mountain range forms a border between Kazusa and Awa, from Mt. Kiyosumi (383m)

However, in the wake of the introduction of the ro-to Mt. Nokogiri (228m). Having their headwaters intary boring technology and the spread of water-

this area, the Yoro, Obitsu, Koito and Minato Rivers

works, the Kazusabori method began losing its

pour into the Bay of Tokyo while the Ichinomiya andprevalence since the mid-1950s, and today, it is no

Isumi Rivers flow into the Pacific Ocean.

longer used at all.
This district resides on the foundation of marine deThe Kazusabori technology is designated as an impor-posits that belong to the Mizuho Series formed in thetant folk-cultural asset, and the tools involved arelater Tertiary Period. Sedimentation continued fromkept in the Chiba Prefectural Kazusa Museum. Al-

the Paleozoic Era through the Cenozoic Era. As a re-though Nagami (1948), Hishida (1955, 1960), andsult of crustal movements at the end of the Mesozoic

Hida (1973) studied its development and the tools,

Era, the entire Kazusa district bulged. In particular,

hardly any studies have been conducted so far on thethe area around the present district-bordering moun-technology itself.

tain range drastically bulged to emerge above the sea.
Those movements formed the monoclinal structure

In February 1981, the author had an opportunity ofthat is sloping northwestward, as we see today. In theseeing reproduced Kazusabori processes demon-

Quaternary Period, sedimentation of gravels, sand,strated by Mr. Haruji Kondo (at Abe 12, Sodegaura-

and clay in the shallow-water zone to form the Narita

machi, Kimitsu-gun, Chiba), a well borer who

Group. Meanwhile, sedimentation and decomposition

inherited and passes on the Kazusabori technology.

of volcanic ashes from activities of the volcanoes in＊Faculty of Geo-Environmental Science, Rissho University

37

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

the Kanto district formed loam, which bulged due to

Tsuneemon's property. Having shared the const-

the Kanto basin-fuilding movements. These move-ruction expenses, the parties shall share well water

ments along with development of alluvial formations

for drinking, and for irrigation in case the water sup-of sand and clay produced the current topographic

ply from the well exceeds the parties' drinking waterfeatures of the Kazusa district.

consumption. In that case, the parties shall use well
water for farming once a day, on a day-to-day rotat-

Kimitsu-gun, the birthplace of Kazusabori, has a

ing basis, rain or shine.

monoclinal structure that inclines northwestward.
Presumably, its geological structure is founded

The event that led to construction of pit wells in thisaround Mt. Kano (352m). The aquifer resides in thearea is introduced as follows;

Kazusa Group formed in the early Pleistocene Epoch.

tradition in the Nakamura area, Nakamura is the

As for the inclinations of these formations, the far-cradle of Kazusabori, whose invention was stimulated

ther from Mt. Kano, the sharper the inclination be-by an incident that a child playfully butted thecomes.

ground with a bamboo stick, causing water to belchout.

According to an oral

(Hishida, 1955). Probably, people in this area

At Tawarada in Obitsu-mura located in the river

were empirically aware of the fact that confinedbasin of the Obitsu River, paddy cultivation was im-

groundwater existed in this area due to the mono-possible since the shallow riverbed could not allow ir-

clinal structure of the foundation. However, they did

rigation from the river, which caused this area to

not have any established, structured well-boring tech-suffer a severe poverty level. However, once the pit

nology. Although the pit well technology was establi-

well technology called Kazusabori was introduced toshed in Tokyo (then Edo) in the year 2 of the Shotoku

this area, the monoclinal structure allowed construc-era (1712), there is no evidence that the well-boringtion of flowing wells utilizing confined groundwater,technology employed in Edo was transferred toenabling paddy cultivation to be carried out. This

Kazusa. As the Kazusabori technology resembles thetechnology spread across the Kazusa district includ-

excavating method used for well construction in theing the river basin of the Yoro River.

continent of China before World War , it may havebeen conveyed from the continent.

