A method and system for identifying a water-soil resource mutual feedback mechanism

Abstract

The application provides a water-soil resource mutual feedback mechanism identification method and system, comprising: obtaining hydrological data, meteorological data, geological data and remote sensing data of a target area; performing energy process simulation, evaporation and heat dissipation process simulation, vertical infiltration calculation, slope runoff generation calculation, slope confluence calculation, river confluence calculation and groundwater movement calculation according to the obtained data to obtain a distributed hydrological model; at the same time, obtaining runoff coefficients and the ratio of evaporation and heat dissipation to net primary productivity in different time periods in the basin space by combining the surface runoff, precipitation, evaporation and heat dissipation of the basin at different time scales and the net primary productivity of different land use types; and determining the water-soil resource interaction law according to the runoff coefficients and the ratio of evaporation and heat dissipation to net primary productivity. The hydrological model obtained based on the simulation of multiple processes and multiple elements of the basin can accurately obtain the water-soil resource interaction law, thereby providing technical support for comprehensive management of the basin and optimal allocation of water-soil resources.

Description

Technical Field

[0001] This invention relates to the field of watershed water cycle simulation technology, and in particular to a method and system for identifying the water and soil resource feedback mechanism based on watershed water cycle simulation. Background Technology

[0002] The competition between humans and land for water, and between humans and water for land, disrupts the balance between natural ecosystems and socio-economic systems. The inconsistent scale of water resource management and land resource management makes it difficult to understand water production and consumption processes and their ecological effects on land patches. Watershed hydrological simulation has long been a research tool in the field of hydrology and water resources. Through hydrological simulation, hydrological processes can be quantified, and the temporal changes and spatial distribution patterns of various hydrological cycle elements under different land use types can be quantitatively described. To better study the laws of hydrological change and the interaction between water and soil resources, it is necessary to further enhance the simulation capabilities of watershed hydrological models, including process refinement and improvement of simulation equations.

[0003] Currently, hydrologists both domestically and internationally have made significant research and contributions in this area, with various modeling software focusing on surface hydrological process simulation, groundwater movement simulation, river channel movement models, and urban stormwater simulation. However, hydrological models that consider all elements of hydrological processes from a whole-basin perspective, encompassing surface to groundwater and from slope to river channel, are still rare. To address these shortcomings, this paper proposes a method for identifying the water-soil resource feedback mechanism based on watershed water cycle simulation. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for identifying the interaction mechanism between water and soil resources. Based on a refined watershed simulation model that considers multiple hydrological processes and factors, the method accurately identifies the interaction mechanism between water and soil resources, expands the technical means of watershed hydrological research, and provides technical support for comprehensive watershed management and optimal allocation of water and soil resources.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method and system for identifying the feedback mechanism between water and soil resources, comprising:

[0007] Acquire hydrological, meteorological, geological, and remote sensing data for the target area;

[0008] Based on the hydrological data, meteorological data, geological data, and remote sensing data, energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation are performed to obtain a distributed hydrological model; the energy process simulation includes longwave radiation and shortwave radiation calculation; the evaporation process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation;

[0009] Based on the distributed hydrological model, the surface runoff at different time scales in the watershed is calculated and statistically analyzed, and the runoff coefficients for different time periods within the watershed are obtained by combining the runoff data with the precipitation data.

[0010] Based on the distributed hydrological model, the evaporative heat loss at different time scales in the watershed is calculated and statistically analyzed, and the ratio of evaporative heat loss to net primary productivity is determined in combination with the net primary productivity of different land use types.

[0011] The interaction law of water and soil resources is determined based on the aforementioned runoff coefficient and the ratio of evaporative heat dissipation to net primary productivity.

[0012] This invention also provides a system for identifying the interaction mechanism between water and soil resources, comprising:

[0013] The data acquisition module is used to acquire hydrological, meteorological, geological, and remote sensing data of the target area; the distributed hydrological model simulation module is used to perform energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation based on the hydrological, meteorological, geological, and remote sensing data to obtain a distributed hydrological model; the energy process simulation includes longwave radiation and shortwave radiation calculation; the evaporation process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation;

[0014] The runoff coefficient calculation module is used to calculate and statistically analyze the surface runoff at different time scales in the watershed based on the distributed hydrological model and combine it with precipitation to obtain the runoff coefficient for different time periods in the watershed space.

[0015] The module for calculating the ratio of evaporative heat dissipation to net primary productivity is used to calculate and statistically analyze the evaporative heat dissipation at different time scales in the watershed based on the distributed hydrological model and to determine the ratio of evaporative heat dissipation to net primary productivity in combination with the net primary productivity of different land use types.

