Method for monitoring water balance elements in different rock surface-soil combinations of rocky desertification cultivated land

Abstract

The invention discloses a method for monitoring water balance elements under different rock surface-soil combinations of rocky desertification cultivated land, which simulates and measures the water balance elements under different rock surface-soil combinations by constructing a set of independently researched and developed monitoring system and replacing the type of rock in a rock surface barrel and the type and thickness of soil in a soil barrel. And detailed classified monitoring of various elements of the soil water balance of the stony desertification cultivated land is realized. Furthermore, the vertical leakage coefficients of different rock materials are measured through a rock surface jacking leakage simulation system, and the influence of the jacking effect of different rock materials on the water balance element of the stony desertification cultivated land is analyzed. According to the invention, various elements in the soil water balance process of the stony desertification cultivated land can be monitored, so that long-time-sequence quantification of rock surface jacking leakage, soil water storage and crop water demand under the field condition is realized, and data support is provided for optimizing regional cultivated land irrigation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of soil hydrology, in particular to the soil hydrological process under the rock surface buttress in karst rocky desertification area and the measurement of crop transpiration, and provides a method for obtaining basic data in the efficient use of water resources in agricultural irrigation in karst rocky desertification area, in particular to a method for monitoring water balance elements under different rock-soil combinations in rocky desertification farmland BACKGROUND

[0002] Rocky desertification is a phenomenon of land degradation in which vegetation is sparse due to natural or human factors during the development of tropical or subtropical karst landforms, causing serious soil erosion, large-area exposure of bedrock, gravel accumulation, and decline or even loss of land productivity, resulting in a desert landscape. The soil of farmland in rocky desertification area is shallow, and the rock below the soil layer is broken and has dense cracks. Therefore, whether it is the abundant rainfall resources or the artificial irrigation water supply, they are all seeped into the underground river and lost through the underground cracks and rock surface buttress. The soil has difficulty in storing water, and the crop water demand is limited, which is a long-standing problem in regional agricultural production. How to reduce water loss in the water balance process, maximize the green water resources stored in the soil and used by plants, and improve the efficiency of irrigation is the key to solving the problem of regional agricultural water use. However, the thickness of the soil in rocky desertification farmland and the strong heterogeneity of the buttress rock below the soil layer result in significant differences in buttress seepage, soil water storage, and crop water demand, and effective monitoring experiments are urgently needed to provide guidance for agricultural irrigation.

[0003] There are currently many types of monitoring methods for soil water storage and crop water demand. These methods are based on soil water physical or chemical properties, or based on soil water balance equation to calculate and deduce. Monitoring the changes in soil water balance process is an important direction for continuous and accurate monitoring without damage. By quantifying each element in the water balance equation, soil water storage and vegetation transpiration can be quickly and accurately monitored. However, in rocky desertification areas, not only is there a large difference in soil thickness, which requires low-cost continuous monitoring in the monitoring process, but more importantly, the rock surface buttress effect below the soil is prominent, resulting in a large amount of vertical and lateral seepage. The existing general monitoring equipment lacks monitoring of lateral seepage, which leads to large calculation errors of soil water balance elements in rocky desertification areas. At the same time, the spatial heterogeneity of the rock surface below the soil in rocky desertification area is strong, and different rock types and particle sizes have different porosities, resulting in differences in vertical seepage rate and lateral seepage. Therefore, to monitor the soil water balance elements in rocky desertification farmland, two problems must be solved. The first is to measure lateral seepage and fill in the missing items in the original monitoring. The second is to quantify the vertical seepage rate of different rock surfaces and determine the buttress seepage effect under different rock surfaces, so as to realize integrated monitoring of rock surface differences, soil thickness changes, and crop planting.

[0004] There are many devices and methods for monitoring water storage in rocky desertification areas in the prior art. These technologies have solved the problem of monitoring soil water storage, seepage and crop water demand in rocky desertification farmland to some extent, but still cannot solve the above technical problems, mainly manifested in the following two points: 1) lack of direct monitoring of vertical and lateral seepage, for example, the TDR soil moisture measuring device (CN201621066761.8) method suitable for rocky desertification areas only analyzes soil water storage, cannot answer the changes of each element in the water resource balance process during rainfall and irrigation, and cannot guide the irrigation of rocky desertification farmland; a distributed nonlinear hydrological simulation method in karst area (CN202111545744.8) mainly observes the runoff change in karst area, and lacks monitoring of each element in the soil water balance process; 2) lack of observation of the difference in capillary effect under lithology change, for example, a simple karst soil leaching test device (CN202322764214.3) method only simulates the leaching process of rocky desertification soil, and cannot simulate and analyze the lateral seepage under different rock surfaces and the capillary effect. SUMMARY

