Knowledge popularization of water conservancy, flood control, and drought relief

I. Flood control knowledge

1. Flood Season

Rivers, lakes, and floods have risen from the beginning to the full fall, which is called flood season. The period in which the largest floods occur in rivers and lakes with seasonal fluctuations is called flood season. Each place is different. The starting and ending periods here are: January 1, June 1-9-August 20. The main flood season is from January 1, July 20-8 to August 20.

2. Flood Control

Measures taken to prevent or mitigate floods are called flood control measures during flood periods. It can be divided into engineering flood control measures (such as flood control dike and flood control reservoir) and non-engineering flood control measures (such as flood control organizations, rescue teams, and regulations ).

3. water disasters

Water disasters and secondary disasters can be called "water disasters ". It mainly includes the following 6 types:

(1) Rainstorm Disaster. Disasters are caused by heavy rainfall, regardless of the duration of heavy rainfall. Mountain floods and mudslides caused by heavy rainfall in mountainous areas and mountainous areas are the same type of waterlogging caused by heavy rainfall in plain areas.

(2) flood disasters. Disasters caused by floods. Flood disasters are generally wide-ranging and have high losses. They often induce other types of water disasters or cause indirect and secondary disasters.

(3) mountain flood disasters. Mountain torrents are most commonly caused by heavy rain. They usually refer to the flood and the landslide, collapse, and debris flow that occur along rivers and troughs in mountainous areas. Flood control facilities can also lead to flood. Flood disasters are the hazards caused by flood outbreaks, including casualties, property losses, infrastructure damages, and environmental resource damages. Mountain Flood Disasters include mudslides, landslides, and river floods.

(4) Hail Disaster. Hail is ice hockey or ice Ice flags that have landed from the yunyun (a strong accumulation of rain). It often appears at the same time as thunderstorms and strong winds. Crops and houses may be damaged or even cause casualties in hail-attacked areas.

(5) storm surge disaster. The effects of strong weather systems such as strong winds or sudden changes in air pressure on the sea surface lead to sharp movements of water levels and disasters near the coast.

(6) Typhoon disasters. Typhoon is a catastrophic weather system with a strong destructive power, but sometimes it can also eliminate drought. There are three main dangers: ① strong winds. The maximum wind power near the typhoon center is generally more than 8 levels. ② Rainstorm. Typhoon is one of the strongest rainstorm weather systems. In the area where the typhoon passes, it usually produces more than 100mm of the rainfall, or even serious rainstorm. ③ Storm surge. Generally, a typhoon can increase water in coastal waters. The city's coastal waters can increase by more than 2 meters, leading to a historical climax.

 

Ii. hydrological knowledge

1. Flood

The phenomenon of rapid increase of water volume and sharp rise of water level caused by heavy rain or sharp ice and snow melting, storm surge and flood control facilities burst is called a flood.

2. Flood traffic

The volume of water passing through a certain water section within the unit time is called traffic, and its unit is cubic meters/second. Traffic is the basic element of river water conditions and one of the indicators of water resources.

3. Total flood volume

The total volume of a flood refers to the volume of a flood that passes through a certain section of a river during or within a given period of time. A period flood refers to the total amount of floods that occur within a period. Generally, the flood volume must be determined for 2-3 periods. The maximum period refers to the maximum amount of flood in a flood process, such as the maximum 1 day, 3 days, 7 days, 15 days, 30 days, 60 days.

4. Runoff

Runoff is the rainwater that lands on the surface of the basin. It is not only used for plant interception, infiltration, evaporation, and fill-out, the remaining part of the water is collected from the ground and ground to a small river under the action of gravity, and the water flow along the river is collectively referred.

5. Flood Forecast

Based on the flood formation and movement rules, the past and real-time water and weather data are used to predict the flood development in a certain period of time in the future.

 

Iii. Meteorological Knowledge

1. rainfall and rainfall level

(1) Rainfall

The rain depth that lands on the horizontal ground (assuming there is no leakage, evaporation, loss, etc.) within a certain period of time is called rainfall. Based on the time period, it can be divided into daily rainfall, monthly rainfall, and annual rainfall. Measured by rain gauge or rain gauge, in millimeters.

(2) rainfall level

According to the rainfall classification criteria of meteorological departments, rainfall can be divided into light rain, moderate rain, heavy rain and special heavy rain. 24-hour precipitation: 0-9.9mm indicates light rain; 10.0-24.9mm indicates moderate rain; 25.0-49.9mm indicates heavy rain; 50.0-99.9mm indicates heavy rain; 100.0-249.9mm indicates heavy rain; and more than 250.0mm indicates heavy rain.

