LU502743B1 - Method and system for identifying mutual feedback mechanism of water and soil resources - Google Patents

Abstract

The invention provides a method and a system for identifying the mutual feedback mechanism of water and soil resources.

Description

DESCRIPTION LU502743

Method and system for identifying mutual feedback mechanism of water and soil resources

TECHNICAL FIELD

The invention relates to the technical field of basin water cycle simulation and simulation, and in particular to a method and a system for identifying mutual feedback mechanism of water and soil resources based on basin water circulating process simulation.

BACKGROUND

The problem of human-land competition for water and human-water competition for land constrains the balanced relationship between natural and socio-economic systems, and the inconsistent scale of the objects of water resources management and land resources management makes it difficult to understand the processes of water production and consumption on land and their ecological effects. Hydrological simulation has always been a research method in the field of hydrology and water resources. Hydrological simulation can quantify hydrological process, quantitatively describe the change process of hydrological cycle elements with time and the spatial distribution under different land use types. In order to better study the law of hydrological change and the water-soil resource interaction law, it is necessary to further strengthen the simulation function of basin hydrological model, including process refinement and improvement of simulation equation.

At present, hydrologists at home and abroad have made a lot of research and contributions in this area. There are many types of prototype software focusing on surface hydrological process simulation, groundwater movement simulation, river movement model, urban rain and flood simulation, etc. However, from the perspective of the whole watershed, from the surface to the underground, from the slope to the river, there are few hydrological models considering the total factor hydrological process simulation. In view of the above shortcomings, this invention provides a method and a system for identifying mutual feedback mechanism of water and soil resources based on basin water circulating process simulation.

SUMMARY LU502743

The objective of the invention is to provide a method and a system for identifying the mutual feedback mechanism of water and soil resources, which is based on a basin refined simulation model considering hydrological multi-process and multi-factors, can accurately obtain the mutual feedback mechanism of water and soil resources, expand the technical means of basin hydrology research, thus providing technical support for basin comprehensive management and optimal allocation of water and soil resources.

To achieve the above objectives, the present invention provides the following solutions.

A method and system for identifying mutual feedback mechanism of water and soil resources, comprising; obtaining hydrological data, meteorological data, geological data and remote sensing data of the target area; carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels-flow confluence calculation and groundwater movement calculation are carried out according to the hydrological data, the meteorological data, the geological data and the remote sensing data to obtain a distributed hydrological model; the energy process simulation comprises calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation comprises vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation;

calculating and counting the surface runoff yield at different time scales of the LUS02743 basin based on the distributed hydrological model, and combining the precipitation to obtain runoff coefficients in different time periods in the basin space; calculating and counting the evapotranspiration in different time scales of the basin based on the distributed hydrological model, and determining the ratio of evapotranspiration to net primary productivity in combination with net primary productivity of different land use types; determining the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity.

The invention also provides an identification system of mutual feedback mechanism of water and soil resources, which comprises: a data acquisition module is used for obtaining hydrological data, meteorological data, geological data and remote sensing data of the target area; a distributed hydrological model simulation module is used for carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels- flow confluence calculation and groundwater movement calculation according to the hydrological data, the meteorological data, the geological data and the remote sensing data, and obtaining a distributed hydrological model; the energy process simulation comprises calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation comprises vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation;

a runoff coefficient calculation module is used for calculating and counting the 502743 surface runoff vield in different time scales of the basin based on the distributed hydrological model, and to obtain runoff coefficients in different time periods in the basin space in combination with the precipitation; a ratio calculation module of evapotranspiration and net primary productivity is used for calculating and counting the evapotranspiration in different time scales of the the basin based on the distributed hydrological model and determining the ratio of evapotranspiration to net primary productivity in combination with the net primary productivity of different land use types; a water-soil resource interaction law acquisition module is used for determining the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects.

The invention provides a method and a system for identifying the mutual feedback mechanism of water and soil resources, which comprise the following steps: obtaining hydrological data, meteorological data, geological data and remote sensing data of a target area; carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels-flow confluence calculation and groundwater movement calculation according to the obtained data to obtain a distributed hydrological model; calculating and counting the surface runoff yield at different time scales of the basin based on the distributed hydrological model, and combining the precipitation to obtain

; Cg ; ; ; ; . ; LU502743 runoff coefficients in different time periods in the basin space; calculating and counting the evapotranspiration in different time scales of the basin based on the distributed hydrological model, and determining the ratio of evapotranspiration to net primary productivity in combination with net primary productivity of different land use types; determining the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity. The hydrological model based on the refined simulation of multi-process and multi-factors in the basin can accurately know the water-soil resource interaction law, and provide technical support for comprehensive management of the basin and optimal allocation of water and soil resources.

