What is a basin wide flood and what is a basin wide flood

It refers to the flood of a large river or the main stream of a large river and its main tributaries, and the flood of the Pearl River basin refers to the simultaneous flood of the main stream of the Pearl River and some of its tributaries, such as the left and right rivers and the Wujiang River.

Watershed floods are based on the river, China's north-south span is large, the southern Nanling near the rainy season begins in May the rainy peak reaches the Yangtze River basin, forming the plum rain, reaching the North China Plain in August, reaching the Northeast Plain in September, and the rain peak retreats back to the South China Sea in October. All rivers in China are divided into three major river basins - the Yellow River Basin, the Yangtze River Basin, and the Pearl River Basin. The floods in the Pearl River basin are generally around May and June, the Yangtze River basin is about early June to mid-July, and the floods in the Yellow River basin are concentrated in July and August.

It is formed by continuous heavy rainfall in the whole basin, and is generally formed by a long and large-scale continuous rainstorm during the Meiyu period. For example, the heavy rain and floods in the Huaihe River Basin are concentrated in the flood season in June and September, and the main occurrence in June is in the Nanshan District of Huai 1653. It can occur in the whole basin in July; In August, it mostly appeared in the Funiu Mountains in the west and the Yimeng Mountains in the northeast, and typhoons and rains often occurred in the eastern coastal areas affected by typhoons.

Flood level. General flooding: return period less than 10 years.

Larger floods: return period 10-20 years.

The Great Flood: Return period 20-50 years.

Mega floods: return period of more than 50 years.

Speaking of 1998, many people must still remember the moving slogan of "vowing to live and die with the embankment", and today I will take you to review the shocking flood 22 years ago.

Basin-wide floods generally occur in areas and years with relatively large precipitation, and it is caused by continuous heavy rainfall in the whole basin of the river, so that the river cannot withstand the sudden increase in water volume and the formation of flood disasters, which will cause serious damage to cities, villages, farmland, factories, etc. in a large range along the coast.

One of the flood types of flood disasters in the middle and lower reaches of the Yangtze River. Basin-wide floods are caused by continuous heavy rainfall throughout the basin, such as the 1931 flood, the 1954 flood, and the 1998 flood.

Influence of watershed vegetation on flooding: suppressing flood hazards.

Vegetation and its soils absorb water to reduce the amount of flooding;

Vegetation cover reduces soil erosion and downstream siltation caused by flooding; (Vegetation cover changes soil properties and reduces soil erosion; The role of vegetation in blocking and intercepting floods, and the protective effect on slope banks).

Ding Yihui is an academician of the Chinese Academy of Engineering, a special adviser on climate change of the China Meteorological Administration, a deputy director of the National Climate Change Expert Committee, and a winner of the first prize of the National Science and Technology Progress Award, the second prize of the National Natural Science Award, the Ho Leung Ho Lee Science Progress Award and the World Meteorological Organization Outstanding Work Achievement Award.

It is mainly found in areas at lower altitudes.

1.Floods are water flows such as rivers, oceans, and lakes that exceed a certain water level, threaten the safety of relevant areas, and even cause disasters. Also known as the Great Water.

2.Flood refers to a disaster in a river basin where the amount of runoff flowing into a river exceeds its flood discharge capacity due to concentrated heavy rainfall or prolonged rainfall, overflowing both banks or causing a dam to burst, resulting in flooding. Flooding: Overflow of water from rivers and lakes.

Flood classification: Floods can be broadly divided into river floods, coastal floods, and lake floods according to the different areas where they occur.

River flooding. According to the direct causes of formation, it can be divided into rainstorm floods, snowmelt floods, ice floods, glacial floods, dam failure floods and soil collapse floods.

Coastal flooding. The main causes are storm tides formed by atmospheric disturbances, astronomical tides, submarine volcanic eruptions, etc., which can be roughly divided into astronomical tides, storm surges, typhoons (hurricanes), tsunamis, etc.

