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#1195612 - 25/05/2013 16:21 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
In the process of understanding a possible relationship / connection between rainfall / upper-soil moisture estimates and relative humidity locally in the Adelaide Hills smile .

Question: can knowing the advection of moisture (precipitable water) in advance of a possible rainfall system (and through it, the relative humidity) provide information about soil conditions / streamflow to come?
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#1196204 - 29/05/2013 12:48 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
Increasing probability of moderate falls (10-20 mm, possibly 20-40 mm over 3-4 days) in the next couple of days (BoM, WZ) - will moisture levels be enough to lead to a moderate change in water level, or even flow?

River has not been flowing properly for months.


Edited by -Cosmic- (naz) (29/05/2013 12:51)
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#1196412 - 30/05/2013 16:45 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
There is the potential for a sharp change in 500-1000 mb thickness (GFS) between today and the 2nd of June 2013, Central SA.

The probability has increased (30th May 2013) sufficiently that the rainfall amounts previously indicated are highly likely within SA, with higher falls possible locally.

The response of runoff could also be potentially sharp due to the infiltration of moderate quantities of moisture into the upper soil layers in recent weeks the paddocks are green, but the river is not flowing.
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#1196730 - 31/05/2013 21:19 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
The response of runoff could also be potentially sharp due to the infiltration of moderate quantities of moisture into the upper soil layers in recent weeks the paddocks are green, but the river is not flowing.

Bold Added.

River is flowing (audible - roaring), water level has risen dramatically (8.40 pm CST) - river level has risen 2-3 metres in places in a very short period of time.


Edited by -Cosmic- (naz) (31/05/2013 21:20)
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#1198291 - 10/06/2013 13:37 Re: Streamflow Observations [Re: Seira]
Seira Offline
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2nd Temporary Flash-flood Event, Witnessed 31st May 2013, Upper Onkaparinga Catchment [1st in December 2010]:
See #897948 - 13-11-2010 10:19 PM (very similar):

Originally Posted By: -Cosmic- (naz)
Peak 2009:



The dramatic change in water level (31st May 2013) was predominantly due to a flash flood where the river rose to levels not seen since just before for a minor flood event in early September 2010. This is apparent from the fact the grass and small vegetation growing in the river bed (in the wake, 2nd June) is angled / bent / flattened in the downstream direction. I am thinking heavier rain probably fell further upstream (Charleston / Lobethal). 48.8 mm was recorded on the 31st, with an additional 25.5 mm the following 24 hours (48 hour total 74.3). The river water level (5 pm 7th June 2013) was maintaining 1-2 metres (steady) above what it was prior to the 31st of May smile ...and flowing (just).

Notes:

Although there was not as sharp a fall in the 500-1000 millibar thickness as first thought per GFS (the overnight low reaching zero did not eventuate), the low-pressure system in the wake of the formation of the northwest cloud band passing over Central SA areas seemed to provide ample change (gradient) in the surface atmospheric pressure (from 1009 hPa on the 30th, to 1002 on the 31st, followed by a return to values 1016-1019 the next day) for the diurnal temperature range to narrow sharply over the period 31st May to 6th June. The mean maximum and minimum during that period were about 13.8 and 7.9 degrees C respectively. Beyond the 31st, no maximum over 20 has been recorded (to 10th June).

Coming (3-4) Weeks (as of Monday 10th June 2013):

More rain appears to be forecast (WZ, BoM, GFS) this coming week (Tomorrow-Wednesday, or thereabouts). With the overnight lows falling (2 degrees C on the 8th June) and the maxima remaining about the same (~12-15 degrees), it seems to diurnal range could narrow yet again, this time, possibly, bringing the temperature down further (into the 10 to -5 deg range). One important factor might then be cloud-cover an indicator of moisture in the lower atmosphere. More of this may mean less chance of frosts and vice versa (in theory). Whatever is the case, it appears winter temperature ranges and variations (at least preliminarily) are setting in.