. The Origin and Development of Kazusabori

２) Development of Kazusabori

１) The origin of Kazusabori

Since the year 14 of the Bunka era (1817), when the

The literature on the origin of Kazusabori includes

pit well construction method was conveyed to the

The History of Kimitsu-gun (1927). In that, there is a

Kazusa district, the technology went through a num-

statement as follows:

A person named Hisazo Ikeda,

ber of improvements before it was perfected in thea resident at Nukata, Nakamura, started a well-

final form, which involves a higo unit, made of jointed

boring business around the year 14 of the Bunka era

split bamboo members, with an iron pipe attached at(1817). It is unknown who conveyed the well-boring

the bottom section, an up-and-down movement

technique to him…

Supporting the fact, The History

booster connected to the bamboo unit above theof Well Boring, kept at the Omiyaji temple located inground for driving boring operation, and a wheel

the Nakamura area clearly indicates that a pit wellcalled higo-guruma that raises the bamboo unit along

was constructed on the premises of the Omiyaji tem-with the iron pipe by rolling higo members up (seeple in the year 1 of the Bunsei era (1818), in the fol-Fig. 1). The following section provides an overview oflowing statement;

the Omiyaji temple completed athe development process of the boring technology in-thrust-bored well, located at the end of Aza-Yarita,

herited in the Kazusa district by roughly dividing thewithin the temple's enclosure that is neighboring

period into its development phase and establishment38

地球環境研究,Vol.6(2004)

phase (see Table 1).

the year 16 of the Meiji era (1883), starting with use

The development phase is when improvements wereof metal rods for butting, to be replaced with oakmade to extend the boring depth. As for the boringrods, and ultimately, with split bamboos. Thus, themethod, improvements were made for 66 years be-

initial boring limit of around 50 m was thus extended

tween the year 14 of the Bunka era (1817) throughto 500 m or more.

Table. 1
Year in
Dominical
Imperial Era
Year
14, Bunka

Decline phase

Peak

Establishment
phase

Development phase

1, Bunsei

Chronology of Kazusabori Technology
Event
Nakamura

Obitsumura

1817

Hisazo Ikeda bored wells using thepit well technology that he learnt
from an unknown person.

1818

Thrust-bored wells were made at 13
locations including Omiyaji in
Momiyama (for drinking/farming
water supply). Eight wells among
these wells naturally discharged
water at the surface (e.i., flowing
wells).

12, Meiji

1879

A well borer from Senju, Tokyo, delivered a pit well, to whom
Yasunosuke Omura apprenticed
himself.

14, Meiji

1881

Omura purchased gas pipes.

15, Meiji

1882

16, Meiji

1883

19, Meiji

1886

Minejiro Ishii developed(bow-type bamboo spring).

26, Meiji

1893

Kinjiro Sawada developed tsukigi(wooden thrust rod).
Kinjiro Sawada developed higoguruma (bamboo wheel).

29, Meiji

1896

Kazusabori spread across the country.

35, Meiji

1902

Kazusabori was introduced into India as

16, Showa

1941

25, Showa

1950

44, Showa

1969

55, Showa

1980

Haruji Kondo re-performed the manual boring procedure.

56, Showa

1981

Haruji Kondo re-performed the manual boring procedure.

57, Showa

1982

The Asia Well Development Association transferred the Kazusabori technology to Philippines.

Tokuzo Ikeda tried the Kashibotsuki method.

Omura developed the Kashibo-tsuki
method (a thrust boring method
using oak rods).
Omura developed the Higo-tsuki
method (a thrust boring method
using split bamboo).

hanegi

Kazusa System.

Mechanical boring technology was developed.
The number of well borers was reported to be decreasing.
Haruji Kondo retired from work as a well borer.

39

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

Fig. 1

Kazusabori SchematicFig. 2 Vice(source: Nagami's literature)

The boring method inherited in the Kazusa district

under the well borer from Tokyo, invented thewas referred to as Kanabo-tsuki (thrust boring with

Kashibo-tsuki method (a thrust boring method using

metal rods) according to The History of Kimitsu-gun

oak rods) and, in the same year, Tokuzo Ikeda, a resi-(1927), as in the following statement;

In those days

dent in Nakamura, also tried this method. With the(around 1817, annotated by the author), they used

Kashibo-tsuki method, they installed scaffolding likeboring tools composed of metal rods equipped withthe one in Fig. 3. The iron ring fixed on an oak rod

herringbone/octagonal ball-shaped metal fixtures...

joint was hooked onto the lever rod to enable the oak

They used a vice, as shown in Fig. 2, to raise the en-rod to be raised when the lever rod was operated.

