A method and system for ecological restoration of desert riparian forests in arid areas

Abstract

The present invention relates to an ecological restoration method and system for desert riverbank forests in arid areas, and belongs to the field of ecological restoration technology. The current real-time remote sensing image of the desert riverbank forest and the historical remote sensing image N years ago are obtained to determine several ecological restoration areas of the desert riverbank forest, and then for each ecological restoration area, irrigation simulation is performed based on the initial restoration plan and the terrain of the ecological restoration area to determine the flooding range, and the initial restoration plan with the largest overlap between the flooding range and the ecological restoration area is selected as the best restoration plan for the ecological restoration area, so that the water inlet position and water diversion method of the desert riverbank forest can be accurately and scientifically determined, so as to improve the ecological restoration effect of the desert riverbank forest in arid areas based on the precise water diversion irrigation method, solve the problem that extensive ecological restoration requires a large amount of ecological restoration subsidy funds, save costs, and avoid waste of water resources.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological restoration, and in particular to an ecological restoration method and system for desert riparian forests in arid areas based on precise flood diversion irrigation. Background Art

[0002] Desert riverside forests in arid areas are natural vegetation belts composed of trees, shrubs and grasses, which can effectively block the desert from advancing into the oasis, maintain the balance of the oasis ecosystem in the basin, and keep the water system connected. Desert riverside forests are the core components and important parts of the desert ecosystem in the inland river basins of arid areas, maintaining the cycle of energy and matter in the desert area, and have very special ecological functions in arid areas.

[0003] At present, flood irrigation is a unique means of water resource allocation and ecological restoration in arid areas. However, the design and operation of flood irrigation in existing arid areas have no basis to follow. It basically relies on the experience of relevant personnel, terrain conditions, and water gravity to carry out ecological management in arid areas. The natural conditions in the desert riverside forest area in the arid area are harsh. Flood irrigation is an emergency project. There is a lack of corresponding supervision and management in its implementation. Most ecological restoration projects are still three-side projects that require command, design, and construction. Therefore, the current ecological restoration method in arid areas is still an extensive ecological restoration, which not only consumes a large amount of ecological restoration subsidy funds, but also is a huge waste of precious water resources in arid areas.

[0004] Based on this, there is an urgent need for an ecological restoration technology for desert riparian forests in arid areas based on precise flood diversion irrigation. Summary of the invention

[0005] The purpose of the present invention is to provide an ecological restoration method and system for desert riparian forests in arid areas, which can accurately and scientifically determine the water inlet location and water diversion method of the desert riparian forests, and improve the ecological restoration effect of the desert riparian forests in arid areas based on precise water diversion and irrigation methods.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An ecological restoration method for desert riparian forests in arid areas, the ecological restoration method comprising:

[0008] Acquire the real-time remote sensing images of the current desert riparian forest and the historical remote sensing images of the desert riparian forest N years ago;

[0009] Determining a plurality of ecological restoration areas of the desert riparian forest according to the real-time remote sensing image and the historical remote sensing image;

[0010] For each of the ecological restoration areas, multiple initial restoration plans for the ecological restoration area are designed; for each of the initial restoration plans, an irrigation simulation is performed based on the initial restoration plan and the terrain of the ecological restoration area to determine the inundation range corresponding to each of the initial restoration plans; the overlap between each inundation range and the ecological restoration area is calculated respectively, and the initial restoration plan with the largest overlap is selected as the optimal restoration plan for the ecological restoration area; the restoration plan includes the location of the water inlet and the water diversion flow and time of the water inlet.

[0011] An ecological restoration system for desert riparian forests in arid areas, the ecological restoration system comprising:

[0012] An image acquisition module, used to acquire the real-time remote sensing image of the current desert riparian forest and the historical remote sensing image of the desert riparian forest N years ago;

[0013] An ecological restoration area determination module, used to determine a plurality of ecological restoration areas of the desert riparian forest according to the real-time remote sensing image and the historical remote sensing image;

[0014] A restoration scheme determination module is used to design multiple initial restoration schemes for each ecological restoration area; for each initial restoration scheme, an irrigation simulation is performed based on the initial restoration scheme and the terrain of the ecological restoration area to determine the inundation range corresponding to each initial restoration scheme; the overlap between each inundation range and the ecological restoration area is calculated respectively, and the initial restoration scheme with the largest overlap is selected as the optimal restoration scheme for the ecological restoration area; the restoration scheme includes the location of the water inlet and the water diversion flow and time of the water inlet.