[0005] The purpose of the present application is to provide a method for monitoring the water balance elements of different rock-soil combinations in rocky desertification farmland, which can monitor each element in the soil water balance process of rocky desertification farmland, realize long-term quantitative rock capillary seepage, soil water storage and crop water demand under field conditions, and provide data support for optimizing regional farmland irrigation. The purpose of the present application is achieved by the following technical scheme:

[0006] A method for monitoring the water balance elements of different rock-soil combinations in rocky desertification farmland, comprising the following steps:

[0007] Step 1: Make rock materials with different lithology;

[0008] Step 2: Build a monitoring system:

[0009] S21 vertically bury the outer protective barrel in the farmland, with the upper edge of the barrel being 5-8 cm higher than the farmland to prevent surface rainwater from flowing in; the outer protective barrel is a hollow cylinder with an open top and a sealed bottom, and a lateral seepage water pipe is perforated on the upper barrel wall;

[0010] S22 install a seepage water collection device at the bottom of the outer protective barrel;

[0011] S23 embed the soil thickness simulation barrel in the outer protective barrel, and set it on the seepage water collecting device; the soil thickness simulation barrel comprises upper and lower parts, the lower part is a rock surface barrel, and the upper part is a soil barrel; a first stainless steel mesh is arranged at the bottom of the rock surface barrel, and the rock material prepared in the first step is filled in the barrel; a second stainless steel mesh is arranged at the bottom of the soil barrel, and farmland soil is filled in the barrel; a side seepage water guide pipe is arranged at the lower part of the barrel wall of the soil barrel, the side seepage water guide pipe passes out through a side seepage water guide pipe perforation in the outer protective barrel wall, and the side seepage water guide pipe is in sealing connection with the side seepage water guide pipe perforation; there is a gap between the soil thickness simulation barrel and the outer protective barrel, the upper end of the gap is sealed by a ring-shaped sealing ring, a hose perforation is formed in the ring-shaped sealing ring, the upper edge of the seepage water collecting device is in sealing connection with the lower edge of the soil thickness simulation barrel;

[0012] S24 embed a side seepage water collecting device in the farmland on one side of the outer protective barrel, and the side seepage water guide pipe is in sealing connection with the side seepage water collecting device through a pipeline;

[0013] S25 set a seepage water extraction and measurement device on the ground; one branch of the water extraction pipeline of the seepage water extraction and measurement device is connected with a water input hose, the water input hose passes into the gap between the soil thickness simulation barrel and the outer protective barrel from the hose perforation and is connected to the seepage water collecting device, and the water input hose is in sealing connection with the hose perforation; the other branch of the water extraction pipeline of the seepage water extraction and measurement device is connected with a side water input pipe, and the lower end of the side water input pipe is in sealing connection with the side seepage water collecting device.

[0014] Step three: water balance element calculation: monitoring is carried out on each element in the soil water balance equation:

[0015] Rainfall P is monitored by setting a rain gauge in the rocky desertification farmland monitoring area; irrigation amount I is measured by a water meter during farmland irrigation;

[0016] Seepage amount g is obtained by measuring the water amount in the seepage water collecting device through the seepage water extraction and measurement device in the monitoring system; and rock surface uplift seepage amount L is obtained by measuring the water amount in the side seepage water collecting device through the seepage water extraction and measurement device.

[0017] Soil evaporation amount E s The following formula is used for calculation:

[0018] E s =G l,ck,n-1 -G l,ck,n

[0019] In the formula, E s is the soil evaporation amount, G l,ck,n-1 is the weight of the soil thickness simulation barrel without planting crops in the last weighing, and G l,ck,n is the weight of the soil thickness simulation barrel without planting crops in the current weighing.

[0020] Plant transpiration E t Calculated using the following formula:

[0021] E t =(G l,n-1 -G l,n )-(G l,ck,n-1 -G l,ck,n )

[0022] In the formula, E t It is crop transpiration, G l,n-1 It is the soil thickness under the planted crops that simulates the weight of the bucket in a previous weighing, G l,n This is a simulation of the soil thickness under the planted crops, simulating the weight of the weighing bucket in this weighing.

