Basic knowledge of dams | Making & town development BtoB information site "Tech Note"

Dam has saved water that nurtures all life on the earth, has supported the modernization of mankind, and has contributed to high economic growth and social development.In the future, it will play an important role in climate change and population growth.In this series, we will explain the basic knowledge of dam six times.In the first one, I will explain what a dam is and what kind of structure it is.What can be called a dam is actually determined by law in Japan and is properly defined overseas.This time, I will explain the role of the dam, along with the definition of a dam that you know and do not know.We will also introduce how many things called dams are in Japan and overseas.

Lottery

1st: What is a dam

The definition of dams is determined by river law in Japan, and the standards are also determined overseas. What is a dam? If you ask, many people say, "I stop the river and accumulate water." Certainly, the dam is a facility (structural) that keeps the river water and accumulates water. In addition, flood control is performed using the function that can store water. On the other hand, water gates and kawaguchi dams are not called dams. Considering the role of dashing the river water, the movable weir on the embankment and the estuary may be a dam from the previous answer (Fig. 1). From the following, we will introduce the definition of the dam, the difference between the movable weir and the flood gate.

First, I will explain the definition of dams in Japan.The structure called dams in Japan today is stipulated by the river law enacted in 1964 (the year of the first Tokyo Olympics).The special rule of the dam (the definition of a dam) is a dam that is installed under the permission set forth in Article 26 of Article 26 of paragraph (1) in order to store or intake river flowing water, and from the foundation ground to the summit.It is written as a height of 15m or more. "

In other words, a structure that can be called a dam refers to a height of 15m or more.The lower one is a weir (cough), stipulating that it is a facility other than a dam that is provided across rivers to control the river water (river management) (river management. "Structural decree such as facilities: established in 1976).However, the definition of the dam by this law is unique to Japan.

また、世界におけるダムとしての基準は、国際大ダム会議（1928年創立）で「堤高5m以上、または貯水容量300万m³以上のもの」をダムと定義しています。これらのことから、堤防はたとえ高さが15mを超えていたとしても、貯留施設ではないため、ダムとはならないことになります。

A slightly unusual dam is a natural dam.Natural dams are dams formed by stopping the flow of river water, such as heavy rains such as torrential rains, landslides caused by earthquakes, and lava flow due to volcanic eruptions.It is often referred to as "Bieber is a master of dam" on television, etc., but if you follow the above definitions, the dam created by the beaver should not be strictly called a dam.

Movable weirs and fluids have a big difference in their functions.The movable weir is ...

>>第1回 第1章の続きを読む（PDFダウンロード）

The role of the dam includes flood adjustments, maintaining normal functions of running water, securing water resources (water supply water, agricultural water, industrial water, etc.), etc.In recent years, flood damage has occurred every year in various places, but it has not rained during the rainy season, and news such as water saving and water cuts has been reported.Even in such a situation, our lives are fulfilled by the fact that the dam plays.If you lose the dam from Japan now, you will not be able to live near the river.In addition, the water breakage continues, and the lives of people will definitely be threatened because crops cannot be made stably.

In Japan, about 70 % of the country is a mountain, and most people live in the remaining 30 % of the plains.Many rivers in Japan have a short distance from the mountains to the sea, as short as the flow, and the flow is steep, so it quickly flows into the sea even if it rains.For this reason, it is necessary to stop the river on the way and accumulate water.In addition, a large amount of sediment is carried during the flood and accumulates at the bottom of the river.In that case, you have to raise the embankment or remove the landslide that has accumulated on the river.Therefore, when heavy rain falls, it is necessary to stop the water on the way so that it does not flow downstream at once.The following are the six roles (functions) of the dam.

1: When the flood control function is heavy rain, adjust the amount of water to the dam and flow downstream to prevent the break of the embankment (Fig. 3).

