Hot spring is a kind of spring water that naturally gushes out from the ground. The temperature of the spring mouth is obviously higher than the local annual average temperature, and it contains mineral water with trace elements beneficial to human health.
There are also many areas where wells are drilled manually, generally 600 ~ 2000 meters. Groundwater is pumped by deep water pump and is rich in many beneficial minerals. The water temperature is generally above 20 degrees Celsius, also known as hot spring well. Because of the different climate, latitude and altitude, it is difficult to unify the lower temperature limit of hot springs.
cause
The formation of hot springs can generally be divided into two types:
One is formed by magmatism in the crust, or accompanied by volcanic eruption. Due to the concentration of heat, a large amount of heat energy will be continuously released in the terrain area of extinct volcano with volcanic activity, the surface uplifted by crustal plate movement, and the uncooled magma under it.
Therefore, as long as there are pores in the nearby aquifer, it will not only be heated into high-temperature hot water, but also boil into steam, mostly sulfate springs.
The second is formed by the infiltration and circulation of surface water.
That is to say, rain drops to the surface, permeates downward, and penetrates into the aquifer in the earth's crust, forming groundwater (sandstone, conglomerate, volcanic rock, these good aquifers).
Groundwater is heated by geothermal energy below to become hot water, and deep hot water mostly contains gas, mainly carbon dioxide. When the temperature of hot water rises, if there is a dense impermeable rock above it to block the way, the pressure will be higher and higher, so that hot water and steam are in a high pressure state, and as long as there are cracks, they will rush up.
After the hot water rises, the closer it is to the surface, the pressure will gradually decrease. As the pressure gradually decreases, the gas contained in it will gradually expand, reducing the density of hot water, which is more conducive to the rise of hot water.
The rising hot water circulates repeatedly with the pressure (hydrostatic pressure difference) generated by the density difference of the cold water that sinks and heats later, resulting in convection. When the resistance of the open crack is small, the hot water rises along the crack and gushes out of the ground, so that the hot water continuously flows out of the ground. Form a hot spring
With the topography of high mountains and deep valleys, the surface water at the bottom of the valley may be higher than that of high mountains, and the groundwater level is in the middle and lower levels. Therefore, the bottom of the deep valley may be the place with the largest hydrostatic pressure difference, and the possibility of hot water rising from the bottom is the greatest. Most hot springs appear on the river bed of the valley.