What are the two factors that affect runoff?

The influencing factors of river runoff are:

1. River recharge (climate: precipitation);

2. Topography (plains, basins);

3. The size of the basin area;

4. How many tributaries;

5. The size of the evaporation amount;

6. Degree of vegetation coverage.

The entire process from the arrival of rainfall to the ground to the collection of water flow and the flow through the outlet section of the watershed is called the runoff formation process.

After the precipitation falls on the surface of the watershed, it first infiltrates into the soil, and a part of the water flows into the ditch in the form of soil flow, forming the upper soil flow. A portion of the water continues to infiltrate and recharge groundwater; There is also a part that is held in the soil in the form of soil water, and part of which is consumed by evaporation. When the soil water content reaches saturation or the precipitation intensity is greater than the infiltration intensity, there is still a surplus of precipitation after deducting infiltration, and the residual water begins to flow to fill the potholes, and then forms a slope flow, which flows into the river channel and forms an outlet flow process together with the soil middle flow. Therefore, the whole process of runoff formation often involves atmospheric precipitation, soil infiltration, soil flow, groundwater, evaporation, depression filling, slope flow and river channel confluence, which is a process of comprehensive action of meteorological factors and natural geographical conditions of the basin.

The formation of runoff is an extremely complex process, and for the sake of conceptual understanding, it can be generalized into two stages, namely the runoff phase and the confluence phase.

1 Abortion stage. When the rainfall satisfies the plant interception, the water storage of the depression and the storage of the surface soil, the subsequent rainfall intensity exceeds the infiltration intensity, and the rainfall that exceeds the infiltration intensity is the beginning of the runoff after it falls to the ground, and begins to flow along the surface slope is called slope diffuse. If the rainfall continues to increase, the scope of the diffuse flow will also increase, forming a comprehensive diffuse, and this super-permeable rain flows along the slope surface into the river channel, which is called slope runoff.

The process of surface flow is called the runoff stage.

2.Confluence phase. The runoff generated by rainfall collects into the nearby river network, flows from upstream to downstream, and finally flows through the outlet section of the river basin, which is called the confluence of the river network, and the confluence process of the river network is the confluence stage.

The main factors influencing runoff are: climatic factors, underlying surface factors of the watershed, and human activities.

Runoff refers to the amount of water that passes through a certain section of a river in a given period of time. Runoff is the main link of the water cycle, and runoff is one of the most important hydrological elements on land and the basic element of water balance.

Runoff refers to the general term for the flow of atmospheric precipitation reaching the surface into rivers, lakes or slippery oceans through the surface and underground after deducting the amount of water such as evaporation, soil infiltration, plant interception and depression storage. According to the characteristics of the water source, it can be divided into rainfall runoff, snowmelt runoff and glacial runoff. According to the composition of water flow, it can be divided into surface runoff (surface runoff), soil runoff and underground runoff.

The main factors influencing runoff are:

1) Meteorological factors, including precipitation characteristics, solar radiation, temperature, wind speed, etc.

2) Physical geographical factors, including watershed area, geology, geomorphological characteristics, vegetation and soil conditions, river channel characteristics, etc.

and 3) impacts of human activities, including land use, agricultural measures and the construction of water conservancy projects.

The amount of runoff is called runoff, which refers to the amount of water flowing through a certain section of the river over a period of time, and the runoff reflects the abundance of water resources in a certain area of residual lead. Our city is located in the lower reaches of the Pearl River Delta, three of the eight major estuaries of the Pearl River Basin go to the sea through our city, the water is abundant, the average annual runoff is 100 million cubic meters, and the vast majority of it is transit passenger water, accounting for 149.7 billion cubic meters.

1. River recharge (climate: precipitation);

2. Topography (plains, basins);

3. The size of the basin area;

4. How many tributaries;

5. The size of the evaporation amount;

6. Degree of vegetation coverage.

Runoff depth is the ratio of the average runoff in a watershed to the area of the watershed, usually expressed in millimeters or cubic meters of seconds. The depth of runoff eliminates the effect of watershed area and can therefore be used to compare runoff from one watershed.