[0015] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0016] The present invention is used to provide an ecological restoration method and system for desert riparian forests in arid areas, which obtains current real-time remote sensing images of desert riparian forests and historical remote sensing images N years ago to determine several ecological restoration areas of the desert riparian forests, and then for each ecological restoration area, irrigation simulation is performed based on an initial restoration plan and the terrain of the ecological restoration area to determine the inundation range, and the initial restoration plan with the largest overlap between the inundation range and the ecological restoration area is selected as the best restoration plan for the ecological restoration area, so that the water inlet position and water diversion method of the desert riparian forest can be accurately and scientifically determined, so as to improve the ecological restoration effect of the desert riparian forests in arid areas based on the precise water diversion irrigation method, solve the problem that extensive ecological restoration requires a large amount of ecological restoration subsidy funds, and avoid waste of water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of the ecological restoration method provided in Example 1 of the present invention;

[0019] Figure 2 The technical system of the ecological restoration method provided in Example 1 of the present invention;

[0020] Figure 3 A schematic diagram of a vector data boundary provided in Embodiment 1 of the present invention;

[0021] Figure 4 A flowchart of two-dimensional modeling provided in Example 1 of the present invention;

[0022] Figure 5 A schematic diagram of a dfs2 terrain file provided in Example 1 of the present invention;

[0023] Figure 6 A schematic diagram of the evolution process of flood irrigation by diversion of water inlets provided in Example 1 of the present invention;

[0024] Figure 7 A schematic diagram of flooding depth for flood diversion irrigation at different water diversion flow rates provided in Example 1 of the present invention;

[0025] Figure 8 This is a system block diagram of the ecological restoration system provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Water is a key factor in determining the social, economic and ecological development of arid areas. The rational allocation and efficient use of limited water resources in arid areas are the scientific way for regional survival and development. Due to the irrational development and utilization of water resources, the degradation of river basin ecosystems has become a common phenomenon. Implementing water transfer projects to dry rivers and ecologically degraded areas, compensating groundwater and improving the water environment are the basic behaviors and inevitable processes for river ecosystem restoration. The reconstruction of hydrodynamic processes plays an important role in the process of ecological dispatching. Traditional ecological dispatching is to achieve river ecosystem protection by ensuring ecological base flow. At present, the main scientific problem facing ecological dispatching is how to determine the appropriate ecological flow and hydrodynamic process. Due to dam construction, the historical consistency of hydrological runoff patterns in most rivers has been destroyed. In future ecological restoration, the reconstruction of river ecological flow processes will dominate. Through pulsed water release, flood dispatching, peak flow and time evolution regulation, hydrodynamic conditions conducive to water environment improvement and water ecological protection are created, providing effective engineering means for coupling ecological processes and hydrological processes in ecological dispatching. Especially for rivers in plain areas, the terrain is flat and the water flow is slow, so the reconstruction of hydrodynamic processes is an important condition for ecological restoration.

[0028] The purpose of the present invention is to provide an ecological restoration method and system for desert riparian forests in arid areas, which can accurately and scientifically determine the water inlet location and water diversion method of the desert riparian forests, and improve the ecological restoration effect of the desert riparian forests in arid areas based on precise water diversion and irrigation methods.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Embodiment 1:

[0031] This embodiment is used to provide an ecological restoration method for desert riparian forests in arid areas, such as Figure 1 and Figure 2 As shown, the ecological restoration method includes:

[0032] S1: Acquire the real-time remote sensing image of the current desert riparian forest and the historical remote sensing image of the desert riparian forest N years ago;

[0033] Specifically, S1 may include:

[0034] (1) Draw the vector data boundary of desert riparian forest;

[0035] In this embodiment, the vector data boundary of the desert riparian forest distribution on both sides of the river can be drawn in ArcGIS based on field surveys and remote sensing satellite images. Figure 3 shown.

[0036] (2) Obtain multiple real-time remote sensing satellite images of the current desert riparian forest and multiple historical remote sensing satellite images of the desert riparian forest N years ago;

[0037] In this embodiment, remote sensing satellite images with a spatial resolution of 30 m can be downloaded from remote sensing satellites (Landsat-8OLI, Sentinel series satellites, etc.) at present and N years ago. These remote sensing satellite images need to be able to completely cover the desert riparian forest.

[0038] (3) Perform image preprocessing on multiple real-time remote sensing satellite images to obtain real-time remote sensing images; perform image preprocessing on multiple historical remote sensing satellite images to obtain historical remote sensing images; image preprocessing includes radiation calibration, atmospheric correction, strip removal, splicing, and cropping according to vector data boundaries.

