Last month I took my Amateur Radio Foundation Licence exams, and Ofcom have now granted me a call-sign, M6TKG. I’m planning on taking my intermediate exams early next year, but for now I’m going to explore some mobile analogue voice and digital text modes, alongside my existing interests in decoding ACARS and ADS messages used in aviation. As I found myself doing more and more diagnostic work on drones (2.4GHz digital, bluetooth, WiFi, GNSS), telemetry (GSM), emergency beacons (406MHz) and satellite telephony (SPOT, Iridium), I thought I should improve my working knowledge of radio. Amateur radio is actually really rewarding, and a practical way to learn about electronics and radio. It was a generous leaving gift from the staff in Geography at The University of Southampton that enabled me to buy the course texts and my first radio transceiver – thanks!
Author: Tom Bishop
New Core Splitter
I’ve just taken delivery of a core-splitter made by Helmut Kawohl in Germany. He personally delivered the rig and it is absolutely excellent! I’ve seen cores split all sorts of different ways over the years – hand and electric saws, Dremels, tile cutters – none of which were ever particularly satisfactory (or safe!). This new rig makes perfect cuts in plastic tubing (haven’t tried metal yet) – for large bore core it can also usefully put double cuts in so a slab can be extracted from the centre.
Helmut has drilled fixed positions for the adjustable surfaces to accommodate our most used core tubes, but the cutter is fully adjustable for any diameter and wall thickness, and can split cores up to 1.5m long.
Core cutting will no longer be a messy, unpredictable team operation!
Replacement of an Old Logger
Back when I worked down south I used to head off every few weeks to service some legacy logging stage gauges in the New Forest. These were running some very old Skye Instruments DataHog loggers connected to an unidentifiable pressure transducer. I wanted to replace this with a system that would require less maintenance and fit with an expanding fleet of loggers in Southampton. I used a Delta-T Devices GP1 but removed the circuitry and fitted it to a different IP64 housing. This had the advantage of having two large screw entries, one of which is large enough for the cable to a Druck PDCR1830 pressure transducer and the other was fitted with a membrane breather plug. This has the advantage of running of a single 9v battery for around six months, and maintaining pressure equalisation for the transducer.
Bill of Materials:
- Delta-T Devices GP1 datalogger
- Bulgin BE03P 80 x 139 x 53mm enclosure
- Bulgin BE123461 M20 cable glands x2
- Hylec JDAE12PA/SW M12 venting element
- Lapp Kabel SKINDICHT light grey KU-M M20 x 1.5 Male/M12 x 1.5 Female Adaptor
- Druck PDCR1830 pressure transducer (options as required)
Simple Single Ring Constant-head Infiltrometer
Here’s how to make a very simple single ring constant head infiltrometer – it could be particularly suitable for school projects at key-stage 4 or 5. Commercially available double-ring infiltrometers with a Mariotte’s bottle would be more suitable for research purposes, but these can be surprisingly expensive.
How To Make It
You’ll need:
- A piece of downpipe (I’ve used 68mm PVC pipe)
- A bottle (I’ve used a Nalgene #2089-0032 1l bottle)
- A rubber bung to fit the bottle (I’ve used a BS2775 #25)
- Two brass tubes (c.4mm ID)
- Access to a 3D printer (or use a 3D printing service) to print the adaptor
- A tube of 2-part epoxy (I’ve used Araldite #ARA-400007)
- A drill and some c.4mm drill-bits
- A stopwatch
Drill two holes in the bung to fit the brass rods, and insert them. Measure the bottle and the downpipe and design and print an adaptor (or use/adapt the 3D model from here). The adaptor is entirely optional – it is only there to neaten things up and allow hands-free operation. Now glue the adaptor onto the bottle using the two-part epoxy, put the bung/pipe assembly in, and fit on-top of the downpipe. You should also drill a small hold into the downpipe just below the adaptor fitting to act as a vent. You will need to put calibrated marks on the bottle in order to measure volume – I suggest filling the bottle and decanting into a volumetric flask, marking e.g. every 10ml.
How to Use It
To use, push the downpipe about 5cm into the sediment, and adjust the brass pipes so one is 10mm from the soil surface, and the other slightly more (perhaps 13mm). Fill the bottle, fit the assembly onto the downpipe and immediately start a stopwatch. Record the water level at regular time intervals appropriate to the rate of flow – this might take some experimentation. Remember to carry a supply of extra water! The data should be processed to convert it to flux, in cubic meters per second. Typically the flux will stabilise after some time – the flux at which it stabilises is referred to as the “(quasi-)steady-infiltration rate”.