2: Maintain the normal function of running water, accumulate or release water to the dam, keep the amount of water flowing in the river constant.Therefore, the flow rate of the river decreases during drought (water deficiency), so that the survival of the fish is not affected, and the depth of the river can not damage the embankment.

3: Upper water supply function We usually use the water (water supply) that we usually use ...

>>第1回 第2章の続きを読む（PDFダウンロード）

It is said that there are about 3,000 dams in Japan.According to the Japan Dam Association, there are 2,753 Japanese dams, as shown in Table 1, and Hokkaido is the most common.The second most common is Okayama Prefecture, followed by Niigata, Hyogo and Hiroshima.While many dams are concentrated in Toyama Prefecture, which has Kurobe Dams, and Nagano Prefecture, which have the Japanese Alps, in fact, Toyama Prefecture is actually 13th in 77 and 66 in Nagano Prefecture.It is 16th.Conversely, Okinawa Prefecture is thought to have no dams, but there are 47 dams, 27th.There are eight dams in Tokyo, then 13 in Kanagawa Prefecture, and 15 in Saitama Prefecture.

So how many dams do you have in the world?It is said that there are about 50,000 units, although the exact number is unknown (Table 2-7).The most common dam is in the United States, and there are about 9,300 units.Next is 4,700 in China and 4,600 India, and Japan is the second largest after India.In Russia, which has a vast territory, it is surprisingly few, with 91 units.

By region, Asia has the most dam, about 34,000, about 14,000 in the North -South America, about 6,300 in Europe, about 2,600 in Africa, and about 1,800 in the Middle East.however,……

>>第1回 第3章の続きを読む（PDFダウンロード）

2nd: Dam history

Last time, I explained what a dam is and what kind of structure it is.Dams have been built for a long time, and their history has been nearly 5,000 years.Some dams have been used for nearly 3,000 years.In Japan, there are no clear materials, but it is said that dams have been built since the Asuka era.And the dam can be used longer than other structures.This time, we will introduce the history of domestic and overseas dams and explain the life of the dam.

In the history of overseas dams, it goes back to Egyptian civilization.Here are four dams: Koshiiishdam, Sad El Cafaradam, Gcodam, and Na El Ashidam.

Koshiiishdam was built by King Menes in Egypt around 2,900 BC, about 4,900 years ago.It is considered the oldest record in the history of the dam.Koshiiishdam is said to have been controlled to Memphis, about 20 km downstream, about 20 km downstream, about 15m high on the Nile River and about 450m in the top of the dike (the width of the dam).Memphis is an ancient city located 20 km south and near Meet Lahina from Giza (southwest of Egypt, the capital of Egypt), famous for the pyramid of Kufu.However, Koshiiishdam has not been discovered until now.

Sad El Cafaradam is the world's oldest dam that exists as archeological sites, and is estimated to have been built about 4,800 years ago and around 2,750 BC. It is a masonry dam with a height of 11m and a 106m top of the embankment length (the amount used is about 100,000 tons). It is believed that this dam was supplied to workers and livestock working in a stone -cutting place during pyramid construction. In any case, there was a dam about 5,000 years ago. Sad El Cafaradam has shown that the dam itself did not have flood vomit (Kozubaki) from the excavation survey, and it is estimated that river water has been broken from the central part 40 years after construction. It has been. In addition, the reign of the Egyptian 12th Dynasty of the 12th Dynasty of Amen Mhatt IV remains that a dam for supplying irrigation water has been built on farmland formed by reclamation.

In addition, the Mesopotamian civilization, which is one of the four major civilizations, has been recorded that a dam was built on the Euphrates River and Euphrates.In the Indus civilization, the Dam archeological site about 4,000 years ago was found in the Marshkai valley on the downstream river (Fig. 1).

GCODADAM has been recorded in China, about 240 BC, more than 2,200 years ago, and a Gcodum with a height of 30m and a 300m peak length of the Tsutsumi was built on the Guko River in the Yellow River basin.This dam is ...