tire boring unit and then dropped it to produce boring

Then this oak rod was dropped to butt the ground forforce. With this method, it was difficult to continue

boring. This method solved the problem with heavy

boring vertically, and the vibration generated whenmetal rods previously used and made it possible to ex-

dropping caused breakage of the metal rods' joints.

tend the boring depth up to 50 to 60 ken (about

Another problem was the limitation of the boring100m).

depth that was dependent on the weight of metal rods
used, which was 27-28 ken (about 50 m) long. Al-

For placing cleaning tools into the wellhole to remove

though it may be questionable if they could construct

the muck, Omura used split bamboo members joined

a well that could supply required amounts of water

together. In the year 18 of the Meiji era (1885), he in-under this limitation of the boring depth, no improve-vented a boring method reusing these split bamboos

ment was made before the Meiji era. In the year 12 offor boring by attaching 5 to 6 m-long iron rods, with

the Meiji era (1879), a well borer came to Obitsumura

a diameter of 3.5cm, on the bamboo tip. This was thefrom Senju, Tokyo, who started well construction inbirth of the Higo-tsuki method (a thrust boringthat area, after which Kazusabori started evolving

method using split bamboo). Meanwhile, Tokuzo

around the two development centers, Nakamura and

Ikeda of Nakamura used joined iron pipes, rather

Obitsu.

than iron rods used by Omura, for boring, that were
equipped with a bit called sentanrin-sakurin-ichi

In the year 15 of the Meiji era (1882), Yasunosuke(ring-type chisel at the tip section). These improve-

Omura, working in Obitsu-mura as an apprenticements helped extending the boring depth limit to40

地球環境研究,Vol.6(2004)

around 1,000m.

Kazusabor technology that had been rooted in the
Kazusa district since the year 14 of the Bunka era

With these developments by the year 19 of the Meiji(1817).

era (1886), the improvement of the boring depth
achieved with the Kazusabori method was completed

３) Mechanization of Kazusabori and its decay

with the invention of the Higo-tsuki method. Thereaf-

Perfected in 1893 as a well-boring technology, as de-ter, the focus of improvement effort was placed on in-

scribed above, Kazusabori was also applied to oil wellnovation for streamlining the operation. This period

boring in Niitsu, Niigata Prefecture, succeeding informs the establishment phase. First, in 1886,

discovery of some oil fields. In the year 29 of the Meiji

Minejiro Ishii of Nakamura invented hanegi (bow-Era (1896), it was transferred to Taiwan, Kyushu,

type bamboo spring).

and Hokkaido to be widely applied in coal mining andboring for hot springs.

When excavating by moving up and down a split bam-Around the year 16 of the Showa era (1941), the pre-boo device with an iron pipe on the tip section, the re-vious manual boring was replaced with mechanicalsilience of hanegi was utilized to reduce manual labor.

excavation using engines. This improvement enabled

Additionally, in the year 26 of the Meiji era (1893),

reduction of the higo-guruma diameter to half of the

Kinjiro Sawada invented shumoku (wooden thrust

initial dimension (to about 2m). The wheel was nowrod) and higo-guruma (bamboo wheel). The invention

operated using a belt to roll up split bamboo mem-of shumoku enabled well borers to change the operat-

bers. A clank was also introduced to convert the ro-ing manner from moving the higo (split bamboo) unit

tary movement into up-and-down movement to drive

up and down by grabbing it to holding it with both

excavation. The development of this mechanical exca-

hands at a right angle to it, which contributed tovation technology enabled to reduce the manpower in-

higher efficiency. With the invention of higo-guruma,

volved to just one borer for most of the entire well-

the operating efficiency of raising iron pipes also im-boring process, from two to three borers previously

proved as a well borer could enter the wheel unit torequired for boring, operating higo-guruma, and shift-

turn it in a manner like a pet mice revolving a wheel

ing.

in a cage. This invention of higo-guruma perfected theFig. 3 Kashibo-tsuki method−
Oak Rod Joints and Scaffolding(Source: Nagami's literature)

Photo. 1 Higo-guruma(Bamboo wheel)

Photo. 2 Turretr and
Hanegi (Spring bars)