One more note: below is a rough guide as to streamflow conditions or expected conditions under changing moisture levels in the immediate atmosphere and soil environments smile .

Streamflow in context (one perspective, a guide only (winter)):

The streamflow conditions below are satisfied when streamflow remains the state for at least 3-5 days. Longer that 3-5 days may be considered a steady-state period. The threshold for a change in steady-state conditions is about is a lack of rain for 2 days at a rate of 3-4 mm/hour, or vice versa, or about 78-80% sustained humidity over 3-4 days, which is thought to affect soil moisture.

Severe drought conditions: 0-10 cm water level, level of water table (cumulative rainfall totals -3 to -5 metres below riverbank, lack of moisture on intermediate- and deep-soil layers (0 to 5% soil moisture)).

Significant drought conditions: 10-20 cm water level (cumulative rainfall totals -4 to -3 metres below riverbank, lack of moisture in deep-soil layers (5 to 10%)).

Moderate drought conditions: 20-50 cm water level (cumulative rainfall totals -3 to -2 metres below riverbank, all soil layers have at least slight moisture content (10 to 20%)).

Mild drought conditions: 50 cm to 1 metre (cumulative rainfall totals -2 to -1 metres below riverbank, all soil layers have at least mild moisture content (15 to 20%)).

Slight drought conditions: 1-1.5 metres (cumulative rainfall totals -1 to -0.75 metres below riverbank, all soil layers have moderate moisture content (20 to 25%)).

Average conditions: riverbank level 0 metre datum (2 metres) (cumulative rainfall totals yield all soil layers have moderate-to-significant moisture content (25 to 30%)).

Potential flooding: 2-3 metres (water level encroaches on riverbank; cumulative rainfall totals yield all soil layers have significant moisture content (30 to 35%)).

Minor flooding: 3-4 metres (flooding of low-lying areas within 10-15 metres of riverbank; cumulative rainfall totals yield all soil layers have significant moisture content (35 to 40%)).

Moderate flooding: 3.5-5 metres (flooding of low-lying areas within 15-20 metres of riverbank; soil fully saturated).

Significant flooding: 4.5-7 metres (flooding of middle ground within 20-30 metres of riverbank).

Major flooding: 7+ metres (flooding within 30-100 metres of river bank).

Flow rate (velocity) thought to increase exponentially beyond threshold conditions, at higher flow rates there is a possible risk to livestock, property and infrastructure.

Currently increasing cloud-cover and 15 deg C.


Edited by -Cosmic- (naz) (10/06/2013 13:42)
Edit Reason: Corrections
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#1201843 - 30/06/2013 16:22 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
I'm going to ask this once more. I have some information relating to this thread and I find it pertinent to quote:

"Coming (3-4) Weeks (as of Monday 10th June 2013)"

in order for it to make sense. I also (with journal references) will be referring to the Southern Annular Mode, Sub-tropical Ridge and El-Nina Southern Oscillation/Indian Ocean Dipole. Is this possible?
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#1202105 - 02/07/2013 16:51 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
Summary (3 weeks / 23 days later):
Whether or not it rains significantly in the next few weeks may depend strongly on whether the dew point temperature remains mostly negative, or increases sharply enough in a short period of time (hours to days). The former seems (per the last few weeks) conducive to the development of frosts, the latter, rain or hail. From the 31st of June to the 1st July the overnight low increased from 1 to 9 degrees C.


Hypothesis:
A change in the latitude and / or strength of the sub-tropical ridge may provide a mechanism for generating favourable sea-surface temperature conditions off the north-western coast of WA, and assist the development of a north-west cloud-band and subsequent cold front (Larsen and Nicholls, 2009 [1]; Evans et al. 2009 [2]).

[1]: Geophysical Research Letters, Vol. 36, L08708, doi:10.1029/2009GL037786, 2009. Abstract.
[2]: Clim Dyn (2009) 33:477493, doi 10.1007/s00382-008-0461-z.

