Sunday, 31 December 2017

Rainfall and Whiskers Creek

Starting in 2010 I have recorded the flow in Whiskers Creek on a daily basis.  I began this, thinking that it might be useful in some way to the Waterwatch project which monitors various aspects of water quality in the watercourses of (inter alia) the Queanbeyan and Molonglo River basins.  Each month I send off a report of the daily flow ratings and rainfall and they get added to the information bank.

However, until now I have never tried analysing the data myself.  Given the difficulties I have found in compiling this post that is possibly not surprising!

Cutting to the chase, what the data suggests is that if there is:
  • a high amount of rain there will be a high number of days with higher flows; or
  • a lot of days of light rain gives a low number of days with higher flows but a high number of days with lower flows
That would seem to be somewhere in the vicinity of a statement of the bleeding obvious, but does at least suggest the quality of the data is reasonable!

The monitoring site is where our driveway crosses the Creek by means of 2, 1m diameter, pipes.  One of the pipes takes the primary flow while the other only gets active in heavier flows.

The flow codes are fairly subjective and the words chosen are such that they sort alphabetically in order of strength of flow:
  • Zero; the pipe under the driveway is dry.
  • Trace; the pipe isn't dry but the sound of running water isn't audible unless close to the outlet;
  • Light: one pipe running noisily;
  • Heavy: both pipes running;
  • Flood: water is across the drive.
I also use a code of "absent" to indicate when we aren't there and thus no readings of Creek flow  are taken.  Over the 8 years of recording we have been at home between 304 and 347 days.  I'm not sure that this makes much difference but have expressed the flow code results as percentages of days present.

Rainfall has been recorded one way or another whether we have been present or not.  I have looked at 5 measures of rainfall - all are quite obvious in their definition.
  • Annual rainfall in mm;
  • Number of days with a fall >5mm;
  • Number of days with any rain recorded;
  • Number of days with 0.2 -5mm of rain;
  • Proportion of rain-days with 0.2 -5mm of rain.

My first way of looking at the data was to chart the % of days in a year for each of the 5 flow codes.

That chart is a bit too complicated to make much sense of, beyond illustrating that in most years the incidence of codes usually follows the alphabetic order (ie most zero, least flood etc).

To try to reduce the complexity I combined the three lowest values and the two highest.  I then looked at the correlations between those two series and for measures of rainfall.   The correlation with heavy-flood has the same number as for the zero-light range , but with reversed sign (ie if one is -0.87 the other is +0.870.  That has logic, but I can't prove why it's so: trust me, this is on the internet so must be true. (I suspect it is something like a zero-sum game - if one item is big the other must be small: this applies to both the flow codes and measures of rainfall.)

Since the combination of flow codes above was more or less chosen arbitrarily I also looked at a few others: combing zero and trace (and thus light - flood); and just looking at zero .  None of them had significant (using the word loosely) values of the correlation coefficient.  The largest measures of correlation were between the 3+2 flood codes with mm of rain (+/- 0.87) and proportion of days with 0.2 -5mm of rain (+/-0.78) so I will concentrate of them.

In initial contemplation of this I realised that I was guilty of Bad Thinking (or possibly Not Thinking) because I should be focusing on the strong positive correlation of r=0.87 between amount of rain and heavy - flood creek flow

 rather than the equal but negative relationship with lower flows.

Note that in the first chart the lines move, more or less in the same direction while in the second they move in the opposite direction.

The conclusion is that with a lot of rain I observe more days with heavy flows.

When thinking about correlations with number of days with some, but not much rainfall, I will only show the comparison of days with light rainfall and zero-light flow. (As demonstrated above the chart for heavier flows would be the mirror of this one.)
Again the two series move in the same direction in most cases.   My conclusion here is that with a high proportion of days with low rainfall there are not enough days of heavier rain to generate heavy or flood flows.  This is the zero-sum situation referred to above. 