BRIEF DESCRIPTION OF THE FIGURES

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the figures that need to be used in the embodiments. Obviously, the figures in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other figures can be obtained according to these figures without any creative effort.

Fig. 1 is a flow chart of a method for identifying the mutual feedback mechanism of water and soil resources provided in Embodiment 1 of the present invention;

Fig. 2 is a hydrological analysis process of Sihe basin provided by Embodiment 1 of the present invention;

Fig. 3 is topographic data of Sihe basin provided by Embodiment 1 of the present invention;

Fig. 4 is meteorological data of Sihe basin provided by Embodiment 1 of the present invention;

Fig. 5 is a mutation test of Sihe basin provided by Embodiment 1 of the present invention;

Fig. 6 is the vertical and horizontal structure of the basin hydrological model LU502743 provided by Embodiment 1 of the present invention;

Fig. 7 1s the parameter adjustment and verification of Sihe basin provided by

Embodiment 1 of the present invention:

Fig. 8 is the spatial distribution of runoff coefficient in Sihe basin provided by

Embodiment 1 of the present invention:

Fig. 9 1s the spatial distribution of NPP/ET in Sihe basin provided by Embodiment 1 of the present invention:

Fig. 10 is a schematic diagram of water balance in the grid provided by

Embodiment 1 of the present invention;

Fig. 11 is a schematic diagram of aquifer system division provided by Embodiment 1 of the present invention;

Fig. 12 is a three-dimensional positional relationship between a peripheral grid and a central grid provided in Embodiment 1 of the present invention;

Fig. 13 is the plane position relationship between the peripheral grid and the central grid provided in Embodiment 1 of the present invention.

DESCRIPTION OF THE INVENTION

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the figures in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, but not all of them. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in the field without creative labor are within the scope of the present invention.

The objective of the invention is to provide a method and a system for identifying the mutual feedback mechanism of water and soil resources, which is based on a basin refined simulation model considering hydrological multi-process and multi-factors, can accurately obtain the mutual feedback mechanism of water and soil resources, expand the technical means of basin hydrology research, thus providing technical support for LUS02743 basin comprehensive management and optimal allocation of water and soil resources.

In order to make the above objectives, features and advantages of the present invention more obvious and understandable, the present invention will be explained in further detail below with reference to the figures and detailed description.

Embodiment 1

As shown in Fig. 1, this embodiment provides a method and system for identifying the mutual feedback mechanism of water and soil resources, including:

First of all, the scheme of this embodiment can be summarized as follows: taking

Sihe basin as an example, the refined simulation method of basin based on coupled distributed hydrological model and groundwater model provided in this embodiment is as follows. (1) Preparation of model input data

Specially including:

Firstly, carry out basin hydrological analysis: based on DEM and using hydrological analysis tools in ArcGIS, carries out depression detention calculation, flow direction calculation, flow accumulation calculation, and basin generation, and take the basin boundary at this time as the boundary for later input data preparation, as shown in Fig. 2;

Secondly, the preparation of topographic data: the basin range generated in the previous step is as the boundary file, and cut DEM, soil type data, soil thickness data, land use type data of each period and river network data, and all the cut files are converted into ASCII files as input files, as shown in Fig. 3;

Thirdly, preparing meteorological data: selecting meteorological stations and LU502743 rainfall stations in and around the basin and numbering them sequentially, and drawing

Thiessen polygons of meteorological stations and rainfall stations with the Create

Thiessen Polygons in ArcGIS. Take the basin as the boundary, convert the drawn

Thiessen polygons into raster files according to the site serial number, and convert it into ASCII files. Extract the required meteorological data and precipitation data, and prepare them into TXT files according to the format of "Year-month-day 1st Station - 2nd Station-... nth Station", as shown in Fig. 4;

Finally, preparing other basic data and parameters: such as latitude, elevation of meteorological station, change rate of precipitation with elevation, vegetation coverage data of each month, leaf area index data of each month, reflectivity of various land use surfaces to short-wave radiation, saturated water content of various soils, field water holdup of various soils, wilting coefficient of various soils, depression reserve of various land use types, horizontal-vertical-vertical permeability coefficient of each soil layer, slope Manning coefficient and Manning coefficient of river channel. (2) Model simulation calculation

Energy process simulation, including calculation of long-wave radiation and short- wave radiation of different underlying surfaces; evapotranspiration process simulation, including vegetation transpiration (Penman-Monteith), vegetation interception evaporation (Penman), water area evaporation (Penman), bare soil evaporation (modified Penman), urban surface evaporation and building evaporation (penman); vertical infiltration calculation (Green-AMPT); slope runoff calculation, including over-infiltration runoff (Horton slope runoff) and runoff yield under saturated storage LUS02743 (saturated slope runoff); slope confluence calculation (motion wave) and river channels-flow confluence calculation (motion wave), groundwater movement calculation (Darcy formula), and the vertical and horizontal structure of each element process of hydrological cycle simulation are shown in Fig. 5. (3) Model parameter adjustment and verification