41

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

In the third decade of the Showa era (after the mid-

An iron pipe is a tool used for breaking into the bot-1950s), with the introduction of the rotary boring

tom layer by butting for boring in the Kazusaboritechnology, Kazuzabori gradually lost opportunities

technology. The iron pipe is complete with sakiwa

to be used even though it had spread throughout the(tip chisel) and claws, as shown in Fig. 4.

country. According to an old document in Mr. Haruji
Kondo's collection, well borers around the Yokota

Sakiwa is the very tool that breaks the bottom layer

area where he lives, organized a union named Suijin-

of soil, whose tip is made of steel. This tool can beko (water-god union, literally) and set out arrange-

considered to be the core device in Kazusabori. Therements twice a year (on the 5th of February and theare three types of sakiwa for different soil properties

5th of October) concerning well prices. The union had(Table 2).

twelve members at the beginning of the Showa era(around the mid-1920s), but continued to decrease

Among these, the gravel thrust iron rod is an inde-

after World War . Mr. Kondo continued to work as

pendent 6.3 m-long iron rod, to be used separately toa well borer despite the trend of decreases in the num-

break gravel layers, and not to be equipped on any

ber of well-boring job opportunities and the number

other iron pipe tip.

of well borers. In the year 44 of the Showa era (1969),

Inside the assembly of nagawa and ichimonji chisel, awhen the order placements for wells dropped to about

device called koshita (component at the lower section

three per year, he ended his carrier as a well borer.

with valve) is installed, which is used to suck out theThat marks the end of Kazusabori as an active tech-

muck from boring, which float in clayey water

nology, after being used for nearly 150 years.

through the discharge port provided on the iron pipe
at its upper section. Koshita has a valve fixed on a. Major Tools Used in Kazusabori and Their
Structures

frame made of oak.

At the tip of the iron pipe and at the back of sakiwa,

The major tools used in Kazusabori can be roughly

two projections called claw are provided. These projec-classified into two categories: boring tools and power

tions are made of steel and assist boring with a longtransmission devices used by well borers on theiron pipe by creating an extra clearance between the

ground.

iron pipe and the bore so that friction may be controlled and the muck be prevented from being stuck１) Boring tools

between the pipe and the bore, which may cause prob-[Iron pipe]

lems.

Fig. 4Iron Pipe Schematic

Table 2

PurposeNagawa (double-ring)

For general-purpose boring into layers of clay/sand or rock mass

Ichimonji(bar-shaped chisel)
Gravel thrust-boring bar

42

Types of Sakiwa

Name

For general-purpose boring into layers of sand or rock mass
For boring into layers of gravel地球環境研究,Vol.6(2004)

Table 3

Classification of Boring Tools

Iron pipes
Name

Diameter(cm)

Length(cm)

Weight
(kg)

Claw
(cm)

Large iron pipe

7.5

630

28.0

4.5

Iron pipe

4.5

900

28.0

3.0

Hon (main) iron pipe

4.5

810

19.1

3.0

Iron pipe

4.2

630

14.5

Tateire (vertical setup)iron pipe

4.6

270

9.1

Used for starting boring

Uchizuki (inside thrusting)iron pipe

3.3

810

13.2

For boring inside vertical water
duct (inner diameter: 4.8cm)

Uchizuki (inside thrusting)iron pipe

2.7

540

6.2

For boring inside nested pipes(inner diameter: 3.3cm)

630

50.0

＊

Gravel thrust-boring bar

Remarks* See the section describing sakiwa
Suiko (suction pipes)
Name

Diameter(cm)

Length
(cm)

Suiko

6.0

630

Suiko

3.0

For cleaning inside vertical water duct

Suiko

2.7

For cleaning inside nested pipes

Suiko for cleaning

4.2

For cleaning inside completed wells

Fig. 5Weight
(kg)

Claw
(cm)

Remarks

Suction Pipe Schematic

The length and the diameter of the iron pipe section

pressure, claddings made of galvanized sheets arevary depending on the well diameter, special usage ofwrapped around the iron pipe at a certain interval,

the well, and other requirements specific to the well.

called hotai (literally, bandage). Like the iron pipe, aAt the upper section of the iron pipe, kama (tapered

Koshita valve is provided at the lower section and ahook) is provided to enable the pipe to be joined with

discharge port at the upper section (Fig. 5). The

split bamboo members so that the iron pipe can belength and the diameter of suiko are determined based

suspended from the section above the ground.

on those of the iron pipe, as classified in Table 3.

