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In the successful defensive battles of ancient times, the relative abundance of materials and water was the key to success. Pen | fun | pavilion www. ｂｉｑｕｇｅ。 ｉｎｆｏ

However, in many cases, it is possible to prepare relatively sufficient materials, but the water source is a big problem.

Because in many cases, the enemy, as the attacking side, will not be unaware of the means of attack of cutting off the water source, the biological contamination of the water source, or the direct cutting off of the surface water source, is the corresponding representative of this method.

In Cloudsdale, the main source of water is groundwater and the storage of water from some canals brought in nearby as a source of water reserves.

Yang Wengzi is not too worried about the big problems with conventional water use, but if these canals are destroyed by the Huns or even use corpses to pollute the water source, then just relying on groundwater, there will not be a big problem in a short time, and the situation may worsen after a long time.

This is mainly related to the adequacy of groundwater sources.

The area around Cloudsdale is a dense grassland or even a lush forest, so groundwater resources are not too scarce.

However, in many cases, groundwater cannot be used directly, and in some cases, if the groundwater resources show signs of drying up, it is undoubtedly a very important test for the defenders fighting the city.

Because if there is a shortage of food, you can use some emergency methods to last for a while, but if there is a shortage of water, then it is very likely that in less than five days, there will be a big problem.

In order to avoid the lack of water in the defensive battle, Zhang Jiashi specially sent members of the Mo family to explore water sources in some cities that were likely to be besieged, and then carried out the excavation of wells.

In fact, such measures are not necessarily effective in avoiding the possibility of depletion of groundwater, because to a large extent, groundwater in a place is likely to be a source of its own.

If one well runs dry, it is inevitable that other wells in the same city will also have such a problem.

Zhang Jiashi's practice was more to avoid being poisoned by the wells, which would cause some of the inherent wells to fail to function and cause the defenders to collapse.

......

In the history of warfare, there is no shortage of examples of wells being poisoned in the defense of a city, either because the defenders were unprepared or because they were too strong.

Maybe one or two wells that are unusable for a short time will not affect the battle situation, but there is no doubt that if this situation is not taken seriously, then if something really goes wrong, Zhang Jiashi himself will have no place to cry.

And in a sense, there is only a thousand days to be a thief, and there is no reason to prevent thieves for a thousand days. Under this premise, Zhang Jiashi thought of increasing the number of wells as much as possible, and then avoiding this situation.

There are more than a dozen relatively large wells in the city itself, and in some places, the wells are in some large mansions and even county mansions.

It is unlikely that these areas will be poisoned.

And as a veteran with quite rich combat experience, Yang Wengzi will not let this happen at will.

Zhang Jiashi knew about this situation, and he asked the Mo family personnel to dig new wells in Cloud City, mainly in some places far away from the original wells, and many of these places themselves are used as material storage areas.

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From the perspective of human history and biology, groundwater is very closely related to human beings, and well water and spring water are the most used groundwater in our daily life.

In later generations, groundwater can be exploited and used as a source of water for residents' domestic water, industrial water and farmland irrigation. Groundwater has the advantages of stable water supply and less pollution. Groundwater with special chemical composition or high water temperature can also be used as a medical treatment, heat source, beverage and raw material for extracting useful elements.

In pits and tunnelling, large amounts of water can inflow, causing hazards to the project. In plains and basins with shallow groundwater level, submersible evaporation may cause soil salinization, and in areas where the groundwater level is high, the soil is too wet for a long time, and the surface is stagnant, it may produce swamping, causing harm to crops.

However, groundwater can also cause some hazards, such as too much groundwater, which can cause railways and highways to collapse, inundate mining tunnels, and form swamps. At the same time, it should be noted that groundwater has an overall balance problem, and it cannot be blindly and over-developed, otherwise it is easy to form underground cavities, stratum subsidence and other problems.

As an important body of water on the earth, groundwater has a close relationship with human society. The storage of groundwater is like forming a huge reservoir underground, with its stable water supply conditions and good water quality, it has become an important source of water for agricultural irrigation, industrial and mining enterprises and urban life, and has become an indispensable important water resource for human society, especially in arid and semi-arid areas where water is scarce on the surface, and groundwater often becomes the main local water supply source.

The spatial three-dimensionality of the groundwater flow system is one of the main differences between groundwater and surface water. The vertical hierarchical structure of groundwater is a specific representation of the spatial three-dimensionality of groundwater. The basic pattern of the vertical hierarchy of groundwater under typical hydrogeological conditions. From the surface to a certain depth of the underground impervious bedrock, it can be divided into two parts: the gas-containing zone and the saturated water zone.