Wednesday, 27 December 2017

Wasps potter around

It is quite common to find wasps building their nest around our house.  While they do indeed potter around, on consulting Roger Farrow's ecological guide to the Insects of South-Eastern Australia I find that these are in fact mud-dauber wasps Sceliphron laetum. 
 All the nests seem to start out like the one shown, but some of them seem to have been decorated - if this is the correct word - with additional layers of mud.
 All the nests comprise cells such as this.
 A paralysed caterpillar is placed in each cell, providing food for the wasp larva which develops in there.

Tuesday, 26 December 2017

4 weather forecasts

I have just looked up 4 weather forecasts for Canberra (or near thereto) the next few days.  I was mainly interested in the likely rainfall. 
Basically pay your money and take a random number!

Unpaid work

In the past the Census only concerned itself with traditional market based employment.  More recently it was widened its scope to include some information on other aspects of employment, notably domestic work and volunteering.  I wouldn't want people to think I'm a stick in the mud so here is a little information about those two aspects of Gazette area activity.

Domestic work

This includes work that the person did without pay, in their own home and in other places, for themselves, their family and other people in the household, in the week prior to Census night.

I can't remember how I answered the Census question (and it was complicated by us being on a camping trip in Queensland at the time) but would be surprised if a two person household (who mainly eat at home) would put in less than 20 hours on these tasks per week.  I'm not sure how much extra time is added by additional people and expect quite a bit would be reduced by eating out (eg lunches at work).  The impact of larger households can't be examined as Table Builder doesn't enable tabulation of Person Data with Household data - in this case number of hours of domestic work and size of household.

The most common analysis of this variable is to look at the traditional/stereotype of women doing the majority of these duties within the household.  That is reflected in this first chart.
I wondered whether the extent of paid employment had an impact on this comparison, so restricted the analysis to full time workers.  There is still a difference between the sexes, but as expected having a full time job does reduce the amount of time put in to domestic duties.
 I thought it might be interesting to combine the two approaches so the next two charts compare total responses to the domestic question and responses by full time workers  for males and females.

To me the outstanding feature of the analysis is the fact that close to 50% of females with a full time job devote 5 -14 hours to domestic work.

Another aspect of stereotyping is that parents do most of the domestic chores while the children are excused such duties.  As the Census question is restricted to people aged 15+ that cant'really be shown.  However it is possible to look at the way domestic duties change by age of the person.  As the hours of domestic work are given in ranges I approximated the actual hours as the mid-point of each range and then calculated the average hours for 10 year age groups.
Bearing in mind the dodgy averaging process this shows a believable picture with hours of domestic work rising in the first two groups and then largely flattening out.  To really look at this would require some form of analysis that looked at age, employment status and household size in one go.  I have neither the data not the analytic tools to do that.


This item records people who spent time doing unpaid voluntary work through an organisation or group, in the twelve months prior to Census night.  It excludes work done:

  • as part of paid employment
  • if main reason is to qualify for Government benefit; obtain an educational qualification; or due to a community work order; or 
  • as part of a family business.

  • Overall 23.3% of people aged 15+ in the Gazette area volunteered.  This contrasts with 19.0 people in Australia as a whole: to quote young Mr Grace "You've all done very well."  (Or at least 23.3% of you have!)

    My first thought was to use a time-budget approach by cross classifying the volunteering rate (ie the % of people in a group who said they did volunteer) by Labour Force Status and sex.  I have included people who did not give a response to this question in the total.  In effect this is saying that no answer = an answer of "No" and conforms with the well known situation that if a true response makes people feel uncomfortable (eg guilt about not volunteering) they'll leave the question blank.
    The most interesting part of this is the contrast between the sexes for the "Other in LF"category.  This is effectively unemployed people.  I'm not going to try to hypothesis why this is so.

    The next approach is to look at the age-specific rates.  As it is easy to do I cross-classified by sex.
    The extremes are the most interesting with a high proportion of females aged 15 to 19 volunteering and no males aged 80 to 89.  Obviously young adults have other things on their minds than volunteering!

    Again this could be the subject of much multivariate analysis if I had the resources (and/or knowledge) to do so..