[0023] Soil water storage capacity ΔS is calculated using the following formula.

[0024] ΔS=P+IE s -E t -gL

[0025] Step 4: Measurement of different soil-lithology combinations: By changing the rock type in the rock surface bucket and the soil type and thickness in the soil bucket in S23, the water balance elements under different rock surface-soil combinations are simulated and measured to achieve detailed classification and monitoring of various elements of soil water balance in rocky desertification farmland.

[0026] In a further optimization, the method of the present invention also includes steps five, six, and seven.

[0027] Step 5: Installation of the rock surface support leakage simulation system:

[0028] First, assemble the rock surface support seepage simulation bucket, which consists of two parts: a lower rock surface bucket and an upper water filling bucket. The bottom of the rock surface bucket is equipped with a first stainless steel mesh and the rock material used in step four is placed inside. The bottom of the water filling bucket is equipped with a movable water-proof base plate made of soft silicone and the bucket is filled with water to a preset height. The movable water-proof base plate is connected to a pull line extending outside the bucket. A water level observation pipe is connected to one side of the water filling bucket wall. Connect the lower end of the rock surface support seepage simulation bucket to a seepage water collection device, and seal the upper edge of the seepage water collection device with the lower edge of the rock surface support seepage simulation bucket.

[0029] Step Six: Measurement of Vertical Leakage Coefficient for Different Rock Materials: Quickly remove the movable water-proof base plate by pulling the string, and record the changes in water level and leakage over time; calculate the vertical leakage coefficient Kv of the test rock surface using the following formula, and use this coefficient to determine the backing effect of different rock surfaces:

[0030]

[0031] In the formula: Qv is the vertical leakage water quantity, collected by the leakage water collection device, unit m 3 ; L is the thickness of the rock layer, which can be the height of the rock surface barrel set, unit m; A is the cross-sectional area of the rock surface barrel, unit m 2 ; Δh is the water head difference, the pressure difference between the upper and lower parts of the rock layer, unit m; t is the leakage time, unit s; according to the different rock types used in step four, the rock materials in the rock surface barrel are replaced, and the vertical leakage coefficients of different rock materials are measured;

[0032] Step seven, based on the vertical leakage coefficients of different rock materials measured in step six and the water balance elements under different rock-soil combinations measured in step four, the influence of the toppling effect of different rock materials on the water balance elements of rocky desertification farmland is analyzed.

[0033] Further, in step one: different lithology test materials are made, different particle size rocks are used, and different mortar proportions are added to make different cylindrical test materials with different fissures; or cylindrical cores of different lithology rocks collected in rocky desertification areas are used as test materials.

[0034] Further, the leakage water extraction measuring device comprises a water pump and a measuring cylinder, the input end of the water pump is connected to the water extraction pipeline, the output end of the water pump is connected to the measuring cylinder through a water outlet pipe, the water extraction pipeline is connected to the water delivery hose and the lateral water delivery pipe through a three-way pipe, and the water delivery hose and the lateral water delivery pipe are respectively provided with control valves.

[0035] Further, the leakage water collection device comprises a funnel-shaped water collector at the top and a sealed bottle at the bottom, the lower end of the funnel-shaped water collector is sealingly connected to the sealed bottle, and the sealed bottle is provided with a water extraction hole.

[0036] Further, the lateral seepage water collection device is provided with a water inlet and a water outlet, the water inlet is sealingly connected between the pipeline and the lateral seepage water pipe, and the water outlet is sealingly connected between the lateral water delivery pipe.

[0037] Further, the mesh of the first stainless steel mesh and the second stainless steel mesh is not greater than 40 mesh.

[0038] Further, in step two, the soil barrel and the rock surface barrel are detachably connected, and the connecting edges of the soil barrel and the rock surface barrel are sealed.

[0039] Further, in step four, the irrigation barrel and the rock surface barrel are detachably connected, and the connecting edges of the irrigation barrel and the rock surface barrel are sealed.

[0040] Further, in step two, a supporting device is further arranged in the outer protective barrel; the supporting device is a supporting rod supported between the bottom of the outer protective barrel and the upper edge of the leakage water collection device.

