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#869727 - 27/06/2010 12:38 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Pools in the local river are filling up. I think as each pool fills up, this flow goes into the next pool downstream. So flows further upstream seem to have started, but pools further downstream are still filling up. I think this might be the base flow part of streamflow (to do with the soil) until we get more rain.
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#869943 - 28/06/2010 21:52 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
The rainfall for this area of the hills continues to be below average. All months this year show totals below the long-term average for those months. The last period when we received enough rain to lead to the local river reaching near the river bank was back during 2004 and 2005. For this period I have rainfall temperature and some climate records. I will wait and see how these records factor into the equation of changing climate. Something will change and most probably has the capacity to change in the southern ocean, and this will probably be particularly important for South Australia smile.


Edited by -Cosmic- (28/06/2010 21:52)
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#869949 - 28/06/2010 22:19 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Originally Posted By: -Cosmic-
Something will change...

I'm sceptical enough of AGW to consider it anyway smile. Streams seem to have fairly long memories lol.


Edited by -Cosmic- (28/06/2010 22:20)
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#870296 - 30/06/2010 12:41 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Onkaparinga River 27th June 2010

In the last 2 days weve had 6.3 mm.

Onkaparinga River 30th June 2010

With 20.2 mm in the last 3 days, the height of water in the local river has risen dramatically. Where there are obstacles to natural flow, the water level at a glance is half to 1 metre below the river bank in parts. There is now definitely streamflow, even though it's still base flow, and a trickle. About 100 metres upstream from the 1st observation point, the river is flowing more strongly with natural flows clearly visible.

Since the start of 2010, we've had roughly 190.2 mm (we don't have an AWS). The long-term mean to date is 346.3. The previous large rain total we've had was 49 mm to the 29th of November last year.
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#870299 - 30/06/2010 12:58 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Monthly/Annual Rainfall Totals 2004, 2005

Year/Month 2004 2005 Long-term
Jan 14.6 32.6 25.5
Feb 8.4 31.3 27.3
Mar 34.9 8.7 29.9
Apr 25.6 10.5 59.7
May 54.6 6.9 93
Jun 199.7 212.2 110.9
Jul 115.2 67 117.2
Aug 158.8 122.3 112.2
Sep 57.4 93.4 91.6
Oct 12.9 128.2 69
Nov 58.8 87.3 40.8
Dec 63 44 32.2
Total 803.9 844.4 809.3
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#871129 - 06/07/2010 10:55 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Onkaparinga River 6th July 2010

Yet another night with sub zero temps. These have been very common in the last few weeks, including a rather big frost only a couple of days ago (very clear in the paddocks). Little or no rain since the last major rainfall event (maybe 0.1 mm). I am thinking that the low temperatures are in someway contributing to reduced river flows. The height of water in the river has not changed much since the 30th, maybe .25 to .3 metres. The flow is still a trickle, although the water in more stagnant than it was a week ago. This seems to mean it takes longer for base flow to be affected by a lack of rain than quick flow (runoff). I would guess that when rains are enough to get above the main base flow water height, that the changes in flow will be more noticeable. I am beginning to get somewhat concerned by the lack from at this point for July, and am getting increasingly suspicious that the effects of pressure, temperature and lack of rain in the region and on larger scales is contributing rather a lot to these seemingly record low flows (in at least 20 years). We should be getting consecutive strong cold front crossing the Bight, and this is just not happening. I am getting a stronger and stronger sense this year will be below average rainfall (we're already way behind).
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#871158 - 06/07/2010 13:37 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
If this year is anything like 2009, we might not see peaks in winter flow until August.
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#871165 - 06/07/2010 14:20 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Photographic evidence from August and December 1992 shows that when the Onkaparinga River bursts its banks, the area covered by water increases from 5-10 metres (river width) to a massive 50-100 metres. In terms of floods, it looks like there was torrential rain in 1992.

Edit: Unfortunately, rainfall records were not kept during this period in the area, so recontructions would probably be needed to estimate flows.


Edited by -Cosmic- (06/07/2010 14:27)
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#871625 - 10/07/2010 12:27 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Reconstructed records indicate that during August 1992, over 70 mm fell in a single day, and that over a 5 day period in December, over 110 mm fell.

Streamflow Observations 6th July 2010
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#871626 - 10/07/2010 12:46 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Streamflow records from the lower Onkaparinga River (see http://e-nrims.dwlbc.sa.gov.au/swa/) appear to indicate 1992 was the wettest year in the period June 1977 to November 2006.
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#871806 - 12/07/2010 14:02 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Some experimental streamflow modelling I have done for catchments in the Adelaide Hills seems to show that, on a daily scale, while streamflow magnitude is not well captured over many years, the response of streamflow to rainfall does seem to be consistent. While I do not fully understand the physics of the modelling, the relationship between rainfall and streamflow on daily and monthly time scales seems to be very similar. I am highly suspicious that rainfall this year will not be sufficient to generate reasonable flows, and more so because the strength of rain events to date since January 1st is reflected in the monthly rainfall totals, which are well below the long-term average. Given catchments tend to have a fairly long memory for rainfall events, this only serves to highlight the importance of significant and sustained rainfall throughout the winter months.
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#871807 - 12/07/2010 14:21 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
My prediction for streamflow response over the next 6 months:

N.B.: This is a guide only.