Firstly, the catastrophe point test, which uses Mann-Kendall method to test the rainfall data, with the period before the catastrophe point as the parameter adjustment period and the period after the catastrophe point as the verification period, as shown in

Fig. 6;

Secondly, the model parameter adjustment: various parameters are debugged, the simulation effect of the model is judged by three indexes: correlation coefficient, Nash coefficient and relative error, and the parameters are adjusted until the three indexes meet the requirements, and the adjustment is finished;

Model verification: on the basis of model parameter adjustment, the parameters are fixed, and then the parameter adjustment period is simulated and verified regularly.

If the three indexes pass, the model verification is passed, and the results of model parameter adjustment and verification are shown in Fig. 7. (4) Study on mutual feedback mechanism of water and soil resources.

Firstly, the surface runoff and precipitation of each grid in the basin at different time scales are calculated and counted by using the above-mentioned compiled and debugged distributed hydrological model, and then the runoff coefficients in different LUS02743 time periods in the basin space are obtained, as shown in Fig. 8;

Secondly, the compiled and debugged distributed hydrological model is used to calculate and count the evapotranspiration of each grid in the basin at different time scales, and the spatial distribution of net primary productivity in the basin is obtained by using the quota of net primary productivity of different land use types and the spatial distribution of land use. Finally, the spatial distribution of NPP/ET at different time scales is obtained by comparing NPP with ET, as shown in Fig. 9.

Finally, the runoff coefficient is used as an index to study the influence of land resources on water resources, and NPP/ET is used as an index to study the influence of water resources on land resources, and the results of runoff coefficient and NPP/ET are analyzed, and the mutual feedback between water and soil resources is analyzed from time and space.

The following is a more detailed step of the method described in this embodiment:

S1, obtaining hydrological data, meteorological data, geological data and remote sensing data of a target area;

The step S1 specifically includes:

S11, basin hydrological analysis: based on DEM and with the help of hydrological analysis tools in ArcGIS, depression detention calculation, flow direction calculation, flow accumulation calculation, and basin generation are carried out, and the basin boundary at this time is used as the boundary for later input data preparation;

S12, preparing topographic data: taking the basin range generated in S11 as LUS02743 boundary file, cutting DEM again as basin elevation data, cutting soil type data, soil thickness data, land use type data of each period and river network data, and converting all the cut files into ASCII files as input files;

S13, selecting meteorological stations and rainfall stations in the basin and their preset ranges, and sequentially numbering the meteorological stations and rainfall stations;

S14, respectively drawing the Thiessen polygons of the meteorological station and the rainfall station by using Create Thiessen Polygons;

S15, taking the basin range as the boundary, respectively converting the drawn

Thiessen polygon installation meteorological station number and rainfall station number into raster files;

S16, extracting meteorological data and precipitation data based on the raster files;

S13-S16 are used to prepare meteorological data, and the meteorological stations and rainfall stations in and around the basin are selected and numbered sequentially, and the Thiessen polygons of the meteorological stations and rainfall stations are respectively drawn by the Create Thiessen Polygons in ArcGIS. Take the basin as the boundary, convert the drawn Thiessen polygons into raster files according to the site serial number, and convert them into ASCII files. Extract the required meteorological data and precipitation data, and prepare them into TXT files according to the format of "Year-month-day 1st Station -2nd Station-... nth Station".

S17: obtaining latitude and elevation of meteorological station, change rate of LUS02743 precipitation with elevation, vegetation coverage data of each month, leaf area index data of each month, reflectivity of various land use surfaces to short-wave radiation, saturated water content of various soils, field water holdup of various soils, wilting coefficient of various soils, depression reserve of various land use types, horizontal- vertical-vertical permeability coefficient of each soil layer, slope Manning coefficient and Manning coefficient of river channel based on the grid files.

Step S17 belongs to the preparation of other basic data and parameters, such as latitude, elevation of meteorological station, change rate of precipitation with elevation, vegetation coverage data of each month, leaf area index data of each month, reflectivity of various land use surfaces to short-wave radiation, saturated water content of various soils, field water holdup of various soils, wilting coefficient of various soils, depression reserve of various land use types, horizontal-vertical-vertical permeability coefficient of each soil layer, slope Manning coefficient and Manning coefficient of river channel.

S2, carrying out energy process simulation, evaporation process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels-flow confluence calculation and groundwater movement calculation according to the hydrological data, the meteorological data, the geological data and the remote sensing data, so as to obtain a distributed hydrological model; the energy process simulation includes calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation includes vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation; slope runoff calculation, including over- LUS02743 infiltration runoff and runoff yield under saturated storage. Among them, the well- known Penman formula is used for evaporation calculation, and the well-known

Penman Monteith formula is used for transpiration.