[0039] The image preprocessing of remote sensing images includes: firstly, performing radiation calibration (selecting a subset), atmospheric correction and striping removal on each remote sensing satellite image, then stitching all the processed remote sensing satellite images, and finally, cropping the stitched images according to the drawn vector data boundaries to form a remote sensing image containing only the complete desert riparian forest.

[0040] S2: determining a plurality of ecological restoration areas of the desert riparian forest according to the real-time remote sensing image and the historical remote sensing image;

[0041] Specifically, S2 may include:

[0042] (1) Calculate the NDVI value of the real-time remote sensing image to obtain the first index value of each pixel;

[0043] (2) Calculate the NDVI value of the historical remote sensing image to obtain the second index value of each pixel;

[0044] The Normalized Difference Vegetation Index (NDVI) can characterize the surface vegetation coverage and vegetation growth conditions. This embodiment calculates the NDVI value based on the red light band and near infrared band of the Landsat 8 OLI remote sensing image, and extracts the NDVI value of the desert riparian forest. The calculation formula of the NDVI value is:

[0045] NDVI=(ρ_ NIR -ρ_ RED ) / (ρ_ NIR +ρ_ RED );

[0046] Among them, ρ_ RED ,ρ_ NIRThey correspond to the 4th and 5th bands of the Landsat 8 OLI remote sensing image, respectively, representing the reflectance values ​​of the infrared band and the near-infrared band.

[0047] (3) determining a number of locations of the desert riparian forest to be restored according to the first index values ​​and the second index values ​​of all pixel points;

[0048] NDVI reflects vegetation characteristics. This embodiment can determine whether a location needs to be repaired based on changes in NDVI at that location.

[0049] This step may include: for each pixel point, determining whether the first index value of the pixel point is less than the first preset threshold, and whether the second index value of the pixel point is greater than the second preset threshold, and the first preset threshold is less than the second preset threshold; if so, the pixel point is a selected pixel point, and the continuous adjacent selected pixel points constitute a position to be repaired. This means that the NDVI value of a position N years ago was greater than the second preset threshold, and the current NDVI value of the position is less than the first preset threshold, proving that after N years, the ecological situation of the position has deteriorated and needs to be repaired.

[0050] As another optional implementation, this step may include: for each pixel point, calculating the difference between the first index value and the second index value of the pixel point, and determining whether the difference is greater than a third preset threshold; if so, the pixel point is a selected pixel point, and consecutive adjacent selected pixel points constitute a position to be repaired.

[0051] (4) For each location to be restored, the location to be restored is connected to the river channel surrounded by the desert riparian forest to obtain the ecological restoration area corresponding to the location to be restored.

[0052] For any location to be restored, if the location to be restored is located on the left side of the river, the left boundary of the desert riparian forest will be used as the left boundary of the ecological restoration area, the left boundary of the river will be used as the right boundary of the ecological restoration area, and the upper and lower boundaries of the location to be restored will be used as the upper and lower boundaries of the ecological restoration area, so as to connect the location to be restored with the river surrounded by the desert riparian forest to obtain the ecological restoration area corresponding to the location to be restored; if the location to be restored is located on the right side of the river, the right boundary of the desert riparian forest will be used as the right boundary of the ecological restoration area, the right boundary of the river will be used as the left boundary of the ecological restoration area, and the upper and lower boundaries of the location to be restored will be used as the upper and lower boundaries of the ecological restoration area, so as to connect the location to be restored with the river surrounded by the desert riparian forest to obtain the ecological restoration area corresponding to the location to be restored.

[0053] This embodiment uses S1 and S2 to perform remote sensing interpretation of desert riparian forest ecological restoration areas. First, satellite remote sensing images are downloaded to construct the distribution calculation area of ​​river desert riparian forests, and then the ecological restoration area is determined using the change characteristics of the normalized difference vegetation index (NDVI). The area where the river desert riparian forest needs to be restored is determined based on the changes in the long series of NDVI values.

[0054] In this embodiment, the ENVI 5.1 software can be used to perform the above-mentioned image preprocessing process and ecological restoration area determination process, wherein the operation of removing stripes is: downloading and installing the Single file gap fill strip removal plug-in, restarting the ENVI software, loading the strip image, opening the strip removal tool, selecting the "Single file gap fill (triangulation)" option, and outputting the strip removal image. The operation of stitching is: using the Seamless Mosaic tool to stitch remote sensing satellite images. The operation of calculating the NDVI value is: using the Band Math tool to calculate the vegetation index.

