CN103999739B - Winter irrigation method and system for saline-alkali land in northern coastal areas - Google Patents

Abstract

The present invention discloses the irrigation method in winter in coastal region salt-soda soil, a kind of north, and the method comprises the steps: 1) dig a well；2) from well, saline groundwater is extracted, and the salt water extracted out with storage reservoir accumulation；3) step 2) the middle salt water glaciation under field conditions (factors) extracted out；4) by step 3) ice cube that is frozen into covers and forms icing at soil surface and irrigate layer；5) by step 4) in the salt water that do not freezes below ice sheet extract out in storage reservoir；6) change in natural conditions, when icing irrigation layer starts to melt, from well, again extract saline groundwater, and salt water is accumulated in storage reservoir；7) repeat to implement step 2) 6), the winter that can realize coastal region salt-soda soil, the north irrigates.The method takes full advantage of salt water resources, decreases the exploitation to deep fresh groundwater, advantageously reduces level of ground water, suppresses the deep soil accumulation of salt in the surface soil.

Description

Winter irrigation method and system for saline-alkali land in northern coastal areas

technical field

The present invention relates to irrigation technology. More specifically, it relates to an irrigation method and system suitable for deep soil leaching and desalination in coastal saline-alkali land in northern my country.

Background technique

Soil salinity is the main limiting factor of the ecological environment in the coastal areas of northern my country, and it is also the limiting factor that leads to the fragility of the ecological environment system and low environmental carrying capacity. It also seriously restricts the growth of agriculture and the development of rural economy. In northern coastal areas, the groundwater table is high, the salinity is strong, the soil salt in the plow layer is accumulated, and the freshwater resources for agricultural irrigation are scarce. In recent years, the salt water freezing irrigation method has achieved good results in the improvement of saline-alkali land irrigation in the Bohai Bay coastal area. Salt water freezing irrigation refers to the extraction of surface salt water to irrigate saline-alkali land in winter. The salt water will form a certain thickness of salt water ice layer on the surface of saline-alkali land under the action of low temperature. When the spring melts, the strong salt water in the salt water ice layer melts first, and the brackish water melts later, thus forming thick salt water and brackish water to melt and infiltrate. This step infiltration has a very good irrigation and salt washing effect on coastal saline soil, can maintain soil moisture, and provide suitable soil moisture conditions for crop growth. However, this kind of irrigation salt water freezes (salt content is about 15g/L) and melts into the soil with more salt, which may raise the groundwater level and generate potential soil salt deposits, increasing the risk of potential soil salinization. Some researchers also use brackish water ice with low salinity to cover soil in saline-alkali soil. Compared with salt water freezing irrigation, this irrigation method reduces the salt entering the soil, increases the amount of fresh water entering the soil in the later stage of melting, and is conducive to soil leaching. Salt and soil moisture improvement for spring sowing. However, salt will accumulate in the deep soil (60-100cm), and there is a risk of returning salt to the surface soil. Therefore, in coastal areas with high groundwater salinity and shallow water level, if the control or reduction of groundwater level is not combined with irrigation measures, no matter what irrigation measures are used, it will inevitably cause groundwater level rise, deep soil salt accumulation, and surface soil return. Salt. Therefore, a new irrigation method and system for coastal saline-alkali land are needed to solve the above problems.

Contents of the invention

The first technical problem to be solved by the present invention is to provide a winter irrigation method for saline-alkali land in northern coastal areas. return salt.

The second technical problem to be solved by the present invention is to provide a winter irrigation system for saline-alkali land in the northern coastal area.

In order to solve the above-mentioned first technical problem, the present invention adopts the following technical solutions:

A winter irrigation method for saline-alkali land in northern coastal areas, the method comprising the steps of:

1) dig a well;

2) Draw underground salt water from the well, and use the reservoir to accumulate the extracted salt water;

3) The salt water extracted in step 2) is frozen into ice under natural conditions; because it is salt water, the accumulated salt water will not all freeze, but will only partially freeze into ice on the surface;

4) Covering the ice cubes frozen in step 3) on the soil surface to form an ice-coated irrigation layer;

5) extract the unfrozen salt water below the ice layer from the reservoir in step 4); the further processing of the salt water can be done with prior art, and has nothing to do with the present invention;

6) When the natural conditions change and the ice-covered irrigation layer begins to melt, the ground salt water is drawn from the well again and stored in the reservoir; through this step, the melting of the ice-covered irrigation layer does not cause the groundwater table to This is because the groundwater level has been lowered after the salt water is extracted again, and the water after the ice-covered irrigation layer melts will not raise the groundwater level, thereby inhibiting the return of salt in the deep soil;

7) Repeat steps 2)-6) to realize winter irrigation of saline-alkali land in the northern coastal area.