S2 specifically includes:

S21, finely classifying the underlying surface types according to the national standard "Classification of Land Use Status"; the refined classification means dividing the underlying surface type into a preset classification number;

S21 belongs to refined simulation. According to the national standard "Classification of Land Use Status", the underlying surface types are refined into 25 categories, each grid corresponds to a land use type, and there is an independent vertical hydrological cycle process. The 25 types of underlying surface here can be changed, increased or decreased, and adjusted according to the simulation requirements.

S22, calculating long-wave radiation and short-wave radiation for each underlying surface to simulate the energy process; energy process simulation, including calculation of long-wave radiation and short- wave radiation of different underlying surfaces.

S23, simulating the evapotranspiration process according to the vegetation transpiration, vegetation interception and evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation;

the evapotranspiration process simulation includes vegetation transpiration, LUS02743 vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation.

S24, calculating the variation of soil water and groundwater according to infiltration and evaporation; that is, in the process of calculating the variation of soil water and groundwater, vertical infiltration calculation and slope runoff calculation are carried out;

Specifically, step S24 specifically includes: obtaining the net rainfall that rainfall enters the soil through interception and depression detention; obtaining the first water yield of the net rainfall of the soil infiltrating into the underground water to replenish the underground water; obtaining the second water yield evaporated back to the atmosphere and a third water yield transpired from vegetation to the atmosphere; obtaining the fourth water yield finally retained in the soil; determining the exchange process of surface and underground water according to the net rainfall, the first water yield, the second water yield, the third water yield and the fourth water yield of the soil, so as to calculate vertical infiltration and slope runoff.

Surface water and underground water are exchanged, precipitation enters the soil through interception and depression detention. Some of the water in the soil infiltrating into the underground water to replenish the underground water, some evaporates back

. LL LU502743 to the atmosphere, some evaporates to the atmosphere through vegetation transpiration, and some remains in the soil. The calculation formula are as follows: b=P-W-H (824-1) w f nzf

P= (S24-2

BP P<f

W=M+W-W,-W, (S24-3)

WxA Ah

OH =Sx—xV (S24-4

N At )

Where: P is precipitation rainfall (mm); Pr is the net rainfall (mm), that is, the runoff yield; Wr is vegetation interception (mm); H is depression reserve (mm); fis the infiltration capacity (mm/t); Wo is the initial soil water content (mm), W; is soil infiltration amount (mm); Ws is the saturated water content of soil (mm); We is evaporation amount (mm); W; is the recharge of groundwater by rainfall (mm); Q is the lateral inflow (m°/t); 4 is the area of the replenishment area (m?); At is the time interval (1); Sis the water storage rate (1/m); Ah is the water level change (m); V is the volume of groundwater control body (m°).

Infiltration amount is W;in formula S24-2, and runoff yield is Pr in formula S24- 1.

S25, carrying out slope confluence simulation and river channels-flow confluence simulation by using motion wave model.

Specifically, step S25 specifically includes:

Step 1, based on the river network system generated by the DEM, determining the topological relationship and calculation order of the slope grid and the river grid through the flow accumulation and the flow direction;

Step 2: building the water balance equation (formula S25-2) in the grid through the continuity equation (formula S25-1), substitute Manning formula (formula S25-3)

and river section equation (formula S25-4) into the water balance equation, and digitize LUS02743 the motion wave equation to obtain simulated slope confluence and simulated river channels-flow confluence. The river channel is generalized into a rectangular river channel, and the slope confluence is generalized into a wide and shallow channel. The schematic diagram of water balance in the grid is shown in Fig. 10. 04 00

Continuity equation: or Tar U (Formula S25- 1)

Water balance equation: (Qin _L1+02, x At =(A2— Al)xdx (Formula S25-2) 2

Manning formula: Q= 2rssy (Formula S25- 3)

River section equation: A=bxh (Formula S25-4)

In the above formulas: A] and A2 are the water cross-sectional areas (m°) at the beginning and end of the grid period; Qin is the upstream water flow rate (m°/s) of the grid (including the lateral water flow Oside of the grid, such as the amount of water flowing into the river from the slope confluence and the runoff vield of the grid itself);

Q1 and Q2 are the amount of grid effluent (m°/s) at the beginning and end of the grid period, respectively; n is the Manning roughness coefficient of grid surface; R is the hydraulic radius (m) of grid channel or slope wide and shallow channel; So is grid slope or longitudinal slope of river channel; b is the width of the grid (m); » is the water depth in the grid (m).

S26: simulate the groundwater movement according to Darcy formula.

