The physical properties of river water mainly refer to water temperature, color, transparency, smell and taste.The chemical properties are determined by the dissolved and dispersed gases, ions, molecules, colloidal substances, suspended solids, microorganisms and the content of these substances in the river water.
river waterdissolutionIts main chemical composition is similar to that of ordinary natural water (seeNatural water quality）Its evaluation index is also the same as that of natural water.Only when the river water is used for a special purpose or an accident occurs, new measurement items will be added.For hydraulic structures, the corrosivity of river water must be measured.When human and animal epidemics occur, the pathogen must be determined.When the river water is seriously polluted, some specific pollutants must be measured.
The chemical components dissolved in river water in the order of their abundance are: HCOthree、Ca2+、SOfour2-、Cl-、Na+、Mg2+And K+。 The content of these main ions increases with the increase of salinity, in which HCOthreeThere is a good linear relationship between the increase of Cl-、K+、Na+The increase is particularly significant.Due to the continuous renewal of river water, the interaction time between river water and riverbed sediment is short, and the salinity of river water is higher than that of lake watergroundwaterAnd the sea water is low.The mineralization degree of river water is divided into four levels: ① weak mineralization, with mineralization degree less than 200 mg/L; ②Medium mineralization, mineralization degree is 200~500 mg/l; ③Strong mineralization, mineralization degree is 500~1000 mg/l; ④It is highly mineralized, and the mineralization degree is more than 1000 mg/l.Most rivers on the earth are weakly mineralized water and moderately mineralized water.The salinity of Chinese river water is generally lower than 200~300 mg/l in the south of Huaihe Qinling Mountains, higher than 200~300 mg/l in the north of Huaihe Qinling Mountains, and can be as high as more than 1000 mg/l in some parts of the northwest.
The main factors affecting the water quality of river water are the source of river water supply, hydrological and climatic factors,basinRock, soil, vegetation conditions and human activities in the area.Snow melt water supplyDue to the cold climate and slow chemical process, the molten water only leaches salt from the surface soil, and the salinity of the river water is low.The river water recharged by groundwater has a high degree of mineralization because the groundwater has been in close contact with soil and rock for a long time and more dissolved components are leached from it.The river water, mainly recharged by rainwater, gathers in the river channel through surface runoff, which is greatly affected by the basin climate and soil cover. The salinity is generally between the river water recharged by snow melt water and groundwater.
In humid and rainy areas, surface chemical elements have been leached by rainwater for a long time, especially elements with strong migration ability, which have little or no residual, resulting in low salinity of river water. In this area, HCO in the ion composition of river waterthreeAnd Ca2+It is absolutely dominant, with low pH value and acidic water.In arid and rainless areas, evaporation is strong, surface salinity accumulates, and river salinity increases. In this area, the ion composition of river water is high in Cl - and Na+, and the river water is mostly alkaline, with high pH value.[1]
River movement
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The movement state of the river
Laminar flow: all water flows in parallel stream, that is, the trajectory (streamline) of water quality point movement is parallel, the direction of movement in the water flow is consistent, and the velocity is uniform;
Turbulence: the velocity and direction of each water quality point in the water flow are changing at any time and anywhere, and the change is jumping up and down around an average value.
The flow in natural rivers is generally turbulent.
Longitudinal movement of river water
In addition to the original stable flow, the longitudinal movement process of the river along the way should also add the movement process of the flood wave in the river channel.
Circulation movement of river water
1. Internal structure of river flow:
Turbulence structure: pulsation of water quality points.
Circulation structure: the local water flows around a certain rotation axis to and fro, moving downward in a spiral or vortex shape.
2. Type of circulation
Vertical axis circulation: the rotation axis is horizontal and basically parallel to the longitudinal mainstream direction.The vertical axis circulation is divided into curved spiral flow and compound spiral flow.The spiral flow in the bend is very large and often fills all river channels.Among various circulations, spiral flow in bend has the greatest influence on sediment movement and channel deformation.The composite circulation mostly occurs in large straight river sections, and consists of two or more vertical circulations with different rotation directions, but the flow direction must be the same on the interface of each circulation.The compound spiral flow is mostly formed due to the sudden change of flow when the water rises or falls.
Horizontal axis circulation: the rotation axis is horizontal, which is perpendicular to the longitudinal main flow.The transverse axis circulation in front of the pier is due to advancing.The water flow is blocked and the momentum is suddenly changed.The transverse circulation downstream of the water retaining structure is formed due to the dissociation of water flow.Flow dissociation can also form oblique axis circulation and vertical axis circulation.
Inclined axis circulation: its rotating axis is also horizontal, and it is oblique to the longitudinal mainstream.The circulation formed at the downstream of the sand spout after the current crosses the sand spout on the bank which is oblique to the main stream belongs to this category.
