Drain Gauge
Contents
1. Installation Valve Box We recommend that you install a sprinkler valve box next to the Drain Gauge to provide easy access and protection to the calibration and sampling tubes Valve boxes are readily available from sprinkler supply stores The valve box should be placed far enough away from the Drain Gauge installation so it does not interfere with the site 1 First dig a hole large enough to accommodate the valve box 11 Drain Gauge User s Manual 2 Installing the Drain Gauge 2 Cut a small trench between the Drain Gauge site and the valve box installation site we recommend this step be completed before replacing the surface vegetation on top of the Drain Gauge 3 Lay the sensor wire and calibration and sampling tubes in the trench and recover them 4 Place the valve box into the hole and arrange the tubes so they can be easily accessed Troubleshooting When the Drain Gauge s read circuit is excited by 2 5 volts the sensor output with a dry sampling chamber should be 10 mV and the output when full should be 120 125 mV The siphon does not drain the measure ment reservoir completely so the sensor should read 30 mV after a siphon event Each of these values can vary 10 from instrument to instrument If the probe output is not between 10 and 135 mV check to be sure the sensor wire was not damaged during installation If you do not see a flushing event after injecting water into the calibra tion tube2. Because of uncertainties in the measurements of the other water balance components deep drainage estimates were subject to large errors The Drain Gauge now allows direct measurement of the deep drainage component of the water balance This is accomplished by intercepting and collecting a representa tive sample of the water that moves below the root zone The Drain Gauge is sometimes referred to as a passive wick lysimeter It has a specially treated fiberglass wick which maintains a tension on the water at the bottom of the soil profile where it is extracting water Without this tension water would pile up at the outflow boundary and force the water in the soil above to move around the Drain Gauge rather than into it The divergence control tube on the top of the Drain Gauge is also for the purpose of maintaining vertical flow above the Gauge so that the Drain Gauge intercepts a representative sample Both the amount of sample and its chemical composition need to be representative of deep drainage in the area where the drain gauge is installed Whether or not this is true is determined largely by the installation The main issues ate e Depth of installation e Soil disturbance above the Drain Gauge e Contact between the wick and the soil profile e Root incursion into the Drain Gauge wick section Following are some general comments related to these issues Specific installation procedures are then outlined in the next chap
3. pull air into the syringe and inject it into the tube This should push all the water out of the sampling tube and into the reservoir Solution Sampling The sample reservoir collects water from the measure ment reservoir after each flush Solution can be retrieved from the sample reservoir through the blue sampling tube Insert a 60cc syringe included into the sampling tube and slowly pull back on the plunger If liquid is present in the sampling reservoir it should slowly begin 12 Drain Gauge User s Manual 2 Installing the Drain Gauge filling the syringe Note The syringe will never completely fill with water NOTE The liquid in the syringe will be a mix of the all the water that has collected in the reservoir over time You should not assume that the composition of the sample water is specific to a single flush event from the reservoir unless you are certain that you have emptied the reservoir since the previous flush Water Balance It is often useful to install ECHO soil moisture probes within the divergence control tube to observe how the water content changes with depth over time in the DCT If you install ECHO probes in the DCT you must take cate so they ate not touching any part of the DCT as this will adversely affect the readings A good rule of thumb is to locate them as close to the center of the divergence tube as possible 13 Drain Gauge User s Manual 3 Theory 3 Theory ee How the