Due to the different areas of different watersheds, direct comparison of runoff in watersheds will be affected by the area. For example, a smaller watershed, despite its higher annual precipitation, may still have less runoff than a larger watershed due to its small size. By calculating the runoff depth, the influence of watershed area on runoff can be eliminated, so that the runoff of different watersheds can be comparable.

Therefore, runoff depth is a commonly used indicator to compare the amount of runoff in different watersheds. In the fields of hydrology and water resources management, runoff depth is often used to assess the hydrology and water resource utilization of watersheds, and provide a reference for watershed management and planning.

Categories: Science & Engineering >> Engineering & Technology Sciences.

Problem description: I am currently doing a review of a water diversion project, and the term "runoff" appears many times in the feasibility study report, what does it mean? Thank you!

Analysis: The precipitation in the basin flows into the river network from the surface and underground and flows out of the outlet section of the basin, which is called runoff. Liquid precipitation forms rainfall runoff, while solid precipitation forms snow and ice melt runoff.

The entire physical process from the time the precipitation reaches the ground to the water flow through the outlet section is called the runoff formation process. Depending on the form of precipitation, the process of runoff formation is also different. China's rivers are dominated by rainfall runoff, and ice and snow melt runoff only occurs in local sections of rivers in the western mountains and high latitudes.

According to the formation process and different runoff pathways, river runoff can be composed of three types of runoff: surface runoff, underground runoff and soil flow (surface flow).

1. River recharge (climate: precipitation);

2. Topography (plains, basins);

3. The size of the basin area;

4. How many tributaries;

5. The size of the evaporation amount;

6. Degree of vegetation coverage.

Question 1: What factors are considered for the size of surface runoff Influencing factors? Effects on surface runoff.

Annual precipitation? The most important factor determining the amount of surface runoff flow.

Watershed area? (Number of tributaries)?It is positively correlated with surface runoff flow.

Vegetation conserves water and plays the role of "shaving peak and replenishing dryness".

Geology? (Soil Texture)?The river flows through the karst landform area and sandy soil, and the river water is easy to infiltrate and decrease.

Evaporate? It is mainly in arid and semi-arid areas, and has a great impact on surface runoff.

Human activity? Coastal water withdrawals can lead to reduced runoff.

Question 2: What is surface runoff? Surface runoff generally refers to the flow of water that flows into a river, lake, or ocean along a different path in a watershed due to precipitation or melting snow and ice.

Surface runoff is an important part of the hydrological cycle and a fundamental factor in the change of river hydrological conditions. Runoff is one of the basic elements of water balance.

The climatic factors and natural geographical factors that affect surface runoff have certain regional distribution laws, and climatic factors also have obvious periodic change laws, so the runoff phenomenon also exists accordingly regional and periodic, and surface runoff in China has the characteristics of uneven regional distribution and large seasonal and interannual variations. In China, the distribution trend of surface runoff is basically consistent with the distribution of precipitation, decreasing from the southeast coast to the northwest inland.

Question 3: How does rainfall runoff occur, and what are the main factors affecting runoff When the atmospheric moisture is sufficient to reach saturation, precipitation will be produced, and when precipitation falls to the surface, it will produce infiltration, but there is a certain limit to infiltration, when the precipitation is enough to exceed the limit of infiltration, the water will remain on the surface, and if there is a drop, the water will move and produce surface runoff.

The main factors influencing the amount of runoff are, such as the amount of precipitation, vegetation cover, soil structure, topographic characteristics, etc.

The factors affecting groundwater runoff include the porosity of the aquifer, the burial conditions of groundwater, the amount of recharge, the topography, the geological structure, and the human factors, among which the human factors, that is, various human production activities, have a greater impact on the flow of groundwater, and even make it fundamentally change.

Groundwater runoff, also known as underground runoff, is the flow of groundwater in the natural terrestrial water cycle under the action of gravity, and the underground runoff and precipitation, evaporation and surface runoff together constitute the terrestrial water balance, and the underground runoff has become a separate terrestrial water balance element. In the water equilibrium formula, it is generally expressed in millimeters of water layer thickness on the average value of many years, and in quantitative evaluation, it is characterized by flow, modulus or total amount.