[Suiko (suction pipe)]

Operation using suiko is performed at the start and

The muck from excavation is let float in clayey waterend of the day's operation, at every two to three me-that is constantly poured into the bore during boringters of boring, or when boring operation has slowed

operation to settle over time. Suiko cleans up thedown due to a massive amount of muck clogging themuck by sucking and discharging them out of theiron pipe when boring a layer of sand.

bore.
２) Power transmission devices
The suiko is a light-weight device made of galvanized[Higo (split bamboo)]sheets. For protection from breakage due to water

Higo suspends the boring tools placed inside the43The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

Fig. 6

Fig. 7

Preparation of Split Bamboo

Kama (Tapered Hook) Made of Iron

wellhole and transmits the power for boring. Tapered

members have been added, reducing the number ofhooks called kama, made of long-jointed bamboo

junctions.

stems, are provided as joints of higo members. To
make a kama hook, a bamboo stem is shaved off, as

Kama hooks for engaging higo members are fabri-shown in Fig. 6, in a width slightly less than 2cm andcated in symmetrical shapes at the ends for okkake-cut in the length indicated in the figure, and the bam-higo and hon-higo. This is an innovative idea withboo stem joints close to the cut end are utilized. Withconsiderations given to the balance and strength of

the joining method using kama (called kama-tsugi),

the bamboo members involved, allowing higo mem-two kama hooks are engaged and iron rings called

bers to be joined using a kama hook with its thicker

higo-wa are installed from each end to completely fix
the bamboo members with the tapered sections.

The depth already bored determines the length of thehigo section. As explained in the

Suikosectionabove, muck deposited inside the iron pipe might affect the boring efficiency due to an increase of theweight of the iron pipe. When that situation arises,
the iron pipe is replaced with a suiko pipe to clean up
inside the wellhole. One unit of boring depth is called
one sage, which is about 1.8m for manual boring.
Each time boring is completed for a depth of one
sage, higo is added to the existing higo section. Therefore, the unit length of higo members is also 1.8m.

As boring develops, additional okkake-higo (extension
split bamboo) having that unit length is attached tothe higo. As the joint is the weak point of higo thatcan lead to accidents if any joint is broken, okkakehigo is replaced with 5.4m-long hon-higo (main split
bamboo44

member)wheneverthree

okkake-higo

Fig. 8Higo Junctions

地球環境研究,Vol.6(2004)

portion down and the back-side portion up. This way,
when rolling up higo members around the higoguruma wheel, the back of bamboo stems face outward.

In addition to such arrangements, iron hooks (Fig. 7)
are also employed to protect higo junctions from wear
due to repeated operations to attach/detach to/fromiron pipes or the suiko unit. The ends of this iron hook
are made in the opposing orientation. To accommodate this design, one higo member called moto-higo(original split bamboo member) is used (Fig. 8) thatis joined with a hook in the same orientation.

[Hanegi (spring bars)]Fig. 9Hanegi is also referred to as yumi (bow). As shown in
Fig. 1, it is connected to the higo unit that suspends anHigo-guruma (bamboo wheel)on the Scaffolding

iron pipe with a rope. This power transmission unit
utilizes the resilience of bamboo to drive up-and-down

how the tools introduced in the previous chapter weremovements of the pipe for boring. Two long-jointed

actually used. Table 4 shows the flow of the processes.

bamboo stems (with a diameter of 12 to 13cm) arebound together with a straw rope, providing a certain

１) Scaffolding

distance between the connecting points, and mounted

In preparation for boring works, a scaffold is set up

onto the uppermost section of the scaffold. The totalthat is unique to the Kazusabori method (Fig. 9).

length of the hanegi unit is about 5 to 6m.

Logs with an average thickness at the bottom of 12 to
13cm are used for the main members of the scaffold,[Shumoku (wooden thrust rod)]with each node fixed with a rope.

Shumoku is the section that the well borer holds togive thrust to the boring device. Shumoku units areFirst, three columns called tateji are erected in line,

made of oak, to the size of each borer's hand. It has aoriented in the east or south, at an interval appropri-grove in the middle for fixing higo in place with a

ate for the diameter of the higo-guruma used. In paral-

wedge. It is installed so that it comes just above thelel to them, another line of columns is installed 120cm

borer's knee when the iron pipe is driven down all theaway from the original columns, on the opposite sideway. So the shumoku unit is moved downward as bor-of the wellhole position that is in between. Next, threeing develops.

rows

of

horizontal

connection

members

calledyokonuno are fixed in place with ropes for each line of

. Boring Method in Kazusaboritateji member.

