When dams are built in the upper reaches of a river, the water temperature in the lower reaches of t

The impact of dams built upstream of rivers on downstream water temperatures varies from case to case. In general, dams can alter the natural flow and water level of a river, which can have a certain impact on the downstream water temperature.

Dams can intercept the flow of water from a river, lowering the water level downstream and slowing the flow rate. This will result in a change in the water temperature downstream. In general, if the construction of the dam causes the downstream water level to drop and the flow of water to slow downstream, then the downstream water temperature may become lower.

This is because the flow and heat dissipation downstream of the dam are somewhat restricted, resulting in lower water temperatures downstream.

However, the construction of dams can also have a positive impact on downstream water temperatures. For example, a dam can store water so that there is still enough water flow downstream to maintain a certain level during dry periods. This can prevent the downstream water temperature from rising excessively during the dry season, which helps to maintain the stability of the downstream ecological environment.

In addition, dams can also improve downstream water quality by regulating water flow. For example, under the regulation of dams, the probability of downstream flooding can be reduced, and the downstream water quality can also be made more stable and pure. This also has an impact on the downstream water temperature.

In short, the impact of dam construction in the upper reaches of the river on the water temperature of the downstream is complex, which is not only affected by factors such as dam type and construction method, but also closely related to the local climate and geographical conditions. Therefore, when building dams, it is necessary to consider a variety of factors to assess and prevent possible impacts.

The water in the reservoir is hotter in winter and cooler in summer than in the absence of a dam. When the reservoir water flows into the river, the temperature of the river changes accordingly. This has an impact on the flora and fauna in both reservoirs and rivers, making their native environment unfamiliar.

Theoretically, there are positive significance and effects such as regulating water resources (spatio-temporal allocation), power generation, shipping (only beneficial to the upstream), flood control, etc., but I think that from the perspective of natural ecological maintenance and actual utilization effect, the negative effects are even greater

1. In terms of water resource allocation, the rainy season (China's monsoon climate characteristics are usually manifested as seasonal or short-term heavy rainfall) usually does not play an effective role in flood discharge, and flood discharge usually aggravates the damage to the middle and lower reaches of the river; During the dry season, stakeholders usually need to store water for their own economic interests, causing water difficulties for life, production (mainly agricultural irrigation) in the middle and lower reaches of the river (there are many relevant examples in China, including some well-known water conservancy projects);

2. Cause sediment accumulation and riverbed elevation in the middle and lower reaches of the river, and aggravate flood disasters under monsoon climate conditions;

3. Artificially cut off and destroy the living environment of river organisms (mainly fish), and fish resources are increasingly depleted (many fish have migratory spawning habits, and the reservoir dam body largely cuts off the migration route of fish);

4. If it is a large-scale reservoir, especially a super-large reservoir, it will also strongly change the landform because of the huge water conservancy project, which is easy to cause landslides, debris flows, ** and other geological disasters (related examples are the same as 1).

Upstream of the dam: Affected by the reservoir, the water level of the river has risen significantly, and the river flow rate is slower than before the construction; Downstream: Due to the regulation of the reservoir, the seasonal variation of river runoff is slower than that before construction.

After the dam is built, the water level of the river section where the reservoir is located rises, and the elevation difference in the basin where the original reservoir section is used as the erosion datum decreases, and the flow rate slows down, which will affect the river and the organisms in Dou Zhaoxiao. The accumulation of reservoirs also causes the groundwater table to rise, exacerbating waterlogging upstream.

The purpose of building a barrage dam is to raise the upstream water level, and when the quality of the water remains the same, increase the height of the water and increase the gravitational potential energy When the water flows down, the gravitational potential energy is converted into kinetic energy, and the more gravitational potential energy there is, the more kinetic energy is converted

The role of the dam is to hold back the high and make up for the low, that is, to store water during the flood period and reduce the possibility of flooding downstream; Water is released during the dry season to replenish the river so that there is not too little water in the river. In general, the amount of water downstream will decrease after the dam is built, but due to the regulating effect of the reservoir, the downstream flow of the river will be relatively stable and the flow rate will slow down throughout the year.

After the dam is built on the river, what is the impact on the river downstream of the dam?

After the dam is built on the river, the impact on the downstream river channel is as follows: (1) destroying and changing the unique function and structure of the river basin ecosystem; (2) Eutrophication or poisoning of water quality in the reservoir area; (3) changing the sediment sedimentation pattern, resulting in the narrowing of the estuarine and bay flood plain and the erosion of the coastline; (4) the downstream channel of the dam is cut down, the river bank is eroded, and the salinity in the river and estuary water increases; (5) It is possible to induce landslides and landslides in the reservoir area; (6) Irrigation caused soil fertility loss and aggravated salinization; (7) lead to the reduction or destruction of vegetation or biological species; (8) The invasion of alien species leads to ecological harm; (9) Submerging cultural relics and historic sites or causing the loss of the ornamental value of the original natural landscape. Hope mine can help you <>

Hello dear, I am happy to answer for you: the reason why the water level of the river downstream of the reservoir has become lower after the construction is because the reservoir is a living lake. That is to say, in the case of a certain dam height, the reservoir capacity is fixed, so as long as the amount of upstream water does not regret or guess the change (the upstream water is only related to the water volume of the source, and has nothing to do with the dam itself, the reservoir dam will not affect the upstream water), the downstream water volume should not change, because as long as there is a drop of water flowing into the reservoir, there must be a drop of water flowing out of the reservoir, no matter how large the reservoir capacity is.