[0016] The water-soil resource interaction law acquisition module is used to determine the water-soil resource interaction law based on the runoff coefficient and the ratio of evaporative heat dissipation to net primary productivity.

[0017] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0018] This invention provides a method and system for identifying the interaction mechanism between water and soil resources, comprising: acquiring hydrological, meteorological, geological, and remote sensing data of a target area; performing energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation based on the acquired data to obtain a distributed hydrological model; calculating and statistically analyzing surface runoff at different time scales within the watershed based on the distributed hydrological model and combining it with precipitation to obtain runoff coefficients for different time periods within the watershed; calculating and statistically analyzing evaporative cooling at different time scales within the watershed based on the distributed hydrological model and combining it with the net primary productivity of different land use types to determine the ratio of evaporative cooling to net primary productivity; and determining the interaction law between water and soil resources based on the runoff coefficients and the ratio of evaporative cooling to net primary productivity. The hydrological model obtained based on the refined simulation of multiple processes and multiple elements within the watershed can accurately reveal the interaction law between water and soil resources, providing technical support for comprehensive watershed management and optimal allocation of water and soil resources. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart of a method for identifying the mutual feedback mechanism of water and soil resources provided in Embodiment 1 of the present invention;

[0021] Figure 2 This is the hydrological analysis process for the Sishui River Basin provided in Embodiment 1 of the present invention;

[0022] Figure 3 The topographic and geomorphological data of the Sihe River Basin provided in Embodiment 1 of the present invention;

[0023] Figure 4 Meteorological data of the Sishui River Basin provided in Embodiment 1 of the present invention;

[0024] Figure 5 This is a mutation detection method for the Sishui River Basin provided in Embodiment 1 of the present invention;

[0025] Figure 6 The vertical and horizontal structures of the watershed hydrological model provided in Embodiment 1 of the present invention;

[0026] Figure 7 The calibration and verification of the Sishui River Basin provided in Embodiment 1 of the present invention;

[0027] Figure 8 The spatial distribution of runoff coefficient in the Sishui River Basin provided in Embodiment 1 of the present invention;

[0028] Figure 9 The spatial distribution of NPP / ET in the Sishui River Basin provided in Embodiment 1 of the present invention;

[0029] Figure 10 This is a schematic diagram of water balance within the grid provided in Embodiment 1 of the present invention;

[0030] Figure 11 This is a schematic diagram of the aquifer system section provided in Embodiment 1 of the present invention;

[0031] Figure 12 The three-dimensional positional relationship between the peripheral grid and the central grid provided in Embodiment 1 of the present invention;

[0032] Figure 13 The planar positional relationship between the peripheral grid and the central grid provided in Embodiment 1 of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a method and system for identifying the interaction mechanism between water and soil resources. Based on a refined watershed simulation model that considers multiple hydrological processes and factors, the method accurately identifies the interaction mechanism between water and soil resources, expands the technical means of watershed hydrological research, and provides technical support for comprehensive watershed management and optimal allocation of water and soil resources.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a method and system for identifying the mutual feedback mechanism of water and soil resources, including:

[0038] First, a general summary of the scheme in this embodiment is provided: taking the Sihe River Basin as an example, this embodiment illustrates the watershed refinement simulation method based on a coupled distributed hydrological model and a groundwater model.

[0039] (1) Preparation of model input data.

[0040] Its specific manifestations are as follows:

[0041] First, watershed hydrological analysis is performed. Based on the DEM (Digital Image Model), hydrological analysis tools in ArcGIS are used to perform depression filling calculations, flow direction calculations, runoff accumulation calculations, and watershed generation. The watershed boundary at this stage is used as the boundary for subsequent input data preparation. Figure 2 As shown;

[0042] Secondly, topographic and geomorphological data preparation: using the watershed range generated in the previous step as the boundary file, the DEM, soil type data, soil thickness data, land use type data for each period, and river network data are segmented. All the segmented files are then converted into ASCII files as input files, such as... Figure 3 As shown;

[0043] Next, meteorological data preparation involves selecting and sequentially numbering meteorological and rainfall stations within and around the watershed. Using ArcGIS's Create Thiessen Polygons tool, Thiessen polygons are drawn for each station. The drawn Thiessen polygons are then converted into raster files according to station numbers, using the watershed area as the boundary, and then converted to ASCII files. The desired meteorological and precipitation data are extracted and prepared into TXT files in the format "Year-Month-Month-1st Station-2nd Station-…nth Station". Figure 4 As shown;

[0044] Finally, other basic data and parameters were prepared, including the latitude and elevation of the meteorological station, the rate of change of precipitation with elevation, monthly vegetation cover data, monthly leaf area index data, reflectance of various land use surfaces to shortwave radiation, saturated water content of various soils, field water holding capacity of various soils, wilting coefficient of various soils, depression storage of various land use types, horizontal-vertical-vertical permeability coefficients of various soil layers, Manning coefficient of slopes, and Manning coefficient of river channels.