This section summarizes the actual boring procedure

The lowest yokonuno members are fixed at a level

used in Kazusabori, based on the manual boring per-about 30cm above the ground so that they can sup-formance reproduced by Mr. Haruji Kondo, an ex-

port a scaffold plate that will function as the working

well borer, demonstrated at the residence of Mr.

deck for boring operations. The middle yokonuno

Hiroshi Kamei, at Abe, Sodegaura-machi, Kimitsu-

members are for supporting the higo-guruma, fixed atgun, Chiba Prefecture, along with the description ofa level about 2.2m above the ground, slightly higher

45

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

Table 4

Flow of Kazusabori Processes

than the radius of the higo-guruma wheel (2m). Sincewith relatively high viscosity was collected fromthis section takes the greatest load, particularly thickaround rice paddies in the area where well borers

logs are used for this part. The uppermost members

lived. It was mixed with water and the supernatantare for maintaining the scaffold's stability and for

liquid is collected and stored in a barrel buried next tomounting the hanegi unit that is used for boring, andthe scaffold.

are fixed at a level about 4m above the ground.
２) Boring [1]At the position of the wellhole, a hole called do-ana is−Boring with tateire iron pipe (vertical setup pipe)−

provided, whose approximate dimensions are 1.8m in

The first phase of boring is carried out by means of alength, 0.8m in width, and 0.7m in depth. This do-ana

tateire iron pipe of about 2.7m in total length. A

contains clayey water for sucking up muck, protect-sakiwa is installed at the tip of the iron pipe, anding the wellhole wall from collapsing, and cooling bits

okkake-higo (extension split bumboo) (2.7m) is joined

used. As for the origin of clayey water used this way,with the kama (tapered hook) at the upper position.

no specific explanation is given in the related litera-

Then, this pipe assembly is made to stand tateire ironture, except that it was already in use in the year 12

pipe in the do-ana in the wellhole.

of the Meiji era (1879). As for the clay, black clay46

地球環境研究,Vol.6(2004)

３) Boring [2]−Boring with a hon iron pipe−
When ground is dug to a depth of 8.1m, a hon (main)iron pipe whose total length is 8.1m is used for welldigging, instead of tateire iron pipe.

With the hon iron pipe that is heavier than tateire iron
pipe, it is easier to break the wellhole bottom layer.
However, the work efficiency becomes lower. To compensate it, a rope is connected to the center of hanegi
installed on the top of yokonuno, and the end of therope is wound around the shumoku, to lift the ironpipe by utilizing the resilience of the bamboo.
Fig. 10Sketch of boring with tateire iron pipe
The hon iron pipe is provided with two projections

The well borer installs the scaffold at the second stage

about 3cm, called tsume (claws), at an interval of 180

of yokonuno to start the work. Boring is performed bydegrees near the end (see  1) [Iron pipe], to prevent

vertical movement of the higo on which the iron pipe

the work efficiency from lowering because of the fric-is suspended; the iron pipe end is made to hit the welltion between the iron pipe and wellhole wall. Whilebottom, to break ground. The shumoku serves as grip

vertical motions for boring are repeated 20 times, thefor this job. As shown in Fig. 10, the well borer sets it

claws turned clockwise and counter-clockwise alter-nearly at the height of knees, and holds it with both

nately around the center line of the wellhole.

hands. The well borer continues the job, with theupper part of higo put on the shoulder.

Boring is carried out at a rate of about 1.8 m per day.
This job is continued, adding extension higo, while

The muck generated by digging is made to float byevaluating the nature of soil at the bottom by reac-

the specific gravity of the clayey water, and it is dis-

tions transmitted to hands, and replacing sakiwa,

charged onto the ground through the outlet at theuntil the target aquifer is reached.

upper part of the pipe, by means of koshita valve installed at the lower section of the iron pipe inside.