4. Decagon and perti nent testing documentation is freely available for verifica tion 32 Drain Gauge User s Manual Index Index CC A adapter cable Wire diagram 21 C calibration 12 CE compliance 33 contact information 1 D data analysis 12 datalogger requirements 23 sample program 28 Declaration of Conformity 33 drain gauge depth of installation 16 installation instructions 3 theory 2 drainage calculating 26 email 1 extension cables 22 35 Drain Gauge User s Manual Index F fax number 1 installation 3 depth considerations 16 location 3 soil disturbance 18 P plug wiring configuration 21 probe layout 14 program 28 S sampling water 12 seller s liability 1 soil disturbance 18 solution sampling 12 T telephone number 1 troubleshooting 12 30 W warranty 1 water balance 13 wiring diagrams 20 36
5. lished by placing a layer of diatomaceous earth over the wick The diatomaceous earth conforms to the irregulari ties of the soil and wick to provide continuity 18 4 Collecting Data Drain Gauge User s Manual 4 Collecting Data Features fi X Syringe y clear and Sampling blue Tubes Calibration PHL 1G F j Z Yi I6 Tubing Shield Drain Gauge User s Manual 4 Collecting Data Measurement Reservoir Siphon Water depth sensor Calibration port Sensor cable port Tubing shield Sampling Reservoir Overflow port Sampling port Fig 7 Close up of Measurement section 20 Drain Gauge User s Manual 4 Collecting Data Wiring Diagrams 3 5mm plug wiring The Drain Gauge s water level sensor comes with a 3 5mm stereo plug style connector This allows for rapid connection directly to Decagon s Em50 data logger Below is a diagram showing the wiring configutation for this connector Analog out Red Ground Bare Excitation White Fig 8 Sensor plug wiring configuration Adapter Cable Wiring The sensor adapter cable model PAP for connection to non Decagon equipment contains 3 wires as shown below The adapter cables are available from Decagon upon tequest The cable plug has integrated inductors designed to provide signal noise reduction Refer to Chap ter 4 for more details about conne
6. previous water level measurement 1 Z X P31 aso Ji X Loc WatrLevel oa 2 Z Loc PrevLevel Read water level sensor and set current water level 2 Excite Delay SE P4 Reps 2500 mV Slow Range SE Channel Excite all reps w Exchan 1 Delay 0 01 sec units DDIAUBAWNH OHHNRRRUH 500 mV Excitation Loc WatrLevel 0 Mult 0 Offset compare previous water level to current level 3 Z X Y P35 Acs ii X Loc WatrLevel 2 2 Y Loc PrevLevel 3 2 3 Z Loc DeltaWwL Set threshold for identification of siphon event 10 mV decrease over 1 second 4 If X lt gt F P89 13 X Loc DeltaWL 2 4 lt 3 10 F 4 30 Then Do set 10s period for outputting water level data to final storage after siphon flush slows i 5 Z F x 10 n P30 Aes 1 F 2T n Exponent of 10 3 4 Z Loc counter 6 End P95 7 If X lt gt F P89 Ls 4 X Loc counter 2 553 gt DeL F 4 30 Then Do counter counter 1 8 Z X F P34 1 4 X Loc counter 28 Drain Gauge User s Manual 4 Collecting Data 2 1 F 3 4 Z Loc counter Output time and water level data to final storage for 10s siphon chamber flushing event 9 Do P86 LEAG Set Output Flag High Flag 0 10 Real Time P77 1 1111 Year Day Hour Minute Seconds midnight 0000 11 Sample P70 eT Reps 2 35 i Loc WatrLevel 12 End P95 Output time and water level every hour Thes
7. s Liability Seller warrants new equipment of its own manufacture against defective workmanship and materials for a period of one year from date of receipt of equipment the results of ordinary wear and tear neglect misuse accident and excessive deterioration due to corrosion from any cause are not to be considered a defect but Seller s liability for Drain Gauge User s Manual l Introduction defective parts shall in no event exceed the furnishing of replacement parts F O B the factory where originally man ufactured Material and equipment covered hereby which is not manufactured by Seller shall be covered only by the warranty of its manufacturer Seller shall not be liable to Buyer for loss damage or injuries to persons including death or to property or things of whatsoever kind including but not without limitation loss of anticipated profits occasioned by or arising out of the installation operation use misuse nonuse repair or replacement of said material and equipment or out of the use of any method or process for which the same may be employed The use of this equipment constitutes Buyer s acceptance of the terms set forth in this warranty There are no under standings representations or warranties of any kind express implied statutory or otherwise including but without limitation the implied warranties of merchantabil ity and fitness for a particular purpose not expressly set forth herein