[0045] (2) Model simulation calculation.

[0046] Energy process simulation, including calculations of longwave and shortwave radiation from different underlying surfaces; evapotranspiration process simulation, including vegetation transpiration (Penman-Monteith), vegetation intercepted evaporation (Penman), water evaporation (Penman), bare soil evaporation (modified Penman), urban surface evaporation, and building evaporation (Penman); vertical infiltration calculation (Green-Ampt); slope runoff calculation, including infiltration excess runoff (Houghton slope runoff) and saturation runoff (saturated slope runoff); slope confluence calculation (kinetic wave) and river confluence calculation (kinetic wave); groundwater movement calculation (Darcy formula). The vertical and horizontal structure of each element process in the hydrological cycle simulation is illustrated as follows: Figure 5 As shown.

[0047] (3) Model calibration and validation.

[0048] First, abrupt change detection is performed using the Mann-Kendall method to detect abrupt changes in the rainfall data. The period before the abrupt change is designated as the calibration period, and the period after the abrupt change is designated as the validation period. Figure 6 As shown;

[0049] Secondly, model calibration involves adjusting various parameters. The simulation effect of the model is judged by three indicators: correlation coefficient, Nash coefficient, and relative error. The parameter adjustment is completed until the three indicators meet the requirements.

[0050] Model validation involves fixing the parameters based on the model calibration and then performing simulations during the calibration period. If all three indicators pass, the model validation is successful. The model calibration and validation results are as follows: Figure 7 As shown.

[0051] (4) Research on the mutual feedback mechanism of water and soil resources.

[0052] First, using the distributed hydrological model that has been written and debugged, surface runoff and precipitation at different time scales for each grid cell in the watershed are calculated and statistically analyzed. This yields the runoff coefficients for different time periods within the watershed space, such as... Figure 8 As shown;

[0053] Secondly, using the distributed hydrological model that has been written and debugged, the evapotranspiration of each grid within the watershed at different time scales is calculated and statistically analyzed. The spatial distribution of net primary productivity (NPP) within the watershed is obtained using the net primary productivity quotas for different land use types and the spatial distribution of land use. Finally, the spatial NPP is compared with ET to obtain the spatial distribution of NPP / ET at different time scales, such as... Figure 9 As shown;

[0054] Finally, the runoff coefficient was used as an indicator to study the impact of land resources on water resources, and NPP / ET was used as an indicator to study the impact of water resources on land resources. The results of the aforementioned runoff coefficient and NPP / ET were analyzed to examine the mutual feedback effect of water and soil resources from both temporal and spatial perspectives.

[0055] The following are more detailed steps of the method described in this embodiment:

[0056] Step S1: Acquire hydrological data, meteorological data, geological data, and remote sensing data for the target area;

[0057] Specifically, step S1 includes:

[0058] Step S11: Watershed hydrological analysis. Based on the DEM, use the hydrological analysis tools in ArcGIS to perform depression filling calculation, flow direction calculation, runoff accumulation calculation, and watershed generation. Use the watershed boundary at this time as the boundary for later input data preparation.

[0059] Step S12: Topographic and geomorphological data preparation. Using the watershed range generated in step S11 as the boundary file, the DEM is cut again to serve as watershed elevation data. Soil type data, soil thickness data, land use type data for each period, and river network data are also cut. All the cut files are converted into ASCII files as input files.

[0060] Step S13: Select meteorological stations and rain gauges within the watershed and within its preset range, and number the meteorological stations and rain gauges sequentially;

[0061] Step S14: Use the Create Thiessen Polygon tool to draw the Thiessen polygons for the weather station and the rain gauge, respectively;

[0062] Step S15: Using the watershed area as the boundary, convert the drawn Thiessen polygon into raster files by installing the weather station numbers and rain gauge numbers respectively;

[0063] Step S16: Extract meteorological data and precipitation data based on the raster file;

[0064] Steps S13 to S16 involve preparing meteorological data. Meteorological stations and rain gauges within and around the watershed are selected and sequentially numbered. Thiessen polygons for each station are drawn using the Create Thiessen Polygons tool in ArcGIS. The drawn Thiessen polygons are then converted into raster files according to station numbers, using the watershed area as the boundary, and then converted to ASCII files. The desired meteorological and precipitation data are extracted and prepared into TXT files in the format "Year-Month-Month-1st Station-2nd Station-…nth Station".