[0055] This embodiment downloads long-term series (i.e., N years, greater than 10 years) of remote sensing images based on the distribution area of ​​desert riparian forests on both sides of the river, processes the remote sensing images using ENVI 5.1 software, interprets the vegetation changes of desert riparian forests on both sides of the river, and judges the vegetation damage area based on the attenuation characteristics of the NDVI value of the desert riparian forest, and determines the ecological restoration area that needs to be restored. This embodiment proposes a method for determining the ecological restoration area, which uses the "remote sensing interpretation of the ecological restoration area of ​​desert riparian forests based on ENVI" combined with the "field investigation and research" method to jointly determine the ecological restoration area of ​​desert riparian forests, which is more reasonable and scientific than simply relying on the experience of local forestry managers to determine the ecological restoration area under current conditions.

[0056] Of course, this embodiment can not only perform remote sensing interpretation of desert riparian forest ecological restoration areas based on ENVI to determine the ecological restoration area, but also use other remote sensing image interpretation software, including but not limited to ERDAS, PCI, etc. As long as NDVI calculation can be carried out, it is applicable to the ecological restoration method proposed in this embodiment.

[0057] As a preferred implementation, before determining several locations of desert riparian forests to be restored based on the first index values ​​and the second index values ​​of all pixel points, the ecological restoration method of this embodiment also includes: calculating the NDVI value of the remote sensing image of each year in the previous M years of the real-time remote sensing image to obtain M historical first index values; calculating the average of the M historical first index values ​​and the first index value to obtain a new first index value. Calculating the NDVI value of the remote sensing image of each year in the previous M years of the historical remote sensing image to obtain M historical second index values, calculating the average of the M historical second index values ​​and the second index value to obtain a new second index value. Thereby, the first index value and the second index value can be determined more accurately, so as to improve the accuracy of the determined ecological restoration area.

[0058] S3: For each of the ecological restoration areas, design multiple initial restoration plans for the ecological restoration area; for each of the initial restoration plans, perform irrigation simulation based on the initial restoration plan and the terrain of the ecological restoration area to determine the inundation range corresponding to each of the initial restoration plans; calculate the overlap between each inundation range and the ecological restoration area, and select the initial restoration plan with the largest overlap as the optimal restoration plan for the ecological restoration area; the restoration plan includes the location of the water inlet and the water diversion flow and time of the water inlet.

[0059] In S3, the initial repair scheme is designed based on experience.

[0060] In S3, the irrigation simulation based on the initial restoration plan and the terrain of the ecological restoration area may include: Taking the initial restoration plan and the terrain of the ecological restoration area as input, the irrigation simulation is performed using fluid calculation software, and the fluid calculation software includes MIKE21, HEC-RES, XP-SWMM, etc. When using fluid calculation software for irrigation simulation, a two-dimensional hydrodynamic calculation model may be used.

[0061] Specifically, this embodiment can calculate the flood inundation range according to river hydrological data and based on the MIEK 21 software model.

[0062] The inundation analysis of MIKE 21 flood diversion irrigation is as follows:

[0063] MIKE 21 can simulate two-dimensional free surface flow. It has a ground two-dimensional model. When the user provides input data such as terrain, bottom roughness, wind field and hydrodynamic boundary conditions for the ground two-dimensional model, the ground two-dimensional model will calculate the water level and flow changes of each grid. The ground two-dimensional model uses the finite difference method of ADI second-order accuracy to solve the continuity equation and momentum conservation equation of dynamic flow.

[0064] (1) The ground two-dimensional model adopts the Mike21 model in the Mike series software. The basic principle of the two-dimensional hydrodynamic calculation model is as follows:

[0065] Continuity equation:

[0066]

[0067] Momentum equation:

[0068]

[0069]

[0070] Where Z is the water level; H is the water depth; u and v are the components of the vertical average velocity in the x and y directions respectively; q is the source-sink intensity per unit area; g is the gravitational acceleration; n is the roughness; v T is the turbulent diffusion coefficient of water flow; τ sx is the water surface wind stress in the x direction; ρ is the water flow density; is the Coriolis force coefficient, ω0 is the angular velocity of the Earth's rotation, is the geographic latitude of the calculation area; u0 is the component of the average source-sink velocity in the x direction; τ sy is the turbulent diffusion coefficient of wind stress on the water surface in the y direction; v0 is the component of the average source-sink velocity in the water depth in the y direction. During the calculation process, the mathematical model can be appropriately simplified according to the actual situation to ignore the influence of wind stress and the Coriolis force of the earth.

[0071] The continuity and momentum equations of the ground two-dimensional model are integrated in time and space respectively using the ADI line-by-line method, and the discrete equations are solved using the pursuit method.