8. Drain Gauge Model G2 Gee Passive Capillary Lysimeter Operators Manual Version 5 DECAGON DEVICES Decagon Devices Inc 2365 NE Hopkins Court Pullman WA 99163 USA Tel 1 509 332 2756 Drain Gauge User s Manual Contents Contents II AA l Introduction ma nsetatonasicecnieneies 1 Welcome alan aata haan aka 1 Contact Information o on aaa 1 Warranty Information aa 1 Sellers Liability 4 2 Bana a akp naka had n 1 2 Installing the Drain Gauge 3 Location Preparation 3 EXCOVGHON ada nasha da Kawa NADA Nk AG ees 4 Method 1 Disturbed Sample 4 Method 2 Intact Monolith Recommended 6 Installation Wick Section 7 Installation Divergence Tube 9 Method 1 Disturbed Sample method 9 Method 2 Intact Soil Monolith method 10 Posi Installation Warning s0 lt s2ssse lt 0 ss 10 Installation Valve Box i Troubleshooting Siascsasedrssecedaiese 12 Solution Sampling 0 e cee ee 12 Water Balance 0 00 eee e eee 13 SB THEO ous ka paaa kA ana bha 14 How the Drain Gauge Works 14 Considerations 000e cece eee 14 Depth of Installatictic se0 vsinineas oie bles 16 Divergence Control Tube length 17 Soil Di stOn bande AKA 18 Soil Wick Contact a s kalang ala NG KATA Gp das 18 Drain Gauge User s Manual Contents 4 Collecting Da
9. Drain Gauge User s Manual 2 Installing the Drain Gauge 2 Installing the Drain Gauge Several references on Drain Gauge installation techniques are given at the end of this section and two of those methods are discussed below The one that you should use depends on your soil type and the purpose of your research If your goal is to investigate an undisturbed soil core recommended you will need to secure a soil mono lith inside the divergence control tube However in some cases repacking the soil in layers is sufficient Both meth ods are explained below Location Preparation 1 Select a location for your installation allow plenty of room to move around the hole and lay a tarp nearby that can be used to hold the vegetation and soil that will be removed from the site 2 Remove the surface vegetation and place it on the tarp Try to preserve as much of the root mass as pos sible Also it is important to organize the vegetation you remove so that it can be replaced as closely as pos sible to its original location Drain Gauge User s Manual 2 Installing the Drain Gauge PP ji ST BF H oe ma W 5 DI AA Mae PF an Pi Weald Me Svat yt Figure 6 Initial excavation above DCT hole Excavation The depth of the Divergence Control Tube DCT hole depends on the depth of the root zone The objective of the installation is to place the middle plate of the Drain Gauge below the root zone of the cover veg
10. Drain Gauge Works The Drain Gauge is first installed below the root zone Water infiltrates down through the divergence control tube and then down a fiberglass wick into a collector As collected water fills the measurement reservoir the water level is monitored by a water depth sensor When the water level in the measurement reservoir teaches the top of the siphon tube the water empties and the event is recorded by an attached data logger The emptied water then drains into the sampling reservoir A sampling syringe attached to the water reservoir sampling port blue tube can draw water samples out of the sampling reservoir for chemical analysis Excess water drains out of an overflow port and into the soil while allowing a volume of water to remain for sampling see fig 7 Considerations A soil water balance takes into consideration the inputs losses and storage of water in a soil profile An important component of the water balance is the water that drains from the bottom of the soil profile often referred to as deep drainage or deep percolation This is water that has gone sufficiently far below the root zone that it cannot be removed from the soil by transpiration or evaporation The other components of the water balance can be mea sured but the deep drainage typically has been computed as the remainder when the other components were mea 14 Drain Gauge User s Manual 3 Theory sured and accounted for
11. cting to a non Decagon data logger Analog a mua Vt Ground Excitation Fig 9 Adapter cable wiring configuration 21 Drain Gauge User s Manual 4 Collecting Data NOTE Be aware that cutting off the cable plug or cutting the cable in any other way will void your war ranty since the plug and cable are both specially engineered for optimal performance and noise reduc tion Extension cables Decagon supplies 50 foot 15 25m and 10 foot 3m extension cables to attach to the sensor cable You can safely connect up to 5 of the 50 foot cables without signif icant signal attenuation For most applications you will want to seal the connections from the elements to main tain a good connection and to prevent corrosion To waterproof the connectors connect the extensions then coat the connection with silicone sealant Next cover the connection with heat shrink and shrink it over the un cured sealant Datalogger Requirements Decagon Em50 and Em50R loggers The Drain Gauge s sensor is designed to work efficiently with Decagon s 5 channel Em50 data logger with firm ware version 1 9 or higher The Em50 automatically recog nizes the Drain Gauge and keeps a running total of drainage since the last time the data logger memory was erased The Em50 will output the cumulative drainage in units of 0 1mm For example if the Drain Gauge has experienced 7 siphon flushes and the siphon chamber is half full at t