[0065] Step S17: Based on the raster file, obtain the latitude and elevation of the meteorological station, the rate of change of precipitation with elevation, monthly vegetation cover data, monthly leaf area index data, reflectance of various land use surfaces to shortwave radiation, saturated water content of various soils, field water holding capacity of various soils, wilting coefficient of various soils, depression storage of various land use types, horizontal-vertical-vertical permeability coefficients of various soil layers, slope Manning coefficient, and river channel Manning coefficient.

[0066] Step S17 involves the preparation of other basic data and parameters, including the latitude and elevation of the meteorological station, the rate of change of precipitation with elevation, monthly vegetation cover data, monthly leaf area index data, reflectance of various land use surfaces to shortwave radiation, saturated water content of various soils, field water holding capacity of various soils, wilting coefficient of various soils, depression storage of various land use types, horizontal-vertical-vertical permeability coefficients of various soil layers, Manning coefficient of slope, and Manning coefficient of river channel.

[0067] Step S2: Based on the hydrological data, meteorological data, geological data, and remote sensing data, perform energy process simulation, evaporation process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation to obtain a distributed hydrological model. The energy process simulation includes longwave radiation and shortwave radiation calculation; the evapotranspiration process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation; the slope runoff calculation includes infiltration excess runoff and saturation runoff. The evaporation calculation uses the well-known Penman formula, and the transpiration calculation uses the well-known Penman-Montis formula.

[0068] Step S2 specifically includes:

[0069] Step S21: The underlying surface type is further classified according to the national standard "Classification of Current Land Use". The further classification means dividing the underlying surface type into a preset number of categories.

[0070] Step S21 involves refined simulation, which subdivides the underlying surface types into 25 categories according to the national standard "Classification of Current Land Use". Each grid cell corresponds to one land use type and has an independent vertical hydrological cycle process. These 25 underlying surface types can be changed, added, or reduced, and adjusted according to the simulation requirements.

[0071] Step S22: For each underlying surface, calculate the long-wave radiation and short-wave radiation to simulate the energy process;

[0072] Energy process simulation, including calculations of long-wave and short-wave radiation from different underlying surfaces.

[0073] Step S23: Simulate the evaporative heat dissipation process based on vegetation transpiration, vegetation interception evaporation, water evaporation, bare soil evaporation, and evaporation of urban landmarks and buildings;

[0074] The evapotranspiration process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation.

[0075] Step S24: Calculate the changes in soil water and groundwater based on infiltration and evaporation; that is, calculate vertical infiltration and slope runoff during the calculation of changes in soil water and groundwater.

[0076] Specifically, step S24 includes:

[0077] Obtain the net amount of rainfall that enters the soil after interception and filling of depressions;

[0078] Obtain the first volume of net rainfall infiltrating into the soil to replenish groundwater;

[0079] The second volume of water evaporated back into the atmosphere and the third volume of water transpired into the atmosphere by vegetation are obtained.

[0080] Obtain the final amount of water retained in the soil;

[0081] The surface water and groundwater exchange process is determined based on the net rainfall, the first water volume, the second water volume, the third water volume, and the fourth water volume of the soil, thereby realizing the calculation of vertical infiltration.

[0082] The exchange of surface and groundwater occurs as follows: precipitation is intercepted and fills depressions to enter the soil; some of the soil water infiltrates to replenish groundwater, some evaporates back into the atmosphere, some transpires into the atmosphere through vegetation, and some remains in the soil. The calculation formula is as follows:

[0083] P n =PW r -H(S24-1)

[0084]

[0085] W g =W0+W i -W s -W e (S24-3)

[0086]

[0087] In the formula: P is the rainfall (mm); P n Net rainfall (mm), i.e., runoff; W r H is the vegetation interception amount (mm); F is the depression retention amount (mm); W0 is the infiltration capacity (mm / t); W0 is the initial soil moisture content (mm); W i Soil infiltration rate (mm); W s Soil saturated water content (mm); W e Evaporation rate (mm); W g denoted as ______, representing the amount of groundwater replenished by rainfall (mm); ______, representing the lateral inflow (m³). 3 / t); A is the area of ​​the recharge zone (m²)2 ); Δt is the time interval (t); S is the water storage rate (1 / m); Δh is the water level change (m); V is the volume of the groundwater control volume (m³). 3 ).

[0088] The infiltration rate is Wi in formula S24-2, and the production rate is Pn in formula S24-1.

[0089] Step S25: Simulate slope confluence and river confluence using a motion wave model.

[0090] Specifically, step S25 includes:

[0091] Step 1: Based on the river network system generated by the DEM, determine the topological relationship and calculation order of the slope grid and the channel grid by the confluence accumulation and flow direction;

[0092] Step 2: Construct the water balance equation within the grid (Equation S25-2) using the continuity equation (Equation S25-1). Substitute the Manning formula (Equation S25-3) and the channel cross-section equation (S25-4) into the water balance equation to quantify the motion wave equation, obtaining simulated slope confluence and simulated channel confluence. In this case, the channel is generalized as a rectangular channel, and the slope confluence is generalized as a wide and shallow channel. The water balance diagram within the grid is shown below. Figure 10 As shown.

