4. Edit data - jkall/qgis-midvatten-plugin GitHub Wiki

Edit / update an existing observation point or line

Select the layer obs_points or obs_lines and start editing (click on pen)
If geometries are to be changed, it is done in the usual way by selecting the point or line and move with common qgis editing tools
If it is the attribute data that is to be changed, you can do either:
1. Open the attribute table and locate the current "cells" where the data is to be updated or added, this method will soon be very much easier and user-friendly when dual-view is implemented into the qgis attribute table
2. Or else, select the Identify features-tool (found in the View menu and the toolbar as an arrow with a small "i") and click on the desired item.
  1. If you made the correct basic settings of QGIS then a special custom dialog will pop up **
  2. Otherwise, you can right click in the "identify results" and select "Edit Feature form" to bring up the specially-adapted dialog
After finishing editing / updating you should finish the editing mode

** Please Note! If you do not get any custom dialog, try reloading the layers as described in 'Load Default Layers' above.

Calculate the water level in meter above sea level for manual measurements

Verify the information about top of casing (h_toc) in the layer obs_points.
Select the layer obs_points and the feature or features for which you want to calculate the water level
In your QGIS project, select Midvatten-Edit Calculate w level above sea level
Select a date range for which the calculation should be performed *

* Note! That there may be old level data in the table w_levels where information on top of casing is uncertain. It is therefore advisable not to routinely calculate the levels for all of the data in the table but only the ones you know are measured to the given measuring point.

Calculate logger w level from logger water head

(<version 1.4)

Select Midvatten-Edit data - Calibrate w level from logger and a dialog shows up (click image to enlarge):
Select the obs point with logger data to be calibrated. Leave the "Logger position" field empty and click "Calibrate" to just get a plot of your logger data together with manual measurements (click image to enlarge).
Perform calibration by repeatedly entering loggerposition (in meter above sea level) for different date and time intervals until levels recorded by logger are consistent with the manual measurements (click image to enlarge).

(version 1.4)

Plot data

Select Midvatten-Edit data - Calibrate w level from logger and a dialog shows up (click image to enlarge):

Select the obs point with logger data to be calibrated. Click "Update plot" to plot the logger data together with manual measurements. By checking the checkbox "Plot logger head" the head measurement is also plotted as a separate line. If there is a large difference between the logger head value and the logger position, checking Normalize head to logger line helps.

Calibration

Calibration is done by entering the logger position (in meter above sea level) or an offset* to the currently calibrated values. Click "Change to offset" to calibrate using offset.
The last used offset will be pre-filled in the field set logger_pos and the from-date will be set to the last date of calibration.
Obsids where the level_masl column in table w_levels_logger contain Null-values will get the string (Uncalibrated) after the obsid in the list. By calibrating all head values, this string will disappear.

Perform calibration by repeatedly entering loggerposition (in meter above sea level) for different date and time intervals until levels recorded by logger are consistent with the manual measurements (click image to enlarge).
Calibration can also be performed using the functions Calibrate by best fit and Calibrate by selection in plot, see separate chapters below.

* If calibration is done by setting logger position, the logger values are calculated from the head (check box Plot original logger head to see it). If calibration is done by setting offset, the logger values are instead calculated from the current logger values. If the logger values is a straight line at -999, it will be a straight line after the calibration also. The calibration is usually first done by setting logger position and calibrate, and then by offset.

Setting From and To from plot

Check the box Circle nodes for logger line and update plot to see the logger nodes more easily.
Chose Select from/Select to and click on the green logger line. Double check the date. Zoom in if necessary.

Setting From and To from current extent

Check the box Circle nodes for logger line and update plot to see the logger nodes more easily.
Use chart zoom and pan to show the date extent (period) of interest.
Click from current extent beside from to set from to the minimum date of the current chart extent. Click from current extent beside to to set to to the maximum date of the current chart extent.

set logger_pos by by best fit/adjust level_masl by best fit

set logger_post by best fit calculates level_masl from logger head against measurements. adjust level_masl by best fit adjusts already calculated level_masl against measurements.

Set the period (From and To) for which the calibration should be done.
Click the button auto set or auto adjust.
If the measurements and the logger nodes are too far apart so that some measurements are excluded from the calibration, the time tolerance can be increased. Enter a new tolerance in the box Tolerance, ex. 10 minutes, 20 minutes, 1 hours, 1 days and so forth. (supports microseconds, milliseconds, seconds, minutes, hours, days, weeks.)

Notes:

A measurement (blue nodes) is matched to the mean of all logger nodes (green nodes) within the measurement time - tolerance and measurement time + tolerance.
If the tolerance is too narrow, there might not be a match for all measurements and if the tolerance is to large, the mean value will be calculated from many logger nodes.
The mean of all differences between measurements and the calculated mean logger levels is used to calibrate all values inside the chosen period.

calculate offset from plot selection

This feature is used to move the logger line by using the mouse.

First set the period (From and To) for which the calibration should be done.
Check the box Circle nodes for logger line and update plot to see the logger nodes more easily.
Click the button current.
Select a node from the logger line. The calibration for the chosen period will depend on the chosen node. *
Click the button new and click on a y-position in the plot. The difference between the chosen node and the chosen y-position will be calculated and written to the field add offset to level_masl.
Click the button add. **

* Make selection as close as possible to a line node. It's especially important to select very close to the node on the x-axis. Zoom in if necessary. Map pan and map zoom buttons can't be activated or the selection will not be registered.
** All values inside the chosen period will be calibrated using the difference between the chosen node and the chosen y-position.

Calculate average flow from accumulated volume

This feature calculates the average flow (in l/s) from the accumulated volume (supposed to be given in m3).

Select the layer obs_points and the object(s) with water flow data to be calculated
Select Midvatten - Edit data - Calculate Aveflow from Accvol and a dialog shows up
Select time span and All or Selected