[GIS tutorial] land use transfer matrix

With the continuous progress of science and Technology Society , The impact and shaping of human activities on the geographical environment are becoming increasingly obvious , The continuous erosion and change of land also leads to a series of environmental problems becoming increasingly prominent . Land use / Cover （LUCC） As a key issue in global environmental change research, more and more international research institutions have attached importance to it , Studying its changes is not only a challenge to the existing industrialization 、 A more intuitive reflection of the urbanization process , It is also an indispensable foundation for the prediction and Simulation of future land change . The study of land use change in a region , It is conducive to better comprehensive evaluation of the ecological environment and rational land spatial planning in the region .

However, it is often used in the study of land use change Land use transfer matrix , It is used to effectively express the conversion of area between two classes of different phases . So what is the land use transfer matrix , How to make the land use transfer matrix ？ Let's have a look ！

   Sample data download link ： Data download link

This paper is mainly divided into the following parts ：

One . Concept

Two . meaning

3、 ... and . Data preparation

Four . Two phase transfer matrix production

5、 ... and . Three phase transfer matrix production

6、 ... and . reference

One 、 Concept

The land use transfer matrix is Markov model Application in land use change . Markov model can not only quantitatively show the transformation between different land use types , It can also reveal the transfer rate between different land use types .

The land use transfer matrix is derived from the analysis of system state and state transfer Quantitative description . In the general land use transfer matrix , Row representation T1 Land use type at time point , Column means T2 Land use type at time point .

Two 、 meaning

Land use transfer matrix In the form of matrix, the land cover types of two different periods are converted to each other Quantitative relation show , It can comprehensively reflect the type of land cover in a region Value and transfer direction . The general form is as follows ( The following explanation can be ignored )：

Schematic diagram of transfer matrix 1

among ,TL Express Last moment ,TN Express The next phase .C1 to Cn Express n Different species Land cover type . hypothesis That's ok Cn=Ci（ Land type of the last phase ）, Column Cn=Cj（ Next phase land type ）.Sij It means the last phase Ci Change to the next phase Cj The area of ,Si* It means the last phase Ci The total area of land cover types ,S*j It means the next phase Cj The total area of land cover types .Si*-Sii by Ci Land type outflow , That is, the last phase Ci The total area of other land types transferred to the next phase in the land type .S*j-Sjj Express Cj Land type Inflow. , That is, the next phase Cj The total area of land type transformed from other types of land in the previous period .

above Sij It can also be replaced by Pij, It is used to show the proportion of transfer volume in the whole , It can reflect the relationship between the whole and the part , And the amount of transfer is also small due to the small total area of a certain land type , Thus, the area can not well reflect the change degree of this land type .

Schematic diagram of transfer matrix 2

3、 ... and 、 Data preparation

Land use data

National provincial and municipal administrative boundaries

  Data source reference ： Geographic remote sensing ecological network www.gisrs.cn

The exercise data are also provided to you at the end of the article .

Four 、 Two phase transfer matrix production

We use first 2000 Years and 2020 Land use transfer matrix is made from annual land cover data .

1. First, land cover data Tiff The map is based on the boundary of the area required for the study tailoring come out , The process is relatively simple . The process, , Because the administrative boundary data is GCS2000 Geographic coordinate system ,global30 Land cover data is WGS1984 Of UTM Projection coordinate system , We will also use the boundary data Convert to WGS1984 Of UTM Projection .

2. take Ground class code excel form Save as 97-2003 edition .

3. After the attribute table of grid data is created , stay 2000 Annual land cover data attribute table Add text type field “2000”, Fill in the specific year here instead of just the land type , To facilitate the production of transfer matrix time-division phase .

4. Because the land cover grid data has been classified and analyzed , After creating the attribute table of this data , Among them VALUE The field represents the pixel value used to define the land type . We base the layer attribute table of land cover data on value Fields and excel Code column fields in the table even Pick up .

5. open Field calculator , take excel The field value of the land class in the table is assigned to the... Of the attribute table “2000” Field .

6. take excel Connection removal , In the same way 2020 The data of the year is used for connection assignment . Besides , This operation can also be done directly through excel Change in .dbf File achieves the purpose of changing the attribute table .