    Monday, 25 December 2017

    Keeping occupied in the Gazette area

    The remaining major element of the workforce data from the 2016 Census is the occupation of people in the area.  While "industry" relates to the goods and services produced by an enterprise "occupation" covers the tasks performed by the individuals who work for the enterprise.

    I'll start this by comparing Industry and Occupation in the Gazette area.  Its a bit messy and uses abbreviated titles but I hope you can work out what's going on!
    Prim inds Manuf' + Utilities Const  Retail W'sale Trade Accom Food Transp + media Finan servs Public Admin Educn  Health Care  Arts etc  Inad and N/S
    Man'rs 21 10 16 24 5 8 22 69 0 12 10 10
    Prof''als 0 5 3 0 0 6 37 68 48 35 7 6
    Trades 6 19 65 8 6 7 8 6 0 3 15 6
    Services 0 0 0 0 10 0 0 20 14 27 12 0
    Clerical 3 8 17 7 4 11 28 78 3 12 10 8
    Sales 0 5 0 42 3 0 9 0 0 0 0 0
    Oper''rs 0 3 16 0 0 12 0 0 0 0 0 3
    Lab'rers 8 0 15 0 8 0 4 3 3 0 3 4
    A key point is that most Industries employ people in a range of Occupations.  By and large the distribution of occupations within a group is as expected (eg Retail mainly employs Managers and Sales staff, while Health Care has Professionals and Service staff).

    The distribution of gazette area residents across Occupation groups is shown here.
     Looking at the number of females per 100 male workers also gives some interesting numbers.  I'm not surprised that there are few female Farmers or Tradies but to have no female Machinery Operators or Drivers is a surprise.
    I thought it might be interesting to compare the ratios for the Gazette area and Australia.
    They are astonishingly similar.  I attribute the zero value for Machinery Operators or Drivers as a function of the small size of our area (and even for Australia the female work force is only 11 per 100 males compared with 18 for Trades and 54 for Labourers) .  We do have a slightly higher femininity ratio for  both Professionals and Managers.

    While comparing the Gazette with other areas lets have a look at the % of people in Occupation Groups for the Gazette area and Queanbeyan.
    It will come as no surprise that there are a higher proportion of Professionals and Managers in the Gazette area and a higher proportion of Labourers and Machine operators in Queanbeyan.  However the categories which particularly struck me were the much higher proportion of Services and Sales staff in Queanbeyan.  This clearly indicates the role of the former City as a nodal centre for the rural catchment.

    The cross classification of Occupation Groups by Income Groups is pretty much as expected.
    It is no surprise that more than 50% of Managers and Professionals reported incomes above $91,000 in the previous year.  At the other end of the scale it could be expected that the largest income group for Labourers and Operators etc is $26,000 to 52,000.  It was a little surprising that over 50% of Sales Workers were in the lowest income group, <$26,000.  An obvious reason for this is that the Sales Workers are all part-time workers, with 2/3 working less than 16 hours per week.  The next chart shows this (with the same information for managers included as a contrast)

    Wednesday, 20 December 2017

    COG does the AIS

    21 members and guests gathered at a warm, dry and calm AIS car park.  Despite moving into summer mode and gathering at 0830 to avoid the heat it was already 28.5C according to the Jetta's thermometer.  Here is a graph of the 2 days temperatures at Carwoola.

    This did not deter our first target species - Superb Parrot - of which 6 were seen before the sign on sheet was completed.  2 of these were recently fledged young, seen being fed by adults.  Others of this species were seen overflying by most of the group at various stages.  Fortunately for our Canadian guests a female posed very clearly in a eucalypt as we returned to the cars.

    We proceeded down to the wetland adjacent to Ginninderra drive which was unfortunately devoid of the hoped-for Australasian Bittern. Indeed, the only member of the Family Ardeidae was a good number of Australian White Ibis, mainly exploring the ground outside the tennis courts.  At the wetlands the most significant sightings were dependent young of each of the common Rallidae (Australasian Swamphen, Eurasian Coot and Dusky Moorhen).