Vertical axis circulation: its rotation axis is vertical to the mainstream and river bottom, which is a relatively closed cyclonic flow.For example, in the suddenly widened river reach, the circulation formed on both banks;For example, in the curved river section, due to the straightening of the flood mainstream, the backflow formed at the concave bank.[1]
Measures for harnessing river water pollution
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1. Enhance people's awareness of environmental protection: human activities are the main source of water pollution, and industrial wastewater, domestic sewage, pesticides, fertilizers, etc. will pollute the water environment.The current pollution of water resources is largely due to the lack of environmental awareness of residents.Therefore, relevant departments should carry out publicity activities to popularize environmental protection knowledge and improve people's awareness and understanding.
2. Reduce water consumption: the current utilization of water resources in China, on the one hand, feels the shortage of water resources, on the other hand, the waste is very serious.Compared with industrial developed countries, water consumption per unit product in China is much higher.Large water consumption not only causes waste of water resources, but also is an important cause of water environment pollution.Through the technological transformation of enterprises, the implementation of cleaner production, the reduction of water consumption per unit product, the multiple use of one water, and the improvement of water reuse rate have all been proved to be effective in practice.
3. Establish urban sewage treatment system: In order to control the development of water pollution, industrial enterprises must also actively control water pollution, especially the discharge of toxic pollutants must be treated or pretreated separately.With the adjustment of industrial layout and urban layout, and the construction and improvement of urban sewage pipe network, the centralized treatment of urban sewage can be gradually realized, which will combine urban sewage treatment with industrial wastewater treatment.Plant more trees along the river to conserve water and soil.If you want to reduce the pollution degree of sewage, you can also use chemical methods to neutralize or precipitate harmful substances in sewage.
4. Industrial structure adjustment: the natural purification capacity of water bodies is limited, and a reasonable industrial layout can make full use of the natural capacity of the natural environment, change the vicious circle into a virtuous circle, and play a role in developing the economy and controlling pollution.Close, stop, merge and transfer enterprises that consume large amount of water, pollute heavily and have high pollution control costs.It is also necessary to adjust the agricultural structure that consumes a lot of water, especially in arid and semi-arid areas, reduce the rice planting area, and take the road of water-saving agriculture and sustainable development.Especially in the upper and middle reaches of the river, the discharge of pollutants is restricted, mainly in paper mills, metallurgical plants, etc.
5. Control agricultural non-point source pollution: agricultural non-point source pollution includes rural living sources, agricultural non-point sources, livestock and poultry breeding, and aquaculture.To solve the problem of non-point source pollution, which is more difficult than industrial pollution and domestic sewage in large and medium-sized cities, measures such as comprehensive prevention and control and ecological agriculture demonstration projects need to be taken to control it.
6. Development of new water sources: China's industrial, agricultural and domestic water conservation potential is not small. We need to do a good job in water conservation, reduce waste, and reduce water consumption per unit of GNP.the South-to-North Water Diversion ProjectThe implementation of the policy will play an important role in alleviating the serious water shortage in North China, Shandong Province.Building reservoirs, exploiting groundwater, purifying seawater, etc. can alleviate the increasingly tense water pressure, but the impact on the ecological environment and social environment should be fully considered when building reservoirs and exploiting groundwater.
7. Strengthen the planning and management of water resources:Water resources planningIt is an important part of regional planning, urban planning and industrial and agricultural development planning, and should be carried out simultaneously with other plans.Reasonable development must also be based on the supply and demand of water, implement quota water use, and unify the development and utilization of surface water, groundwater and sewage resources to prevent the exhaustion of surface water sources and the decline of groundwater level, and effectively achieve reasonable development, comprehensive utilization, active protection and scientific management.
8. Scientification of domestic water use: Try to use less detergent and no phosphorus containing washing products, reduce pollution to water source and enhance water-saving awareness.
9. The attention of relevant departments: people's weak awareness of environmental protection, coupled with the laissez faire of relevant departments, led to today's river water pollution.Protecting the environment is everyone's obligation and responsibility, so the government should strengthen management, take a series of planning measures, and implement them to make the environment better.
Water is an important material for human survival. Clean water can bring people verdant flowers and trees, birds singing and flowers fragrance, quiet and comfortable, beautiful and picturesque beautiful environment, and bring people peace, joy and peace.But today's polluted water brings people pain, terror and disaster.In order to make life better, let the beautiful mountains and waters stay in the world forever, and let the water flow continuously, so far I only put forward the above suggestions.It is hoped that the relevant departments will step up the promotion and implementation, and return a clear river to us.