[0072] (2) Grid division

[0073] According to the technical requirements of the Technical Specifications for the Preparation of Flood Risk Maps, in the two-dimensional hydraulic model, regular grids or irregular grids are used. For regular grids, the side length should not exceed 300m, and for irregular grids, the maximum grid area should not exceed 0.1km 2 The calculation grids in important areas and parts with large terrain changes should be appropriately encrypted. In order to improve the calculation accuracy of the ground two-dimensional model, this embodiment uses MIKE software to divide the terrain of the ecological restoration area into 0.001km 2 The following irregular triangular grid, that is, the calculation grid of this embodiment is controlled at 0.001km 2 the following.

[0074] (3) Model building process

[0075] The ground two-dimensional model was constructed using MIKE21 software. Figure 4As shown in the figure, the modeling process is: 1) create a flood diversion irrigation area terrain file, that is, the terrain of the ecological restoration area (file extension: .dfs2); 2) build a simulation file, that is, the initial restoration plan, (file extension: .m21); 3) set the basic model parameters and hydrodynamic parameters, including simulation time and calculation step size, boundary conditions, source and sink, dry and wet areas, initial water level, eddy viscosity coefficient, roughness, wave radiation stress and wind friction coefficient, etc. These parameters are all artificially defined;

[0076] 4) Output the model calculation results, that is, output the flood range layer (file extension: .dfs2 file).

[0077] (4) Create terrain file

[0078] Import 5m precision raster data into ArcGIS to form a raster file, then convert the raster file into an ASCII file and export it, and then convert it into a dfs2 terrain file in MIKEZero to obtain the basic terrain file of the ecological restoration area, such as Figure 5 shown.

[0079] (5) Setting basic model parameters and hydrodynamic parameters

[0080] The water diversion time step is determined to be 2s. The initial water level of the MIKE 21 model can be set using a constant or read from the dfs2 data file. The study area is considered as a dry boundary, and the initial water depth is 0, that is, the initial water level is the ground elevation. The eddy viscosity coefficient, wave radiation stress, and wind friction coefficient all use the default values. The model output options are flooding data such as water depth, surface water depth, and flow velocity. At the same time, the flooding statistical calculation data dfs2 file is output, which contains output items such as maximum water depth and maximum flooding range.

[0081] This embodiment proposes a flood diversion irrigation method for ecological restoration areas, and adopts the "MIKE 21 flood diversion irrigation inundation analysis" to numerically simulate flood overflow in the ecological restoration area. It is more scientific and reasonable than simply relying on the terrain height difference in the ecological restoration area for gravity diversion irrigation under the current conditions, and can effectively improve water utilization efficiency.

[0082] The MIKE 21 flood irrigation inundation analysis method proposed in this embodiment can also use other fluid calculation software, such as HEC-RES, XP-SWMM, etc. As long as it can carry out two-dimensional flood inundation calculation, the method proposed in this embodiment is applicable.

[0083] In S3, respectively calculating the overlap between each flooded range and ecological restoration area may include: for each flooded range, performing GIS spatial overlay analysis on the flooded range and the ecological restoration area, and calculating the overlap between the flooded range and the ecological restoration area. The principle of GIS spatial overlay analysis is: establishing polygons with multiple attributes (synthetic overlay) or performing statistical analysis of attribute characteristics within the polygon range (statistical overlay) based on the intersection of two sets of polygon boundaries, and performing one-by-one overlay analysis on the flood inundation layers and ecological restoration areas under different initial restoration plans. The one with the largest overlap is the best restoration plan.

[0084] This embodiment is based on GIS spatial overlay analysis, compares the overlap between the flood-inundated area and the ecological restoration area, and determines the optimal water inlet location and water diversion method in the vegetation ecological restoration area. That is, through the technical means of GIS spatial overlay analysis, by comparing the overlap between the flood-inundated area and the ecological restoration area, through the optimal scheme, the location, water diversion flow rate and water diversion time of the water inlet in the vegetation ecological restoration area are determined. The ecological restoration scheme of the desert riparian forest finally proposed will be more accurate and scientific. It should be noted that the water inlet of this embodiment is set on the riverside surrounded by the desert riparian forest, so that the desert riparian forest can be ecologically restored by the water in the river.

[0085] At present, the ecological water supply of desert riparian forests in arid areas still relies on the experience of engineering and technical personnel, and there are no technical standards and specifications for reference. Therefore, it is particularly necessary and urgent to explore a method for precise flood diversion and irrigation for ecological restoration of desert riparian forests in arid areas. This embodiment proposes for the first time an ecological restoration method for desert riparian forests in arid areas with precise flood diversion and irrigation, which is an original technology and solution, filling the gap in ecological restoration technology for desert riparian forests in arid areas. This embodiment constructs an ecological restoration technology system for desert riparian forests in arid desert areas. The main contents of the solution include: regional remote sensing interpretation of ecological restoration of desert riparian forests based on ENVI, MIKE 21 flood diversion irrigation inundation analysis and GIS spatial overlay analysis. Through the combined application of the above three methods, the setting position and operation mode of the water inlet (the water inlet can be an ecological gate) in the entire flood diversion and irrigation area are determined, that is, the appropriate position, flow rate and duration of the water inlet in the ecological restoration area can be accurately determined, which can provide basic support for watershed ecological restoration and efficient development and utilization of water resources.