[0041] The advantages and beneficial effects of the present application are:

[0042] The method for monitoring the water balance elements of different rock-soil combinations of rocky desertification farmland of the present application monitors each element of the soil water balance process of rocky desertification farmland based on the self-developed monitoring system, so as to realize long-term quantitative rock toppling seepage, soil water storage and crop water requirement under field conditions, and provide data support for optimizing regional farmland irrigation.

[0043] The method of the present application can more truly simulate the seepage condition of rocky desertification farmland by monitoring each water balance element of the soil of rocky desertification farmland: 1) direct monitoring of vertical and lateral seepage; by measuring lateral seepage, the missing item in the original monitoring is supplemented; 2) differential observation of the toppling effect under the change of lithology; quantifying the vertical seepage rate of different rock surfaces, determining the toppling seepage effect under different rock surfaces, and realizing integrated monitoring of rock surface difference, soil thickness change and crop planting.

[0044] The present application will be further described below in conjunction with the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a schematic diagram of the connection structure of the monitoring system in the examples;

[0046] Figure 2 It is a schematic diagram of the use state of the monitoring system in the examples;

[0047] Figure 3 It is a schematic diagram of the outer protection barrel structure;

[0048] Figure 4 It is a schematic diagram of the supporting device structure;

[0049] Figure 5 It is a schematic diagram of the soil thickness simulation barrel structure;

[0050] Figure 6 It is a schematic diagram of the operation of measuring the water balance elements under different rock-soil combinations;

[0051] Figure 7 It is a schematic diagram of the rock toppling seepage simulation barrel structure;

[0052] Figure 8 It is a schematic diagram of the irrigation barrel structure;

[0053] Figure 9 It is a schematic diagram of the operation of measuring the vertical seepage coefficient of different rock materials.

[0054] Reference signs:

[0055] 1, outer protective barrel; 11, side seepage water pipe perforation; 2, supporting device; 3, soil thickness simulation barrel; 31, rock surface barrel; 32, soil barrel; 33, first stainless steel mesh; 34, second stainless steel mesh; 35, side seepage water pipe; 36, handle; 37, watering barrel; 371, water level observation pipe; 38, movable waterproof bottom plate; 39, pull wire; 4, seepage water collection device; 41, funnel-shaped water collector; 42, sealed bottle; 43, water pumping hole; 5, seepage water pumping and measuring device; 51, water conveying hose; 52, water pumping pump; 53, measuring cylinder; 6, annular sealing ring; 61, hose perforation; 7, side seepage water collection device; 71, water inlet; 72, water outlet; 8, gravel. DETAILED DESCRIPTION

[0056] Example 1

[0057] A method for monitoring the water balance elements of stony desertification farmland under different rock-soil combinations, comprising the following steps:

[0058] Step one: making rock materials of different lithology: different lithology test materials are made by using rocks of different particle sizes and adding different mortar ratios to make cylindrical test materials of different fissures. Meanwhile, cylindrical rock cores of different lithology rocks collected in stony desertification areas can also be used as test materials. The diameter and height of the test materials can be adjusted according to experimental requirements.

[0059] Step two: constructing a monitoring system, the overall structure is shown in Figure 1, and the use state is shown in Figure Figure 2

[0060] S21 vertically burying the outer protective barrel 1 in the farmland, with the upper edge of the barrel being 5-8 cm higher than the farmland to prevent surface rainwater from flowing in; the outer protective barrel 1 is a hollow cylinder with an open top and a sealed bottom, and a side seepage water pipe perforation 11 is formed in the upper part of the barrel wall; a transparent material can be used. The outer protective barrel is shown in Figure 3

[0061] S22 installing a seepage water collection device 4 at the bottom of the outer protective barrel 1: in this embodiment, the seepage water collection device 4 includes a funnel-shaped water collector 41 at the top and a sealed bottle 42 at the bottom, the upper edge of the funnel-shaped water collector 41 is sealingly connected to the lower edge of the soil thickness simulation barrel 3, the lower end of the funnel-shaped water collector 41 is sealingly connected to the sealed bottle 42 through a hard pipe and a sealing ring, a water pumping hole 43 with a diameter of 1 cm is provided on the sealed bottle 42, and the water pumping hole 43 is sealingly connected to the lower end of the water conveying hose 51.

