4. Project management (Project Information Manger)
5.3 The creation of drainage course
To set the value for judging cell type (number of upstream cells)
The default value for CellType0 is 1-2, CellType1 is 3-4, CellType2 is 5-64, and CellType3 is 65 or more.
The mentioned number of cells indicates to the number of upstream cells of each cell (target cell included)
① Click the “Set Cell Type” button.
② The setting dialog will display, type the number of upstream cells.
③ Click the “Set” button to complete setting.
④ Click the “Default” button to return default setting.
⑤ Click the “Close” button to close the dialog.
Cell type outline chart
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③
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Cell Type 0：The cell through which water flows only into a surface tank and an aquifer tank from a surface tank (The cell without a river channel tank of the upstream part)
Cell Type 1： The cell through which water flows into an aquifer tank and a river channel tank from a surface tank Cell Type 2： The cell through which water flows into a river channel tank also from an aquifer tank
Cell Type 3： The cell which performs operation pursuit by the kinematick waving method among river channel tanks (The cell displayed as a Pseude river channel)
Cell Type 0 Cell Type 1 Cell Type 2
Surface tank
Aquifer tank
River tank
5.3.2 The creation of drainage course
The Drainage Path Diagram shows the direction in which the rain water flows. Here, it is assumed that the direction of the underground water, the intermediate flow, the surface flow and the river flow are all the same. In order to calculate the volume of the flow, it is necessary to determine the direction in which all the cells flow (the drainage path), and there will be only one place for end of downstream (the exit for the water to flow outside the basin).
In addition, depending on the number of the cells that constitute the basin, the thing which shows only the relatively big river courses(It corresponds to CellType3) will be made into a pseudo river course.
Last but not least, when using elevation to create the drainage path, a coordinate which does not determine the direction of the flow will be shown if the elevation of the spot makes a hollow which is lower than the surrounding spots. The IFAS conducts elevation revision that carries out the establishment of the drainage path for all the cells and will eliminate the hollows. However, in some cases river courses do not converge because they flow through large area of level ground, and the positions of the river courses and elevation would be changed dramatically from the original data because of the elevation revision. Therefore, attention is necessary.
The maximum loop of repeating hollow ground treatment is 1000000. If exceed the number, calculation can not cover that.
Fig. 5.2 Directions of the drainage path
① Click the “Create Pseudo River” button and the drainage network processing will be performed. The river basin end grid selection window will be displayed.
② Select the river basin end grid above the ground plan. Select only one part of the river basin end and
① ②
③ The confirmation window will be displayed. Click “OK”, and the drainage course will be created.
Click the “Create Sub Basin” button. It will automatically divide into the tributary stream basin, and will be displayed. The threshold amount of the pseudo water way shows the number of cells that ascribe to the tributary stream, and the tributary stream basin display can be changed. When the threshold amount is set to zero, the drainage network for every cell is shown.
④ For a threshold amount set to 64, a drainage course forms from an upstream location of more than 64 cells to a water gathering location, and the cells gathered in each tributary river will be created as a tributary river basin. The default division is the same as above-mentioned CellType3.
⑤ An example of a threshold value of 20.
Confirm that the pseudo river course was created correctly, then save and close.
③ ④ ⑤
⑦ The red framed cells displayed above the ground plan show the result of the performed depression processing and the cells with changed elevation variables. The changed elevation variables will be displayed in a list by selecting a cell and it can be used to confirm that they match the unchanged elevation variables.
5.3.3 Alternation of elevation inside the basin
① Click the cell to be changed, and select the range. b) Input the value to
② Click the elevation setting button of the cells outside the basin after selecting the unit which is either m or %, the alternation of cells outside the basin to the cells in the basin is done. After the elevation alternation, in order to set the Drainage Path for all cells, it is necessary to carry out the process of River course Network Creation(5.3 The creation of drainage course).
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5.3.4 Alternation of elevation by Table Edit function
When the altitude is corrected, the value can be edited using the Table Edit function.
The cell within the range corrected as shown in the figure below is selected with the mouse drug.
“Table” button is clicked, the following dialog is displayed.
The value of an arbitrary cell can be edited.
“OK” button is clicked, the edited value is rewritten in the altitude value.
Besides, it is not possible to edit it though
“Grid” and “Original” can be selected with Type, and it is possible to inspect it.
Selected Area
6 Importing Rainfall Data (Rainfall Data Manager)