How to Process the Data
The aim is to establish a soils hydraulic conductivity, or “field-saturated hydraulic conductivity”, expressed as . There are two main groups of equations that can be used: those that recognise the lateral flow, and those that only recognise the vertical flow. I’ll illustrate a couple of simpler models here, but check the references below for detail of the theory and limitations. Both the examples given here require the steady-infiltration rate mentioned above.
Simplified Method
Where is the field saturated hydraulic conductivity, in m/s, and
is the (quasi-) steady infiltration rate in m3/s. This method assumes one-dimensional, vertical flow and is known to over-estimate conductivity; see Reynolds et al. (2002) for a fuller appraisal.
Bouwer Method
Where is the depth from the infiltration surface to the wetting front in meters (or, the depth of soil),
is the water height in meters, and
is the macroscopic capillary length parameter in m-1 (Bouwer, 1966, 1986). Choosing a value of
is important but can be difficult; in the table below I’ve paraphrased some common values from Reynolds et al. (2002) , table 2.4-4 (p.820).
| Soil Type | (m-1) |
| Compacted, unstructured, clayey or silty materials e.g. lacustrine or marine sediments, landfill caps. | 0.0001 |
| Fine textured, unstructured soils (clayey or silty). Also fine sands. | 0.0004 |
| Most structured soils from clays to loams, unstructured medium to find sands. Most frequently used for agricultural soils | 0.0012 |
| Coarse and gravelly sands, or highly structured, largely cracked, or aggregated soils, or soils with macropores. | 0.0036 |
Some main sources of error are:
- that the small sample area may not be representative of the study area
- this could be tempered by taking a number of measurements across the study area and making an appraisal of the consistency of otherwise of the results
- the soil is disturbed by the insertion of the infiltrometer ring
- this is largely unavoidable, but some care can be taken to gently insert the rings, and to ensure they aren’t jostled or wiggled as they are handled
- that there is edge flow that causes an over-estimation of the hydraulic conductivity
- edge flow is when water takes a “shortcut” by running along the side of the infiltrometer ring wall.
- the model used in calculating hydraulic conductivity is insufficiently accurate
- there are a range of models – see for example the work of Reynolds, Wu or Young’s as alternatives to the simpler models presented above.
- the assumptions of the model cannot be met. For example, ponding of water outside the ring is incompatible with some models.
Leaving Southampton, Joining Manchester
Yesterday was my first day in my new post at The University of Manchester; I have taken up an exciting new position as laboratory technician and join a team with John, Jon and Pete. I had been at the University of Southampton since 2009, initially as a PhD candidate, then as a laboratory technician, so it was a difficult farewell after all those years. I do, however, return to the department where I read my undergraduate degree in Geography (in 2006!), and I’m looking forward to the opportunities the new post in Manchester presents.
So far I’ve seen well-appointed laboratories that seem to be very busy! Over the next few weeks I’ll be taking over some day-to-day running of some of the facilities, and developing a plan with John and the team for some improvements over the next few months. You can find out more about the laboratories here.
El Chorro Fieldcourse 2016
I’ve just got back from assisting with our 2nd year field-course to El Chorro, near Malaga in Spain. The format consists of a couple of days of site visits interspersed with group and individual project work. On project work days students conducted projects on geomorphology, geology and ecology, including studying some of the exposed geological sections, tafoni and related erosional landforms, controlling factors on vegetation and soil types, and “bad-land” soil and geomorphology. Others still made studies of river flow dynamics and landslide hazards. On site visits we had to opportunity to visit many of the large dams that define the areas economy, as well as my personal highlight, a visit to the Caminito del Rey, a now preserved ramshackle path made around the turn of the last century from concrete, railway sleepers and tracks, perched perilously above one of the deepest and steepest gorges in the region. Originally built out of necessity for the dam building projects in the area, it later became a playground for adventurers, attempting to traverse the increasingly dangerous path. It is now restored and preserved and tourists can enjoy a walk along the entire length of the path. We also visited the limestone plateaux at El Parque Torcal, which features some limestone features that could be taken directly from a textbook!