The above steps can realize the freezing irrigation of soil, make full use of salt water resources, reduce the exploitation of deep underground fresh water, and help to inhibit the return of salt in deep soil.

Preferably, if the amount of ice-covered irrigation layer obtained by one freezing is insufficient, repeat steps 2)-5).

Preferably, the depth of the well in step 1) is 15-20 meters, and the diameter of the wellhead is 0.4-0.6 meters.

Preferably, the salt water in the reservoir in step 2) is at least 1.5 meters deep, and the salinity of the salt water is 15-20g/L.

Preferably, the thickness of the ice layer of the ice-coated irrigation layer in step 4) is 40-60 cm, and the salinity of the ice layer is 2-4 g/L. In actual coverage, different ice-covered irrigation amounts on the soil surface are set according to the soil salinity of the cultivated layer in saline-alkali land, and the thickness of the cultivated layer in saline-alkali land is 0-40cm.

The irrigation method of the present invention is to build a pumping well on the saline-alkali ground in the coastal area, and use the pump to pump underground salt water in winter and store it in the reservoir, so that the groundwater level drops in time and space, and the brackish water ice frozen in the reservoir is covered to On the soil surface of the saline-alkali land, an ice-covered irrigation layer of a certain thickness is formed to drain the unfrozen salty water with high salinity in the reservoir, and then pump the underground salt water from the well again to further reduce the groundwater level. The brackish water is frozen into brackish water ice, and the brackish water ice is covered on the soil surface. In this way, the deep soil of the saline-alkali soil is irrigated and washed by reducing the groundwater level and the brackish water ice melts in spring.

In order to solve the above-mentioned second technical problem, the present invention adopts the following technical solutions:

A winter irrigation system for saline-alkali land in northern coastal areas, the system includes pumping wells, submersible pumps, pipelines, reservoirs and salt water;

The depth of the pumping well is 15-20 meters, and the diameter of the wellhead is 0.4-0.6 meters. The well wall of the pumping well is fixed with a water riser and a water filter pipe, and the water riser and the water filter pipe are connected and perpendicular to the bottom of the well. , the riser is fixed in the pipe wall below the well depth of 2 meters, and the water filter pipe is fixed on the ground to the depth of the well at 2 meters;

The submersible pump is placed in the pumping well and leads to the reservoir through a pipeline; it is used to pump the salt water in the well to the reservoir.

Preferably, there are multiple pumping wells, each well is 50-60 meters apart, and the multiple pumping wells are arranged in a square.

In the northern coastal saline-alkali land, pumping wells are installed. Risers and filter pipes are installed on the well walls of the pumping wells. The risers installed below the depth of the well are to prevent deep soil water from infiltrating into the pumping well; The filter pipe installed at 2 meters) is to allow the soil water more than 2 meters deep to infiltrate the pumping well. When the winter comes, the underground saline water is pumped into the reservoir, which not only lowers the groundwater level and reduces the salinity of the deep soil, but also provides saline water resources for the formation of brackish water ice in winter. The low temperature in winter causes the salty water in the reservoir to freeze, forming a layer of salty water ice with a thickness of 10-15 cm on the surface of the salty water, with a salinity of 2-4g/L; Collect and cover the soil surface of saline-alkali land to form an ice-covered irrigation layer with a thickness of 40-60 cm to provide water for soil irrigation in saline-alkali land in winter. In winter, due to the high salinity of the brine cells in the brackish water ice, they are still liquid and will not freeze under normal low temperature conditions. The brine cells will be discharged from the bottom of the ice body under the action of gravity to leave fresh water ice crystals. After high salinity water enters the soil, the soil salinity will increase and the soil permeability will improve. As the temperature rises in spring, the freshwater ice crystals melt slowly, and at the same time, the salt water from the pumping well is accumulated in the reservoir again, lowering the groundwater level; It will dissolve part of the soil salt and wash it into the deep soil, and then cooperate with the pumping well to pump groundwater, further reduce the groundwater level, and desalinate the deep soil. At the same time, fresh water enters the soil in spring to improve soil moisture and provide good soil desalination and water conditions for spring crop germination and seedling growth.