Step S26 specifically includes: making grid division of groundwater simulation area; for each grid, applying mass conservation and Darcy formula, the flow between two adjacent grids is obtained; selecting a central grid in the grids, and for each central grid, determining the first flow of peripheral grids flowing into the corresponding central grid according to the

; ; ; ; ; ; LU502743 flow rate between two adjacent grids; the peripheral grids refer to grids connected with the central grid, and the central grid is a grid surrounded by other grids; calculating the second flow of any source flow of aquifer to the central grid; calculating the third flow of aquifer multi-source flow to the central grid; determining a difference equation of each grid according to the first flow, the second flow and the third flow combined with the continuity equation: obtaining the water level of each grid according to the difference equation of each grid.

For more specific description of groundwater movement simulation: Darcy formula is used for calculation. According to the simulation requirements, making grid division of groundwater simulation area based on the aforementioned grid division method, as shown in Fig. 11. The size of groundwater grid is consistent with that of surface water simulation grid. The thickness of underground aquifer is divided according to the local actual situation. The calculation of a single grid 1s related to 1ts adjacent grids (top, bottom, left, right, front and back), as shown in Fig. 12. 1,j and k represent rows, columns, and layers, respectively.

The principle of conservation of mass and Darcy law applied to cells (i,j,k), obtaining the following formula: h ..—h ,

Gin =KR ya Dev, Boum) (Formula S26-1)

Or, va

J

Where: hijx and hij-ıx are the head values at the nodes (i,j,k) and (ij-1,k) respectively. gij-inx 1s the flow between node (i,j,k) and node (i,j-1,k), KRij-ink is hydraulic conductivity; Ac;Av; is the cross-sectional area; Arj-12 is the distance between two points.

In the same way, the following formula can be obtained.

(A, ik Ah, x)

Dijin = KC, Url, —

Cian (A4, ik —h, 4) qin 7 KC ya Onl, Ta 2 (Formula S26-2)

Gp run = KV, pan Or O9 ses TR) i,j, k+1/2 if k+1/2—" à k Ov. (A, i k— —h, x)

Di jr-wr 7 KV, rw OV, PS

Viva

CR, 1a = KR, Helv, 1 Fin

CR, an = KR, jan GV, 1 Tian cc, ,=KC_, Orv Mc; 1/2, j,k 1/2, j,k J k 1/2 (Formula $26-3)

CC, 2.74 = KC, 12,72 IV, Me, 2

CV, jan = KV, apelin, vy,

CV, en = KV node UF, /0 Vian

Where, KV, KR and KC are a whole variable, representing vertical, row and column, respectively, on each axis of xyz as shown in Fig. 11.

Therefore, the formula S26-2 can be written as:

Gi jeux 7 CR, i (A 5x T hi)

INE 7 CR ys (Aux - hi) qd jh = CV, van (4a =n) (Formula 826-4) qk 7 CV, han (A jun T hii)

Danie 7 CC in (My - hi)

Gap jk 7 CC, v2,jk yj i a hj )

Where, CR, CC and CV here are a whole variable, representing vertical, row and column respectively. These three variables are intermediate variables, which have no actual meaning and are used to simplify the equation.

The formula S26-4 represents the flow from the adjacent six surfaces to the node (i, j, k). The flow from any source outside the aquifer to the node (i, j, k) can be expressed by the following formula: a; kon = Pin + Gi j ken ( S26-5)

Where: a refers to the external supply to this grid (m°/d); P refers to the influence of surface water circulation process on groundwater in this grid, such as river leakage recharge, rainfall infiltration recharge (m°/d) and so on; q the influence of human use LU502743 on groundwater in this grid, such as pumping capacity (m°/d).

Generally, if there are N sources affecting the node (i,j, £), then the total flow from these N sources to the node (i,j,k) is as follows:

N N N

OS, = Sa jen = SPs +} 4,1, (Formula S26-6) n=2 n=l n=l

N N

Make FR; 4 = > R; nn and Or => jan n=1 n=l

Formula S26-6 can be as follows:

OS, ju FR hi +0 4 (Formula S26-7)

According to the continuity equation:

Grane TG jar Tame Tan re Gig À Mi jean Ÿ OS,

Oh, ,, (Formula S26-8) =S , —Ur Uc lv,

I], J I

Of

Where: “+ is the change of water level with time (L/t); S;;x is the water storage ae rate (1/L) of node (i,j,k); ArjAciAvz is the volume (L°) of the node (i,j,k).

Substituting Formula S26-4 and S26-5 into Formula 26-8, the finite difference equation at the node (i,j,k) is as follows:

CR, ips (Ajax = hi) + CR, 14 (A ju = hi) +CC, yh A CC (ho, ja TR 14) 12,j,k 1,j,k Sik 1/2, j,k 1,j,k dk (Formula $26-9) +CV, tan (Arr = hi, ) + CV, van (Ar = hi) +B uh Qi 755,5 x Or, De Ov, dh, Ot

Where, S is the parameter expression after difference, which also means water storage rate.