[0093] Continuity equation

[0094] Water balance equation

[0095] Manning Formula

[0096] The equation for the river channel cross-section is A = b × h (Equation S25-4)

[0097] In the above formula: A1 and A2 are the cross-sectional areas of the water flow at the beginning and end of the grid time period (m²). 2 Qin represents the upstream water flow rate (m³ / s) of the grid (including the lateral water flow rate Qside, such as the water volume flowing into the river from the slope and the grid's own flow rate); Q1 and Q2 represent the outflow rates of the grid at the beginning and end of the time period, respectively (m³ / s). 3 / s); n is the Manning roughness coefficient of the grid surface; R is the hydraulic radius of the grid channel or slope shallow channel (m); S0 is the longitudinal slope of the grid slope or channel; b is the grid width (m); h is the water depth inside the grid (m).

[0098] Step S26: Simulate groundwater movement according to Darcy's formula.

[0099] Step S26 specifically includes:

[0100] The groundwater simulation area is meshed;

[0101] By applying mass conservation and Darcy's formula to a single grid cell, the flow rate between two adjacent grid cells can be obtained.

[0102] Select the center grid in the grid, and for each center grid, determine the first flow from the surrounding grids into the corresponding center grid based on the flow between two adjacent grids; the surrounding grids refer to the grids connected to the center grid, and the center grid is the grid surrounded by other grids;

[0103] Calculate the second flow rate from any source flow in the aquifer to the central grid;

[0104] Calculate the third flow rate from the aquifer multi-source flow to the central grid;

[0105] The difference equation for each grid cell is determined based on the first flow rate, the second flow rate, and the third flow rate, combined with the continuity equation.

[0106] The water level of each grid is obtained based on the difference equation of each grid.

[0107] A more detailed description of the groundwater movement simulation: Darcy's formula is used for calculation. Based on the simulation requirements and the aforementioned grid partitioning method, the groundwater simulation area is meshed, as follows: Figure 11 As shown. The groundwater grid size is consistent with the surface water simulation grid. The aquifer thickness is determined according to local conditions. The calculation of a single grid cell is related to its adjacent grid cells (top, bottom, left, right, front, back), as shown. Figure 12 As shown in the figure. Where i, j, k represent rows, columns, and layers, respectively.

[0108] Applying the principle of conservation of mass and Darcy's law to cell (i,j,k), we have:

[0109]

[0110] Where: h i,j,k ,h i,j-1,k q represents the head values ​​at nodes (i,j,k) and (i,j-1,k), respectively. i,j-1 / 2,k KR represents the flow between node (i,j,k) and node (i,j-1,k); i,j-1 / 2,k is the hydraulic conductivity coefficient; is the cross-sectional area; is the distance between the two points.

[0111] Similarly, we can conclude that:

[0112]

[0113]

[0114] Here, KV, KR, and KC are a single variable, representing vertical, row, and column respectively. Figure 11 The x, y, and x axes are labeled.

[0115] Therefore, equation S26-2 can be written as:

[0116]

[0117] Here, CR, CC, and CV are a single variable, representing vertical, row, and column respectively. These three variables are intermediate variables with no actual meaning; they are used to simplify the equation.

[0118] Equation S26-4 represents the flow rate from the six adjacent surfaces to node (i,j,k). The flow rate from any source outside the aquifer to node (i,j,k) can be expressed by the following equation:

[0119] a i,j,k,n =P i,j,k,n +q i,j,k,n (S26-5)

[0120] Where: is the external supply amount to this grid (m 3 / d); represents the impact of surface water cycle processes on the groundwater of this grid, such as river seepage recharge and rainfall infiltration recharge (m³). 2 / d) etc.; the impact of human work on the groundwater of this grid, such as pumping volume (m³) 3 / d).

[0121] Generally, if there are N sources that affect node (i,j,k), then the total flow from these N sources to node (i,j,k) is:

[0122]

[0123] make

[0124] Equation S26-6 can be written as:

[0125] QS i,j,k =P i,j,k h i,j,k +Q i,j,k (Equation S26-7)

[0126] According to the continuity equation, we can obtain:

[0127]

[0128] Where: is the change in water level over time (L / t); is the storage capacity of node (i,j,k) (1 / L); is the volume of node (i,j,k) (L). 3 ).

[0129] Substituting equations S26-4 and S26-5 into equation 26-8, we obtain the following finite difference equation at node (i,j,k):

[0130]

[0131] Where S is the parameter representation after differentiation, and its meaning is also the water storage rate.