４) Boring [3]−Job with suiko (suction pipe)−

Along with the progress of the boring, the shumoku is

Along with progress of boring, muck floating in thedisplaced. When boring advances, with the whole ofclayey water increases in amount, and begins to settle

the pipe entered into ground, the work bench is moved

in the iron pipe and wellhole. Then, the iron pipe isto the 1st stage of yokonuno, and work is resumed.

lifted up by means of the higo-guruma, to be replacedwith suiko to clean the wellhole.

When boring corresponding to one okkake-higo iscompleted, another okkake-higo is joined with the end

The suiko is lowered into the wellhole, and moved ver-of the higo.

tically more than ten times, to suck the clayey watercontaining much muck in the bottom. Then, the suiko

Boring by the tateire iron pipe is carried out to theis lifted up, and moved vertically above ground to dis-

depth equal to the iron pipe length (2.7m) plus two

charge the clayey water. This job is repeated several

okkake-higo (2.7m each), that is, 8.1m.

times. As a general rule, this job with the suiko is performed when ground is excavated about 2 to 3m.

47

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

After cleaning the wellhole, the suiko is replaced with
the iron pipe to resume boring.

５) Finish process [1]−Wellhole shaping−
When boring reaches, through the clay layer, thesand layer, i.e., aquifer (calledshikibaby wellborers), which contains many shells, the well borer
stops boring to proceed with finishing process.

To smoothly insert the toi (vertical water duct) (seethe next page), the wellhole is shaped. This job uses ahole shaping tool made of a cedar log around whichnails are driven. The diameter of the toi is measured,and a margin is added to the measured diameter.
Based on this dimension, the projecting length of thenails is adjusted so that the finished hole may havethe desired diameter. Then, this tool is mounted at
the tip of the hon iron pipe, and the shumoku (wooden
thrust rod) is set as in the boring job, to shape theFig. 11Toi (vertical water duct) and its joint

wellhole wall.
the bamboos made straight, joints called hane are
When the hole is shaped to the bottom, muck gener-

provided.

ated by shaping is removed by means of the suiko.
After these preparations, four to eight water collect６) Finish process [2]ing ports, called mado (window), are made between−Placing toi (vertical water duct)−nodes. These ports are designed to introduce ground-

To prevent the wellhole from collapsing, a toi is in-water contained in the aquifer into the toi. These

serted into the whole length of the wellhole (Fig. 11).

ports are made in parallel with the bamboo fiber with

The toi was initially made of moso bamboo (a species

a tatebiki noko (saw with teeth for cutting along theof bamboo of large diameter). Currently, PVC pipes

direction of grain). Except for flowing (artesian)

are used. It is easy to connect toi of PVC pipes to-wells, to prevent sand from entering through madogether, and also easy to make connected pipes

during pumping, two or three plies of palm barks are

straight. In contrast, with bamboo toi, rather diffi-

wound around the mado. The toi duct is introduced

cult preparations are necessary, involving correction

into the shaped wellhole, and their joints are woundof bend, piercing nodes, and processing the jointed

with newspaper and palm barks to prevent intrusion

portion.

of mud and sand. In the case of a flowing well, the toi
is made to project about 50cm on the surface, to pro-

The bend of bamboo is corrected by warming its

vide a flowing port.

nodes of the bent portion over fire, and cooling down
it to solidify. For allowing water to pass through the７) Finish process [3]bamboo duct, its nodes are pierced by means of a rod− Mizuyobi (inducing water inflow), Ikashi (putting

about 1.2m long with wavy projections. To connect

into work)−48

地球環境研究,Vol.6(2004)

During the jobs described above, groundwater spring-

Well Development Association. As seen by this fact,

ing is prevented by injecting clayey water of large

this well boring technology is being reevaluated in de-specific gravity into the wellhole. At the final stage ofveloping countries.

well creation, the clayey water in the pit is discharged, and jobs for making groundwater spring

Those wishing to conduct an in-depth research on dis-start.

tribution of Kazusabori wells and their status of use
are advised to refer to Hiroki Takamura (1973)

At first, mizuyobi (inducing water inflow) is carried

Jifuntai no Kotai to Jifunryo(Recession of the areaout. For this purpose, a suiko thinner than the suiko

of artesian flow and the flowing volume) in Isamu

for cleaning is lowered to the position of mado, which

Kayane (ed.) Chikasui Shigen no Kaihatsu to Hozen

is lifted up about one meter per cycle. Generating zero

(Development and conservation of groundwater re-water pressure at an instant, groundwater is made tosources), Water Science Research Institute, in addi-

flow into the well pit. This priming job is repeatedtion to the following references.

several tens of times.
References
After priming, ikashi (putting into work) begins.
This job is to pump up the clayey water in thewellhole to decrease the concentration of clayeywater, thereby removing the clay sticking to the wellwall, and making groundwater spring. Nowadays, apump is used for this job, but once clayey water was
pumped with the suiko.