Whilst we had some personal time we also made a visit to The Cave of Ardales, which features hundreds of examples of prehistoric cave art, including numerous depictions of animals, as well as rare negative hand impressions (manos negativos) made by blowing paint from a cup, using a tube, over a hand placed on a wall. Some of the art is dated at well over 20,000 years B.P. and the guided, small group tour led by a knowledgeable local volunteer was really special.
From a technical point of view: most notably, the students got their hands on the M9 River Surveyor and a Leica TS06 Total Station, and at the other end of technological sophistication, the constant-head infiltrometers I made a few weeks ago (blog post to follow)! Unfortunately our 3DR Solo survey drone didn’t get an outing as the weather was very windy for the duration of our visit.
Refurbished Logging Tipping Bucket Rain Gauge
I found an old tipping bucket rain gauge knocking around stores. It wasn’t like the plastic funnel jobs that flood the market – it was a proper stainless steel gauge. Although it’s accompanying datalogger was long gone, I thought there might be a little life left in it. I tested the reed switch with a multimeter and it seemed to be in perfect working order, so I bought an inexpensive Tinytag Plus Re-Ed count input datalogger (TGPR-1201) with cable (CAB-3246). I wired this into the reed-switch, calibrated the rain-gauge (it was pretty close to the calibration printed on the unit) and programmed the logger to report in mm/hour. After a big scrub its ready to use – I look forward to seeing the first data produced with this kit.
Fieldwork Manual Handling
Sometimes manual handling of heavy or awkward equipment gets overlooked in the field, often because the correct equipment isn’t available. Here’s some handy things I found to make life a little easier in the field.
Tipke Foldit Folding Cart
This cart folds completely flat so it fits easily in the car or shipping pallets. It’s available in the UK from www.utilitycarts.co.uk. It’s seriously helpful for shifting kit across small sites.
Alps OutdoorZ Commander Freighter Frame
Frame rucksacks are difficult to come by – especially good ones. I’ve been through a few from local army surplus, but I finally caved and imported this model via an eBay seller. Its designed for American hunters, but it has excellent straps (including extensions) and padding and is great for longer hauls of large boxes or coring equipment. Rucksack by Alps, clothes models own.
SporTube Ski Tubes
Ski tubes are perfect for coring rods and core heads. SporTube make hard plastic cases of adjustable length. They have well engineered wheels and a clip on handle, and are lockable. Their wider ski and snowboard models can fit an entire rod-driven coring system. They are great for getting kit through airports, and can be easily strapped to roof-racks for transport. They are available in the UK from www.edgeandwax.co.uk but there’s a good second-hand market on eBay and Gumtree.
Chironomid Preparation Video
When I was a doctoral candidate, I, alongside my colleague Hayley Goodes produced an instructional video to explain the procedure for preparing sediment samples for the analysis of sub-fossil chironomids. This was meant to be part of a wider series of video method statements to be used internally, but my thesis got in the way and we didn’t make any more. One day I hope to return to this idea and produce a series of these. In the meantime I thought it totally useless sitting in my old files, so I thought I’d share it here.
The method is adapted from Brooks, Langdon & Heiri (2007). It doesn’t expand to cover the procedure for picking and mounting specimens, so I’ll just say that they are picked from a Bogorov sorting tray into a glass staining block (Brunel Microscopes), using fine forceps (Ideal-Tek 5.SA and 5TTH.S are my personal favorites, available from Farnell), and mounted using either Euparal (available from Agar Scientific or Asco Labs), or Hydromatrix (Micro Tech Lab) under 6mm coverslips (VWR #631-0168). Need a Bogorov tray? I have a stock of trays modified just for chironomid work for sale – click here for more information.
Brooks, S. J., Langdon, P. G. & Heiri, O. (2007). The identification and use of Palaearctic Chironomiae larvae in palaeoecology. QRA Technical Guide No. 10, Quaternary Research Organisation, London. 276pp
Peat Coring Video
We use a variety of systems for extracting cores from bogs and lakes. Here’s a video we made a few years ago of how we use a Russian Corer to extract a 50cm long core from a peat bog. This bog is around six meters deep, so we extract a sequence of cores that, together, form an uninterrupted sample of the entire depth of the bog.
Peat bogs accumulate over time, as living things die but do not decompose in the wet conditions. This means the material at the bottom is the oldest, and the material at the top is the youngest. Radiocarbon dating and other methods allow us to establish exactly how old, and microscopic analysis of the material allows us to reconstruct changes in conditions of the bog through time.