[0132] The orientation-based finite difference method, equation S26-9 can be written as:

[0133]

[0134] Similarly, the difference equations for each grid cell in the groundwater simulation area are obtained, and the number of grid cells corresponds to the number of equations.

[0135] Rearrange equation S26-10, and include the groundwater level (h) at the current time in the equation. m The relevant terms are placed on the left side of the equation, and the groundwater level and known terms from the previous moment are placed on the right side of the equation, as shown in equation S26-11.

[0136]

[0137] make

[0138] Form a matrix: [A]×{h}={q}.

[0139] In the formula: A is the coefficient matrix; h is the water level of each grid at this moment, the matrix of variables to be determined; q is the matrix of known terms.

[0140] The above equation is transformed into the explicit form S26-13 and solved iteratively (the water level of the central grid at time m is calculated using the water levels of the surrounding grids at time m-1; the upper limit of the number of iterations is 10, and the iteration error is 0.01m). Calculate the grid (i,j) and its surrounding grids, such as... Figure 13 As shown.

[0141]

[0142] Step S3: Calculate and statistically analyze the surface runoff at different time scales in the watershed based on the distributed hydrological model, and combine it with precipitation to obtain the runoff coefficient for different time periods within the watershed space;

[0143] Step S4: Calculate and statistically analyze the evaporative heat dissipation at different time scales in the watershed based on the distributed hydrological model, and determine the ratio of evaporative heat dissipation to net primary productivity (NPP / ET) by combining the net primary productivity of different land use types.

[0144] Using the distributed hydrological model that has been written and debugged, the evapotranspiration of each grid in the watershed at different time scales is calculated and statistically analyzed. The spatial distribution of net primary productivity (NPP) in the watershed is obtained by using the net primary productivity quotas of different land use types and the spatial distribution of land use. Finally, the spatial NPP is compared with ET to obtain the spatial distribution of NPP / ET at different time scales.

[0145] Specifically, step S4 includes:

[0146] The distributed hydrological model is used to calculate and statistically analyze the evaporative heat loss at different time scales in the watershed.

[0147] The spatial distribution of net primary productivity within the watershed was obtained by using net primary productivity quotas for different land use types and spatial distribution of land use.

[0148] The ratio between the evaporative heat dissipation and the net primary productivity in space is determined, and the spatial distribution of the ratio of the evaporative heat dissipation and the net primary productivity at different time scales is obtained.

[0149] Step S5: Determine the interaction law of water and soil resources based on the generated flow coefficient and the ratio of evaporative heat dissipation to net primary productivity.

[0150] Step S5 specifically includes:

[0151] The runoff coefficient at different time periods within the watershed is used as an indicator to study the impact of land resources on water resources. The spatial distribution of the ratio of evaporative heat dissipation to net primary productivity at different time scales is used as an indicator to study the impact of water resources on land resources. The mutual feedback effect of water and soil resources is analyzed from both temporal and spatial perspectives.

[0152] It should be noted that after obtaining the distributed hydrological model, model calibration and validation are also included, specifically:

[0153] Abrupt point detection: The Mann-Kendall method was used to detect abrupt changes in the rainfall data. The period before the abrupt change was designated as the calibration period, and the period after the abrupt change was designated as the validation period.

[0154] Model calibration involves adjusting various parameters and using three indicators—correlation coefficient, Nash coefficient, and relative error—to determine the model's simulation performance. Parameter tuning continues until the three indicators meet the requirements, at which point the tuning process is complete.

[0155] Model validation involves fixing the parameters based on the model calibration and then performing simulations to verify the calibration period. If the three indicators pass, the model validation is successful.

[0156] In this embodiment, a refined hydrological model simulating the watershed from the surface to the subsurface and from slopes to river channels is developed using Python and applied to the study of water and soil resource feedback. The model input data preparation includes topographic data: elevation, slope, land use type, soil type and thickness, river network; meteorological data: weather station information, precipitation, temperature, wind speed, relative humidity, and sunshine duration; and other basic data and parameters. The refined simulation involves classifying the underlying surface into 25 types, with each simulation unit having its own set of hydrological parameters for independent vertical hydrological simulation. Model calibration and validation are performed by analyzing the abrupt changes in rainfall data, defining the period before the abrupt change as the calibration period and the period after the abrupt change as the validation period. The model application outputs precipitation, runoff, and evapotranspiration at different times and spatial locations within the watershed. The identification of water and soil resource feedback is also included. It can achieve refined simulation of multiple processes and elements in a watershed. Each simulation unit has its own set of hydrological parameters and can perform separate vertical hydrological simulations. Then, it can achieve horizontal connections through grid topology relationships, and finally obtain the runoff on the slope, underground and in the river channel, providing technical support for comprehensive watershed management and optimal allocation of water and soil resources.