    Moving around the campus we found a clan of 6 White-winged Choughs occupying a nest which had shown some chicks therein.  
    (Later in the outing a second group of 18 White-winged Choughs were observed. )  The nesting Choughs were soon followed by a Sulphur-crested Cockatoo emerging from a hollow.  
    A good number (at least 10) Red-rumped Parrots were found 

    ... as were 11 Crested Pigeons.

    It was surprising (to me if no-one else) that the return through bush along the foot of Bruce Ridge added only one species (Noisy Friarbird) to the trip.  Perhaps that is what happens when an area is bisected by a highway and subject to very frequent proclaimed burns.

    Through the day representatives of many species of bush birds were seen giving a total of 40 species of which 6 were at various stages of the breeding process.  A full list is here.

    Monday, 18 December 2017

    Feeling the heat

    We are currently experiencing a disgusting spell of hot weather.  I am reminded of a couple of lines from the poem "Integrated Adjective" by John O'Grady:
    ".... drinkin' beer and arguin' an' talkin' of the heat, 
    An' boggin' in the bitumen in the middle of the street; "
    This post started off "talking'of the heat,"and in particular the heat of December but then wandered off into general issues of maximum and minimum temperatures.  I have discovered that there appear to be a few anomalies in some of the temperatures recorded for Carwoola between 2000 and 2006(ish) but they appear to vary somewhat according to the variable being examined. 

    My conclusions thus far are that
    • there seems to have been a change of an unknown nature to site conditions in the early noughties;
    • in most cases, more recent data appears to correlate well with data for Canberra airport;
    • for the principal use to which the Carwoola series is applied - general interest information for residents of the area - the series is probably fit for purpose; but
    • if it is applied to matters requiring more rigour only the data since 2010 should be used.
    In what follows I have marked some text in blue to indicate a general grizzle about parts of the BoM system.  They can be ignored  at no risk to the overall narrative.

    The main attribute of this heatwave so far has been its duration, and forecast continuation, but it led me to contemplate maximum temperatures in Carwoola for past Decembers.  That in turn led me to ponder the equivalent annual maxima.  On raising the findings of these musings with some folk who know about meteorology severe doubts (which I now share) were cast on the peak annual maximum of 45.1oC recorded on 24 January 2001.  So I explored the BoM climate data online series to find some local benchmarks, finding two sites which together fill my needs;
    • Station 070014 Canberra Airport Comparison NSW (now closed but contains readings from March 1939 to November 2010); and 
    • Station 070351 Canberra Airport NSW (still open containing data from September 2008 until November 2017).
    In case you wonder why 'NSW' is mentioned in the station name it is apparently because the ACT is part of the BoM administrative region and it is too difficult to change the database system to reflect the Constitution (and/or the ACT being self-governing).  Words - or at least polite ones - fail me!!!

    Whatever: here is the graph of the series for Carwoola and Canberra. 
    It is important to note that the BoM series is of "Highest Temperature" as the series including the word "Maximum" is Monthly Means.  (As another aside each observation in the Highest series not only has the temperature but also the date on which it was recorded.  While interesting, it becomes a major pain to select only the temperature data if, as in this case, it is that in which one is interested.  Again, my search for polite words comes up empty!)

    Eyeballing the chart shows that the two series match quite well apart from the years 2000 to 2006.  This led me to investigate the history of the Carwoola series. 

    • It was at one site until 2010; when 
    • the device was moved to a second location; and then 
    • since 2014 a third location (and different device) has been used.  

    I have been able to contact the recorder for the period 2010-13 and he suspects that there may have been a temporary change in the earlier site (eg a tree being pruned, leading to more direct sunlight hitting the sensor) over the period of difference.  However it basically gets into the category "Interesting but unknown"!  

    For what it is worth (not much) the overall Correlation Coefficient is 0.64.  The level of agreement since 2013 is very good.