Streamflow (particularly runoff) appears to be steady though gradually receding.


Edited by -Cosmic- (naz) (02/07/2013 16:54)
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#1202196 - 03/07/2013 10:41 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 7393
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
Originally Posted By: -Cosmic- (naz)
The response of runoff could also be potentially sharp due to the infiltration of moderate quantities of moisture into the upper soil layers in recent weeks the paddocks are green, but the river is not flowing.

Bold Added.

River is flowing (audible - roaring), water level has risen dramatically (8.40 pm CST) - river level has risen 2-3 metres in places in a very short period of time.

For information, one of the most significant and noticeable changes in flow I have witnessed in a short period of time in years. Potentially coincided with an abrupt shift in the sub-tropical ridge per 1st reference in last post.
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#1202203 - 03/07/2013 10:58 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
#1202105 - Edit Note: 30th June, not 31st.
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#1202588 - 06/07/2013 10:19 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
River has responded quite quickly to 35.5 mm to 9 am since the 30th of June, and flow is now fairly steady. Frequent moderate-to-heavy showers continue.


Edited by -Cosmic- (naz) (06/07/2013 10:23)
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#1203285 - 13/07/2013 10:31 Re: Streamflow Observations [Re: Seira]
Seira Offline
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59.9 mm in the 120 hours to midnight on the 8th of July 2013, plus another 21.2 mm, 12 midnight yesterday to 9 am this morning (most of that falling overnight 12th-13th) brings the river to moderate flow conditions.

The guide to streamflow and soil-moisture conditions in post #1198291 may need to be revised.


Edited by -Cosmic- (naz) (13/07/2013 10:31)
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#1203392 - 14/07/2013 09:53 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
The response of the local river water volume and speed to rainfall is becoming quicker with each passing weather system. Run-off is increasing as surface water becomes more apparent. This appears to imply less rain is infiltrating upper soil layers.

Should not next [significant] weather system yield moderate-to-major rainfall, I would think [moderate] flooding is possible (per the guide provided previously).

It also appears that within the space of 3-4 months contrasting weather patterns are emerging this year.
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#1203402 - 14/07/2013 12:06 Re: Streamflow Observations [Re: Seira]
reckless Offline
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Don't see that very often. Currently Brisbane, Sydney, Melbourne, Perth and Adelaide are all on 16 degrees.

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#1203561 - 15/07/2013 21:34 Re: Streamflow Observations [Re: reckless]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Originally Posted By: reckless
Don't see that very often. Currently Brisbane, Sydney, Melbourne, Perth and Adelaide are all on 16 degrees.

Unless it's an error of some kind, today's max in Adelaide was about equal to locally.

Preliminary estimates indicate streamflow could increase from the current approx 0.3 metres to possibly 1.12 (proxy, local obs, also see GFS MSLP maps/Bureau Mt. Barker forecast) within 3-4 days.

[Disclaimer: guide only]


Edited by -Cosmic- (naz) (15/07/2013 21:38)
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#1204327 - 19/07/2013 17:02 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
Written 17th July 2013:

Originally Posted By: -Cosmic- (naz)
Preliminary estimates indicate streamflow could increase from the current approx 0.3 metres to possibly 1.12 (proxy, local obs, also see GFS MSLP maps/Bureau Mt. Barker forecast) within 3-4 days.

[Disclaimer: guide only]

Now ~ 1.5 metres by Saturday 20th July.* [see also flood level BoM]
Update ~ 1.78 today by Sunday. Estimated total rainfall 18th-24th: 64.5 mm* (conservative estimate).

* Valid for 18th to 24th July 2013.

Pressure has dropped and thickness is forecast (BoM, GFS) to fall to perhaps 5340 metres with chance of sleet / snow on higher ground south of about the Flinders Ranges (BoM).