Education Association of Kimitsu-gun, Chiba Prefecture(1927)

History of Kimitsu-gun, Chiba PrefecturePart, 1010-1011.
Hishida, Tadayoshi (1955)

Kazusabori Ko(Study on the

Kazusabori well-boring) Part , Boso Tembo (Boso Outlook), August 1955, 8-10.
Hishida, Tadayoshi (1955)

Kazusabori Ko(Study on the

Kazusabori well-boring) Part , Boso Tembo (Boso Outlook), September 1955, 4-6.

After mizuyobi and ikashi, the creation of a well by
the Kazusabori is completed, and the well is handed
over by the well borers to the client.

Hishida, Tadayoshi (1960)

Kazusabori Ko(Study on the

Kazusabori well-boring), Bunkazai Shiryo (Materials on
cultural assets), Chiba Prefecture.
Kayane,Isamu(1973)

Kazusabori I no Riyono

Hattatsuto. Conclusions

well-boring

This study has overviewed the Kazusabori manualand conservation of groundwater resources), Water Science

well-boring method, its tools and the history of its de-

Research Institute, 200-208.

velopment. However, there are still some facts yet to

Kurata, Nobuo (ed.) (1975)

be revealed, including the origins of the Kazusaboritechnique and of the use of clayey water. With regard

andKazusabori(Development of the KazusaboriutilizationofKazusabori

Chikasui Shigen no Kaihatsu to Hozen

Chikasuiwells),(Development

Chiiki Shakai no Naka no(Groundwater in the community), Ground-water Engineering Center.
Nagami, Shuzo (1948)

Kazusabori no Kenkyu(Research

to the technical origin among others, a document inon the Kazusabori well-boring), Museum Research Collec-

the FAO library shows that Chinese Drilling bears ation.

close resemblance. The investigation should be left to
future studies.

Takamura, Hiroki et al. (1975)

Boso Hanto Chubu no

Chikei Chishitsu to Chikasui(Topography, geologicalconditions and groundwater in the central part of the

Triggered by this restoration of the technology, thesecond restoring demonstration was carried out in

Boso Peninsula), Junken Annai (Excursion guidebook),
the Association of Japanese Geographers, 11-13.

the city of Kimitsu by Mr. Haruji Kondo and Mr.
Aoto Morooka (cinematographist), and this technology was exported to the Philippines through the Asia

49

The Techniques and Tools of the Kazusabori Well-boring (TAKAMURA)

上総掘りの手法と用具について


村

弘

毅

立正大学地球環境科学部

上総掘りは､ 古く江戸､ 文化年間に現在の千葉県君津郡において発祥したもので､ この方法により数多くの自噴井が掘られ､ 人々の生活や農耕のために水を供給してきた｡ 明治25年には､ 新潟・秋田の油田開発にまで利用され､ 広く海外 (インド) にまでも The Kazusa System として紹介された､ わが国でも最高水準を誇る井戸掘りの技術であった｡
しかし､ ロータリー式ボーリング技術の流入や上水道の普及により､ 昭和30年代末以降上総掘りは次第に行われなくなり､ 現在ではまったく利用されなくなってしまった｡
上総掘りは現在､ 国の重要有形民俗文化財に指定されており､ その用具は千葉県立上総博物館に所蔵されている｡ 発達・用具についての研究は､ 永海 (1948)､ 菱田 (1955､ 1960)､ 肥田 (1973) によって行われているが､ 上総掘りの技術に関する研究はほとんど行われていない｡
筆者は1981年２月､ 上総掘りの技術を伝える職人､ 近藤靖治氏 (千葉県君津郡袖ヶ浦町阿部12) の手による上総掘りの再現を見ることができたので､ この機会に､ 石渡久洋君 (立正大) とともに上総掘りの詳細な技術・用具・発達史についての研究を行った｡

キーワード：ボーリング技術､ 下部更新統､ 民俗､ 竹籤50