This combination of digging and pumping wells, pumping groundwater, freezing salt water into ice, and ice-covered irrigation can lower the groundwater level and reduce deep soil salinity. The process of infiltration reduces the salinity of the soil in the plow layer and increases the soil moisture, so that the coastal areas can make full use of underground salt water resources to the maximum extent, and realize the purpose of soil irrigation in saline-alkali land without surface fresh water irrigation.

The beneficial effects of the present invention are as follows:

1. Make full use of salt water resources. The invention makes full use of abundant underground saline water resources in coastal saline-alkali land areas, and reduces the exploitation of deep underground fresh water;

2. Make full use of the low-temperature resources in the northern coastal area, so that the salt water in the shallow reservoir freezes in winter to form brackish water ice, providing water for irrigation of saline-alkali soil;

3. Build pumping wells on saline-alkali soil to extract groundwater, lower the groundwater level, and inhibit the deep soil from returning to salt;

4. Extract groundwater from saline-alkali land, vacate underground storage capacity, increase the depth of ice-melt irrigation in winter into the soil, and desalinate deep soil in saline-alkali land;

5. A large amount of fresh water infiltrates into the soil in the later stage of ice melting, increasing soil water content, improving soil moisture, and providing favorable water conditions for the germination or seedling growth of spring-sown crops;

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 shows the principle schematic diagram of saline-alkali land irrigation method and system of the present invention;

Figure 2 shows a cross-sectional view of the pumping well of the present invention.

detailed description

In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

In the figure, 1 is a pumping well, 2 is a submersible pump, 3 is an aqueduct, 4 is a reservoir, 5 is salt water, 6 is brackish water ice, 7 is an ice-covered irrigation layer, 8 is a water riser, and 9 is filter tube.

As shown in Fig. 1 and Fig. 2, a pumping well 1 is set on the coastal saline-alkali ground, and in winter, a submersible pump 2 is used to connect the aqueduct 3 to extract the underground salt water in the pumping well 1 to the reservoir 4, and the salt water in the reservoir 4 5. Under the action of low temperature in winter, brackish water ice 6 with a certain thickness is formed, and these brackish water ice 6 are taken out and piled up on the soil surface of the saline-alkali land to form an ice-covered irrigation layer 7 of 40-60 cm.

The well wall of the pumping well 1 adopts the pipe string that the water riser 8 and the filter pipe 9 combine, and is vertically installed in the pre-drilled well hole, and the pipe is vertical to the bottom of the well. The water riser is installed below 2 meters underground, and the water filter pipe is installed from the ground to 2 meters underground.

The winter irrigation method of the present invention is tested at 13 team saline-alkali lands in Zhongjie Friendship Farm, Huanghua City, Hebei Province, comprising the steps:

1. In the spring of 2012, three pumping wells were drilled on the saline-alkali wasteland (soil salinity was 2.5g/kg). The pipe column where the water riser and the water filter pipe want to be combined is installed vertically in the pre-drilled well hole; the water riser is installed at a place below 2 meters underground, and the water filter pipe is wrapped with non-woven fabric and installed at a place from the ground to 2 meters underground;

2. In winter, the submersible pump is used to continuously extract groundwater and discharge it into the reservoir, so that the water level in the pumping well is reduced to below 2 meters; a 1.7-meter-deep saltwater layer is formed in the reservoir, and the salinity of the saltwater is 15g/ L;

3. The low temperature in winter caused the salt water in the reservoir to freeze, and a layer of salt water ice formed on the surface of the salt water on December 20, 2012; on December 30, 2012, the thickness of the salt water ice was 15 cm, and its salinity was 2.5g/ L;

4. Repeat steps 1-3.

5. The salty water ice collected from the storage reservoir is covered to the soil surface of the saline-alkali land many times, and finally an ice-coated irrigation layer with a thickness of 40 cm is formed on the saline-alkali soil;

6. The unfrozen salt water below the ice layer in step 5 is extracted from the reservoir for processing;

7. When the natural conditions change in spring and the ice-covered irrigation layer begins to melt, pump the ground salt water from the well again and store the salt water in the reservoir; through this step, the melting of the ice-covered irrigation layer will not cause groundwater This is because the groundwater level has been lowered after the salt water is extracted again, and the water after the ice-covered irrigation layer melts will not raise the groundwater level, thereby inhibiting the return of salt in the deep soil.