[18th July MSLP 1003 hPa was ~1 hPa higher than forecast by GFS day before.]
Latest BoM flood level (3:38 pm CST 19th July): 0.89 metres, peak 0.96 between 12 midday-2 pm.

Will go with 110-130 mm by the 24th (currently 40.1 mm since 18th), but might change again.
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#1204539 - 20/07/2013 10:58 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
Written 17th July 2013:

Originally Posted By: -Cosmic- (naz)
Preliminary estimates indicate streamflow could increase from the current approx 0.3 metres to possibly 1.12 (proxy, local obs, also see GFS MSLP maps/Bureau Mt. Barker forecast) within 3-4 days.

[Disclaimer: guide only]

Now ~ 1.5 metres by Saturday 20th July.* [see also flood level BoM]
Update ~ 1.78 today by Sunday. Estimated total rainfall 18th-24th: 64.5 mm* (conservative estimate).

* Valid for 18th to 24th July 2013.

Pressure has dropped and thickness is forecast (BoM, GFS) to fall to perhaps 5340 metres with chance of sleet / snow on higher ground south of about the Flinders Ranges (BoM).

[18th July MSLP 1003 hPa was ~1 hPa higher than forecast by GFS day before.]
Latest BoM flood level (3:38 pm CST 19th July): 0.89 metres, peak 0.96 between 12 midday-2 pm.

Will go with 110-130 mm by the 24th (currently 40.1 mm since 18th), but might change again.

Notes of Benefit (for those interested):
  • The estimated flow height depends on the weather being consistently wet for a prolonged period of time; in other words, once the Sun starts to come out or the rain rate drops for more than a few hours below 3-4 mm per hour, this probability diminishes significantly.
  • The 64.5 mm mentioned is conservative, meaning middle of the range. The falls 110-130 mm are therefore an upper limit, meaning they take into account as much as possible.
  • The chance of sleet / snow means showers or consistent and prolonged periods, not just a few flakes or single shower.
  • At least 78-80% humidity or 3-4 mm per hour must be sustained for 2-3 days (under current conditions) for significant flooding to be possible. So far for this period (ending 24th) this has not been the case.
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#1204987 - 22/07/2013 12:38 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
The Woodside Weir water level reached 1.12 metres at 11:38 am this morning. Water is lapping the riverbank in places. See here, link will update.

14.8 mm overnight (6.40 pm to 9 am) brings the system total to 78.2 to 9 am, showers to follow.
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#1206485 - 06/08/2013 21:45 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
After 25.5 mm to 2.30 pm CST today since the beginning of August (this year) the recession rate in the streamflow water level (gradual decline of water level from peak flow conditions towards a steady state) is nearing the 0.2 m mark, per link in previous post. This appears to indicate healthy flow conditions and a moderately rapid response/onset of runoff after moderate rains.


Edited by -Cosmic- (naz) (06/08/2013 21:48)
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#1206711 - 08/08/2013 22:05 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
River Height for King River at Docker Road Bridge (582004, Victoria) at approximately Moderate Flood Level (link will update) at ~ 21:16, 6th August 2013 station time, Other gauges at Minor Flood Level in the area. Forecast (BoM) range 25-100 mm, 8 days 6th to 13th August 2013.

Update: Gauge steady at approx. moderate flood level since gauge time above. Rainfall in the area or near-west 25 to 49 mm (BoM) to 9 am this morning. Currently at gauge time 20:49 8th August water level is 4.00 m. See Victorian Flood Warnings for more information.

Outlook for region ~ +80% chance of exceeding median rainfall August to October 2013 (BoM).
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#1206911 - 11/08/2013 20:35 Re: Streamflow Observations [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
71 days of the maximum temperature registering less than or equal to ~ 17 deg C broken by 2 days ~ 19 deg.

4.55 pm CST Bureau forecast for Adelaide: 70% chance of 1 to 3 mm tomorrow (may affect streamflow slightly-to-moderately in next 1-2 days, possibly 2-3 days, not just in Central SA).
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