Tuesday, 21 March 2017

Wildlife and washoff

We have been getting some nice rain recently (although according to my correspondent Paddy Hanrahan we need more).  This has led to an outbreak of fungi along Widgiewa Rd.
Later in the day we came across a puffball ...
 .. and some field mushrooms.
The weather has also caused frogs to be very evident in and around the house.  On a recent evening I found these 2 sitting at the bottom of a window.
 My best guess at an ID for this one was a Broad-palmed Frog (Litoria latopalmata) but on listening to its call I have never hard anything like that on our property.  My second guess is Common Eastern Froglet (Crinia signifera) which is quite common in the area.  However a Frogwatch expert has identified it as Litoria verreauxii- whistling tree frog
 The other is a Perons Tree Frog (Litoria peronii) aka The Usual Suspect).
Interestingly, this morning 21 March we went to check that the water pumped satisfactorily to the main tank and found a Peron's Tree Frog sitting on the float in the big tank.  No idea how it got there!

The early morning (around 5am) of 21 March was notable for a pretty severe thunderstorm.  This dropped 7.6mm of rain on us in about 10 minutes.  A first consequence was scouring on the drive.
 A second consequence was washing a lot of charcoal flakes into the Creek!


It seemed that most of this black stuff came down from a small gully which I have never noticed running when it was vegetated.
Looking at a topo map suggests the catchment of this gully is as shown by the red dashed line.

Switching to Google Earth gives this polygon for the catchment of the gully, which measures 2.8Ha.  
 I hope in what follows I have got my zeroes right.  2.8 Hectares is 28,000 square metres and putting 7.6mm of water on to that gives 212.8 cubic metres of wet stuff.  This resolves to 212,000 litres of water arriving almost instantaneously on a baked, largely vegetation-free landscape.  No wonder there was a bit of run-off!

(Another way of looking at 212.8 cubic metres is an ice cube 6m to a side!)

After lunch another storm came through dumping 10+mm of rain in short order (taking the day's total to 17.8mm).  Here is the gully discussed above shortly thereafter.
A few metres upstream more water was flowing in:
A few more shots of the runoff.  This is runoff channeled around the garden which ends up coming down beside the drive.
 Heavy flow in the creek.
 Runoff from the Northern side of block coming into the Creek.
For various reasons I ended up later in the day on Captains Flat Rd where Whiskers Creek goes under the road.  The soot etc hasn't made it that far yet - although I suspect the liquid has an unusual chemical composition.  The first image looks North (towards the Molonglo) ...
 ... and the second South (ie towards home).


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