[0062] In order to make the support of the soil thickness simulation barrel 3 more stable, as shown in Figure 4 ​​As shown, the embodiment is also provided with a supporting device 2 for supporting the soil thickness simulation barrel 3 in the outer protective barrel 1; the supporting device 2 is a metal supporting rod supported between the bottom of the outer protective barrel 1 and the upper edge of the leakage water collecting device 4. The supporting rod can be integrated with the funnel-shaped water collector 41, such as welded connection.

[0063] S23 embeds the soil thickness simulation barrel 3, which can be transparent material, in the outer protective barrel 1, above the leakage water collecting device 4; as shown, Figure 5 As shown, the soil thickness simulation barrel 3 includes upper and lower two parts, the lower part is a rock surface barrel 31, and the upper part is a soil barrel 32; the rock surface barrel 31 is provided with a first stainless steel mesh 33 at the bottom and filled with the rock material made in the first step in the barrel, and the soil barrel 32 is provided with a second stainless steel mesh 34 at the bottom and filled with the farmland soil; the upper edge of the leakage water collecting device 4 is in sealing connection with the lower edge of the soil thickness simulation barrel 3;

[0064] In the embodiment, the soil barrel 32 and the rock surface barrel 31 are two independent barrels with the same outer diameter, the lower end of the soil barrel 32 has a flange with a smaller diameter than the outer diameter, so as to be inserted into the rock surface barrel 31, and a sealing ring can also be added at the edge where the soil barrel 32 and the rock surface barrel 31 meet for more sealing. In the embodiment, the mesh of the first stainless steel mesh 33 and the second stainless steel mesh 34 is not greater than 40 meshes, the area is not less than 90% of the cross-sectional area of the soil thickness simulation barrel 3, and the edge is as narrow as possible. The upper end of the soil barrel 32 is provided with a handle 36 for easy removal. The lower part of the barrel wall of the soil barrel 32 is provided with a side seepage water guide pipe 35, which is led out through the side seepage water guide pipe perforation 11 of the outer protective barrel 1 wall, and a sealing ring is arranged between the side seepage water guide pipe 35 and the side seepage water guide pipe perforation 11; there is a gap (1 cm) between the soil thickness simulation barrel 3 and the outer protective barrel 1, and the upper end of the gap is sealed with a ring-shaped sealing ring 6, and a hose perforation 61 is formed in the ring-shaped sealing ring 6.

[0065] S24 embeds a side seepage water collecting device 7 in the farmland on one side of the outer protective barrel 1, and is sealingly connected with the side seepage water guide pipe 35 through a pipeline; the side seepage water collecting device 7 has a water inlet 71 and a water outlet 72, the water inlet 71 is sealingly connected between the side seepage water guide pipe 35 and a sealing ring through a pipeline, and the water outlet 72 is sealingly connected between the side seepage water guide pipe 35 and a sealing ring, which can be sealed by a rubber ring.

[0066] S25 sets up the seepage water extraction measuring device 5 on the ground; in the embodiment, the seepage water extraction measuring device 5 includes a water pump 52 and a measuring cylinder 53, the input end of the water pump 52 is connected with a water pumping pipeline, the output end of the water pump 52 is connected to the measuring cylinder 53 through a water outlet pipe, the water pumping pipeline is connected with the water conveying hose 51 and the lateral water conveying pipe 54 through a three-way pipe respectively, and the water conveying hose 51 and the lateral water conveying pipe 54 are respectively provided with control valves. One branch of the water pumping pipeline is connected with the water conveying hose 51, the water conveying hose 51 is connected to the seepage water collecting device 4 through the gap between the soil thickness simulation barrel 3 and the outer protective barrel 1 from the hose perforation 61, and the input hose 51 and the hose perforation 61 are in sealed connection; the other branch of the water pumping pipeline is connected with the lateral water conveying pipe 54, and the lower end of the lateral water conveying pipe 54 is connected to the lateral seepage water collecting device 7 in a sealed manner.