12. e data provide information about j infiltration events that are not large enough to cause gauge to flush and are also useful to ensure that program is catching all gauge flush events 3 If time is P92 1 0 Minutes Seconds into a 2 60 Interval same units as above 3 3 10 Set Output Flag High Flag 0 14 Real Time P77 Ta LLTO Year Day Hour Minute midnight 0000 15 7 Sample P70 alay 0d Reps 2 Loc WatrLevel Table 2 Program 02 0 0000 Execution Interval seconds Table 3 Subroutines End Program Troubleshooting If you encounter problems with the Drain Gauge sensor they most likely will manifest themselves in the form of incorrect or erroneous readings Before contacting Deca gon about the sensor do the following 29 Drain Gauge User s Manual 4 Collecting Data e Check the sensor cable to ensure it was not cut or damaged e Check to make sure the connections to the data logger are both correct and secure e Ensure that your data logger s batteries are not dead or weakened If you encounter problems specific to the Drain Gauge please contact Decagon at 509 332 2756 and at support decagon com 30 Drain Gauge User s Manual Further Reading Further Reading PD Fpj a Gee G W et al A vadose zone water fluxmeter with divergence control Water Resources Research vol 38 No 8 10 1029 2001 WR 000816 2002 Gee G W A L Ward Z F Zhang and A A
13. en performing a custom calibration to flush the entire injected solution volume from the calibration tube into the calibration chamber with air before recording the mV output from the water level sensor Root Incursion If the Drain Gauge is installed at too shallow a depth it is possible for plant roots to grow into the wick and either use water from or potentially clog the drain gauge To prevent this each new drain gauge is shipped with a root inhibiting fabric Bio barrier Reemay Inc placed below the wick fabric on the wick plate This fabric is impregnated with Treflan Trifluralin root inhibitor The root inhibitor is slowly released into the soil sur rounding the fabric and builds up a layer of 10cm thick ness where roots will not penetrate The effective lifetime of the Bio barrier is several decades so the fabric should not have to be replaced over the life of the drain gauge Treflan is a mitosis inhibitor which prevents plant roots from growing via cell splitting It is possible although unlikely that the roots of woody species that grow via elongation may be able to penetrate the inhibitor layer and grow into the wick If this is a concern it may be neces sary to place additional Bio barrier in the divergence con 26 Drain Gauge User s Manual 4 Collecting Data trol tube during installation contact Decagon for additional Bio barrier If you are confident that the drain gauge will be installed
14. etation Thus the depth of the hole will vary between installations but it must be at least 70 cm deep The DCT should be com pletely buried below the soil surface There are two different methods see above for installing the drain gauge depending on whether you use a dis turbed sample Method 1 or an intact monolith Method 2 Method 1 Disturbed Sample Digging the hole for the Drain Gauge is most effective with a sharpshooter shovel or post hole digger and an otchard auger with a long extension 1 Make the initial vertical hole for the divergence con trol tube about 25 cm 10 in in diameter slightly larger than the tube itself and at least 70 cm 27 5 in deep Drain Gauge User s Manual 2 Installing the Drain Gauge Dig a 7 5 cm 3 in diameter by 122 cm 4 ft deep hole for the PVC pipe that surrounds the wick section of the drain gauge at the bottom center of the DCT hole you just made An orchard auger can be very effective for this portion of the hole because of its long handle Insert the PVC tube included with your drain gauge into the wick section hole This tube will help protect the wick section and prevent contamination of the lower sampling chamber from surrounding soil Pour 12 inches of rock gravel or sand into the PVC tube This will allow for free movement of the effluent water from the Drain Gauge Be sure not to overfill the PVC pipe with gravel as the Drain Gauge plate shou
