Van Overloop, Peter-Jules

Vierstra, Meinte

English

Hydraulic Engineering Repository

Article, Published VersionVan Overloop, Peter-Jules; Vierstra, MeinteThe mobile TrackerHydrolinkVerfügbar unter/Available at: https://hdl.handle.net/20.500.11970/109214Vorgeschlagene Zitierweise/Suggested citation:Van Overloop, Peter-Jules; Vierstra, Meinte (2013): The mobile Tracker. In: Hydrolink2013/4. Madrid: International Association for Hydro-Environment Engineering and Research(IAHR). S. 104-106. https://iahr.oss-accelerate.aliyuncs.com/library/HydroLink/HydroLink2013_04_Hydroinformatics.pdf.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding.104 hydrolink number 4/2013IntroductionWater boards are responsible for managing thewater in their area. To do this, they must knowthe behavior of their catchment very well. Themost direct way of doing this is throughmeasurements. Measurements are alsonecessary to calibrate physically based,numerical models, to better understand thewater systems and forecast extreme scenarios.A third reason why water boards take measure-ments is to satisfy agreements with neighboringwater districts. Finally, these field measurementsare used for the operational managements ofpumps and gates. It can thus be said thatmeasurements are the heartbeat of watermanagement.Measuring AutomaticallyMany water quantity variables are currentlyautomatically measured and sent to a centraldatabase. The costs for such automaticmeasuring apparatus have declined in recentyears, which is why the number ofmeasurement spots is still increasing. Risingmanagement and maintenance costs will,however, lead to a saturation point in thenumber of automatic measurement apparatus:Wear and tear from outside weather, dirt fromorganisms in the water, animals and vandalismare only a few of the reasons for which theapparatus frequently needs to be replaced andmaintained. Measurements that are done byhand are much less susceptible to such wear,and will thus in many instances remain anattractive measurement method in severallocations in the area. An additional benefit isthat water district employees continue tooperate in the field, and thus can identifyproblems which are not noticed by automaticapparatus.Manual Measurements The problem with manual measurements is thatthese are less accurate than automaticmeasurements and often cannot be completelyreproduced. The first problem primarily has todo with entering data manually, while the secondproblem is caused by different colleagues in thefield taking measurements in different ways suchas rounding up differently, incorrect use ofmeasurement apparatus or an inability to seethe readings. The recent, “Gage Repeatability &Reproducibility” [Tennant 2001] field experimentconducted at a water district in The Netherlandsrevealed how substantial these mistakes can be.THE MOBILETRACKERBY PETER-JULES VAN OVERLOOP AND MEINTE VIERSTRA Table 1. Results from measurement experimentsusing different measurement tools or methods byexperienced field operators. Every year water districts can save a fortune by making measurements from the field more cost-efficient. Field measurements are often still jotted down in a notebook, only to be manuallyprocessed at the end of the week. These measurements are then sent to the boss, who archivesthem. This whole procedure can be reduced to one click using the Mobile Tracker.Figure 1.   Mobile Tracker measuring a water levelStandard deviation (mm)R&R Uploading Total 95% experiment 1 experiment 2 significancetape measure4.7 9 10 20measuring stick8.1 9 12 24staff gauge 2.0 9 9 18105hydrolink number 4/2013IAHRFigure 2.   Mobile Tracker measuring a gate position (on the left is the original photo, onthe right the manipulated photo with the perspectivecorrection and how the angle resulting in the gate position isdetermined)Figure 3.   Mobile Tracker measuring a ground water leveluploaded). This second experiment was doneusing 1000 measurement readings. The totalinaccuracies can be determined by, per exper-iment, adding up the squared values and takingthe square root of this summation. Theseresults are shown in Table 1. It can thus be saidwith 95% significance that the uploaded readingis within 20 millimeters of the truemeasurement.Real-time MeasurementsAnother difficulty with manual measurements isthat these are noted down and are only lateradded to a database for further use. As a result,these data are not a reflection of the actualstate of the water system, and are thus notsuitable as a basis upon which to take opera-tional decisions. The measurements are oftenonly available weeks after they were taken forInaccuracies caused by manual data entry werealso researched. The first experiment revealedhow inaccurate measurement data was whenread from measurement tools in the field. Thesecond experiment revealed the inaccuracies injotting down and analyzing the