July 2010: Below Average Streamflow Response.
August 2010: Above Average Streamflow Response (Streamflow Will Peak).
September 2010: Above Average Streamflow Response.
October 2010: Below Average Streamflow Response.
November 2010: Average Streamflow Response.
December 2010: Below Average Streamflow Response.
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#872124 - 14/07/2010 14:42 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
Onkaparinga River 14th July 2010

22 mm between 12 pm on the 8th and 9:55 pm last night, plus 19 mm to 9 am this morning, plus another 5 mm to 10:20 am has lead to the level of water in the local river rising to about 0.5 m from the riverbank. The river (at 10:20 am) was flowing strongly, yet steadily, without signs of flooding yet apart from water in paddocks which is yet to soak into the soil (up to an inch deep in places). Of the 46 mm we have received over the last week, the 19 mm to 9 am has been the most significant and sustained rainfall event for the year. After 9 am, at least 2-3 thunderstorms moved through the area with sharp downpours and frequent thunder. Small hail has been intermittent. The rain which has already fallen has probably increased the streamflow response from slight to mild-to-moderate, so there are strong signs the winter pattern has set in. I would say the water is about 1.5-2 m deep in sections of the river where there are no visible rapids. At this stage I would not say streamflow has reached its peak given were still in the middle of winter, which would seem somewhat obvious. Indications are that we are approaching peak flow, which seems likely to occur sometime in late July/early August (given whats happened to date this year) *. (* See Bottom of Post).

As a side note on a previous post about floods in August and December 1992, the vegetation (trees and shrubs) covering the riverbanks and surrounds at the time was very young and not very tall or dense, indicating there could have been a greater potential flooding than the is now because of the difference in surface vegetation cover and its density (including the tree canopy). I have a feeling that the local river environment actually increases rainfall somewhat or supports itself through generating an environment which contributes to increased humidity and in someway changes local dynamics in the atmosphere. Most unwanted species of plants have been removed from the area closest, leaving the native species to thrive. Judging from photographs 18 years ago, this landscape was very bare (only grass) back then which may mean its capacity to absorb large quantities of water has increased significantly since then.

* [One thing that is somewhat unusual for this time of year is that some flowering plants have begun to bloom this leaves me wondering whether an August forecast for peak flow truly reflects these observations, and whether July will be the wettest monthsomething to keep in mind (local knowledge suggests the seasons may have shifted forward 2-3 months of the standard 3 month definitions).]


Edited by -Cosmic- (14/07/2010 14:45)
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#872125 - 14/07/2010 15:00 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
The difference in the water level between photos taken of the river at 9 am and at 10:20 am was not really noticeable after a strong downpour. I may have the photos from 10:20 up soon after I upload them smile.
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#872160 - 14/07/2010 19:27 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
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#872161 - 14/07/2010 19:38 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
This is the riverbed for comparison in a deep section with what looks like bedrock

Riverbed Pre-Winter 2010, 11th May 2010, 11.04 am

I'm thinking about getting the old flood photos digitised to give an idea of just how wet it can get smile (in the absence of dense tree cover).


Edited by -Cosmic- (14/07/2010 19:45)
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#872164 - 14/07/2010 19:56 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
It interesting to note that, in the above photo, there is boundary line through the riverbank. I believe this could be the minimum flow level, or what is supposed to be minimum flow level. I have another photo of the same boundary line further upstream at right angles to the river bank and the it looks very similar. It's about half a metre above the water level (where there is water), taken on the same day.
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#872217 - 15/07/2010 07:55 Re: Streamflow Observations [Re: Seira]
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 14829
Loc: Seaford Meadows, SA
Good stuff mate smile enjoy these obs, all very interesting. Keep the pics coming!

TS cool

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#872249 - 15/07/2010 12:10 Re: Streamflow Observations [Re: Thunderstruck]
_Johnno_ Offline
Weatherzone Addict

Registered: 08/11/2009
Posts: 1608
Interesting to see 5 river systems having minor flood warnings for North East Victoria haven't seen that for a while, hope it continues rest of Winter & into Spring
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#872250 - 15/07/2010 12:13 Re: Streamflow Observations [Re: _Johnno_]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6847
Loc: Adelaide Hills.
If you have any obs for rivers anywhere else you would like to post in here, you're more than welcome smile.
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