>>第2回 第1章の続きを読む（PDFダウンロード）

In the history of Japanese dams, the pond for irrigation began, and from the latter half of the Meiji era, dams were built with concrete.Below are the four dams: Sayama Pond Dam, Mannoike, Honkawachi Takabe Dam, and Funobiki Gomonmatsu Dam.

Sayama Ike Dam is the oldest pond in Japan in Osaka Prefecture (Figure 2).Sayama Ike Dam has a record in the Nihon Shoki and Kojiki that was built in 616 AD, but it is not clear when it was actually built.However, it is determined to be 616 based on the annual ring age measurement result of wood used in the gutter in the reservoir, and it is thought that there is no doubt that it will be built at this time.The Sayama Ike Dam has been renovated by Gyoki in the Nara era (responsible for the establishment of the Great Buddha of Todaiji Temple) and the Kamakura period (a monk who rebuilt the Todaiji Temple Buddha Hall, which was destroyed by the southern city of Hira Shibu).

Manno Pond is a pond for irrigation in Japan in Shikoku (Fig. 3). The water storage is 15.4 million tons, and it is thought to have been built around 704. In 818, heavy rains broke the weir, and despite the difficulty of restoration, Kukai was restored in just two months in 821. Manno Pond is still used as a pond for irrigation. Kukai is the founder of the Shingon sect, known for the Kobo Daishi's shogun (a name after death, a name based on the evaluation of his life performance), and is an early Heian monk. He is young and excels in learning, and at the age of 30, he has been selected as a messenger and travels to China. At this time, he moved to China together, the Supreme, who opened Hieizan Enryaku -ji Temple with the founder of the Tendai sect. They have learned not only Buddhism but also civil engineering engineering, pharmacy and medicine in China, and Kukai seems to have repaired the Manno Pond weir using the cutting -edge civil engineering technology learned in Tang.

Motokawachi Takabe Dam is Japan's first water supply dam in Nagasaki.Completed in 1891 (Meiji 24), 1891 (1891).With a 6m zone -type earth dam, ...

>>第2回 第2章の続きを読む（PDFダウンロード）

What is the life of the dam? The dam is a water storage facility, so if the water cannot be broken, the life of the dam has exhausted. For example, if the sediment caused by the inflow of sediment from the upstream, if the reservoir is buried, the water will not be able to accumulate and the life will be exhausted. Also, if it breaks, the function as a dam will not be able to be fulfilled, so it can be said that this is also exhausted. The dams built in ancient times had no flood vomit, so they broke after flooding several times. Therefore, it is thought that ancient dams had only been lasted for decades. It is said that the first flood vomit was established in the dam at the Maribu Dam, which was built around 750 BC. The life of the dam has been dramatically extended due to the establishment of flood vomit.

So how much sedimentation in the dam will stop working?In the case of Japanese dams, it will not decrease for at least 100 years, as it is built for 100 years.However, after that, as the amount of sedimentation increases, the function will decrease.If you leave it alone without any measures, you will gradually lose the function of the dam.

Of course, we take various measures for this sedimentation.for example,……

>>第2回 第3章の続きを読む（PDFダウンロード）

3rd: Dam type

Last time, I explained the history of domestic and overseas dams and its life.This time, I will explain the type of dam.Dam categories are often divided into materials and models.Category for materials used includes concrete dams using concrete, soil, rocks, and filts using stones.In the case of concrete dams, there are gravity, arch, and battress type.In the case of Fildum, there are Earth Dam, Rock Dam and Facing Dam.In addition, there is a complex (combine) dam that combines concrete dams and fildum.

Concrete dams are roughly divided into five models: gravity type, arch, gravity archidam, battress type, and hollow gravity type listed below.

Gravity concrete dams are the most constructed of concrete dams (Fig. 1).There are about 1,200 concrete dams built in Japan so far, of which about 92%are this model.Looking around the world, about 70 % of the dams are filedums using soil and rocks, and most of the remaining 30 % of concrete dams are made in gravity.The reason is that design and construction are relatively easier than other model dams.One of the major reasons is that the gravitational dam can be built even if the surrounding rocks are not so strong.

