Limits of detection and values

Sometimes for some parameters, the measured values may be below the device detection limit. However, in the database, there are only numerical values(Therefore, it is not possible to indicate “<Detection Limit”). The convention used in H+ is to put the value at 0 and to specify the detection limit of the device.

An example of content of a file :

Ploemeur ;MF3;978 ;fluoride;0,0731018348009312 ;;0,07 ;; ;;Chromato_ionique_Geosciences_Rennes ;;

Ploemeur ;MF3;978 ;nitrite;0 ;;0,07 ;; ;;Chromato_ionique_Geosciences_Rennes ;;

The outlier or abnormal values are not inserted in the database.


Depths (relative z)

The saved depths in the various files are indicated in a column “z_relatif/relative z”.

Three columns must always be present in a given file regarding depth:

-        definition z_relatif /relative_z definition : free text indicating what reference point was used to estimate the depth registered in the column z_relatif/relative z.
For instance: top of the well

-        definition of the reference for relative z: the French NGF altitude in meters of the point used to define the depths in the column definition relative z

-        relative z : depth where the measurement is done in meters, measured in curvilinear way along the borehole, from the reference point. This measurement is in positive values!


Pumping flow rate

The pumping flow rates are expressed as follows:

Positive if the water is injected in the borehole

Negative if the water is pumped out of the borehole


Hydraulic and chemical tests

We consider four types of tests:

Tracer tests: the test is described in the file experience.csv; the injected tracer concentrations are saved in the file tracer_tests_measurements.csv

Flowmeter tests: the test is described in thr file experience.csv; the values of flow and speed are registered in the file flowmeter_logs.csv

Pumping tests: the test is described in the file experience.csv; the values of injected or pumped volumes (and temperature if the device indicates it) are registered in the file pumped_borehole.csv

Slugs (hydraulic hits): the test is described in the file experience.csv; the values of injected volume and level of the perturbation) are registered in the file slug_tested_borehole.csv

There is an additional optional information (experiment name) in the templates for piezometric level or in situ measurements to indicate that there is an on-going experiment for these values.

For the pumped or injected volumes, one line must be created in the file for every flow rate change. A line with a flow rate 0 indicates the end of the injection or of the pumping.

Example :

- Email address of the provider

- Email address of the collaborators

Columns :
Site name, borehole name, definition of relative z, reference for the definition of relative z, date, hour, flow rate, temperature, method to measure the flow rate, ID of the pump, relative z for packer sup, relative z for packer inf, description packers

"poitiers","M1"," top of borehole",104,10/10/2004,14:00:00,1,,,,5,12,

"poitiers","M1","top of borehole ",104,10/10/2004,15:00:00,0,,,,5,12,

"poitiers","M1"," top of borehole ",104,10/10/2004,15:15:00,3,,,,5,12,

"poitiers","M1"," top of borehole ",104,10/10/2004,15:30:00,0,,,,5,12,

The example above indicates that the injection was done between 14h – 15h with a flow rate of 1m3/s then between 15h15-15h30 with a flow rate of 3m3/s.


Packers description

relative z upper packer: upper limit of the chamber between the packers (in which the flow rate is controlled) If there is no packer, let this box empty.

relative z lower packer: lower limit of the chamber between the packers


Technical description of the boreholes

The technical descriptions of the boreholes are in the file technical log.xls 

One should use the following conventions: there should be a line for every tube. The indicated relative z corresponds to the depth at which there is the change. For instance, if the well has an external pre tube from 0 to 10m and an internal tube from 8 to 15m, there will be 4 lines in the file  technical log for every depth where there is a change (relative z =[0,8,10,15]).

The nature of the tube is in the list “tube materials”


Geological logs

The data selection allows extracting measurements using of the geological log of a borehole (for instance, you can extract all the measurements concerning the limestone part from a borehole).

The experimental measurements can be linked to the geological logs if they are registered with the same depths.

Conventions: the file "geological log" has a line for every change of the geology in the borehole. The relative z corresponds to the depth where there is a change.

For instance, if in the well there is vegetal soil from 0 to 10m and a limestone from 8 to 15m, there will be 4 lines in the file  geological log for every depth where there is a change (relative z =[0,8,10,15]).

Therefore all log_geological file has in the first line a relative z = 0 with the geology of the top of the borehole.


Piezometric level

- Raw data = original file of the sensor, in which the data are given with respect to a reference level that may be different in various files.

 - relative corrected depth: piezometric data, validated, with the z reference indicated in the column " relative z definition"


Time format rules

For time,  use the format:

hh:mm:ss:ms with the milliseconds in the format mmm. (e.g. 10:00:00:500)


Integration of raw data and interpreted data

In situ measurement, hydraulics or flow rates measurements are obtained with measurement devices, the raw data should be inserted. The abnormal values can be suppressed.

For the deformation measurements, we:

-        keep the raw data with the timeline of the modifications and change of instruments

-        have “clean data” useable by hydrogeologists (without abnormal values, with corrected values), a correct calibration and the correction for the seatides.

Therefore, for tiltmeter measurements, of different structures, different templates have been created:

-        for the Blums, there is a template with the raw data, the calibrated data and the corrected data

-        for the longue bases, there are 2 templates :

o   raw data for each pot

o   treated and corrected data for the inclinometer

This solution ensures the best transmission of data for hydrogeologists. In addition, every operation should also of course be described in the correct lines/columns.