    I decided to repeat the exercise for annual maxima .
    Much the same picture is presented although while Carwoola is higher from 1999 to 2007 the pattern of variation in the BoM series between 2000 and 2006 is matched rather better.  As a consequence the overall Correlation Coefficient is higher at 0.73.

    Having looked at the highest temperatures I wondered what might be revealed by looking at the Average Maxima for December and Annual periods might show.  (For simplicity I have only used a single line in these graphs: the comments above about site shifts still apply.)

    The first chart is for December and closely resembles the Highest Temperature Chart.
    The next chart is for Annual Mean Maximum.
     Much of the pattern is similar to other series.  The significantly lower readings from 2014 onwards are interesting.  As a case study I compared the daily maxima for 2015 between the two series.  In that year nearly every day from February to August showed a Carwoola maximum more than 1oC below the Canberra value.  Only in November and December was there more than a handful of days in which Carwoola was warmer.   Given that Carwoola is about 200m higher than Canberra this would seem quite believable.

    For the sake of completeness I have also looked at the Average Monthly Minimum Temperatures, with an expectation that Carwoola would be cooler than Canberra.  This would reflect both the increased elevation of Carwoola and, in Summer, the greater exposure to the cooling Easterlies in the evening.

    My expectation is met!  I find the "closing of the gap" between 1997 and 2000 interesting, as is the slide in Canberra minima following the shift to the new site in 2010 (just because its BoM data doesn't make it free from error) and the subsequent resumption of situation normal.

    Sunday, 17 December 2017

    From the sunroom

    We are spending quite a bit of time in the sunroom at present as it is out of the direct sun for much of the day.  When it gets really hot we head up to the lounge and turn on the AC!

    When I went down this afternoon Frances drew my attention to a Jacky Lizard on a stump in the garden bed.
    With a tail that long it has to be a Jacky Lizard!

    As is usual for this time of year, and despite the unpleasantness in February, the Red Hot Pokers (Kniphofia sp) are flowering well.  They are (also as usual) attracting Honeyeaters.

    Noisy Friarbird
    I have included this second shot of a Friarbird because it shows the yellow from the pollen so well. 
     An Eastern Spinebill: as usual this little blighter wouldn't stay still long enough to get a decent photo.
    A Red Wattlebird turned up and flaunted its wattles until just before I pointed the camera at it.

    Friday, 15 December 2017

    progress report n+x

    This morning I was up in the top paddock and was pleased to find that the dam up there was completely full.
    I was also pleased to see a Long-necked Tortoise swimming about.  I was astonished onreviewing the photo to see a small face peering at me! 
    The reason for my presence in the paddock was some guys from Active Tree Services  had come to knock over a dangerous tree.  It took Essential Energy about 4 months to approve the submission they'd put in.

    The guys spent a few minutes working out out a plan.  Very wise when a possible outcome of not planning is getting a large Yellow Box falling on you!
    A relatively thin rope was pulled up into the tree - arrows mark the rope - and after tightening it was tied to another tree some distance away.
     Sawdust was made.  on the fall side of the tree ....
     ...  and the other side.
     The non-wielder of the Stihl leant on the rope.
     And down came the tree.
     Many hours of harmless fun to come in cutting it up.

    Meanwhile back at the ranch our new big shed had arrived.
     Work on the wire sides of the vegie garden is almost complete
    I am almost ready to say we are moving towards getting there.

    Weather of 14-15 December

    Carwoola has recently been having a heat wave (the maximum today - 15 December - is slated for 28oC so the sequence will break briefly).  Yesterday was interesting in that the day was mainly cloudy which kept the temperatures not too bad although the maximum of 33.6oC was a bit ugly.

    Here are the temperature through the day.
    I have highlighted 3Pm and 5PM as that is when very brief showers (not enough rain to register on the weather station) occurred, showing up as little dips in the high temperature line.  as soon as the showers passed the temperature went up again.

    The midnight temperature of 20.5oC is also notable.

    There has been more significant precipitation early on 15 December with 4mm by 06:45.  The coolness and dampness has got the fire danger back to Low/Moderate.