measurementstaken. The results from these two experimentstogether revealed the total inaccuracies from thefield data.The data used in the gage R&R experiment wastaken from three experienced operators on threedifferent locations that used three differentmeasurement tools:  tape measure, measuringstick, and local staff gauge fixed to theembankment.This gage R&R experiment determined thestandard deviation of the different measurementtools. The tape measure has a standarddeviation of 4.7 mm. This means that themeasurement value taken from the tapemeasure is (with 95% significance) within 9 mm(double the standard deviation) of the truemeasure. For the other measurement tools(measuring staff and staff gauge this is respec-tively 16 mm and 4 mm.The second experiment, whereby themeasurement values are manually entered in alaptop and later in a central system led to afurther 9 millimeters of standard deviation (thus a95% significance of the true reading beingalmost 18 millimeters different from the onePeter-Jules Van Overloop is a scientistand entrepreneur in the field of operational water management with abroad experience in modeling andcontrol of river, urban and rural watersystems. He has written over 40 international and national publicationsand has presently a part-time positionas Associate Professor at the Delft University of Technology. He is also founder and CEO of the spin-off company Mobile CanalControl.Meinte Vierstra is a civil engineerspecialized in water resourcesengineering & management. He isco-founder of the Delft Universityof Technology spin-off MobileCanal Control of which he ismanaging director.further use and analysis. While there arecurrently several systems in use which make itpossible to make the data directly available to acentral unit, these all require manual uploadingof the measurements.A recent innovation called The Mobile Tracker(MT) can be seen as the next generation ofsemi-automatic measurement devices. MT ismade for the smart phone and uses thetelephone’s camera and special pattern-recog-nition software [Shih 2010]. This technologymakes manual data entry of water variablesunnecessary. Mobile TrackerThe Mobile Tracker works as follows: When afield operator arrives at a location, they take thesmart-phone and start an application that makescontact with the central database. The appli-cation uses the GPS coordinates and angles ofthe smart phone to identify the location andstore all the relevant data. For water levelmeasurements these would usually be thereference level, subsidence of the staff gaugeand known impairments of the staff gauge. Forflow measurements these are, for example,width of the gate and calibration coefficient. Forground water measurements it is the level of thetop of the groundwater pipe. With one click onthe app, a photo is taken and from the photowater variables such as water level, flow andgroundwater level can be measured. Thesevalues are then sent to a database and savedincluding information pertaining to location witha time check, the field operator on duty, GPScoordinates and camera angles. The photo isalso sent and saved with the other information.The advantage of this procedure is that is fasterthan manual data and no data errors can bemade. Because the photo is saved, it can bereferred to afterwards using the correct photo atthe right place and at the right time to verifyconcerns about inaccurate readings or disputesabout a presumed situation. The central systemcan be managed from FEWS [FEWS 2013]. TheMobile Tracker is also connected to WISKI[WISKI 2013]. Figure 1 to 3 indicate themeasurement methods for water level, gateposition/flow  and ground water level.ConclusionThe Mobile Tracker is an innovation that makesmanual measurement of water variables signifi-cantly faster and reproducible. The procedurefor taking measurements is as simple as takinga photo with a smart-phone. It can thus also beused by less experienced personnel. In excep-tional circumstances it could even be used byfarmers in remote areas or students passing astream on their way to school. The onlyrequirement is a smart-phone. The Mobile Tracker is currently being tested atdifferent water districts in The Netherlands. Theinitial results have shown an accuracy of lessthan 10mm. ReferencesTennant, G., ‘SIX SIGMA: SPC and TQM in Manufacturing andServices’, Gower Publishing Ltd., 2001.FEWS, http://www.deltares.nl/nl/software/479962/delft-fewsWISKI, http://www.kisters.net/wiski.htmlShih, F. Y., ‘Image processing and pattern recognition, Fundamentalsand techniques’, John Wiley & Sons, Inc., New Jersey, 2010.www.rdinstruments.com   Take me to the River...It’s that easy.Power and go with Teledyne RDI’s  ADCP.Drop me in the Water.            RiverRay

The mobile Tracker

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The mobile Tracker

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