Lake flooding. The large lakes in China, such as Dongting Lake and Poyang Lake on the Yangtze River, have some of the characteristics of river and coastal floods. Lake flooding can occur due to the exchange of water volume between rivers and lakes or the action of meteorological factors on the lake surface, or both.

China's main focus is on flooding in the Yangtze River basin. The Yangtze River basin is the longest river in China, with a water deficit area of more than 1.6 million square kilometers. Because the Yangtze River runs through central China, it flows through a vast area, and with the heavy rainfall, the flow into the Yangtze River is huge.

As a result, the Yangtze River basin has become an important area in China where frequent floods occur. To tackle the flood problem, China** has carried out decades-long remediation work, including building embankments, widening rivers, building reservoirs and strengthening silt adjustment. Among them, the most representative is the Three Gorges Project, which is one of the largest water conservancy projects in the world, which not only has the effect of preventing forest cavity floods, but also can generate electricity and regulate shipping.

At present, tremendous results have been achieved in the management of the Yangtze River Basin. Through years of hard work, the flood disaster has been effectively controlled, and the ecological environment of the Yangtze River basin has also been greatly improved. At the same time, it also pays more attention to the ecological environment of the river, protects many rare animal and plant species, and makes the entire river basin more beautiful.

The use of valley reservoirs and lake dust to regulate waterproofing during the flood season and prevent flood disasters is called flood storage. In the upper and middle reaches of the river, whenever a flash flood breaks out, the flood is ferocious, and the plain areas on both sides of the middle and lower reaches suffer flood disasters. After the storage of the valley reservoir, the flood peak was reduced, and the flood threat in the middle and lower reaches was reduced.

However, due to the fact that there is still a large amount of flood water to be discharged, and flood disasters will still occur in large areas of the plains in the middle and lower reaches. Therefore, in a river, in addition to using the valley to build a reservoir to store floodwater in the upper and middle reaches, it is also necessary to build a plain reservoir to store floodwater in the middle and lower reaches of the river. The capacity of a river to store floodwater is the flood storage capacity of the river.

Hello dear! <>

Compared with other types of reservoirs, such as deep valley reservoirs or flat reservoirs, <> river reservoirs are more likely to overflow due to the following reasons:1The reservoir has a large storage capacity:

River-type reservoirs are often located in mountainous areas, where there is a lot of rain, so the storage capacity of their reservoirs is usually large. Flooding is prone to occur when rainfall exceeds the capacity of a reservoir to hold. 2.

Large upstream watershed area of fluvial reservoirs: Because fluvial reservoirs are usually located in mountainous areas, which are characterized by relatively large watershed areas, the likelihood of a sharp increase in runoff is also high. When the rainfall intensity in the upstream basin is high and the runoff of the lack of forest increases sharply, the reservoir capacity may not be able to support this large amount of runoff, resulting in the occurrence of spillway rocks.

3.Limited outflow capacity: Because river-type reservoirs are generally built along the river, the outlet position is fixed.

When rainfall or runoff increases dramatically, the outflow capacity of the outlet may not be able to meet demand, causing a spill to occur. In summary, river-type reservoirs are relatively prone to overflow due to their large water storage, large upstream basin area, and limited outflow capacity. In order to effectively deal with this problem, it is necessary to carry out scientific water resources management and flood dispatching, and reasonably plan the water storage capacity and outflow capacity of the reservoir to ensure the safe operation of the reservoir and reduce the risk of overflow.

Hope mine can help you! 

Design flood refers to the potential flood in the local area that is drafted for the design of flood control and other engineering cavities and meets the specified flood control design standards. That is, the maximum flood that is expected to be fortified by flood control planning and flood control projects. Flood exceeding the standard refers to exceeding the design standards of the flood control system or flood control project.

of the flood. The content of the design flood includes the design flood peak, the design flood volume in different time periods, the design flood process line, the regional composition of the design flood and the phased design flood. All or part of its content can be calculated according to the engineering characteristics and design requirements.

Proceeding from the economic rationality and the actual situation, the guarantee rate of flood control facilities can only meet certain design standards, while floods are affected by natural factors and human activities, etc., and have great randomness and may exceed the design standards.