[0067] Step three: water balance element calculation: monitoring each element in the soil water balance equation:

[0068] Rainfall P is monitored by setting a rain gauge in the rocky desertification farmland monitoring area; irrigation amount I is measured by a water meter during farmland irrigation;

[0069] The seepage amount g is obtained by measuring the water amount in the seepage water collecting device 4 through the seepage water extraction measuring device 5 in the monitoring system, and the rock surface supporting seepage amount L is obtained by measuring the water amount in the lateral seepage water collecting device 7 through the seepage water extraction measuring device 5;

[0070] Soil evaporation amount E s The following formula is used for calculation:

[0071] E s = G l,ck,n-1 - G l,ck,n

[0072] In the formula, E s is the soil evaporation amount, G l,ck,n-1 is the last time weight of the soil thickness simulation barrel 3 without planting crops, and G l,ck,n is the current weight of the soil thickness simulation barrel 3 without planting crops;

[0073] Plant transpiration amount E t The following formula is used for calculation:

[0074]

[0075] In the formula, E t is the crop transpiration amount, G l,n-1 is the last time weight of the soil thickness simulation barrel 3 under the planted crops, and G l,n is the current weight of the soil thickness simulation barrel 3 under the planted crops;

[0076] Soil water storage AS is calculated by the following formula

[0077] AS = P + I - E s -E t -g-L

[0078] Step four: Different soil-lithology matching measurement: as shown in the following figure, by changing the rock type in the rock surface barrel 31, the soil type and thickness in the soil barrel 32 in S23, the water balance elements under different rock surface-soil combinations are simulated and measured, realizing detailed classification monitoring of the water balance elements of rocky desertification farmland soil. Figure 6

[0079] Embodiment 2

[0080] This embodiment is a further optimized technical solution based on embodiment 1. On the basis of embodiment 1, steps five, six and seven are further added, so as to not only monitor the change of the water balance element quantity under different rock surface-soil combinations, but also further study the correlation between the top support effect of different rock materials and the water balance elements of rocky desertification farmland.

[0081] Step five, rock surface top support leakage simulation system installation:

[0082] First, assemble the rock surface top support leakage simulation barrel, as shown in the following figure, which includes upper and lower parts. The lower part is the same rock surface barrel 31 as in embodiment 1, and the upper part is replaced by a watering barrel 37. The rock surface barrel 31 is provided with a first stainless steel mesh 33 at the bottom and filled with the rock material used in step four. As shown in the following figure, the bottom of the watering barrel 37 is provided with a movable water-blocking bottom plate 38 made of soft silica gel (which can ensure good water-blocking performance), and the barrel is filled with water to a predetermined height (diameter 1-1.5 cm). The movable water-blocking bottom plate 38 is connected with a pull line 39 extending outside the barrel. The watering barrel 37 is connected with a water level observation pipe 371 on one side of the barrel wall, provided with a scale for observing the change of water level. The lower end of the rock surface top support leakage simulation barrel is connected with the leakage water collecting device 4, and the upper edge of the leakage water collecting device 4 is sealingly connected with the lower edge of the rock surface top support leakage simulation barrel. The leakage water collecting device 4 can be the same device as in embodiment 1, and is also connected with the leakage water extraction and measurement device 5. However, since it does not need to be buried underground, the leakage water collecting device 4 can also be a transparent container with a scale for direct reading, without the need to be connected with the leakage water extraction and measurement device 5. Figure 7 Figure 8

[0083] ​​​Step six, vertical permeability coefficient measurement of different rock materials: quickly take out the movable water-resisting floor 38 by pulling the pull line 39, record the water level, leakage amount and time change value; calculate the vertical permeability coefficient Kv of the rock surface by the following formula, and use the coefficient to determine the different rock surface jacking effect:

[0084]

[0085] In the formula: Q v is the vertical leakage water quantity, which is collected by the leakage water collecting device 4, unit m 3 ; L is the thickness of the rock layer, which can be the height of the rock surface barrel, unit m; A is the cross-sectional area of the rock surface barrel, unit m 2 ; Δh is the water head difference, unit m, the greater the height of the water in the upper water barrel, the greater the water head difference; t is the leakage time, unit s; as shown in Figure 9 , according to the different rock types used in step four, the rock materials in the rock surface barrel 31 are replaced, and the vertical permeability coefficient of different rock materials is measured;

[0086] Step seven, based on the vertical permeability coefficient of different rock materials measured in step six and the water balance elements under the combination of different rock surfaces-soil measured in step four, the influence of the jacking effect of different rock materials on the water balance elements of the rocky desertification farmland is analyzed.