15. he time of measurement storage the output would be 75 indicating 7 5 mm of drainage The total drainage will not reset to zero when data are downloaded 22 Drain Gauge User s Manual 4 Collecting Data from the Em50 so the drainage reported is the cumulative amount since the Em50 memory was last erased The Em50 will also output the water depth sensor ADC counts at each measurement interval Other Data Logging Systems The Drain Gauge can also be adapted for use with other data loggers such as those from Campbell Scientific Inc The Drain Gauge sensor requires an excitation in the range of 2 5 volts Any data logger which can produce 2 5 5 V excitation with approximately 10 millisecond duration and read a volt level signal with 12 bit or better resolution should be compatible with the Drain Gauge The current requirement at 2 5 V is around 2 mA and at 5V it is 7 8mA The calibration equations presented in this manual are only valid for a 2 5 V excitation If another excitation is chosen then the user will need to calibrate the water depth sensor by injecting water into the clear calibration tube and recording the mV output of the sensor after each incremental injection Important Considerations 1 The Drain Gauge sensor is intended only for use with data loggers and readout devices which can provide short excitation pulses Continuous excitation not only wastes battery power but may under certain citcum stances cau
16. ick and use water from or clog the Drain Gauge This can be minimized by the Treflan impregnated root inhibitor fabric at the bottom of the divergence control tube installed 16 Drain Gauge User s Manual 3 Theory Divergence Control Tube Length Optimal performance of traditional passive capillary lysimeters is only achieved by precisely matching wick length to soil type The addition of an innovative diver gence control tube DCT negates the need for precise wick soil matching in the Drain Gauge Numerical and laboratory simulations performed by Gee et al 2002 have demonstrated the effectiveness of the DCT in pre venting flux divergence around the collection point Fig ure 5 shows the collection effectiveness of the drain gauge as a function of DCT height for six different flux rates in a coarse sand It is apparent that in this medium reasonable collection effectiveness can be achieved with a DCT height of as little as 30 cm even at very low drainage fluxes where divergence most readily occurs For finer tex tured soils a DCT height of up to 60 cm may be neces saty In the extreme case of very fine soils with low drainage fluxes i e lt 50 mm yr a DCT height of more than 60 cm may be necessary to prevent flow divergence a J 1mm yr J 30 mm yr a Jaq 160 mm yr Ja 300 mm yr Ng o J 500mm yr j e J 1000 mmy f Ji seei 10 10 10 Height of Divergence Ba
17. ld sit flush on the top of the PVC pipe If an auger was not used to dig the wick section hole and a significant gap remains between the soil and the PVC tube pour some additional gravel or sand into this gap and backfill with soil Drain Gauge User s Manual 2 Installing the Drain Gauge Figure 1 Installation of protective PVC pipe and gravel Method 2 Intact Monolith Recommended If you would like an undisturbed soil monolith it can be obtained from either the installation site or an adjacent site If you choose a monolith from an adjacent but similar site you can minimize disturbance to your measurement site 1 Carefully remove soil to the depth where you want the top of the DCT to be Nove The hole you dig must be wide enough to allow you to easily dig around the outside of the DCT 2 Place the DCT at the bottom center of the hole Pound the DCT into the soil by by placing a board on top of the tube to prevent damaging the tube and Drain Gauge User s Manual 2 Installing the Drain Gauge striking it repeatedly with a sledgehammer Then dig away the soil around the portion of the DCT that you just pounded into the soil Repeat the process until the DCT is filled with soil Use a shovel to free the DCT from the surrounding soil and lay it aside If you have harvested a monolith from a separate site than you wish to install your drain gauge use an 8 auger to dig a narrow hole for
