The phenomenon of underwater infiltration of rivers and lakes is an important part of the natural water cycle, which not only affects the water balance of rivers and lakes, but also has a profound impact on the recharge of groundwater resources, the stability of river and lake ecosystems and the utilization of water resources in surrounding areas. The speed and degree of underwater infiltration in rivers and lakes are affected by many factors, among which the size of sediment particles in the riverbed is one of the key factors.
The size and type of sediment particles in the riverbed determine its water seepage capacity. The smaller the particles, the smaller the pores between the sediment, the greater the resistance of the water flow through, and the slower the infiltration rate. Conversely, the larger the particles, the larger the pores, the less resistance the water flow through, and the faster the infiltration rate. Taking the Yangtze River as an example, the riverbed of the Yangtze River is mainly composed of pure sand, and this large-grained sediment structure gives the Yangtze River a strong water permeability. The seepage rate of pure sand can reach several meters per minute, which is much higher than that of other types of riverbed sediment.
In addition to the size of sediment particles, the underwater infiltration of rivers and lakes is also affected by other factors. The first is the influence of topography. The slope of the river, the undulation of the riverbed, and the morphology of the banks all affect the speed and direction of the flow, which in turn affects the rate of infiltration. For example, in steep sections of the river, the flow speed is fast and the infiltration rate is relatively slow; In the gentle section of the river, the flow is slow and the infiltration rate is relatively fast.
The second is the influence of hydrological conditions. River flows, water levels, and seasonal changes in water levels can all have an impact on infiltration. During the flood season, the water level rises, the water pressure increases, and the rate of infiltration may increase; In the dry season, when the water level drops and the water pressure decreases, the rate of infiltration may slow down. In addition, the velocity of the river also affects the infiltration, with the fast flow of the river usually having a slower rate of infiltration, while the slow flow of the river has a faster rate of infiltration.
Climatic conditions are also important factors affecting the underwater infiltration of rivers and lakes. Climatic factors such as precipitation, evaporation, temperature, and humidity all have an impact on the amount of water and the rate of infiltration in a river. During the rainy season, the amount of water in the river increases, and the rate of infiltration may increase; And during the dry season, when the amount of water in the river decreases, the rate of infiltration may slow down. In addition, an increase in temperature increases the evaporation of water, which reduces the amount of water infiltrated.
The impact of human activities on the underwater infiltration of rivers and lakes cannot be ignored. The excavation of the river, the hardening of the riverbed, the construction of the riverbank, etc., will change the natural state of the river and affect the infiltration. For example, riverbed hardening reduces the porosity of sediment and reduces water seepage capacity; The construction of river banks may change the direction and speed of water flow, affecting infiltration.
Underwater infiltration of rivers and lakes plays an important role in the recharge of groundwater resources. Seepage water from rivers and lakes can be an important source of groundwater, especially in arid areas, where the recharge of groundwater resources is particularly important. However, excessive infiltration may lead to a decrease in river water, affecting the ecological balance of the river and the sustainable use of water resources.
Underwater infiltration of rivers and lakes also has an impact on river and lake ecosystems. Infiltration water can provide nutrients and oxygen to groundwater ecosystems and maintain groundwater biodiversity. However, if the infiltration rate is too fast, it may lead to a decrease in dissolved oxygen in the surface water of rivers and lakes, affecting the survival of aquatic organisms.
In summary, underwater infiltration of rivers and lakes is a complex natural phenomenon that is affected by a variety of natural and man-made factors. Understanding and studying these influencing factors is of great significance for protecting the ecological environment of rivers and lakes, rationally utilizing water resources, and realizing the sustainable development of hydrological cycle.
The influence of underground rock structure on underwater infiltration is multifaceted, which not only determines the distribution and flow characteristics of groundwater, but also has a direct relationship with the recharge of surface water and the development and utilization of groundwater resources. The depth, type, porosity and fracture development of underground rock structure are all important factors affecting the underwater infiltration capacity.
First of all, the depth of the subsurface rock has a significant impact on the ability to infiltrate the water. Generally speaking, the deeper the underground rock structure, the higher its density, the lower the porosity, and the weaker the ability of water to infiltrate. This is because as the depth increases, the pressure on the rock increases, and the voids between the rock particles are compressed, making it difficult for water molecules to penetrate. For example, in shallow surface layers, water permeates easily due to the high porosity of soil and rocks; In the deep underground, the rock structure is compact, and the infiltration of water is limited.
Secondly, the type of rock is also a key factor affecting the ability to infiltrate underwater. Due to the sedimentation in the process of formation, sedimentary rocks usually have a high degree of porosity and fracture development, and are easily eroded by groundwater, forming karst caves and dark rivers. These caves and rivers provide good access to groundwater and enhance the ability of water to infiltrate. Limestone, for example, is a typical sedimentary rock whose dissolution creates karst landforms that provide a wide space for the storage and flow of groundwater.
Compared to sedimentary rocks, magmatic rocks have a harder structure, lower porosity, and underdeveloped fractures, so it is difficult for water to infiltrate. During the formation of magmatic rocks, due to the action of high temperature and high pressure, the rock particles are closely arranged to form a dense structure. This structure acts as a hindrance to the penetration of water and limits the infiltration of water. Granite, for example, is a common type of magmatic rock whose hard structure makes it difficult for water to penetrate.
In addition to the depth and type of rock, the porosity and fracture development of the rock are also important factors affecting the underwater infiltration capacity. Porosity refers to the ratio of the total volume of pores in a rock to the total volume of the rock, the higher the porosity, the better the permeability of the rock, and the stronger the infiltration ability of water. The degree of fracture development refers to the number and connectivity of fractures in the rock, the higher the degree of fracture development, the better the permeability of the rock, and the stronger the infiltration ability of water. For example, in some rocks where fissures develop, groundwater can flow rapidly through the fissures, forming underground rivers.
In addition, the geological age and geological structure of the underground rock structure also affect the underwater infiltration capacity. Due to the short geological action time, the structure of young rocks may be loose, and the degree of porosity and fracture development is high, which is conducive to water infiltration. Ancient rocks, on the other hand, may have a denser structure and lower degree of porosity and fissures due to long-term geological processes, which is not conducive to water infiltration. Geological formations, such as faults, folds, etc., can also change the structure of the rock and affect the infiltration of water.
In general, the influence of underground rock structures on underwater infiltration is complex and multidimensional. Understanding the characteristics of underground rock structures is of great significance for the exploration, development and protection of groundwater resources. By studying the influence of underground rock structure on underwater infiltration, we can make better use of groundwater resources, protect the groundwater environment, and promote the sustainable use of water resources.