[0087] Finally, it should be noted that the above is only used to illustrate the technical solutions of the present application and is not limited. Although the present application has been described in detail with reference to the preferred arrangement, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for monitoring the water balance elements under different rock-soil combinations in stony desertification farmland, characterized in that, The method comprises the following steps: Step one: making rock materials of different lithology; Step two: constructing a monitoring system: S21 vertically burying the outer protective barrel (1) in the cultivated land, with the upper edge of the barrel being 5-8 cm higher than the cultivated land; the outer protective barrel (1) is a hollow cylinder with an open upper part and a sealed bottom, and a side seepage water pipe perforation (11) is formed in the upper part of the barrel wall; S22 installing a seepage water collecting device (4) at the bottom of the outer protective barrel (1); S23 nesting a soil thickness simulation barrel (3) in the outer protective barrel (1), which is arranged above the seepage water collecting device (4); the soil thickness simulation barrel (3) comprises an upper part and a lower part, the lower part is a rock surface barrel (31), and the upper part is a soil barrel (32); the rock surface barrel (31) is provided with a first stainless steel mesh (33) at the bottom and filled with the rock material made in the first step, and the soil barrel (32) is provided with a second stainless steel mesh (34) at the bottom and filled with cultivated soil; a side seepage water pipe (35) is arranged at the lower part of the barrel wall of the soil barrel (32), the side seepage water pipe (35) penetrates out of the side seepage water pipe perforation (11) of the outer protective barrel (1) wall, and the side seepage water pipe (35) and the side seepage water pipe perforation (11) are in sealing connection; there is a gap between the soil thickness simulation barrel (3) and the outer protective barrel (1), and the upper end of the gap is sealed by a ring-shaped sealing ring (6) provided with a hose perforation (61); the upper edge of the seepage water collecting device (4) is in sealing connection with the lower edge of the soil thickness simulation barrel (3); S24 burying a side seepage water collecting device (7) in the cultivated land on one side of the outer protective barrel (1), and sealing connecting the side seepage water pipe (35) through a pipeline; S25 arranging a seepage water extraction and measurement device (5) on the ground; one branch of the water extraction pipeline of the seepage water extraction and measurement device (5) is connected with a water input hose (51), the water input hose (51) penetrates into the gap between the soil thickness simulation barrel (3) and the outer protective barrel (1) from the hose perforation (61) and is connected to the seepage water collecting device (4), and the water input hose (51) and the hose perforation (61) are in sealing connection; the other branch of the water extraction pipeline of the seepage water extraction and measurement device (5) is connected with a side water input pipe (54), and the lower end of the side water input pipe (54) is sealing connected to the side seepage water collecting device (7). Step three: calculating the elements of water balance: monitoring each element in the soil water balance equation: In the rocky desertification cultivated land monitoring area, the rainfall P is monitored by arranging a rain gauge, and the irrigation amount I is measured by a water meter during irrigation of the cultivated land; The seepage amount g is obtained by measuring the water amount in the seepage water collecting device (4) through the seepage water extraction and measurement device (5) in the monitoring system, and the rock surface top support seepage amount L is obtained by measuring the water amount in the side seepage water collecting device (7) through the seepage water extraction and measurement device (5); Evaporation from the soil E s is calculated by the formula: In the formula, E s is the soil evaporation amount, G l,ck,n-1 is the last time the weight of the soil thickness simulation barrel (3) without planting crops is weighed, G l,ck,n is the current time the weight of the soil thickness simulation barrel (3) without planting crops is weighed; Plant transpiration E t is calculated by the following equation: In the formula, E t is the transpiration of the crop, G l,n-1 is the weight of the simulated bucket (3) of the soil thickness under the planted crop at the last weighing, G l,n is the weight of the simulated bucket (3) of the soil thickness under the planted crop at the present weighing; The soil water storage capacity ΔS is calculated by the following formula AS = P + I - E s - E t - g - L Step four: Different soil-lithology matching measurement: By changing the rock type in the rock surface barrel (31), the soil type and thickness in the soil barrel (32) in S23, the water balance elements under different rock surface-soil combinations are simulated and measured, and the detailed classification monitoring of the water balance elements of the rocky desertification cultivated land soil is realized.

