CATDOLL : CATDOLL: What are the positive and negative effects of hydroelectric power stations on the natural environment?

What are the positive and negative effects of hydroelectric power stations on the natural environment?

There are two types of hydroelectric power stations: those with dams and those without dams.

1.

Dams are common, such as the Three Gorges Dam and many other world-famous dams.

A power station with a dam blocks water through the dam, raising the water level upstream and thus using the water level difference to generate electricity.

All human activities change nature, and cannot be said to be beneficial to the "natural environment". Human activities are either beneficial to "humans" or detrimental to the "natural environment" or/and "humans themselves".

The most important function of a dam-type hydroelectric power station is not that it can generate electricity (this is its second most important function, because hydroelectric power generation is very environmentally friendly - compared to thermal power generation - it does not produce waste gas and waste residue), its greatest function is that it is a "water conservancy project", that is, the reservoir formed by the dam itself has important functions such as water storage and flood control. The reservoir can also be used for aquaculture, tourism and other purposes. Since the dam must use the terrain, this type of power station is mostly built in canyons, valleys and high-lying locations on both sides of the river. The rising water level also brings safety and convenience to shipping.

The negative impact is that it will inevitably cause the water level to rise. The rising water level will submerge a large number of rich vegetation and fertile and moist land on the river bank, forcing a large number of animals to relocate. Their previous homes will be submerged, and they may not know what to do in the new environment. A large number of precious trees will also be dormant under the water. After the dam is built, it will be difficult for aquatic animals to pass through the dam, which will affect the reproduction of fish (some fish will return to the upstream to reproduce).

Here you can refer to this article:

"Environmental Impact Analysis and Protection of Hydropower Development in Dadu River Basin"

2.

The second type of hydropower station is the untrimmed dam. This type is very common in the upper reaches (mountainous areas). The terrain in the upper reaches changes rapidly and the hydropower resources are abundant. This type of power station draws water from the upper reaches. Because the water pipe/hole is flat, after a few kilometers, the water pipe/hole forms a huge drop with the natural riverbed. Then the drop is used to generate electricity. If you see a few one-meter-thick metal pipes on the hillside going straight down from the top, it is this type of power station.

The advantage of this type of power station is that it is small in scale, easy to build and inexpensive. The water volume in the upper reaches is small (usually only a few dozen water - that is, a flow of a few dozen m3/s), and the water is often diverted away when diverting water. Therefore, there is a completely dry area in the middle of the stream. The aquatic plants in this area will die completely after the water flow is cut off, and fish will not be able to pass through this area. Compared with large (dam) power stations, this type of small hydropower station is generally built by the region, lacks a natural environmental impact assessment report, and causes great damage to the natural environment. There are many in Sichuan (I don’t know about the surrounding provinces). At the same time, it must be said that this type of hydropower station has brought electricity and income to relatively poor mountainous areas, and has greatly promoted regional education and economic development.

Finally, I would like to say what I said before: human activities have always brought disasters to nature. All the advantages and disadvantages are relative to selfish humans, just like we divide insects into beneficial insects and harmful insects according to human interests. Nature really has no way to express its suffering.

Request information about fish

The main purpose of fish swimming around underwater is to find food, because this is their only means of survival. Fish are cold-blooded animals, and their body temperature changes with the water temperature. Therefore, the changes in water temperature in different seasons greatly limit the range of fish activities.

Fish have different activity ranges in different seasons, and their activity locations change from time to time during the day. This is affected by changes in food and water temperature, and human interference cannot be ignored. Because there are many fishermen and tourists in some waters, fish survive in this environment and their anti-fishing instinct is enhanced. At the same time, they also become extremely alert.

Fish are greatly affected by the weather when foraging. When the weather is hot and humid and the air pressure is low, fish will become anorexic, and larger fish will hide in the water and not eat or move. On the contrary, if the water temperature is too low, the fish's metabolic function will slow down, and they will also refuse to eat. When the water temperature is suitable and the dissolved oxygen is sufficient, especially after the summer rain, the fish will become abnormally active, forage actively, and the bite rate will increase exponentially. When there is food in some places, the fish will transmit information to each other in a unique way and flock to find food. Once the reservoir is released, the water level will drop rapidly, and the fish will become terrified, hiding in deeper water and rarely eating. These are also the habits and characteristics of fish.

In short, fish have a habit of synchronous, directional and group migration in their life activities, and we call this phenomenon migration. Migration is a phenomenon. It is through this activity that fish meet the external conditions they need in a certain period of life, so that their population reproduction is reliably guaranteed. There are four main types of fish migration: reproductive migration, feeding migration, warming migration, and wintering migration. When fishing, we often find that carp, crucian carp, catfish and other fish species come from deep water to shallow water for mating in spring; carp in the reservoir will go upstream to the upstream water inlet to find food after rain in summer; after mid-autumn, fish will move from shallow water to deep water for wintering. All of the above phenomena are within the scope of fish migration habits.