Package stream_gauging

source code

The sub-module stream_gauging is used to do all things stream gauging:

1. stage measurements
2. conductivity measurements
3. conductivity sensor calibration
4. dilution gauging
5. stage-discharge relation
6. discharge time series

0 Example

Probably it is easiest to go by an example which is located in the folder fieldpy/stream_gauging/example_stream_site_2010/. There look through the script in analyse_it.py which follows the layout below. If you like it, then the best way of using it is to copy the contents of the fieldpy/stream_gauging/template/ folder to where you have your data and edit it accordingly.

1 Stage measurements

The stage measurements are done by the SR50 ultrasonic depth gauge.

Workflow stage measurements:

1. Create a logged_data.Stage instance by:

     st = Stage([filenames_of_TOA5_file])
   

2. plot it with logged_data.Stage.plot_date
3. Filter it by running logged_data.Stage.apply_all_filters

2 Conductivity measurements

The conductivity measurements are done by Garry Clarke's home made conductivity sensor. Note that the sensor reading is not the actual conductivity but the ratio between measured and excitation voltage.

Workflow conductivity measurements:

1. Create a logged_data.Conductivity instance by:

     ec = Conductivity([filenames_of_TOA5_file])
   

2. plot it with logged_data.Conductivity.plot_date
3. Filter it by running logged_data.Conductivity.apply_all_filters

3 Conductivity sensor calibration

This is handled by the classes in calibration.

Workflow calibration:

1. For each calibration make a .maw file like e.g.:

      #maw 1st Conductivity Calibration 13 July 2010
      #
      # Calibration of the older conductivity sensor in the proglacial river of
      # GL1 on 13 July at 10:30.
      #
      # Note: Times in calibration are not accurate.
      #
      # Calibration was done by premixing 20g NaCl in 2L of water, to get a 10g/L solution.
      # This solution was then added into a 5000mL bucket of water, in the steps written below.
      #
      # Metadata:
      #metadata.experimenter = 'MAW + UM'
      #metadata.bucket_size = 5.0
      #metadata.bucket_size_units = 'l'
      #metadata.calibaration_solution_concentration = 10.0
      #metadata.calibaration_solution_concentration_units = 'g/l'
      #metadata.sensor = 'older Garry sensor'
      #metadata.reference_resistor = 10e3
      #metadata.reference_resistor_units = 'Ohm'
      #metadata.note = 'Times in calibration are not accurate'
      #
      # Format:
      # time (UTC-7) [time_str], calibration_solution (ml) [float], sensor_readout () [float]
      "2010-07-13 10:30:00",0,    0.3030
      "2010-07-13 10:31:00",1.25, 0.2965
      "2010-07-13 10:32:00",2.5,  0.2890
      "2010-07-13 10:33:00",3.75, 0.2815
      "2010-07-13 10:34:00",5,    0.2730
      "2010-07-13 10:35:00",7.5,  0.2595
      "2010-07-13 10:36:00",10,   0.2500
      "2010-07-13 10:37:00",15,   0.2320
      "2010-07-13 10:38:00",20,   0.2175
      "2010-07-13 10:39:00",25,   0.2055
      "2010-07-13 10:40:00",30,   0.1945
      "2010-07-13 10:41:00",35,   0.1860
      "2010-07-13 10:42:00",40,   0.1760
      "2010-07-13 10:43:00",45,   0.1685
      "2010-07-13 10:44:00",50,   0.1620
   

2. Create an calibration.AllCalibrations instance which holds all the calibrations of a season:

   ac = AllCalibartions(list_of_calibration_files)
   

3. Check that all the calibrations are suitably similar by:
   • check the output of the program and see whether the slopes are similar (the 'a' in the printout)
   • plot all calibrations with calibration.AllCalibrations.plot_all and see if they look good. It's ok for the lines to be offset but the slope should be identical-ish.

4 Dilution gauging

The dilution gauging will consist of individual salt injections recorded as conductivity change of the water. This is translated into a concentration with the help of the calibration. Then the concentration is related to the discharge via:

M / ∫ c dt = Q

where M is the amount of injected salt, c is the concentration and Q is the discharge.

Workflow dilution gauging:

1. have the stage, conductivity and calibrations set-up as above
2. Create a .maw file listing all salt injections with the following format:

   #maw Dilution gauging injections from 13 July 2010
   #
   # Metadata:
   #metadata.experimenter = 'MAW + UM'
   #metadata.injection_point = "MAW's injection point"
   #metadata.sensor = 'older Garry sensor'
   #
   # Format:
   # time (UTC-7) [time_str], amount (kg) [float]
   "2010-07-13 09:07:00", 0.2
   "2010-07-13 09:22:45", 0.4
   "2010-07-13 11:17:00", 0.4
   "2010-07-13 13:16:00", 0.4
   "2010-07-13 13:16:00", 0.4
   

3. create a dilution_gauging.DilutionGauging instance like so:

      dilg = DilutionGauging(injections_maw_file, (0,150), ec, ac, st)
   

4. Check that you're happy with the windows chosen for the injections:

      dilg.plot_all()
   

5. Make the stage-discharge relation for the day:

      dilg.make_stage_discharge_relation(verbose_=True, order_of_poly=2)
   

5 Stage-discharge relation

With the dilution_gauging.DilutionGauging we created a stage-discharge relation for one day of dilution-gauging experiments. But presumably more than one day of dilution gauging was done, so these need to be combined to lead to a stage-discharge relation for the whole season. Which is done with the stage2discharge.Stage2Discharge class.

Workflow stage-discharge relation:

1. have the stage, conductivity, calibrations and dilution-gauging set-up as above.
2. make a stage2discharge.Stage2Discharge instance:

      s2d = stage2discharge.Stage2Discharge(xxx)
   

3. have a look how the individual stage-discharge relations compare:

      s2d.plot_all()
   

6 Discharge time series

Now, finally we are in a position to convert the stage records into a discharge time series.

Workflow discharge time series:

1. have the stage, conductivity, calibrations, dilution-gauging and stage-discharge relation made as above.
2. tell your logged_data.Stage instance how to convert the stage into a discharge:

   st.set_stage2discharge_method(s2d.stage2discharge)
   

   note you can choose here from different methods (once implemented):

   • stage2discharge.Stage2Discharge.stage2dis_average
3. convert the stage:

      st.make_discharge()
   

4. admire (and check) it: st.plot_date('discharge')
5. THE END