2. The method for monitoring the water balance elements of different rock-soil combinations under rocky desertification farmland according to claim 1, characterized in that, It also includes steps five, six and seven, Step five, rock surface jacking leakage simulation system installation: First, assemble the rock surface jacking leakage simulation barrel, which includes upper and lower parts, the lower part is the rock surface barrel (31), and the upper part is the irrigation barrel (37); The bottom of the rock surface barrel (31) is provided with a first stainless steel mesh (33) and the barrel is filled with rock materials used in step four, the bottom of the irrigation barrel (37) is provided with a movable waterproof bottom plate (38) made of soft silica gel and the barrel is filled with water to a predetermined height, the movable waterproof bottom plate (38) is connected with a pull wire (39) extending outside the barrel; The water level observation tube (371) is connected to one side of the barrel wall of the irrigation barrel (37); The lower end of the rock surface jacking leakage simulation barrel is connected with the leakage water collecting device (4), and the upper edge of the leakage water collecting device (4) is sealingly connected with the lower edge of the rock surface jacking leakage simulation barrel; Step six, measurement of vertical permeability coefficient of different rock materials: Pull out the movable waterproof bottom plate (38) quickly by pulling the pull wire (39), and record the water level and leakage amount value changing with time; The vertical permeability coefficient Kv of the rock surface is calculated by the following formula, and the coefficient is used to determine the jacking effect of different rock surfaces: In the formula: Q v is the amount of vertical seepage water collected by the seepage water collection device (4), unit m 3 ; L is the rock layer thickness, unit m; A is the rock surface barrel cross-sectional area, unit m 2 ; Δh is the water head difference, unit m; t is the leakage time, unit s; According to the different rock types used in step four, replace the rock materials in the rock surface barrel (31), and measure the vertical permeability coefficient of different rock materials; Step seven, based on the vertical permeability coefficient of different rock materials measured in step six and the water balance elements under different rock surface-soil combinations measured in step four, analyze the influence of the jacking effect of different rock materials on the water balance elements of the rocky desertification cultivated land.

3. The method for monitoring the water balance elements of different rock-soil combinations in rocky desertification farmland according to claim 1, characterized in that: In step one: Different particle size rocks, different mortar ratios are added to make different cylindrical test materials; Or collect cylindrical cores of different lithology rocks in rocky desertification areas as test materials.

4. The method for monitoring the water balance elements of different rock-soil combinations in rocky desertification farmland according to claim 1, characterized in that: The leakage water extraction measuring device (5) includes a water pump (52) and a measuring cylinder (53), the input end of the water pump (52) is connected with the water extraction pipeline, the output end of the water pump (52) is connected with the measuring cylinder (53) through the water outlet pipe, the water extraction pipeline is connected with the water delivery hose (51) and the lateral water delivery pipe (54) through a three-way pipe, and the water delivery hose (51) and the lateral water delivery pipe (54) are respectively provided with control valves.

5. The method for monitoring the water balance elements of different rock-soil combinations under rocky desertification farmland according to claim 1 or 2, characterized in that: The leakage water collecting device (4) includes an upper funnel-shaped water collector (41) and a lower sealed bottle (42), the lower end of the funnel-shaped water collector (41) is sealingly connected with the sealed bottle (42), and the sealed bottle (42) is provided with a water extraction hole (43).

6. The method of claim 1, wherein the balance of water elements of different rock-soil combinations in rocky desertification farmland is monitored. The side seepage water collecting device (7) is provided with a water inlet (71) and a water outlet (72), the water inlet (71) is sealingly connected with the side seepage water guide pipe (35) through a pipeline, and the water outlet (72) is sealingly connected with the lateral water delivery pipe (54).

7. The method of claim 1, wherein the balance of water elements in different rock-soil combinations of rocky desertification farmland is monitored. The mesh of the first stainless steel mesh (33) and the second stainless steel mesh (34) is not greater than 40 mesh.

8. The method of claim 1, wherein the balance of water elements in different rock-soil combinations of rocky desertification farmland is monitored. In step two, the soil barrel (32) and the rock surface barrel (31) are detachably connected, and the connecting edges of the soil barrel (32) and the rock surface barrel (31) are sealed.

9. The method of claim 2, wherein the balance of water elements of different rock-soil combinations in rocky desertification farmland is monitored. In step four, the water filling barrel (37) and the rock surface barrel (31) are detachably connected, and the connecting edges of the water filling barrel (37) and the rock surface barrel (31) are sealed.

10. The method of claim 1, wherein the balance of water elements in different rock-soil combinations of rocky desertification farmland is monitored. In step two, a supporting device (2) is further arranged in the outer protective barrel (1); the supporting device (2) is a supporting rod supported between the bottom of the outer protective barrel (1) and the upper edge of the water leakage collecting device (4).

Images