There are basically two types of concrete composition: external concrete and internal concrete.In the case of a gravity -type dam, the external concrete uses a strong concrete to prevent it from being damaged due to the invasion of water and the temperature change.On the other hand, the internal concrete is a concrete that emphasizes weight rather than strength.The gravity concrete dam is designed to withstand the water pressure by the concrete itself.Therefore, the basic shape (cross section) of the gravitational concrete dam is triangular.The upstream side is basically vertical.Since the water pressure grows in proportion to the depth from the surface of the water, it is an ideal form that resists the water pressure.

Archidam has a structure that conveys the pressure of water to the rocks on both sides, and has a slender shape than the gravity type.Therefore, it is important that the surrounding rocks are strong when building a dam.The most common of the archidam shape is the dome type.There are also parabolics and cylindrical ones (Fig. 2).The combination of concrete used is basically one type of external concrete in the case of a gravity dam, while the gravity dams use two types, while the archidam is used.This is due to the slender structure compared to the gravitational dam.

A gravity -type archedam is a dam that combines the stability of the gravity dam and the slenderness of the archidam.Gravity archidam was constructed in Japan to resolve postwar power shortage.At a time when it was difficult to secure enough concrete materials, the surrounding rocks were not solid enough to build an archidam, but it was constructed under location conditions that allow you to avoid the use of a large amount of concrete like a normal gravity dam.I did it.Therefore, most of them have been built by the 1960s.Since the late 1970s, cement, one of the concrete materials, has become relatively inexpensive, so gravity -type dams that are not so affected by rock conditions have been constructed.

The oldest gravity archidam in Japan is ...

>>第3回 第1章の続きを読む（PDFダウンロード）

Fildam is a structure built with natural sediment and rocks.Dam construction requires a large amount of ingredients.Also, many dams are built in the mountains, so it takes time and money to transport materials from a distant place.Therefore, there are many filadams using soil and rocks, which are familiar ingredients.Basically, the dam made of soil alone is called an earth dam, a dam made of soil, sand, gravel, and rock is called rock filadam.In addition, there is a facing dam that uses asphalt in addition to soil and rocks.

アースダムは、最も古いダム型式です。国内では、7世紀に造られた狭山池ダム（第2回、図3参照）が最も古いアースダム（ため池）となります。アースダムは、基本的に土を盛って造ることから、ロックフィルダムのようなゾーン型フィルダムに対して均一型フィルダムとも呼ばれます。国内では地震が多いため、堤高が高いアースダムは造られていません。対して、海外では地震が少ない地域に超巨大なアースダムがいくつもあります。世界最大のアースダムは、タジキスタンにあるヌレークダムで、高さが300m、堤体積が5,800万m³です（図4）。

Rock filadam is ...

>>第3回 第2章の続きを読む（PDFダウンロード）

Dams are intended to accumulate water, while the sabo dam is intended to prevent sediment from earth and sand to prevent sediment -related disasters from earthlets instead of water (Fig. 6).The shape of the sabo dam is very similar to the shape of the general dam.However, the center of the dam is made lower than on both sides, and a large hole is open on the dam itself.Like a gravity -type dam, if the overall height is the same, the dam will fall down by water pressure, so the center is lowered so that the water does not accumulate as much as possible, and a hole for draining water is made.。

In addition, the slope (inclination) downstream of the dam is steeper than the gravity -type dam.If the slope on the downstream side is gentle, the sediment that flows out at the same time as the water will hit the water at the time of the dam will be shaved, so the slope is rushed to prevent it.Sabo dam is ...