[0157] Example 2

[0158] This embodiment provides a system for identifying the interaction mechanism between water and soil resources, including:

[0159] The data acquisition module M1 is used to acquire hydrological data, meteorological data, geological data and remote sensing data of the target area;

[0160] The distributed hydrological model simulation module M2 is used to perform energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation based on the hydrological data, meteorological data, geological data, and remote sensing data, to obtain a distributed hydrological model; the energy process simulation includes longwave radiation and shortwave radiation calculation; the evaporative cooling process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation;

[0161] The runoff coefficient calculation module M3 is used to calculate and statistically analyze the surface runoff at different time scales in the watershed based on the distributed hydrological model and combine it with precipitation to obtain the runoff coefficient for different time periods in the watershed space.

[0162] The evaporative heat dissipation to net primary productivity ratio calculation module M4 is used to calculate and statistically analyze the evaporative heat dissipation at different time scales in the watershed based on the distributed hydrological model and determine the ratio of evaporative heat dissipation to net primary productivity in combination with the net primary productivity of different land use types.

[0163] The water-soil resource interaction law acquisition module M5 is used to determine the water-soil resource interaction law based on the runoff coefficient and the ratio of evaporative heat dissipation to net primary productivity.

[0164] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for identifying the mutual feedback mechanism of water and soil resources, characterized in that, include: Acquire hydrological, meteorological, geological, and remote sensing data for the target area; Based on the hydrological data, meteorological data, geological data, and remote sensing data, energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation are performed to obtain a distributed hydrological model; the energy process simulation includes longwave radiation and shortwave radiation calculation; the evaporative cooling process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation; Based on the distributed hydrological model, the surface runoff at different time scales in the watershed is calculated and statistically analyzed, and the runoff coefficients for different time periods within the watershed are obtained by combining the runoff data with the precipitation data. Based on the distributed hydrological model, the evaporative heat dissipation at different time scales in the watershed is calculated and statistically analyzed, and the ratio of net primary productivity to evaporative heat dissipation is determined in combination with the net primary productivity of different land use types. The interaction law of water and soil resources is determined based on the aforementioned runoff coefficient and the ratio of net primary productivity to evaporative heat loss. The determination of the water-soil resource interaction law based on the runoff coefficient and the ratio of net primary productivity to evaporative heat loss specifically includes: The runoff coefficient at different time periods within the watershed is used as an indicator to study the impact of land resources on water resources. The spatial distribution of the ratio of net primary productivity to evaporative heat dissipation at different time scales is used as an indicator to study the impact of water resources on land resources. The mutual feedback effect of water and soil resources is analyzed from both temporal and spatial perspectives.

2. The method according to claim 1, characterized in that, The acquisition of hydrological, meteorological, geological, and remote sensing data of the target area specifically includes: Based on the digital elevation model (DEM) of the target area, the watershed is generated by using hydrological analysis tools to perform depression filling calculations, flow direction calculations, and runoff accumulation calculations, thus obtaining watershed hydrological analysis data. Using the watershed extent in the watershed moisture analysis data as boundary conditions, the digital elevation model (DEM) is segmented to obtain watershed elevation data, soil type data, soil thickness data, land use type data, and river network data. Meteorological stations and rain gauges within the basin and within a preset range are selected and numbered sequentially. Use the Create Thiessen Polygon tool to draw Thiessen polygons for the weather station and the rain gauge, respectively; Using the aforementioned watershed area as the boundary, the meteorological station numbers and rain gauge numbers of the drawn Thiessen polygons are converted into raster files respectively; Meteorological and precipitation data are extracted based on the raster file; Based on the raster file, the latitude and elevation of the meteorological station, the rate of change of precipitation with elevation, monthly vegetation cover data, monthly leaf area index data, reflectance of land surface to shortwave radiation for various land uses, saturated water content of various soils, field water holding capacity of various soils, wilting coefficient of various soils, depression storage of various land use types, transverse-longitudinal-vertical permeability coefficients of various soil layers, Manning coefficient of slope and Manning coefficient of river channel are obtained.

3. The method according to claim 2, characterized in that, The calculation and statistical analysis of evaporative cooling at different time scales within the watershed based on the distributed hydrological model, combined with the net primary productivity of different land use types, to determine the ratio of net primary productivity to evaporative cooling specifically includes: The distributed hydrological model is used to calculate and statistically analyze the evaporative heat loss at different time scales in the watershed. The spatial distribution of net primary productivity within the watershed was obtained by using net primary productivity quotas for different land use types and spatial distribution of land use. The ratio between the net primary productivity and the evaporative heat dissipation in space is determined to obtain the spatial distribution of the ratio of net primary productivity and evaporative heat dissipation at different time scales.