Among them, the aeration zone can be further divided into three subzones: soil water zone, intermediate transition zone and capillary water zone, while saturated water zone can be divided into two subzones: sub-zone and confined water zone. From the point of view of water storage form, there is bound water and capillary water corresponding to the gas-containing zone, and gravity water corresponding to the saturated water zone.

The above is the basic model of groundwater hierarchy, and the actual hierarchy of groundwater in different regions is not consistent under specific hydrogeological conditions. Some levels may be fully developed, while others are not. For example, in the severely arid desert area, the aeration zone is very thick, and the saturated water zone is buried deep in the ground, or even basically non-existent; on the contrary, in the rainy humid area, especially in the low-lying and flood-prone area where the groundwater discharge is not smooth, the aeration zone is often very thin, and even the surface of the underground diving surface is exposed, so the groundwater hierarchy is not obvious.

As for the existence of confined water belts, specific water storage structures and confined conditions are required. However, this kind of structure and confined conditions are not available everywhere, so the distribution of confined water is greatly limited. However, the regional differences in the above-mentioned groundwater hierarchy do not negate the overall regularity of the vertical hierarchy of groundwater. This hierarchy is of great significance for people to understand and grasp the properties of groundwater, and has become the basic basis for classifying groundwater according to burial conditions.

The vertical hierarchical structure of groundwater also shows that there are obvious differences in the forces on groundwater at different levels, forming different mechanical properties. For example, the hygroscopic water and film water in the air-encapsulated zone are combined on the surface of the rock and soil particles by the action of molecular suction.

In general, the finer the rock and soil particles, the larger the specific surface area of the particles, the greater the molecular adsorption capacity, and the higher the content of hygroscopic water and film water. Among them, hygroscopic water, also known as strongly bound water, the molecular attraction between water molecules and the surface of rock and soil particles can reach thousands or even tens of thousands of atmospheres, so it is not affected by gravity, can not move freely, has a density greater than 1, does not dissolve salts, has no conductivity, and cannot be absorbed by plant roots.

Thin film water, also known as weakly bound water, is affected by molecular force, but the adsorption force between film water and rock and soil particles is much weaker than that of hygroscopic water, and with the thickening of the film, the effect of molecular force continues to weaken until it transitions to free water. Therefore, the properties of film water are also between free water and hygroscopic water, which can dissolve salts, but the solubility is low.

Thin film water can also move from the surface of a thick film to the surface of a thin film water layer until the thickness of the two films is comparable. Moreover, the water in the outer layer can be absorbed by the plant roots. When the external force is greater than the shear strength of the bound water itself (the ultimate ability to resist shear stress failure), the membrane water can not only move, but also transmit hydrostatic pressure.

Capillary waterWhen the voids in the rock and soil are less than 1 mm, the voids are connected to each other, just like capillaries, when these small voids store liquid water, capillary water is formed. If the capillary water rises from the groundwater level, it is called capillary rising water, and if it has nothing to do with the groundwater surface, the capillary water formed by the infiltration of the ground is called hanging capillary water.

Capillary water is subject to gravity and negative hydrostatic pressure, and its moisture is continuous, and can connect the saturated water belt with the air belt. Capillary water transmits hydrostatic pressure and can be absorbed by plant roots.

Gravity waterWhen the voids in the aquifer are filled with water, the groundwater will infiltrate and move in the rock and soil pores under the action of gravity, forming permeable gravity water. It is under the action of gravity that the groundwater in the saturated water zone moves from high to low and transmits hydrostatic pressure.

In summary, groundwater not only forms different hierarchical structures such as binding water, capillary water and gravity water in the vertical direction, but also has different forces at each level, forming a vertical mechanical structure.

The existence of wells is a thought embodiment of the use of groundwater.

Wells, engineering structures mainly used to extract groundwater. It can be vertical, oblique and a combination of different directions, but it is generally vertical, which can be used for domestic water intake, irrigation, and can also be used to hide or store some things.

Wells are of great significance to the development of human civilization. Before the advent of wells, human beings lived in water and could only live in places with surface water or springs.

According to a later view, China was one of the earliest countries in the world to develop and utilize groundwater. The earliest water well that has been discovered in China is the well of the ancient cultural site of Yuyaohe, Zhejiang, which dates back to about 5,700 years ago. It is a fairly elaborate square timber well, with a depth of 1.35 meters and a side length of 2 meters. It can be inferred from this that the appearance of the primitive form of the well was much earlier.