Of course, you can say that the water surface of the reservoir is causing the evaporation of water, but a reservoir like the Three Gorges built in a humid area (where the precipitation is greater than the evaporation and the evaporation is not large) (and because the water surface area of the Three Gorges has not expanded much because it is in the canyon), it still causes a serious reduction in the amount of water downstream.

The construction of the reservoir will have a certain impact on the downstream rivers for the following reasons: 1Impounding effect:

The construction of the reservoir allows the upstream water chain to be impounded for a certain period of time, resulting in a decrease in the flow of water downstream. 2.Flood season scheduling:

The reservoir is dispatched for flood control and flood season, and the amount of water dispatched is small, which will lead to a decrease in the downstream water level in an unfavorable situation. 3.Terrain changes:

The construction of reservoirs may lead to changes in the topography, such as reservoir siltation, which will reduce the area of the river channel and lead to lower water levels downstream. 4.Aftereffects:

After the construction of the reservoir, the ecological environment downstream will also change with the change of dispatch, which will also affect the water level of the river. In summary, there are many factors influencing the lower water level of the downstream river after the construction of the reservoir, which needs to be analyzed according to the specific situation.

Hello dear, after the construction of the reservoir, the reasons for the low water level of the old river are mainly as follows: the reservoir intercepts the water flow: after the construction of the reservoir, a part of the water flow will be intercepted in the upstream, so that the downstream lacks a part of the water flow from the upstream, resulting in the reduction of the water level of the downstream river.

Water storage and water management: The reservoir management department carries out water storage and release scheduling of the reservoir, in order to regulate the water level of the reservoir, it will store as much water as possible during the rainy season, and gradually release water during the dry season, which will lead to fluctuations in the water level of the downstream river. Riparian erosion:

When the reservoir is impounded, the upstream water level rises and the water pressure increases, which may cut the riverbed and riverbank, causing the downstream river water level to drop. Reservoir evapovaporation: Reservoir water storage will increase the water surface area and water depth, so that the water body of the reservoir will be exposed to the air for more time, thereby increasing the evaporation loss of the reservoir, resulting in a decrease in the water level of the river below the outlet of the reservoir.

Anthropogenic activity: Human activities around the reservoir can also affect the water level of the river downstream. For example, excessive water intake for agricultural or industrial purposes, or the discharge of wastewater into rivers can affect downstream river levels.

Natural conditions of the river: The morphology, topography and geological conditions of the river itself will also affect the upgrading of the downstream river water friend. For example, the narrowing of the river, the siltation of the riverbed, and the bending of the river channel will increase the flow rate of the river and reduce the water level.

Considering the differences in hydrological conditions, the above reasons have different degrees of effect on different reservoirs and rivers, so a comprehensive hydrogeological survey is required before the construction of the reservoir to minimize the impact on the water level of the downstream river.

Upstream of the dam: Affected by the reservoir, the water level of the river has risen significantly, and the river flow rate is slower than before the construction;

Downstream: Due to the regulation of the reservoir, the seasonal variation of river runoff is slower than that before construction.

Flood control of reservoirs.

Reservoirs are one of the widely used engineering measures for flood control in China. A comprehensive utilization reservoir capable of regulating and storing floodwaters should be built at appropriate locations in the upstream rivers of the flood control areas, and the reservoir capacity should be used to hold back and store floodwaters, so as to reduce the peak flow of floods entering the downstream rivers and achieve the purpose of reducing and reducing flood disasters. There are two different ways for reservoirs to regulate floods, one plays the role of flood detention and the other plays the role of flood storage.

1) Flood detention.

Flood detention is the temporary retention of flood water in a reservoir. When there is no gate control on the spillway of the reservoir, and the reservoir storage level is level with the elevation of the spillway weir crest, the reservoir can only play the role of temporary flood retention.

2) Flood storage.

In the case that there is no sluice gate in the spillway, if the reservoir water level can be lowered to the reservoir limit water level before the flood season in the reservoir management and operation stage, and the reservoir limit water level is lower than the spillway weir crest elevation, the reservoir capacity between the restricted water level and the spillway weir crest elevation can play a role in flood storage. A portion of the flood water stored in the reservoir can be used in a planned way during the dry season.

When the spillway is equipped with a sluice gate, the reservoir can play a greater role in flood storage, and the reservoir can adjust the amount of discharge by changing the opening degree of the sluice gate.

Due to the gate control, the flood control limit water level of this kind of reservoir can be higher than the top of the spillway weir, and the opening degree of the gate can be adjusted at any time during the flood discharge process to control the discharge flow, which has the dual role of flood detention and flood storage.

1. The downstream of the dam is regulated by the reservoir, and the seasonal variation of river runoff is slower than that before construction.

2. Affected by the seasonal release of water from the reservoir, the downstream riverbed is eroded by flowing water (undercut), and the riverbed declines.

3. The reservoir is easy to cause sediment accumulation, which seriously affects the life of the reservoir; It causes sediment accumulation in the upper reaches of the reservoir, which is easy to cause flooding; It is easy to cause geological disasters such as ** and threaten the safety of reservoirs; Pollution has increased upstream, deteriorating the water quality of the reservoir.

Upstream. Precipitation is less in summer and more in winter, and the lateral erosion of rivers increases, the water level rises, and the siltation increases.