What are the water-saving measures taken by countries around the world?

Advanced foreign water-saving measures

(1) Water-saving measures in the United States

The main measures taken in the development and utilization of water resources in the United States include: reducing Reduce water consumption and loss, use water rationally and save water. Including: protecting water sources and preventing soil erosion; reusing water sources, focusing on treating urban sewage and then using it as irrigation water source; regulating river runoff; breeding drought-resistant varieties; diverting water to recharge groundwater; reducing evaporation, applying plant growth regulators; and adjusting crops Types and market supply, etc. Currently, the development of water-saving irrigation agriculture in the United States mainly uses a combination of advanced water-saving irrigation technology and agricultural technology to replace the traditional single surface irrigation technology. The utilization efficiency of farmland irrigation water has reached 70-80%.

(1) Water-saving measures in Tucson, USA

Tucson is located in south-central Arizona. It has hot summers with temperatures often exceeding 37.8 degrees Celsius. The city's peak water use is determined by high temperatures in the summer. The city's average annual precipitation is 245 mm, about half of which occurs in summer, while the average annual evaporation is as high as 1524-1778 mm.

Among the many categories of water users at the Tucson Water Plant, some water users are seasonal in nature: they use little water in winter and their water consumption is relatively stable; they use more water in summer, And reach peaks with temperature and rainfall conditions. In the summer of 1974, Tucson experienced the hottest dry season in history. The city's water wells could no longer meet peak water requirements. The water supply system was out of service in some areas and the water delivery pressure dropped. In order to deliver water normally, the city of Tucson has reduced peak water consumption, and the amount of water used is not affected by the season. After the implementation of this plan, various water users have gradually adjusted their outdoor water consumption. The total water consumption per person per day has dropped from 776.5 liters in 1974 to about 549.2 liters currently.

(2) Rainwater collection system for residents in California, USA

Drought occurred in California from 1975 to 1977, and there was an urgent need to explore appropriate water supply solutions. Generally speaking, the most feasible way for rural residents to use water is to collect rainwater from rooftops, store it in some containers, and then provide it for use. Rainwater collection can fully meet the minimum household water needs.

(2) Water-saving irrigation measures in Israel

Israel is located in an arid and semi-arid desert zone. The rainfall in the north is 700-800mm, in the central part is 400-600mm, and in the south there is only 25 mm. To overcome the problem of insufficient rainfall, Israel has vigorously developed irrigated land. Among the current 437,000 hm2 of cultivated land, 193,000 hm2 (about 44.2% of the total cultivated land area) is irrigated land. Annual agricultural irrigation water reaches 1.18 billion m3, of which 900 million m3 is potable water. The agricultural irrigation method is pressure irrigation, mainly drip irrigation and sprinkler irrigation. The water utilization rate can reach 95% and 80% respectively, and all are managed by computers. Water sensors are used to automatically adjust irrigation, including irrigation time, frequency, interval, and irrigation amount. wait. According to the Israeli water law, all water in the country is state-owned and is managed by the Water Commission, which includes formulating policies, determining water use quotas, and formulating water resources development plans. In order to encourage farmers to save water, on the one hand, farmers are required to pay water fees, and on the other hand, the water price for the second half of the quota within the quota range is set to be higher than the first half. At present, the main research direction of the irrigation industry is to develop non-drinking water resources, such as wastewater, floods, saline-alkali water, etc., to ensure the continuous increase of agricultural water use.

In the early 1990s, sprinkler irrigation and drip irrigation technologies had been applied to 25% and 75% of the country's planting area respectively. Farmland and lawns generally use spraying and drip irrigation, and are highly automated, all controlled by computers. Each central computer controls dozens or even hundreds of hectares of surrounding land. Drip irrigation technology has been widely used throughout the country. The application of sprinkler irrigation and drip irrigation has greatly improved the utilization rate of water resources, reducing the irrigation water consumption per hectare of land by 1/3. Moreover, 70% of the country's sewage is treated and used for agricultural irrigation.

(3) Water-saving measures in Australia

70% of areas in Australia have rainfall below 500 mm, making drought prone. There are not many surface water sources in the country, and the average annual runoff is only 345.4 billion cubic meters. Although groundwater is abundant, 60% is artesian well area, and the available water source is only 1.76 million square kilometers. Australia continues to adopt new water-saving irrigation methods.

Burying a 12cm drip pipe underground and drip-irrigating the water and fertilizer solution directly to the roots of tomatoes and other crops not only saves a lot of water and fertilizer, but also harvests 90% of high-quality vegetables, while traditional irrigation methods can only harvest 60% - 70%, this irrigation method prevents excess fertilizer from polluting water canals. Another example is that in an orchard, when leaves fall in spring, the fruit trees are not watered or watered less, which inhibits the growth of the fruit trees. In summer, more water is applied to promote the growth of the fruits. This method allows the fruit trees to grow shorter, requiring less watering and pruning, but increasing fruit production. Tests show that it can save 20% of water and increase fruit production by 20%. Most orchards have adopted this measure.

(4) Measures for water conservation in the former Soviet Union

The distribution of water per unit land area and per capita water source in the former Soviet Union and other countries is extremely uneven, with numerical gaps Up to dozens of times. The former Soviet Union had 11 trillion cubic meters of atmospheric precipitation, about 40% of which was converted into river runoff. However, the regional distribution is extremely uneven. Some developed areas, which account for 90% of the cultivated land area and 80% of the industrial output value, only have 24% of the water resources of the former Soviet Union, while some southern regions with great demand for water resources only have about 16% of the water resources. % of available water resources. In addition to the above shortcomings, an important feature of the rivers of the former Soviet Union is the uneven distribution of time. In order to solve these shortcomings, the serious water shortage problem can only be solved by transferring water from other river basins through large water diversion channels and building many seasonal regulation reservoirs.

In order to rationally utilize water resources, the former Soviet Union formulated a series of water-saving measures: (1) perform three-level treatment of urban sewage and then use it; (2) treat surface runoff before use (3) Research and utilize drainage from industrial and mining enterprises; (4) Pump water from mines and formation water in industrial and mining areas; (5) Develop and utilize seawater in coastal areas; (6) Some equipment uses air cooling instead of water cooling; (7) Increase the capacity of a single power generation unit ; (8) Strengthen water management and treatment; (9) Adopt a progressive water fee system, etc.

(5) Water conservation and rational water use measures in India

In many areas of India, surface water is more abundant than groundwater, but the supply of surface water in many channels is often unstable. Sometimes there is even a serious shortage, so it is increasingly necessary to supplement surface water with groundwater. Groundwater supplementation of canal water increases the supply of canal water and can be used directly for irrigation during periods of low canal water supply or during canal closures for annual maintenance. In many areas, potential groundwater can be effectively combined with surface water for intensive irrigation.

Due to the excessive concentration of rainfall, in order to control rainwater loss, India uses ponds in farmland catchment areas to retain surface runoff, so that rainwater in dry lands can be preserved for supplementary irrigation during the dry season. This practice can save irrigation water and supplement insufficient irrigation water during the dry season to ensure normal growth, stable and high yield of crops.

In terms of irrigation technology, in order to improve water resource utilization and prevent soil salinization, India requires irrigation methods to be determined based on the depth of regional water levels. Due to the imbalance in the seasonal supply of water resources, the research department proposed a plan to pump large amounts of groundwater near rivers for irrigation before the rainy season, in order to lower the groundwater level and allow more floods to penetrate into the ground during the rainy season. This requires rationing water supply, recycling irrigation and other methods to save water resources before the arrival of the dry season.