[0086] Here, the ecological restoration method of this embodiment is further described by a specific example:

[0087] The Hotan River is located in the heart of the desert. The Hotan River Green Corridor is an important ecological corridor in the Tarim Basin that runs through the Taklimakan Desert from north to south. The runoff of the Hotan River is not only the lifeline for the survival and development of the Hotan Oasis, but also the water source for the ecological maintenance and restoration of the Hotan Green Corridor, and the reliance of the sustainable development of the social economy and ecology of the Tarim River Basin. The Hotan River must not only ensure the amount of water discharged, but also maintain industrial and agricultural production in the basin and meet ecological needs. Therefore, improving the efficiency of water resource utilization in the Hotan River Basin is an important way to solve the contradiction between supply and demand of the ecological environment in the Hotan area.

[0088] (1) Analysis of flood irrigation overflow process in the broad-leaved Lashi ecological restoration area of ​​the Hotan River desert section

[0089] The evolution process of flood irrigation flood from water diversion port is as follows Figure 6 As shown in the figure, as the water diversion time increases, the flooding gradually evolves to the downstream area, the flooded area gradually increases, and finally completely floods the ecological restoration area of ​​the broad-leaved Rush ecological forest. If the flow rate is too small, the water transfer purpose cannot be achieved. If the flow rate is too large, most of the water will be wasted in the dry desert. In order to reasonably and effectively carry out flood diversion irrigation in the ecological restoration area, the flooded area is taken as the calculation target, and the water transfer time, water transfer volume and corresponding flooded area are quantitatively analyzed and discussed. Using the MIKE FLOOD model simulation, it is calculated that 3m 3 / s working conditions, the water can flood the ecological forest in 45 days, 5m 3 / s working conditions, the flooded ecological forest can be completed in about 30 days.

[0090] The maximum flooding depth under different flow rates is as follows Figure 7 As shown, it can be seen that 3m 3 / s scenario, the maximum water depth is 5m on the 12th day after water transfer. 3 The maximum water depth was reached on the 9th day in the / s scenario. The larger flow rate accelerated the movement of water in the ecological forest, leading to the advance of the maximum water depth. The maximum flooding depth at different time scales did not change much when the topography remained unchanged.

[0091] (2) Optimization analysis of water inlet in the broad-leaved Lashi ecological restoration area of ​​the Hotan River desert section

[0092] A field survey was conducted in the study area. The location of the water inlet in the study area was adjusted according to the terrain conditions. A new water inlet was set up 2.5 km downstream of the original water inlet. The original water inlet was defined as the 1# water inlet and the 2# water inlet. The flood flow rate was 3m 3 / s The flooded areas of different water intakes are shown in Table 1. As can be seen from Table 1, at 3m 3 / s scenario, the flooded area of ​​No. 2 water intake is greater than that of No. 1 water intake.

[0093] Table 1. Flood diversion flow is 3m 3 / sDifferent water intake flooded areas

[0094]

[0095] The flood flow is 5m 3 The flooded areas of different water intakes are shown in Table 2. 3 The flooded area of ​​No. 2 water intake under the / s scenario is also larger than that of No. 1 water intake, indicating that the location of No. 2 water intake is more reasonable than that of No. 1 water intake.

[0096] Table 2. Flood diversion flow rate is 5m 3 / sDifferent water intake flooded areas

[0097]

[0098] The flooding depth of No. 1 and No. 2 intakes is 3m 3 / s scenario is basically the same, but at 5m 3 / s scenario, the water delivery lasts for 35 days, and the flooded area of ​​No. 2 water intake is significantly larger than that of No. 1 water intake, with an increase of 3.11 km 2 This further shows that using the No. 2 water intake for flood diversion irrigation is more effective.

[0099] The two-dimensional hydrodynamic model of the Kumatake Ecological Forest Area in the desert section of the Hotan River was established using MIKE 21, and the flood diversion irrigation in the Kumatake Ecological Forest Area with different water diversion flows at the No. 1 and No. 2 ecological water diversion outlets was simulated. The results show that:

[0100] 1) The model is relatively stable and reliable. There is no oscillation or divergence during the calculation process. The model simulation effect is good and can accurately reflect the flood evolution process and the flow characteristics of flood overflow.