18. ly clog the drain age ports Figure 2 Lower wick section installed Drain Gauge User s Manual 2 Installing the Drain Gauge Installation Divergence Tube Depending on whether or not you are using the Dis turbed Sample method or Intact Soil Monolith method described earlier there are also two different methods for installing the DCT divergence control tube Method 1 Disturbed Sample method 1 Set the empty DCT on top of the plate segment of the wick section The outer edge of the DCT should fit inside the lip of the plate Repack the soil you removed from the DCT hole Take care to repack the soil layers in the same order that they came out and at the approximate density as the adjacent undisturbed soil Place and pack the soil from the root zone You may want to mound additional soil on top of the drain gauge to compensate for soil settling Replace the cover vegetation if desired Some users keep subsur face soil moist and allow it to settle for a week prior to replacing the topsoil and vegetation Backfill and pack soil around the outside of the DCT Place and pack the soil from the root zone You may want to mound additional soil on top of the drain gauge to compensate for soil settling Replace the cover vegetation if desired Some users keep subsur face soil moist and allow it to settle for a week prior to replacing the topsoil and vegetation Drain Gauge User s Manual 2 Ins
19. nandacoomar aswamy Use of water fluxmeters to measure drainage pp 321 331 In R A Cooke ed Drain age VIII Proceedings of the Eighth International Drainage Symposium 21 24 Mar 2004 Sacra mento CA Am Soc Ag Engr St Joseph MI Installation References Brown K W et al 1974 A procedure for placing large undisturbed monoliths in lysimeters Soil Sci Soc Am J 38 981 983 Quinlan P R Burman and e Siemer 1982 In Situ lysime ter installation ASAE Tech Paper 82 2015 Amer ican Society of Agricultural Engineers St Joseph MI http kilburn keene edu tresearch hydrology RLA index html lysimeter For more rigourous installation techniques http www soilsci ndsu nodak edu research soil_physics bmp 1989 1989 html 31 Drain Gauge User s Manual Declaration of Conformity Declaration of Conformity a Application of Council 89 336 EEC Directive Standards to which EN61326 1998 Conformity is Declared EN55022 1998 Manufacturer s Name Decagon Devices Inc 2365 NE Hopkins Court Pullman WA 99163 USA Type of Equipment Gee Passive Capillary Lysimeter Drain Gauge Model Number G2 Year of First Manufacture 2003 This is to certify that the Drain Gauge manufactured by Decagon Devices Inc a corporation based in Pullman Washington USA meets or exceeds the standards for CE compliance as per the Council Directives noted above All instruments are built at the factory at
20. rrier cm Figure 5 Collection effectiveness of Drain Gauge for several different flux rates as a function of DCT height in a coarse sand J 4 is the actual drain age flux and is the drainage flux measured by the Drain Gauge Fig ure adapted from Gee et al 2002 17 Drain Gauge User s Manual 3 Theory Soil Disturbance It is impossible to install the Drain Gauge without disturb ing the soil The goal is to install it in such a way that the disturbance has minimal impact on the Gauge s ability to measure deep drainage The three factors that will affect deep drainage are changes in root uptake patterns changes in soil moisture storage and changes in evapora tion In some cases it may be necessary to install the Drain Gauge beneath an undisturbed core of soil In all cases it will be necessary to allow time for roots to grow back into disturbed soil If the soil surface is tilled there is no point in trying to keep that part of the soil undisturbed since it is already disturbed Soil Wick Contact In order for the bottom of the soil profile to be under ten sion the tension in the wick must be transferred to the bottom of the soil column There must therefore be good capillary continuity between the soil column and the wick If the Drain Gauge is installed by backfilling with soil the contact is likely to be good without further effort If an undisturbed core is installed capillary continuity is estab