The soil salinity and desalination rate of each layer before and after saltwater ice irrigation in saline-alkali land are as follows:

Table 1 Changes of soil moisture and salinity in saline-alkali land under ice-covered irrigation

After the ice-covered irrigation of the present invention and the prior art, the salinity of the soil in the 0-20cm and 20-40cm layers of the saline-alkali land is reduced from 3.50g/kg and 3.70g/kg to 1.50g/kg and 2.50g/kg respectively. Ice-covered irrigation in the prior art increases the salinity of the soil in the 60-80cm and 80-100cm layers of saline-alkali soil, forming a deep layer of soil salt accumulation, and there is a risk of returning salt to the 0-40cm layer of soil; and the saline-alkali soil of 60-80cm and The soil salinity in the 80-100cm layer is reduced, and no deep soil salt accumulation layer is formed, reducing the risk of returning to salt in the 0-40cm layer.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those of ordinary skill in the art can also make It is impossible to exhaustively list all the implementation modes here, and any obvious changes or changes derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims (5)

1. the irrigation method in winter in a northern coastal region salt-soda soil, it is characterised in that: include walking as follows Rapid:

1) dig a well；

2) from well, saline groundwater is extracted, and the salt water extracted out with storage reservoir accumulation；

3) step 2) the middle salt water glaciation under field conditions (factors) extracted out；

4) by step 3) ice cube that is frozen into covers and forms icing at soil surface and irrigate layer；

5) by step 3) in the salt water that do not freezes below ice sheet extract out in storage reservoir；

6) change in natural conditions, when icing irrigation layer starts to melt, from well, again extract underground Salt water, and salt water is accumulated in storage reservoir；

7) repeat to implement step 2)-6), the winter that can realize coastal region salt-soda soil, the north irrigates；

When the icing obtained if once frozen irrigates layer amount deficiency, repeat step 2)-5)；

Step 2) at least 1.5 meters of salt water in described storage reservoir is deep, and the salinity of described salt water is 15-20g/L；

Step 4) described icing irrigate layer ice layer thickness be 40-60cm, ice sheet salinity is 2-4g/L.

The most according to claim 1, the irrigation method in winter in coastal region salt-soda soil, the north, its feature exists In preferably, step 1) degree of depth of described well is 15-20 rice, well head a diameter of 0.4-0.6 rice.

3. the irrigation method in winter for the north as claimed in claim 1 coastal region salt-soda soil The north coastal region salt-soda soil irrigation system in winter, it is characterised in that: this system include pumped well (1), Immersible pump (2), pipeline (3), storage reservoir (4) and salt water (5)；

The degree of depth of described pumped well (1) is 15-20 rice, well head a diameter of 0.4-0.6 rice, described pumped well The borehole wall is fixed with marine riser (8) and filter pipe (9), described marine riser (8) and filter pipe (9) and connects and be perpendicular to well The end, described marine riser (8) is packed in the tube wall of well depth less than 2 meters, and described filter pipe (9) is packed in ground To well depth 2 meters.

Described immersible pump (2) is placed in pumped well (1), leads to storage reservoir (4) by pipeline (3).

Winter the most according to claim 3 irrigation system, it is characterised in that: described pumped well (1) It is provided with many mouthfuls, at a distance of 50-60 rice between every mouthful of well, by square arrangement between described many mouthfuls of pumped wells.

Winter the most according to claim 3 irrigation system, it is characterised in that: described storage reservoir (4) In salt water (5) degree of depth at least 1.5 meters, the salinity of described salt water is 15-20g/L；Described salt water is frozen The ice layer thickness of Cheng Bing is 15-20cm, and ice sheet salinity is 2-4g/L.