The formula S26-9 can be written as:

CR, ; vx CA = ni) + CR, ("x = ni)

HCC j (a, j =n", j )+CC, j (a, j —h", j ) 12,j,k î 1,j,k î dk 1/2,j,k , 1,j,k , dk (Formula $26-10) +CV jean (h ij k-1 —h ii) + CV, van (h i,j k+l —h ik) +P pe Qu je #98, Or De Ov, OA”, Ah) [Ot

Similarly, the difference equation of each grid in the groundwater simulation area LUS02743 is obtained, and the number of grids forms the corresponding number of equations.

Sort out the formula S26-10, put the related terms of the formula with the current groundwater level (h™) on the left side of the equation, and put the groundwater level of last moment and the known terms on the right side of the equation, as shown in formula S26-11.

CR, nih”, pue FOR pa" a FCC u FCC ij +CV, nh" ACV nh” a= (CR, FOR jap +CC,,, (Formula S26-11)

ACC age TCV ian FEV py 7 HCOF , OR”, =RHS,

RHS, 54 = Op SCH M I(t, —1,.)

Make (SCI, = SS 0r0c OV, (Formula 26-12), = SCH eb )—F }

Forming a matrix: [A]x{h}={q}.

Where: A is the coefficient matrix; h is the water level of each grid at this moment, and the variable matrix is to be calculated; q is a matrix of known terms.

The above equation is converted into explicit format S26-13, achieving solution in iterative algorithm (the water level of the central grid at moment of m is calculated by the water level of the peripheral grids at moment of m-1, and the upper limit of the iteration number is 10 times, with an iteration error of 0.01 m). Calculate the grid (i,j) and its peripheral grids, as shown in Fig. 13. pe DER ga" 4 CR RS, HCC a MU HCC pay M" RES, à 1 CR, FOR, ,,+CC,,, +CC,,, —HCOF, (Formula S26-13)

S3, calculating and counting the surface runoff yield at different time scales of the basin based on the distributed hydrological model, and combining the precipitation to obtain runoff coefficients in different time periods in the basin space;

S4, calculating and counting the evapotranspiration in different time scales of the basin based on the distributed hydrological model, and determining the ratio of evapotranspiration to net primary productivity (NPP/ET) in combination with the net primary productivity of different land use types.

The above-mentioned compiled and debugged distributed hydrological model is LUS02743 used to calculate and count the evapotranspiration of each grid in the basin at different time scales, and the spatial distribution of net primary productivity in the basin is obtained by using the quota of net primary productivity of different land use types and the spatial distribution of land use. Finally, compare the spatial NPP with ET, and the spatial distribution of NPP/ET at different time scales is obtained.

The step S4 specifically includes: calculating and counting the evapotranspiration of different time scales of the basin based on the distributed hydrological model; obtaining the spatial distribution of net primary productivity of the basin by using the quota of net primary productivity of different land use types and the spatial distribution of land use; determining the ratio between the evapotranspiration and the net primary productivity in space, and obtaining the spatial distribution of the ratio of the evapotranspiration and the net primary productivity in different time scales.

S5, determining the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity.

SS specifically includes:

The runoff coefficient in different time periods in the basin space is used as the index to study the influence of soil resources on water resources, and the spatial distribution of the ratio of evapotranspiration and net primary productivity in different time scales is used as the index to study the influence of water resources on soil resources. The mutual feedback between water and soil resources is analyzed from the time and space perspectives.

It should be noted that after the distributed hydrological model is obtained, it also includes model parameter adjustment and verification, specifically including:

catastrophe point test: using Mann-Kendall method to carry out catastrophe test LU502743 on the rainfall data, taking the period before the catastrophe point as the parameter adjustment period and the period after the catastrophe point as the verification period: model parameter adjustment, debugging of various parameters, judging the simulation effect of the model by three indicators: correlation coefficient, Nash coefficient and relative error, adjusting the parameters until the three indicators meet the requirements, and ending the adjustment; and model verification: on the basis of model parameter adjustment, the parameters are fixed, and then the parameter adjustment period is simulated regularly. If the three indexes pass, the model verification is passed.