2. Wind level and typhoon

(1) Wind level

The wind level is determined based on the level of influence relative to the ground or sea surface objects. It can be used to estimate the wind speed. It is divided into 18 levels. Where:

Level 6: wind speed: 10.8-13.8 m/second, 39-49 km per hour. It is difficult to raise an umbrella, the branches shake, and the wires call for sound.

Level 7: wind speed: 13.9-17.1 m/second, 50-61 km per hour, full tree shaking, walking in the wind is inconvenient.

Level 8: wind speed: 17.2-20.7 M/second,-74 km per hour, branches broken, people walking forward great resistance.

Level 9: wind speed: 20.8-24.4 m/second,-88 km per hour, blow down the grass room, blow the house tiles.

Level 10: wind speed: 24.5-28.4 m/second,-km per hour, can blow down the woods, damage ordinary buildings.

Level 11: wind speed: 28.5-32.6 m/second,-km per hour, great damage, blow down big trees, usually serious damage to buildings.

Level 12: The wind speed is greater than 32.6 metersper second, and more than 117 kilometers per hour.

(2) Typhoon (tropical storm, strong tropical storm)

Typhoon is a strong tropical cyclone generated on the tropical ocean. Typhoon often accompanied by strong winds and heavy rain. The main tropical cyclone affecting our city is the North migration path, most of which occurred from late July to early September. Internationally, the largest wind forces near the center are used to determine the intensity and classification: Level 12 or above is called a typhoon; level 10-11 is a strong tropical storm; Level 8-9 is a tropical storm; level 8 is tropical low. A strong tropical cyclone is accompanied by storms, waves, and storm surges. As it moves and lands, it will cause great damage to vessels on the ocean and farmland and houses on land.

(3) Typhoon Warning Signals

Typhoon warning signals are divided into four levels, marked in blue, yellow, orange, and red.

Blue typhoon warning signal: the typhoon may or has been affected by a tropical cyclone within 24 hours. The average coastal or land wind volume is more than 6 levels, or the gust is more than 8 levels and may continue.

Typhoon yellow warning signal: within 24 hours may or has been affected by Tropical Cyclone, coastal or land average wind Level 8 or above, or gust level 10 or above and may continue.

Typhoon orange warning signal: within 12 hours may or has been affected by Tropical Cyclone, coastal or land average wind level 10 or above, or gust Level 12 or above and may continue.

Typhoon red warning signal: within six hours may or has been affected by tropical cyclone, the average coastal or land wind level is more than 12, or the gust level is more than 14 and may continue.

3. Rainstorm

(1) rainstorm type features

Rainstorm is an important cause of flood disaster. The flood disaster in our city is mainly caused by rainstorm. According to the temporal and temporal characteristics of rainstorm, there are roughly two types: Local Rainstorm with short duration, large center intensity, covering dozens or even hundreds of square kilometers, the flood disasters are also local. The other type is heavy rain, which lasts for a long time and covers a wide range. This can cause floods to occur in one region or several large rivers at the same time.

(2) Rainstorm Warning Signals

Rainstorm warning signals are divided into four levels, marked in blue, yellow, orange, and red.

Rainstorm blue warning signal: The rainfall within 12 hours will reach more than 50mm, or more than 50mm, and the rainfall may continue.

Rainstorm yellow warning signal: Rainfall in six hours will reach more than 50mm, or more than 50mm, and the rainfall may continue.

Rainstorm orange warning signal: the rainfall in three hours will reach more than 50mm, or more than 50mm, and the rainfall may continue.

Red Rainstorm Warning Signal: the rainfall in three hours will reach more than 100mm, or more than 100mm, and the rainfall may continue.

 

Some common concepts:

Extraordinary rainstorm:

The 12-hour rainfall is equal to or greater than 140mm, or the 24-hour rainfall is greater than 200mm.

 

Rainstorm:

Heavy rain: the 12-hour rainfall is equal to or greater than 70.1-140mm, or the 24-hour rainfall is equal to or greater than 100.1-200mm.

 

Rainstorm:

It generally refers to heavy rainfall. It is a disastrous weather. Quantitative rainstorm standards vary across regions, depending on the specific situation

 

Rainfall intensity:

Rainfall per unit time period. Mm/min or mm/min. The rainfall intensity standard adopted by meteorological departments in China is light rain: rainfall within 12 hours is less than 0.2-5mm, or rainfall within 24 hours is less than 10mm; moderate rain: rainfall within 12 hours is 5-15mm, or the rainfall within 24 hours is 10.1-25mm; heavy rain: The rainfall within 12 hours is 15.1-30mm, or the rainfall within 24 hours is 25.1-50mm.