7. Through the tool “ Grid to surface ” take tiff Format data to shp vector . Field selection “2000”, Uncheck simplify face , In the same way 2020 Year data .

8. adopt “ The fusion ” Tools , Merge the same class attribute elements of each year into one element , Easy to calculate .

here , The attribute table is as follows .

9. take 2000 Years and 2020 Years of data fusion The intersection Handle .

10. Add... To the property sheet after intersection “ area ” Field , Right click the field name and select Computational geometry Calculate the area , The unit is square hectare .

11. choice “ Surface rotation excel” Tools , Transfer out property sheet .

12. Open the saved .xls file , choice Insert - PivotTable , With 2000 For the line ,2020 Column , The sum of areas is the value , Get the following table , This is the preliminary transfer matrix table .

13. Set null value as 0 fill , It means that there is no transfer of these two kinds of land . Modify header , Columns and totals , Finally, the transfer matrix is as follows , The unit is square hectare .

2000-2020 Shanghai land use transfer matrix

5、 ... and 、 Three phase transfer matrix production

At present, most of the researches involving multi temporal land use change , The produced transfer matrix is generally drawn separately according to the time nodes . Therefore, when multiple phases are involved, such as three phases , We need to draw two separate transfer matrices and a total transfer matrix graph .

As we did in the previous section 2000-2020 The annual land transfer matrix is the general matrix , We should also add 2000-2010 Years and 2010 year -2020 Transition matrix for year , The three figures are listed as follows .

2000-2010 Shanghai land use transfer matrix

2010-2020 Shanghai land use transfer matrix

2000-2020 Shanghai land use transfer matrix

In addition to using the land use transfer matrix , Combined with the calculation of the land use coverage ratio in each period 、 Range of land use change 、 Land use dynamic degree and other information , It can help us to analyze the land use change in the study area in time , It can provide more references for land use change decision-making for double assessment of land spatial planning and other related topics .

It is worth mentioning that , Land use transfer matrix is just one of the many methods for analyzing land use change , It is an expression of pure numbers , Not intuitive enough . And it can only show the numerical relationship of the change of the transfer amount in time , It is usually necessary to combine other methods and charts to show the quantitative relationship of various dimensions , Or to show the changes in space .

6、 ... and 、 reference

[1] Wangxufan . Research and implementation of visual expression of land cover spatio-temporal change [D]. China university of geosciences ( Beijing ),2019.

[2] Luyanan , Yaoshunbo , Dengyuanjie , Dingzhenmin , Houmengyang , Zheng Xue , Liyanan . The impact of land use and landscape pattern changes on the value of ecological services in Northern Shaanxi —— Based on returning farmland to forests ( The grass ) background [J]. Agricultural resources and Regionalization in China ,2019,40(11):180-192.

[3] Panden . Land use of Suzhou Based on complex network / Study on cover change [D]. Zhejiang Normal University ,2014.

[4] Miao Lizhi . be based on GIS Analysis and Research on land use trend in Aksu area [D]. Shandong University of science and technology ,2005.

[5] Fengwenjing , Weiyanfei , Tongxinhua . be based on Landsat Land use classification and change analysis of Gangbei District of Guigang City Based on image [J]. Guangdong land science ,2019,18(05):22-28.

To be continued ...

Data source reference ： Geographic remote sensing ecological network www.gisrs.cn

meanwhile , Geographic remote sensing ecological network www.gisrs.cn Many scientific data in the field of Geographical remote sensing are shared on the website （ Land use data 、npp Net primary productivity data 、NDVI data 、 Weather data （ rainfall 、 The temperature 、 Evapotranspiration 、 radiation 、 humidity 、 Sunshine hours 、 The wind speed 、 Vapor pressure data ）、 Runoff data 、 Night light data 、 Statistical yearbook 、 road network 、POI Point of interest data 、GDP Distribution 、 Population density distribution 、 Vector boundary of tertiary watershed 、 Geological hazard distribution data 、 Soil type 、 Soil texture 、 Soil organic matter 、 soil PH value 、 Soil texture 、 Soil erosion 、 Vegetation type 、 Distribution of nature reserves 、 Building contour distribution and other geographic data , And about the gis、 A tutorial on remote sensing ）.