In this embodiment, Python language is used to compile a hydrological model for refined simulation of river basins from the surface to the ground and from the slope to the river, and it is applied to the study of mutual feedback between water and soil resources. Preparation of input data of the model, including topographic data: elevation, slope, land use type, soil type and thickness, river network, meteorological data: meteorological station information, precipitation, temperature, wind speed, relative humidity and illumination time, and other basic data and parameters; refined simulation, with 25 types of refined underlying surface, and each simulation unit has its own hydrological parameters, and separate vertical hydrological simulation is carried out; model parameter adjustment and verification: by analyzing the mutagenicity of rainfall data, taking the period before the catastrophe point as the parameter adjustment period and the period after the catastrophe point as the verification period; the model application: output precipitation, runoff, evapotranspiration, etc. at different time and different spatial positions in the basin; identification of mutual feedback between water and soil resources. It can realize the refined simulation of multi-process and multi- factors, and each simulation unit has its own hydrological parameters, and can carry out a separate vertical hydrological simulation, and then realize the horizontal connection through the grid topological relationship, and finally get the runoff of slope, underground and river, which provides technical support for comprehensive management of river basin and optimal allocation of water and soil resources.

Embodiment 2 LUS02743

This embodiment provides an identification system of mutual feedback mechanism of water and soil resources, including: a data acquisition module M1 is used for obtaining hydrological data, meteorological data, geological data and remote sensing data of the target area; a distributed hydrological model simulation module M2 is used for carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels- flow confluence calculation and groundwater movement calculation according to the hydrological data, the meteorological data, the geological data and the remote sensing data, and obtaining a distributed hydrological model; the energy process simulation comprises calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation comprises vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation; a runoff coefficient calculation module M3 is used for calculating and counting the surface runoff yield in different time scales of the basin based on the distributed hydrological model, and to obtain runoff coefficients in different time periods in the basin space in combination with the precipitation; a ratio calculation module M4 of evapotranspiration and net primary productivity is used for calculating and counting the evapotranspiration in different time scales of the the basin based on the distributed hydrological model and determining the ratio of evapotranspiration to net primary productivity in combination with the net primary productivity of different land use types; a water-soil resource interaction law acquisition module M5 is used for determining the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity.

In this paper, specific examples are used to explain the principle and implementation of the present invention, and the explanations of the above embodiments are only used to help understand the method and core ideas of the present invention; At the same time, according to the idea of the present invention, there will LU502743 be some changes in the specific implementation and application scope for those of ordinary skill in the field.

To sum up, the contents of this specification should not be construed as limiting the present invention.

Claims (9)

CLAIMS LU502743

1. A method and system for identifying mutual feedback mechanism of water and soil resources, characterized by comprising: obtaining hydrological data, meteorological data, geological data and remote sensing data of the target area; carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels-flow confluence calculation and groundwater movement calculation are carried out according to the hydrological data, the meteorological data, the geological data and the remote sensing data to obtain a distributed hydrological model; the energy process simulation comprises calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation comprises vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation; calculating and counting the surface runoff yield at different time scales of the basin based on the distributed hydrological model, and combining the precipitation to obtain runoff coefficients in different time periods in the basin space; calculating and counting the evapotranspiration in different time scales of the basin based on the distributed hydrological model, and determining the ratio of evapotranspiration to net primary productivity in combination with net primary productivity of different land use types;

determining the water-soil resource interaction law according to the runoff LUS02743 coefficient and the ratio of evapotranspiration to net primary productivity.

2. The method according to claim 1, characterized in that obtaining the hydrological data, meteorological data, geological data and remote sensing data of the target area specifically comprises: on the basis of the digital elevation model (DEM) of the target area, using hydrological analysis tools to perform depression detention calculation, flow direction calculation and flow accumulation calculation to generate a watershed, so as to obtain basin hydrological analysis data; cutting the digital elevation model (DEM) with the basin range in the basin hydrological analysis data as a boundary condition to obtain basin elevation data, soil type data, soil thickness data, land use type data and river network data; selecting meteorological stations and rainfall stations in the basin and its preset range, and sequentially numbering the meteorological stations and rainfall stations; drawing the Thiessen polygons of the meteorological station and the rainfall station respectively by using the Create Thiessen Polygons; taking the basin range as the boundary, sequentially numbering the meteorological stations and rainfall stations for the Thiessen polygons respectively and converting into raster files; extracting meteorological data and precipitation data based on the raster files; obtaining the latitude and elevation of the meteorological station, the change rate of precipitation with elevation, the vegetation coverage data of each month, the leaf area index data of each month, the reflectivity of surfaces to short-wave radiation under LUS02743 various land use types, the saturated water content of various soils, the field water holdup of various soils, the wilting coefficient of various soils, the depression reserve of various land use types, the horizontal-vertical-vertical permeability coefficient of each soil layer, the slope Manning coefficient and the Manning coefficient of river channel are obtained based on the raster file.

3. The method according to claim 2, characterized in that calculating and counting the evapotranspiration at different time scales of the basin based on the distributed hydrological model and determining the ratio of evapotranspiration to net primary productivity in combination with net primary productivity of different land use types, specifically comprises: calculating and counting the evapotranspiration of different time scales of the basin based on the distributed hydrological model; obtaining the spatial distribution of net primary productivity of the basin by using the quota of net primary productivity of different land use types and the spatial distribution of land use; determining the ratio between the evapotranspiration and the net primary productivity in space, and obtaining the spatial distribution of the ratio of the evapotranspiration and the net primary productivity in different time scales.

