What water-saving measures are there?

(A) water-saving measures in the United States

The main measures taken by the United States in the development and utilization of water resources include: reducing water consumption and loss, rational use of water and water conservation. Including: protecting water sources and preventing soil erosion; Reuse of water source, focusing on treating urban sewage and then using it as irrigation water source; Regulating river runoff; Cultivate drought-resistant varieties; Diversion to replenish groundwater; Reduce evaporation and apply plant growth regulators; Adjust crop varieties and market supply. At present, the development of water-saving irrigation agriculture in the United States mainly adopts the combination of advanced water-saving irrigation technology and agricultural technology to replace the traditional single surface irrigation technology, and 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 is very hot in summer, and the temperature often exceeds 37.8 degrees Celsius. The peak of water consumption in this city is determined by the high temperature period in summer. The average annual precipitation in this city is 245 mm, about half of which occurs in summer, and the average annual evaporation is as high as 1524- 1778 mm.

Among the many types of water users in Tucson Waterworks, some users are seasonal in nature: the water consumption is small in winter and relatively stable; Water consumption is large in summer, and it reaches its peak with temperature and rainfall. 1974 In the summer, Tucson experienced the hottest dry season in history, and the wells in the city could not meet the peak water demand. The water supply system stopped in some areas, and the water supply pressure dropped. In order to deliver water normally, Tucson reduced the peak water consumption, and the water consumption was not affected by seasons. After the implementation of the scheme, all kinds of water users have gradually adjusted their outdoor water use methods, and the per capita daily total water consumption has dropped from 65,438+776.5 liters in 0974 to about 549.2 liters at present.

(2) California resident rainwater collection system.

1975 to 1977, there is a drought in California, and it is urgent to explore a suitable water supply scheme. Generally speaking, the most feasible way for rural residents to use water is to collect rainwater from the roof and store it in some containers. Rainwater collection can completely meet the low-level domestic water demand.

(B) Israel's water-saving irrigation measures

Israel is located in arid and semi-arid desert, with rainfall of 700-800 mm in the north, 400-600 mm in the middle and only 25 mm in the south. In order to overcome the problem of insufficient precipitation, Israel has vigorously developed irrigated land. At present, among the 437,000 hectares of cultivated land, 6.5438+093 million hectares (about 44.2% of the total cultivated land area) are irrigated land, and the annual agricultural irrigation water consumption reaches 65.438+065438+800 million m3, of which 900 million m3 is drinking water. Agricultural irrigation is pressure irrigation, mainly drip irrigation and sprinkler irrigation. The water utilization rate can reach 95% and 80% respectively, and all of them are managed by computer. Irrigation is automatically adjusted by water sensors, including irrigation time, frequency, interval and irrigation amount. According to Israel's water law, all water resources in the country are state-owned and managed by the Water Affairs Committee, including making policies, determining water quotas and making water resources development plans. In order to encourage farmers to save water, on the one hand, farmers are required to pay water charges, on the other hand, the water price in the second half of the quota is higher than that in the first half. At present, the main research direction of irrigation industry is to develop non-drinking water resources, such as wastewater, flood, saline-alkali water and so on. To ensure the sustainable growth of agricultural water use.

In the early 1990s, sprinkler irrigation and drip irrigation were applied to 25% and 75% of the planting area in China respectively. Desert spraying and drip irrigation are generally used in farmland and lawn, which are highly automated and all controlled by computer. Each central computer controls dozens or even hundreds of hectares of land around it. Drip irrigation technology has been widely used all over the country. The application of sprinkler irrigation and drip irrigation has greatly improved the utilization rate of water resources, and the irrigation water consumption per hectare has decreased by 1/3. In addition, 70% of the country's sewage is treated for agricultural irrigation.

(3) Water saving measures in Australia

70% of the rainfall in Australia is below 500 mm, which is prone to drought. There are not many surface water resources in China, and the average annual runoff is only 345.4 billion cubic meters. Although the groundwater is abundant, 60% of it is ziliujing district, and the available water source is only 6.5438+0.76 million square kilometers. Australia is constantly adopting new water-saving irrigation methods. Burying 1.2cm drip irrigation pipe in the roots of tomatoes and other crops and directly drip irrigation with water and fertilizer solution can not only save a lot of water and fertilizer, but also harvest 90% of high-quality vegetables, while traditional irrigation methods can only harvest 60%-70%. This irrigation method can prevent excessive fertilizer from polluting the canal. Another example is the orchard, where the fallen leaves in spring are not watered or watered less, which inhibits the growth of fruit trees. In summer, water more to promote the growth of fruits. This method makes the fruit trees grow very short without too much watering and pruning, but the fruit yield has increased. The experiment shows that it saves water by 20% and increases production by 20%. Most orchards have taken this measure.

(D) the former Soviet Union's water-saving measures

The distribution of water quantity per unit land area and per capita water quantity in the former Soviet Union is extremely uneven, and the digital gap is as many as dozens of times. The former Soviet Union had 1 1 trillion cubic meters of atmospheric precipitation, of which about 40% was converted into river runoff. However, the regional distribution is extremely uneven. In some developed areas, which account for 90% of cultivated land and 80% of industrial output value, the water resources are only 24% of that of the whole former Soviet Union, while in some southern areas with great demand for water resources, the available water resources are only about 16%. In addition to these shortcomings, the important feature of rivers in the former Soviet Union is uneven time distribution. In order to solve these problems, the serious water shortage problem can only be solved by transferring water from other basins through large-scale water diversion channels and building many seasonally adjusted reservoirs.

In order to make rational use of water resources, the former Soviet Union has formulated a series of water-saving measures: (1) municipal sewage is reused after tertiary treatment; (2) Surface runoff is treated and utilized; (3) Research and utilization of drainage in industrial and mining enterprises; (4) extracting mine water and formation water from industrial and mining areas; (five) the development and utilization of seawater in coastal areas; (6) Some equipment adopts air cooling instead of water cooling; (7) Increase the capacity of a single generator; (8) Strengthen water management and treatment; (9) Adopt progressive water fee system.

(v) Water saving and rational water use measures in India

Surface water is more abundant than groundwater in many places in India, but the supply of surface water in many channels is often unstable and sometimes even seriously insufficient, so groundwater is increasingly needed to supplement surface water. Groundwater supplements channel water to increase the supply of channel water, and it can be directly used for irrigation during the low peak period of channel water supply or the annual maintenance period of channel closure. In many areas, potential groundwater can be effectively combined with surface water for intensive irrigation.

Because the precipitation time is too concentrated, in order to control rainwater loss, India uses ponds in farmland catchment to intercept surface runoff, so that rainwater can be stored in arid areas for supplementary irrigation in dry season. This practice can save irrigation water and make up for the shortage of irrigation water in dry season, thus ensuring the normal growth and stable and high yield of crops.

In terms of irrigation technology, in order to improve the utilization rate of water resources and prevent soil salinization, India requires that irrigation methods be determined according to the depth of regional water level. Due to the unbalanced seasonal supply of water resources, the research department put forward a scheme of pumping a large amount of groundwater near the river for irrigation before the rainy season, so as to reduce the groundwater level and make the rainy season flood penetrate into the ground more. This requires that before the arrival of dry season, quantitative water supply and circular irrigation should be adopted to save water resources.