21. se the sensor to exceed government speci fied limits on electromagnetic emissions 2 All Decagon readout devices use 3 0V excitation so the remainder of the discussion assumes this as the excitation If other voltages are used adjustments to the calibration equations provided will be needed 23 Drain Gauge User s Manual 4 Collecting Data 3 If your data logget is programmed to wait too long between readings you may miss a flushing event Connecting to a Datalogger Connect the wires from the pigtail adapter to the data log ger as shown with the supply wire white connected to the excitation the analog out wire red to an analog input and the bare ground wire to ground Analog Supply out Ground Exc H Analog In Datalogger Fig 10 Datalogger configuration Drainage Calculation Data Analysis amp Calibration The Drain Gauge is designed with a flush volume of 31 cm 10 If the sampling area is taken as the surface area of the opening in the divergence control tube 310 2 a cm each flush event corresponds to 1 mm of drainage Em50 loggers with firmware v 1 9 and greater will auto matically recognize the Drain Gauge and keep a running count of Drain Gauge flushing events see reading the Drain Gauge with Em50 loggers With other data acquisi 24 Drain Gauge User s Manual 4 Collecting Data tion systems the flushing events must be identified from the time
22. series data from the drain gauge water depth sen sor Figure 11 The data will be chatacterized by filling and flushing events A total count of the readily apparent flushing events is multiplied by 1 mm to calculate the total drainage during the period of interest Drain Gauge Under Potatoes 140 N o o o oo O Drain Gauge Output my D o FA o nN o o 55 60 65 70 75 80 Time days Figure 11 Typical time series data from Drain Gauge water depth sensor during wet conditions A sample program for use with CSI data loggers is included at the end of this manual If drainage resolution of less than 1 mm is desired the drainage can be calculated from the volume of solution accumulated in the siphon chamber The volume of solu tion in the siphon chamber can be calculated using the generic drain gauge calibration function Vol cm 0 33 mV 9 8 25 Drain Gauge User s Manual 4 Collecting Data where mV is the output from the water depth sensor in the siphon chamber This generic calibration function should be accurate enough for nearly all applications If extreme accuracy is desired in inter flush solution volume measurement then you must perform a custom calibra tion by incrementally injecting known volumes of local soil solution into the calibration port clear tube and recording sensor mV output after each solution injection Note that care should be taken wh
23. ta 19 Ko AA APAN 19 Wiring Diagrams aa NAGA LAA GANANG 21 3 Smm Plg KULAY 21 Adapter cable wiring 4 puwaia saba pan sae 21 Extension CADIES cis saman nananana aaa 22 Datalogger Requirements 23 Decagon Em50 and Em5OR loggers 23 Other Data Logging Systems 23 Important Considerations 24 Connecting to a Datalogger 24 Drainage Calculation Data Analysis 8 Calibration 25 ROOK IM GUL SION Uy ts Kayan wa ads carmese bla ara DIN 27 Saniple Program 4 20veeiideetaieens ces 28 Troubleshooting 0ee eee eens 30 Further Reading 32 Declaration of Conformity 33 INDEX E AA 35 Drain Gauge User s Manual l Introduction 1 Introduction fa JJ Welcome Thank you for purchasing the Drain Gauge The Drain Gauge is designed for long term monitoring of soil water drainage with an estimated minimum 10 year lifetime The Drain Gauge also has a collection system that allows for rapid sampling of drainage waters This innovative device will enable you to monitor soil water movement and chemical leaching accurately and affordably Contact Information e E mail support decagon com e Fax 509 332 5158 e Phone 1 800 755 2751 US and Canada only or 509 332 2756 Warranty Information The Drain Gauge has a 30 day satisfaction guarantee and a one year warranty Seller
24. talling the Drain Gauge Method 2 Intact Soil Monolith method 1 Set the DCT containing the intact soil monolith onto the diatomaceous earth that was applied on top of the fiberglass fabric on top of the wick section plate Figure 3 DCT installation filled with intact soil monolith 2 Backfill and pack the soil around the outside of the DCT 3 Place and pack the soil from the root zone You may want to mound additional soil on top of the drain gauge to compensate for soil settling Replace the cover vegetation if desired Some users keep subsut face soil moist and allow it to settle for a week prior to replacing the topsoil and vegetation Post Installation Warning To reduce the amount of time until the soil equilibrates back to a more natural state many users moderately irri gate the Drain Gauge immediately after installation If you wish to do this make sure not to irrigate too heavily and too quickly Over irrigation of unconsolidated soil can cause preferential flow of solids down the PVC tube which fills the gravel with fine sediments that can retard drainage from the Drain Gauge s overflow port In 10 Drain Gauge User s Manual 2 Installing the Drain Gauge extreme cases sediments can also enter the sampling tes ervoit leading to erroneous readings This will not occur once the soil has experienced moderate irrigations or rain fall events Figure 4 Final Drain Gauge installation