4. The method according to claim 3, characterized in that determining the water- soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity, specifically comprises:

the runoff coefficient in different time periods in the basin space is used as the 502743 index to study the influence of soil resources on water resources, and the spatial distribution of the ratio of evapotranspiration and net primary productivity in different time scales is used as the index to study the influence of water resources on soil resources; the mutual feedback between water and soil resources is analyzed from the time and space perspectives.

5. The method according to claim 2, characterized in that according to the hydrological data, the meteorological data, the geological data and the remote sensing data, the distributed hydrological model is obtained through energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels-flow confluence calculation and groundwater movement calculation, which specifically comprises: according to the national standard "Classification of Land Use Status", the underlying surface types are finely classified; the refined classification means dividing the underlying surface type into a preset classification number; for each underlying surface, calculating long-wave radiation and short-wave radiation to simulate the energy process; simulating the process of evapotranspiration according to vegetation transpiration, vegetation interception and evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation; carrying out vertical infiltration calculation and slope runoff calculation in the process of calculating the variation of soil water and groundwater;

carrying out simulation of slope confluence and river channels-flow confluence by LUS02743 using motion wave model; simulating the groundwater movement according to Darcy formula.

6. The method according to claim 5, characterized in that the vertical infiltration calculation and slope runoff calculation are carried out in the process of calculating the variation of soil water and groundwater, specifically comprises: obtaining the net rainfall that rainfall enters the soil through interception and depression detention; obtaining the first water yield of the net rainfall of the soil infiltrating into the underground water to replenish the underground water; obtaining the second water yield evaporated back to the atmosphere and a third water yield transpired from vegetation to the atmosphere; obtaining the fourth water yield finally retained in the soil; determining the exchange process of surface and underground water according to the net rainfall, the first water yield, the second water yield, the third water yield and the fourth water yield of the soil, so as to calculate vertical infiltration and slope runoff.

7. The method according to claim 5, wherein the simulation of slope confluence and river channels-flow confluence by using the motion wave model specifically comprises: on the basis of the river network water system generated by the DEM, determining the topological relationship and calculation order of the slope grid and the river channels grid by the flow accumulation and the flow direction;

constructing the water balance equation in the grid according to the continuity LUS02743 equation, and combining with Manning formula and river end face equation, the data of motion wave equation is valued to obtain the simulated slope confluence and simulated river channels-flow confluence.

8. The method according to claim 5, characterized in that the simulation of groundwater movement is carried out according to Darcy formula, specifically comprises: making grid division of groundwater simulation area; for each grid, applying mass conservation and Darcy formula, the flow between two adjacent grids is obtained; selecting a central grid in the grids, and for each central grid, determining the first flow of peripheral grids flowing into the corresponding central grid according to the flow rate between two adjacent grids; the peripheral grids refer to grids connected with the central grid, and the central grid is a grid surrounded by other grids; calculating the second flow of any source flow of aquifer to the central grid; calculating the third flow of aquifer multi-source flow to the central grid; determining a difference equation of each grid according to the first flow, the second flow and the third flow combined with the continuity equation; obtaining the water level of each grid according to the difference equation of each grid.

9. An identification system of mutual feedback mechanism of water and soil resources, characterized by comprising:

a data acquisition module is used for obtaining hydrological data, meteorological LUS02743 data, geological data and remote sensing data of the target area;

a distributed hydrological model simulation module is used for carrying out energy process simulation, evapotranspiration process simulation, vertical infiltration calculation, slope runoff calculation, slope confluence calculation, river channels- flow confluence calculation and groundwater movement calculation according to the hydrological data, the meteorological data, the geological data and the remote sensing data, and obtaining a distributed hydrological model; the energy process simulation comprises calculation of long-wave radiation and short-wave radiation; the evapotranspiration process simulation comprises vegetation transpiration, vegetation interception evaporation, water area evaporation, bare soil evaporation, urban surface evaporation and building evaporation;

a runoff coefficient calculation module is used for calculating and counting the surface runoff yield in different time scales of the basin based on the distributed hydrological model, and to obtain runoff coefficients in different time periods in the basin space in combination with the precipitation;

a ratio calculation module of evapotranspiration and net primary productivity is used for calculating and counting the evapotranspiration in different time scales of the the basin based on the distributed hydrological model and determining the ratio of evapotranspiration to net primary productivity in combination with the net primary productivity of different land use types;

a water-soil resource interaction law acquisition module is used for determining 502743 the water-soil resource interaction law according to the runoff coefficient and the ratio of evapotranspiration to net primary productivity.