[0101] 2) In the broad-leaved Lashi ecological forest area of ​​the Hotan River desert section, according to the calculation of the MIKE FLOOD model, flood diversion irrigation is carried out at 3m 3 / s working conditions, the water can flood the ecological forest area in 45 days, 5m 3 / s working conditions, it takes about 30 days to flood the ecological forest area.

[0102] 3) The Hotan River Basin Management Bureau has transferred too much water within the research area, far exceeding the actual demand. The water transfer time is too long, resulting in a waste of water resources. It is recommended to adjust the location 2.5km downstream of the existing water intake to be more conducive to flood diversion irrigation.

[0103] The method for ecological restoration of desert riparian forests in arid areas based on precise flood diversion and irrigation proposed in this embodiment solves the technical problems of ecological restoration of desert riparian forests in the desert section of the Hotan River. Through remote sensing technology, the ecological restoration area is determined, and the flood evolution process and inundation range are calculated using numerical simulation methods. Based on GIS spatial overlay analysis, the location of the water inlet and the appropriate water intake and release time can be reasonably determined, which will scientifically solve the problem of ecological water transfer in the desert section of the Hotan River Basin.

[0104] (1) Aiming at the problem of excessive loss caused by overflow irrigation of ecological sluices in the desert section of Hotan River, the goal is to restore the ecology and improve water utilization efficiency through overflow irrigation of ecological sluices in the desert section of Hotan River, so as to achieve timely and appropriate ecological irrigation, precise irrigation and save water resources in the basin.

[0105] (2) Based on the hydrological and geological characteristics of the desert section of the Hotan River, the problem of lack of basis and rules for planning and construction of ecological sluices in the desert section of the Hotan River should be solved.

[0106] Embodiment 2:

[0107] This embodiment is used to provide an ecological restoration system for desert riverside forests in arid areas, such as Figure 8 As shown, the ecological restoration system includes:

[0108] An image acquisition module M1 is used to acquire a real-time remote sensing image of the current desert riparian forest and a historical remote sensing image of the desert riparian forest N years ago;

[0109] An ecological restoration area determination module M2 is used to determine a number of ecological restoration areas of the desert riparian forest based on the real-time remote sensing image and the historical remote sensing image;

[0110] The restoration plan determination module M3 is used to design multiple initial restoration plans for each ecological restoration area; for each initial restoration plan, an irrigation simulation is performed based on the initial restoration plan and the terrain of the ecological restoration area to determine the flooding range corresponding to each initial restoration plan; the overlap between each flooding range and the ecological restoration area is calculated respectively, and the initial restoration plan with the largest overlap is selected as the optimal restoration plan for the ecological restoration area; the restoration plan includes the location of the water inlet and the water diversion flow and time of the water inlet.

[0111] Each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0112] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for ecological restoration of desert riparian forests in arid areas, characterized in that: The ecological restoration method comprises: Acquire the real-time remote sensing images of the current desert riparian forest and the historical remote sensing images of the desert riparian forest N years ago; Determine several ecological restoration areas of the desert riparian forest according to the real-time remote sensing image and the historical remote sensing image, specifically including: calculating the NDVI value of the real-time remote sensing image to obtain a first index value for each pixel; calculating the NDVI value of the remote sensing image of each year in the previous M years of the real-time remote sensing image to obtain M historical first index values; calculating the average of the M historical first index values ​​and the first index value to obtain a new first index value; calculating the NDVI value of the historical remote sensing image to obtain a second index value for each pixel; calculating the NDVI value of the remote sensing image of each year in the previous M years of the historical remote sensing image to obtain M historical second index values; calculating the average of the M historical second index values ​​and the second index value to obtain a new second index value; determine several positions to be restored of the desert riparian forest according to the new first index values ​​and the new second index values ​​of all the pixels; for each position to be restored, connect the position to be restored with the river surrounded by the desert riparian forest to obtain the ecological restoration area corresponding to the position to be restored; For each of the ecological restoration areas, a plurality of initial restoration plans for the ecological restoration area are designed; for each of the initial restoration plans, an irrigation simulation is performed based on the initial restoration plan and the terrain of the ecological restoration area to determine the flooding range corresponding to each of the initial restoration plans; the overlap between each of the flooding ranges and the ecological restoration area is calculated respectively, and the initial restoration plan with the largest overlap is selected as the optimal restoration plan for the ecological restoration area; the restoration plan includes the location of the water inlet and the water diversion flow and time of the water inlet; Determining a number of positions to be repaired in the desert riparian forest based on the new first index values ​​and the new second index values ​​of all the pixel points specifically includes: for each pixel point, judging whether the new first index value of the pixel point is less than a first preset threshold, and whether the new second index value of the pixel point is greater than a second preset threshold; the second preset threshold is greater than the first preset threshold; if so, the pixel point is a selected pixel point; and the continuous adjacent selected pixel points constitute a position to be repaired.