25. ter 15 Drain Gauge User s Manual 3 Theory Depth of Installation In any soil profile there is a zone of recharge and seasonal depletion extending to the bottom of the root zone Since root density decreases with depth the bottom of this zone may be difficult to locate In annual crops it is typically around 1 m 3 ft but can be much deeper in perennials There is of course a practical limit to how deep the Drain Gauge can be installed With shallow rooted crops this is not an issue but with deep rooted plants one may need to strike a compromise between getting below all roots and installing the Drain Gauge at a practical depth Even when roots go quite deep the amount of water taken up by these roots may be quite small Another consideration is the depth of the water table The water table depth must always be below the bottom of the Drain Gauge so that water can drain out This might sometimes require that the Drain Gauge be installed at a shallower depth than would be ideal to accommodate the root zone The consequence of installing the Drain Gauge at too deep a depth is that it will require a long time to come to steady state and give drainage numbers that are represen tative The consequence of installing it at too shallow a depth is an over estimation of deep drainage because some water that would have been transpired is intercepted and measured as drainage It is also possible that roots could grow down the w
26. well below the potential root zone or are concerned about the presence of trace amounts of Trifluralin in your solu tion analysis the Bio barrier fabric can be easily removed before installation Simply remove the retaining ring and fiberglass filter that sit above the wick and remove the Bio barrier yellow fabric with black knobs that sits below the un woven portion of the wick Be sure to evenly spread the unwoven wick portion and re fasten the fiber glass filter with the plastic retaining ring before installing the drain gauge Sample Program The following is an abbreviated program that can be used with a CR10X data logger This program outputs the raw mV output from the water level sensor during flushing events so that the flush volume can be calculated during post processing using either a factory supplied or custom calibration The program additionally samples water level sensor mV signal once per hour CR10X Drain Gauge Program This short program is designed to limit the amount of program memory used Note due to minimization this program requires significant post processing Siphon chamber water level mV data are output every hour Additional water level data are output during each siphon chamber flushing event Drainage is calculated using the methods discussed earlier in the manual Table 1 Program 01 1 Execution Interval seconds 27 Drain Gauge User s Manual 4 Collecting Data Shift
27. your DCT in the loca tion in the location where you wish to take your mea surement Finally dig the hole for the wick section according to Method 1 Installation Wick Section 1 Cut a slot into the soil at the top of the wick section hole so the tubes and wire can pass under the edge of the middle plate without damage Make sure the protective PVC pipe is installed in the hole such that the top of the pipe is flush with the bot tom of the DCT hole and that the notch in the PVC is aligned with the slot you just cut in the soil Then care fully lower the wick section into the hole being espe cially careful not to kink or break the sensor wire and calibration and sampling tubes The plate should rest on the shoulder around the wick section hole flush with the top edge of the PVC pipe The tubes and wire should pass out through the notch in the PVC pipe and the slot in the soil Drain Gauge User s Manual 2 Installing the Drain Gauge 3 After the lower section is installed check to make sure it is roughly level Apply a 2 cm 3 4 in thick layer of diatomaceous earth included in your Drain Gauge kit on top of the fiberglass fabric The diatomaceous eatth will enhance the contact between the soil in the DCT and the fiberglass wick Note in order to make sure there is enough space beneath the Drain Gauge for proper drainage DO NOT pound the wick tube into the ground This can lead to improper drainage and potential
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