According to the buried distribution of groundwater and the lithological structure of the aquifer, humans have created a variety of well types.

Chinese folk have long been accustomed to using circular tube wells. The diameter is mostly 1~2 meters, and the depth is generally a few meters to 20~30 meters. Such wells are only suitable for the extraction of shallow groundwater.

For the exploitation of deep groundwater, tube wells with a small diameter (a few centimeters to tens of centimeters) and a considerable depth (tens to hundreds of meters) were developed.

Drilling tube wells requires specialized drilling machinery and more complex processes. As early as 250 B.C., in present-day Sichuan Province, China, a large number of wells with a depth of tens or even hundreds of meters were dug in the hard rock to mine underground brine for boiling salt. After drilling a well to reveal a confined aquifer containing brine, groundwater often flows out of the well on its own, and such wells are artesian wells.

Later countries mainly used tube wells to extract groundwater, power drilling rigs to drill wells, and various pumps as water lifting tools. Before 1949, only a few cities in China had a small number of tube wells, and there were only a few wells that used power to lift water, but by 1980, the number of power water lifting wells in the country had grown to 2.2 million, which were widely used for water supply in industrial and mining towns, agricultural irrigation and other purposes.

Adapting to different formation conditions, inclined wells and horizontal wells were developed. In order to increase the amount of water produced by the well, radiant wells that combined a horizontal water filter pipe with a vertical wellbore appeared later. The diameter of the main wellbore of this kind of well can reach several meters, and the horizontal water filter pipe is tens of meters to more than 100 meters long, which is suitable for mining loose or semi-cemented aquifers with shallow burial and small thickness, and can also be used to intercept the undercurrent under the riverbank and riverbed. Radiant wells in the gravel layer can produce up to 1 cubic meter per second.

The water output of radiant wells drilled in the loess of northwest China is often more than ten to dozens of times higher than that of tube wells of the same diameter.

And there is also a type of well produced by Chinese culture, called karez.

Qanats are non-powered water absorption facilities that use and develop groundwater and can self-flow to the surface through underground channels for irrigation and domestic water. Karez has a long history and is widely distributed in the Turpan Basin.

Qanats are a product of Chinese civilization.

Sheng Hongzhi's "Jingzhou Chronicles" recorded: "There is a strong village in the north of Sui County, there is a heavy mountain in the south of the village, and there is a hole under the mountain. Another cloud: Draw a well, then the water of the wells moves, that is, this is the Shennong Society, and the temple is often worshipped. ”

Nine wells are self-penetrating and interconnected, and one well leads to all wells, which is the same as the structure of the qanats connected by underground culverts.

Sima Qian's "Historical Records: The Five Emperors" cloud: "Su Su also made Shun pass through the well, and Shun passed through the well to hide the void. Shun is deep, and the elephant goes down to the earth well. Shun went out from the void. When Shun penetrated the well, he dug a "hidden hollow" (tunnel) from the side, which is very similar to the excavation method of the qanats. If the "hidden emptiness" is a horizontal tunnel, it is a qanats, which are historical sites in the 21st century BC, more than 1,000 years earlier than the legend that Persia had kanats in the 8th century BC.

"Zhuangzi Heaven and Earth" chapter cloud: "Zigong traveled south to Chu, against Jin, through Hanyin, and saw a zhang person, Fang will be a nursery, dig a tunnel and enter the well, hold the urn and irrigate, and use a lot of force, and see little success. Zigong said: 'If you have a weapon here, you will soak in a hundred furrows a day, and you will do a lot of work with little effort, and the master will not want it'?" Zigong introduced him to the advanced irrigation and water-lifting tool at that time, and the gardener replied, "I don't know, and I'm ashamed." Fearing the use of clever tools and distracting his mind, he insisted on digging tunnels to get water in accordance with the ancient method. It can be seen that in the Spring and Autumn Period, digging tunnels to extract water was an ancient technology, and this technology was applied to the large slope of the area, which can be dug into a well.

The "Chengjing" in the chapter of "Zhuangzi Qiushui" is "Kanjing". The frog is "good at a ravine of water, and the joy of crossing the well". This type of well seems to be the same as a gully, which should be a deep ditch or an underground culvert.

"Xunzi Zhenglun" is also cloudy: "The frog of Kanjing cannot be compared with the joy of the East China Sea." ”

The name of Kanjing officially appeared in the pre-Qin classics. (To be continued.) )

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