>>第3回 第3章の続きを読む（PDFダウンロード）

4th: Dam structure

Last time, we introduced various types of dams.This time, I will explain the structure of the dam.Dam design is based on three principles: not falling, not sliding, or being destroyed by water pressure.In addition, the strength and terrain of the surrounding bedrocks are important as a condition for selecting a dam model (fildam, concrete dam).Ideally, the dam to be built is as small as possible, and it is ideal to secure a large amount of water storage.The materials used for the construction of the dam include soil, earth and sand, rocks, concrete, asphalt, and rubber.

After completion, the dam will receive a large water pressure from the upstream reservoir.In the design of the dam, the study to make the structure that can withstand this water pressure is based on the following three principles (Fig. 1).

A study of falling is a study to prevent dams from being turned upside down due to water pressure.You may think that a huge structure called dam will not fall.However, the power of water is very huge and horrible.For example, in the debris flow, hundreds of tons of tons of tons of tonnes are on a muddy current and move like a pebble.In addition, the tsunami can fall for thousands of tons of reinforced concrete buildings and tons of seawalls, and hundreds of tons of ships may be carried several kilometers away from the sea.Therefore, the shape of the dam is determined from the calculation of the water pressure assumed to occur in the dam, and the structure is designed so that it does not fall.

A study of sliding is to prevent the dam from slipping with water pressure and starting to move.If a shearing force occurs between the dam and the surrounding rocks, the dam itself starts (slides), which breaks down.For this reason, the shape is determined so that the dam does not start, and ...

>>第4回 第1章の続きを読む（PDFダウンロード）

I've heard an interesting story from a university professor about the selection of dam construction sites.According to the professor, "In the past, there was a master at the XX station in the Ministry of Construction, and the person in charge of the dam construction plan brought a map near the planned land, and looked at the map for a while and said," I made it here.Please point out and decide where to build the dam. "

Even if the biggest purpose of the dam is to accumulate water, if the dam body is large, the cost will be bulky and the construction period will be longer. Therefore, it is important to build a dam body with a small volume and store more water. To that end, look at the map near the dam construction site, as the professor's story (I don't know the truth of the thing), and how high and how high the dam will accumulate. It may not be a mistake to judge a person who is long for spatial cognitive ability that can imagine whether it will be. The judgment is, of course, and information such as the geological status of the construction site. In addition, if you know how the terrain was formed, you may be able to determine the location by pinpoint.

A place where water is easy is not necessarily a place where dams are easy to build.The construction location of the Kurobe Dam, which boasts the highest height in Japan, has been known before the war, but it has been abandoned because there is no way to carry the materials and it costs a huge cost.I did it.However, after the war, in order to solve the shortage of power in the Kansai region ...

>>第4回 第2章の続きを読む（PDFダウンロード）

Dams are classified by the main materials used.This section describes concrete dams, filadams, and faceing dams.

The construction of the concrete dam uses a coarse aggregate of 80 to 150 mm in size (gravel mixed with water and cement when making concrete) (Fig. 2).A large -dimensional coarse ingredient is used for small dimensions, which increases the amount of cement and water, which makes it easier to cause temperature cracks and dried shrink cracks.In addition, by increasing the rough skin dimensions, it is possible to reduce the amount of cement and water as much as possible as much as possible, and reduce the surface area of the coarse ingredients in contact with the mortar.Since the coarse ingredients are large, the weight of the dam concrete itself increases as the ratio of the aggregate is increased in this way and the ratio of the aggregate is increased.

Fildum has a rock filadam and earth filadam, which is made by combining natural ingredients.

In the case of rock filadam, the center of the dam is built with clay material that is difficult to pass through water (Fig. 3).At that time, if there is a lot of sand in the clay, the workability will improve, but ...

>>第4回 第3章の続きを読む（PDFダウンロード）

5th: Dam construction

Last time, I explained the structure of the dam structure, such as the three principles, formats, and materials used.This time, I will introduce the construction of the dam.The shape of the dam and the construction method vary greatly depending on the material used.We will also introduce concrete dams that use concrete, filadams that combine natural materials, and CSG methods built with mixture of water and cement for local generated materials.