4. The method according to claim 2, characterized in that, The process involves simulating energy processes, evaporative cooling processes, vertical infiltration, slope runoff generation, slope runoff collection, river runoff collection, and groundwater movement based on the hydrological data, meteorological data, geological data, and remote sensing data to obtain a distributed hydrological model, specifically including: The underlying surface types are further refined according to the national standard "Classification of Current Land Use". The refined classification means dividing the underlying surface types into a preset number of categories. For each underlying surface, energy process simulations are performed by calculating long-wave and short-wave radiation; The evaporative heat dissipation process is simulated based on vegetation transpiration, vegetation interception evaporation, water evaporation, bare soil evaporation, and evaporation of urban landmarks and buildings. Vertical infiltration and slope runoff calculations are performed during the calculation of changes in soil water and groundwater. Simulation of slope confluence and river confluence using a motion wave model; The Darcy formula was used to simulate groundwater movement.

5. The method according to claim 4, characterized in that, The calculation of vertical infiltration and slope runoff during the calculation of changes in soil water and groundwater specifically includes: Obtain the net amount of rainfall that enters the soil after interception and filling of depressions; Obtain the first volume of net rainfall infiltrating into the soil to replenish groundwater; The second volume of water evaporated back into the atmosphere and the third volume of water transpired into the atmosphere by vegetation are obtained. Obtain the final amount of water retained in the soil; The surface water and groundwater exchange process is determined based on the net rainfall, the first water volume, the second water volume, the third water volume, and the fourth water volume of the soil, thereby realizing vertical infiltration calculation and slope runoff calculation.

6. The method according to claim 4, characterized in that, The simulation of slope confluence and river confluence using a motion wave model specifically includes: Based on the river network system generated by the DEM, the topological relationship and calculation order of the slope grid and the channel grid are determined by the confluence accumulation and flow direction; Based on the continuity equation, a water balance equation within the grid is constructed. Combined with Manning's formula and the river end face equation, the motion wave equation data is valued to obtain simulated slope confluence and simulated river confluence.

7. The method according to claim 4, characterized in that, The simulation of groundwater movement based on Darcy's formula specifically includes: The groundwater simulation area is meshed; By applying mass conservation and Darcy's formula to a single grid cell, the flow rate between two adjacent grid cells can be obtained. Select the center grid in the grid, and for each center grid, determine the first flow from the surrounding grids into the corresponding center grid based on the flow between two adjacent grids; the surrounding grids refer to the grids connected to the center grid, and the center grid is the grid surrounded by other grids; Calculate the second flow rate from any source flow in the aquifer to the central grid; Calculate the third flow rate from the aquifer multi-source flow to the central grid; The difference equation for each grid cell is determined based on the first flow rate, the second flow rate, and the third flow rate, combined with the continuity equation. The water level of each grid is obtained based on the difference equation of each grid.

8. A system for identifying the mutual feedback mechanism of water and soil resources, characterized in that, include: The data acquisition module is used to acquire hydrological data, meteorological data, geological data, and remote sensing data of the target area; The distributed hydrological model simulation module is used to perform energy process simulation, evaporative cooling process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river confluence calculation, and groundwater movement calculation based on the hydrological data, meteorological data, geological data, and remote sensing data, to obtain a distributed hydrological model; the energy process simulation includes longwave radiation and shortwave radiation calculation; the evaporative cooling process simulation includes vegetation transpiration, vegetation intercepted evaporation, water evaporation, bare soil evaporation, urban surface evaporation, and building evaporation; The runoff coefficient calculation module is used to calculate and statistically analyze the surface runoff at different time scales in the watershed based on the distributed hydrological model and combine it with precipitation to obtain the runoff coefficient for different time periods in the watershed space. The net primary productivity to evaporative heat dissipation ratio calculation module is used to calculate and statistically analyze the evaporative heat dissipation at different time scales in the watershed based on the distributed hydrological model and determine the ratio of net primary productivity to evaporative heat dissipation in combination with the net primary productivity of different land use types. The water-soil resource interaction law acquisition module is used to determine the water-soil resource interaction law based on the runoff coefficient and the ratio of net primary productivity to evaporative heat dissipation. The determination of the water-soil resource interaction law based on the runoff coefficient and the ratio of net primary productivity to evaporative heat loss specifically includes: The runoff coefficient at different time periods within the watershed is used as an indicator to study the impact of land resources on water resources. The spatial distribution of the ratio of net primary productivity to evaporative heat dissipation at different time scales is used as an indicator to study the impact of water resources on land resources. The mutual feedback effect of water and soil resources is analyzed from both temporal and spatial perspectives.

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