What are the factors that affect underground runoff?

Question 1: Why do trees grow leaves to give us shade in summer? In spring, when the weather gets warmer, plants sprout and grow leaves. In summer, sunlight makes plants multiply under the action of light, so the leaves are getting bigger and bigger!

Question 2: What are the influencing factors of the formation and change of river runoff?

Runoff is the product of the comprehensive action of climate and various natural and geographical factors in the basin.

Climatic factors. It is the most basic and important factor affecting river runoff. Precipitation and evaporation in climatic factors directly affect the formation and change of river runoff. In terms of precipitation, the form, total amount, intensity, process and spatial distribution of precipitation will affect the change of river runoff. For example, the greater the precipitation, the greater the river runoff; The greater the intensity of precipitation, the greater the possibility of flood in a short time. Evaporation is mainly controlled by air saturation deficit and wind speed. The greater the saturation deficit, the greater the wind speed and the stronger the evaporation. Other climatic factors such as temperature, wind and humidity usually affect river runoff through precipitation and evaporation.

Underlying factors in basin B The underlying factors mainly include topography, geology, vegetation, lakes and swamps. On the landform, the elevation and slope direction of the mountain affect the precipitation, with the windward slope rainy and the leeward slope rainy. Slope affects the confluence and infiltration in the basin, such as the water in a mountain stream, which is prone to steep rise and fall. The geological and soil conditions in the basin often determine the infiltration, evaporation and maximum groundwater storage capacity of the basin, such as the development of faults, joints and fractures. River runoff is greatly influenced by groundwater. Vegetation, especially forest vegetation, can play the role of water storage, water conservation and soil conservation, reduce peak flow, increase low water flow, and make the distribution of river runoff tend to be even during the year.

Human activities. For example, increasing river runoff through artificial rainfall, artificial melting of ice and snow, and inter-basin water transfer; Adjust runoff change by planting trees, building terraces and building ditches; Change the temporal and spatial distribution of runoff through reservoir construction, flood storage, flood diversion and flood discharge.

Runoff is an important link in the process of water circulation on the earth's surface, and its chemical and physical characteristics play an important role in geographical environment and ecosystem.

Question 3: What are the main factors affecting groundwater dynamics?

1. Climate is the most active factor affecting diving dynamics. In rainy season, the groundwater level rises and the salt content of groundwater decreases due to precipitation infiltration recharge; After the rainy season, evaporation and runoff discharge gradually reduce the groundwater level, and before the rainy season in the following year, the valley value appears and the salt content of groundwater increases. This periodic change in a year is called seasonal change. The long-term change of climate makes the groundwater level fluctuate periodically for many years.

2. Near the surface water body, groundwater dynamics is obviously influenced by surface water. When the river water level rises, the nearshore groundwater level rises the fastest and the largest; Away from the river bank, the variation range of groundwater level becomes smaller and the reaction time lags behind.

3. Climatic and hydrological factors determine the basic model of groundwater dynamics, while geological factors affect its change range and speed. For example, the confined aquifer is limited by the overlying water-resisting layer, and the dynamic change of recharge area is strong and rapid, but it becomes weak and lagging away from recharge area. For diving, the greater the thickness of the vadose zone, the more water remains in the vadose zone, and the change of groundwater level will lag behind the precipitation.

4. Human factors will also affect the natural dynamics of groundwater. For example, after drilling for water, part or all of the natural discharge is discharged through the water producing well. If the water yield exceeds the recharge, the groundwater level will decrease year by year. For another example, if surface water overflows without strengthening drainage, the groundwater level will rise year by year due to irrigation infiltration recharge, resulting in secondary swamping or salinization of soil.

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Groundwater dynamics-types of groundwater dynamics under the influence of human activities

Human activities have changed the natural dynamics of groundwater by adding new recharge sources or new discharge methods.

Under natural conditions, the recharge and discharge of aquifer or aquifer system remain in balance for many years, because climate factors tend to be average for many years. The groundwater level, which reflects the groundwater reserves, fluctuates within a certain range and will not rise or fall continuously. The quality of groundwater has been developing in a certain direction (salinization or desalination) for many years.

Manual mining and drainage of groundwater: after drilling wells for water or draining groundwater in mine passages, manual mining and drainage will become a new drainage method of groundwater; The original balance of aquifer or aquifer system is destroyed, some or all natural discharge is converted into artificial discharge, natural discharge no longer exists, or the quantity is reduced (spring flow and discharge are reduced, evaporation is weakened), which may increase new recharge.

If, after a period of groundwater exploitation and drainage, the newly increased recharge and reduced natural drainage are equal to artificial drainage, the aquifer water balance will reach a new balance. On the dynamic curve, the annual amplitude fluctuation of groundwater level increases at a lower position than before, but it does not continue to decrease. For example, in Wugong area of Raoyang County, Hebei Province, Quaternary phreatic water and shallow confined water are exploited as irrigation water sources. Water is collected for irrigation from March to May (June) every year, and the water level drops to the lowest point. 6(7) When the rainy season begins, water collection stops, precipitation seeps down and the surrounding groundwater runoff supplies, so that the water level rises rapidly. After the rainy season, the surrounding runoff flows into the filling mining funnel, and the water level continues to rise slowly. In the early stage of water collection the following year, the water level reached the highest point. This dynamic change shows the comprehensive influence of natural factors and human factors. Dynamic type is called mining runoff type.