2. The ecological restoration method according to claim 1, characterized in that: The obtaining of the current real-time remote sensing image of the desert riparian forest and the historical remote sensing image of the desert riparian forest N years ago specifically includes: Draw the vector data boundary of desert riparian forest; Acquire a plurality of current real-time remote sensing satellite images of the desert riparian forest and a plurality of historical remote sensing satellite images of the desert riparian forest N years ago; Image preprocessing is performed on a plurality of the real-time remote sensing satellite images to obtain real-time remote sensing images; image preprocessing is performed on a plurality of the historical remote sensing satellite images to obtain historical remote sensing images; the image preprocessing includes radiation calibration, atmospheric correction, strip removal, splicing and cropping according to the vector data boundary.

3. The ecological restoration method according to claim 1, characterized in that: The step of determining a plurality of locations to be restored of the desert riparian forest according to the new first index values ​​and the new second index values ​​of all the pixel points specifically includes: For each of the pixel points, calculating a difference between a new first index value and a new second index value of the pixel point, and determining whether the difference is greater than a third preset threshold; If so, the pixel point is a selected pixel point; the continuous adjacent selected pixel points constitute a position to be repaired.

4. The ecological restoration method according to claim 1, characterized in that: The irrigation simulation based on the initial restoration plan and the topography of the ecological restoration area specifically includes: The initial restoration plan and the topography of the ecological restoration area are used as inputs, and irrigation simulation is performed using fluid calculation software; the fluid calculation software includes MIKE21, HEC-RES, and XP-SWMM.

5. The ecological restoration method according to claim 4, characterized in that: When using fluid calculation software for irrigation simulation, a two-dimensional hydrodynamic calculation model is used.

6. The ecological restoration method according to claim 1, characterized in that: The respectively calculating the overlap between each of the flooded areas and the ecological restoration area specifically includes: For each of the inundation areas, a GIS spatial overlay analysis is performed on the inundation area and the ecological restoration area to calculate the degree of overlap between the inundation area and the ecological restoration area.

7. An ecological restoration system for desert riparian forests in arid areas, characterized in that: The ecological restoration system comprises: An image acquisition module, used to acquire the real-time remote sensing image of the current desert riparian forest and the historical remote sensing image of the desert riparian forest N years ago; The ecological restoration area determination module is used to determine several ecological restoration areas of the desert riparian forest according to the real-time remote sensing image and the historical remote sensing image, specifically including: calculating the NDVI value of the real-time remote sensing image to obtain a first index value for each pixel; calculating the NDVI value of the remote sensing image of each year in the previous M years of the real-time remote sensing image to obtain M historical first index values; calculating the average of the M historical first index values ​​and the first index value to obtain a new first index value; calculating the NDVI value of the historical remote sensing image to obtain a second index value for each pixel; calculating the NDVI value of the remote sensing image of each year in the previous M years of the historical remote sensing image to obtain M historical second index values; calculating the average of the M historical second index values ​​and the second index value to obtain a new second index value; determining several locations to be restored of the desert riparian forest according to the new first index values ​​and the new second index values ​​of all the pixels; for each location to be restored, connecting the location to be restored with the river surrounded by the desert riparian forest to obtain the ecological restoration area corresponding to the location to be restored; A restoration scheme determination module is used to design multiple initial restoration schemes for each ecological restoration area; for each initial restoration scheme, perform irrigation simulation based on the initial restoration scheme and the terrain of the ecological restoration area to determine the flooding range corresponding to each initial restoration scheme; calculate the overlap between each flooding range and the ecological restoration area, and select the initial restoration scheme with the largest overlap as the optimal restoration scheme for the ecological restoration area; the restoration scheme includes the location of the water inlet and the water diversion flow and water diversion time of the water inlet; Determining a number of positions to be repaired in the desert riparian forest based on the new first index values ​​and the new second index values ​​of all the pixel points specifically includes: for each pixel point, judging whether the new first index value of the pixel point is less than a first preset threshold, and whether the new second index value of the pixel point is greater than a second preset threshold; the second preset threshold is greater than the first preset threshold; if so, the pixel point is a selected pixel point; and the continuous adjacent selected pixel points constitute a position to be repaired.

Images