 

Average basin rainfall:

It is also called area rainfall. In hydrological work, we often need to calculate the average rainfall on the whole basin. The most common method is the arithmetic mean method and the vertical mean method (also called the tysen Polygon method). It is also used to draw an equal rain line diagram to calculate.

 

Ground runoff:

After precipitation, in addition to direct evaporation, plant interception, infiltration into the ground, fill the land, the other through the basin into the river trough, and along the river flow. Because of the different precipitation forms, the ground runoff can be divided into the rain-flood runoff and the snow-melt runoff. The former is formed by rainfall, and the latter is produced by snowmelt. Their nature and formation process are different.

 

Runoff:

The general term for the flow of water from the ground and ground in the river basin to the river troughs due to precipitation. It can be divided into two types: ground runoff and underground runoff. Water regime changes of rivers and lakes caused by runoff are the basic elements of hydrological circulation and water balance. The methods that indicate the runoff size include traffic, total runoff, deep runoff, and runoff modulus.

Fengshui period:

It refers to the period in which river flow mainly relies on rainfall or snowmelt supply. Generally, the water volume in the river is rich during the rainy season or the period in which the temperature increases continuously in spring.

Dry season:

It is also called the dry season. It refers to the period in which the flow of surface water in a basin is exhausted and the source is replenished mainly by groundwater. The duration of the dry season varies with the natural geographical and meteorological conditions.

Flood control:

A water conservancy work that studies flood laws and Flood Characteristics and takes various countermeasures to minimize or prevent flood hazards. The main contents of flood control work include: flood control planning and construction, management and application of flood control facilities, flood defense and rescue during flood periods, flood forecasting and scheduling, post-disaster work, and anti-ling work.

Flood control:

Various maintenance work to prevent flood disasters during flood periods. For example, the defense and emergency repair of dike, gate, dam, railway, bridge, etc. In the principle of "mainly preventing floods, focusing on preventing floods, and focusing on snatching", flood control should be done well, mainly including pre-detection, reporting, organizing rescue teams, material preparation, and technical preparation.

Flood Disaster Recovery:

Flood Disaster: due to excessive local precipitation, ground runoff cannot be ruled out in a timely manner. The water in farmland exceeds the flood-tolerant capacity of crops, resulting in agricultural reduction. The cause of reduced crop yield is that the water depth is too large and the time is too long, so that the air in the soil is discharged one after another, resulting in insufficient oxygen at the roots of the crop, difficulty breathing at the root, and the production of toxic and harmful substances such as ethanol, this affects crop growth and even causes death.

Rainfall intensity:

Rainfall per unit time period. Mm/min or mm/min. The rainfall intensity standard adopted by meteorological departments in China is light rain: rainfall within 12 hours is less than 0.2-5mm, or rainfall within 24 hours is less than 10mm; moderate rain: rainfall within 12 hours is 5-15mm, or the rainfall within 24 hours is 10.1-25mm; heavy rain: The rainfall within 12 hours is 15.1-30mm, or the rainfall within 24 hours is 25.1-50mm.

Guaranteed water level:

Guaranteed water level: it is also a super high water level. It is the highest water level determined by major river sections after the Yangtze River experienced a serious flood in 1954. For example, zhijiang Liuxiang is 47.36 meters, and the dipper is 46.59 meters. At this level of water level, we have to do everything necessary to ensure the safe passage of the dike.

Alert Level:

Alert level: the main river sections along the Yangtze River are protected against floods Based on the Dike's Flood Resistance and flood control capabilities. At this level of water, the flood control army should go to the dike for defense, patrol around the clock, and always prepare for emergency rescue.

Fortification level:

Protected water level: in the flood season, when a river or embankment reaches its foot, the water level is called a protected water level. At this level, flood control professionals should check the dangerous sections of ports, Gates, and dike to ensure security. Each major section along the Yangtze River has its own level of protected water level.

Watershed:

A watershed is a watershed or watershed surrounded by surface water and groundwater. Because it is difficult to determine the drainage line, it is often called a watershed.

 

Common site types and code relation tables

Type	Code	Type	Code	Type	Code	Type	Code
Weather Station	Mm	Tide Station	TT	Rain Station	PP	Reservoir water level Station	Rr
Evaporation Station	Bb	Pumping Station	DP	River and hydrological stations	ZQ	Groundwater Station	ZG
Dam gate hydrological station	Dd	Moisture Stations	SS	River level Station	Zz	Flood Diversion site	ZB