Concrete dam construction includes conventional columnar method, expansion rare method, and RCD method.I will explain these three.

The columnar construction method (block construction) is a representative construction method of concrete dams.The dams to be built are blocked on the left and right shore, and if it is longer in the upper and lower streams, the upper and lower stream directions are also divided into blocks.In "Hoover Dam" (USA) (Fig. 1), which is said to have established a modern dam construction method, concrete block construction is 1 day1feet (hit concrete 1 FET a day), and the width and length are within 15m.increase.If you apply it to the actual construction, if one lift (concrete height to be constructed at one time) is 2m, 1feet is about 30 cm, so it will be inherited in about 7 days.In other words, it is ideal to use one lift concrete at about one week, and to construct the width and length of one block as 15m.

If the width and length of one block are set to 15m or more, the temperature stress associated with the hydrate heat of cement increases the possibility of cracks between the blocks.For this reason, the difference between the rigidity between the next lift and the lift that was driven one week ago is not large, and the rigidity of the lift is generated due to the temperature due to the temperature due to the detention of the lift below.It also decreases.These are the results of the study of the above -mentioned Hoover Dam, and are currently the norms of concrete dams in concrete dams, based on the subsequent experience of concrete dams.In this columnar method, the unevenness of the paradise in the up and down direction of the block is attached so that there is no shift between blocks when large water pressure is applied.

Expansion Reya method (ECLM method: Extended Layer Constration Method, surface method) is thinner (less than 1 m) of the lift to be driven at a time (less than 1 m), and does not perform joints or pipe cooling.Multiple blocks are constructed together (Fig. 2).Until now, columnar construction methods were the mainstream in concrete dam construction.However,……

>>第5回 第1章の続きを読む（PDFダウンロード）

Fildam is roughly divided into two types: soil, sand and gravel, rockfylm made of rocks, and earth dams made only with soil.

The lockfylum uses a highly water -based clay material in the center of the embankment (called the core) (see Fig. 3).The core zone is carefully performed through human hands, as it has an important function to stop water.In particular, the part that is in contact with the bedrock with large water pressure is installed by stuck in the bedrock with human power.Most of the other constructions are mainly used mainly in heavy equipment soil work.Furthermore, using vibration tumping rollers for rotation, the number of times is more common than filter zone and rock zone (Fig. 4).In the construction of a filter zone, it is common to lay a relatively fine rock material with a bulldozer and tighten it with a rotation roller.

Until the 1950s, the construction of the rock zone had a method of dropping a hard and large rock (lock material) from a high place with a high -voltage of several mm to several tens of meters (a stoning water construction method).In the 1960s, turning pressure using a bulldozer and dump trucks began to be performed, and now it is a common construction method to roll with a large vibration roller.

ロックフィルダムで国内最大となる「徳山ダム」の堤体積は1,370万m³で、コンクリートダムで国内最大の堤体積を誇る「宮ケ瀬ダム」（200万m³）の6倍以上です。さすがに、ダムの堤高はコンクリートダムの方が高いものが多いものの、……

>>第5回 第2章の続きを読む（PDFダウンロード）

The CSG (Cemented Sand and Gravel) method is a new method used as concrete material as it is, without cleaning, class and granular adjustment on gravel (sand and stone) on the riverbed around the dam.Originally, concrete is made of about 70%of the composition material from aggregates.In the case of conventional concrete dams, regular examinations are performed from the perspective of securing the quality of the aggregate used, and those that do not meet the standards are discarded.However, in recent years, it has become difficult to collect a large amount of high -quality aggregates as before, so the CSG method has been developed.

The manufactured CSG material is sprayed with a bulldozer like the RCD method, and the dam embankment is built by pressure with vibration rollers as shown in Fig. 5.The shape of the dam built by the CSG method is ...

>>第5回 第3章の続きを読む（PDFダウンロード）

6th: Future Dam

Last time, I explained the construction of the dam.Renewal work, which is said to be a dam regeneration, has begun, in response to flood damage that has become intense due to recent abnormal weather.In addition, various facilities, plans, and events that use the area around the dam and dam lake as tourism resources and regional revitalization cigarettes are also being held.This is the last round.We will introduce the way of the dams in the future, such as the playback of the dam and the value of the dam as a tourism resource.

Dam regeneration refers to renewal construction aimed at improving functions such as enhancing flood adjustment capabilities of existing dams.In recent years, flooding of rivers due to intensive rain due to abnormal weather and guerrilla heavy rains has frequently occur nationwide, and the damage has been increasing year by year, such as the broken embankment caused by abnormal floods.On the other hand, the Ministry of Land, Infrastructure, Transport and Tourism has launched a guideline for advance release at the Toshiwater Dam to enhance the flood adjustment function of the dam.However, this is not enough for flood damage, which is expected to increase in the future.Nevertheless, there is no time to set up a new dam over several decades.Therefore, renewal work of dams that effectively utilizes existing dams is underway.

The method of increasing the amount of water storage of the dam is to increase the bulb (Fig. 1).Raise the dam is to accumulate new concrete and the like on the downstream side of the existing dam and increase the dam even higher.In this raising work, it is important to ensure the unity between the existing dam and the newly established part, so the surface part in the lower flow of the existing dam, which is expected to deteriorate over time, to integrate with the new part.I am.

In addition, as a construction to enhance the flood adjustment ability of the dam ...

>>第6回 第1章の続きを読む（PDFダウンロード）

Dam construction brings great economic effects to the local area.Replacement road construction for dam construction is often performed by local construction companies.In the construction of the dam itself, the construction company is often JV (co -corporate), and in most cases, local construction companies are added.The cost of the dam body construction can be 10 billion yen, which is a major revenue for local construction companies.However, since these are limited to the economic effects during dam construction, it is necessary to consider tourist projects centered on dams after the dam is completed.

By completing the dam, there is a lake with a lot of water on the upstream side. The seasonal scenery around the dam is published in the tourist guide (Fig. 2). Such a dam lake all over the country is a great tourism resource. In fact, many artificial lakes made by the construction of dams are tourist attractions, and in most cases, the lake is named into the area, so it is a detonation that revitalizes the area where depopulation is progressing. In some cases, it is a drug. Around the dam lake, there may be a campsite and hotel that will be a tourist resource, as well as a sports facility and a comprehensive sports ground where you can enjoy recreation. The dam management facility itself is a dam or a local museum, or it may be a facility where you can get dam cards (cards distributed to tourists who have visited the dam). Products such as local dam curry, which can only be eaten around the dam, are also popular all over the country.

Recently, there have been tours where you can experience dam facilities.For example, visit the audit corridor in the dam, ...

>>第6回 第2章の続きを読む（PDFダウンロード）

Dams are in our lives, such as supplying and power generation to people, generating agricultural water for irrigation and manufacturing, and adjusting floods to suppress river flooding due to heavy rain.It is a facility that provides indispensable items.On the other hand, forcing changes in the living infrastructure itself, such as the migration of local residents in the dam lake for dam construction, and the impact of rare flora and fauna in the planned land associated with dam construction, and Mt.It is also true that dam construction work, such as body digging and clay dumps, has damaged the surrounding nature.

Previously, there were businesses that were promoted with a dam construction plan without regard to changes in social conditions.Furthermore, more than 100 dam businesses have been canceled due to unnecessary dams due to extra water and the opinions of the "green dam" that makes use of the water retention of mountain trees.On the other hand, it is also true that dams for flood control such as flood control have been reviewed for landslides and huge flood damage due to frequent torrential rains in recent years.In addition, the newly created dam lake was adapted to the environment after the dam was completed.

>>第6回 第3章の続きを読む（PDFダウンロード）