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#860816 - 27/04/2010 12:05 Streamflow Observations
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Streamflow Lowest in Memory…More than 20 years.

Streamflow Onkaparinga River March 2010.


Edited by Nazdeck (27/04/2010 12:10)
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#862456 - 09/05/2010 13:15 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Summary of Observations

The level of the water table (level of groundwater in the absence of pressure) for this area in the Mount Lofty Ranges (MLR) appears to be at the bottom of the local river. Judging from the lack of rain in recent months, the Onkaparinga River does not appear to be perennial. It seems more ephemeral, meaning it only flows when there are significant rains, and that it has a stop-start nature. Although there are signs of spring activity further upstream, it does not appear to be enough to sustain continuous flows. I suspect that as low-pressure systems (or more specifically, significant pre-frontal pressure gradients) approach that this may cause upstream spring flows to increase gradually. This would probably require additional research into MSLP observations for the area. Depending on the water content of the soil and aquifers beneath, this atmospheric-surface water-groundwater system may act like more dynamically, like a sponge rather than a rigid structure, responding to various dynamic fluxes. It also seems that changes in sub-surface groundwater pressure result it changes in detention rates (rate of transfer of moisture between groundwater and surface systems), wherein the moisture entering the soil is not the same moisture leaving the sub-surface saturated zone and groundwater aquifers. This seems fairly straightforward reasoning, and also suggests that fluxes in groundwater pressure due to soil and sub-surface structural properties (soil type) are highly dependent on atmospheric input, as the evident ephemeral nature of the Onkaparinga River seems to imply. That said the Onkaparinga River appears to be a losing stream, meaning it does not retain as much moisture as it receives. Interestingly, this may mean it is possible for both losing and gaining streams to be located within the same catchment region.

The rainfall in these parts also appears to reflect in the nature of the local river’s behaviour. Most rain falls in short periods, over a localised area, with differences in rainfall over as little as half a kilometre. When the soil in floodplain areas is very dry, there appears to be a greater potential for flooding as moisture does not have enough time to infiltrate the soil if the rate of rainfall is too great (recent summer downpours indicate that perhaps only 14-18 mm in an hour). This lack of infiltrating may also be influenced by the dryness of the soil in that there is a disconnect between the hydrologic flow of sub-surface moisture and surface water, which in turn would be dependent on the pressure between pores with and without water content. This would no doubt affect the dynamics and responses of the groundwater to surface water systems, as the sponge characterisation of soil moisture absorption comes into effect.

The actual stream flow appears to be very dependent on the rate of detention of moisture from aquifers deep underground. Once a threshold is reached, it only takes a few millimetres for there to be stream flow (quick flow). And provided rain continues for long enough, it will only take a few millimetres over hours for the stream’s volume to begin increasing rapidly – exponentially in nature. This rapid increase in stream flow is likely also assisted by surface-pressure changes – a general region-wide drop in atmospheric pressure, which would take the pressure off underground aquifers (again a sponge-like effect) and lead to more moisture being able to approach the surface. During heavy rains this is the likely characteristic behaviour of an artesian spring, in which water gushes from the surface. Added to these effects, as rain continues to fall, there is a counter balance to the effects of low surface pressures, and more rain leads to more pressure to sub-surface detention rates, and more stream flow.

Again interestingly, the microclimate of the area, involving ground cover (grass) and trees, appears to add to micro scale rainfall effects. Significant evaporation and transpiration from plants and soil surface adds to the moisture already passing through or stagnant in the region (probably 5-15 mm per day in the summer, and maybe 2-3 during rainfall). This drop in evaporation and transpiration appears to be inversely related to rainfall, and thus stream flow. Possibly, too much humidity near the surface means this moisture remains stagnant, as more clouds prevent the energy needed for converting water to vapour from reaching the surface.

The typical water retention and osmotic potential of plants in the area is probably around 0.3, meaning 30% of surface-water (including evaporation) is retained in plants on average throughout the year. This surface layer of moisture or humidity extends up to 30 metres vertically along the river where the density of trees is high. Added to this humidity effect, which increases the precipitable water in the near-surface atmosphere (especially during rain and thunderstorms) is the observed micro climate effect of rain leading to more rain when the precipitable water experiences a downward pressure due to super-saturated conditions, which the 30% osmotic effect contributes to. As a note of benefit, precipitable water is dependent on both the MSLP and vapour pressure, so atmospheric pressure and water vapour changes in the atmosphere above the Onkaparinga’s riparian environment (and within it) are likely to have some measurable influence on river flows.

All in all, the effects of microclimatic conditions on the Onkaparinga River (and the rainfall which leads to stream flow) appear to be quite pronounced. The big question mark is over sub-surface moisture retention, and, quantitatively, how much is down there. The indications are there is a lot more sub-surface water than surface water.
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#862764 - 11/05/2010 15:48 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Comparisons of Stream flow discharge (volume/height):

Peak Flow, Winter 2009

This image is a bit blurry probably partly due to the weather conditions, and also because the river could have breached its blanks (I was in a rush):

“IDS20364
AUSTRALIAN GOVERNMENT - BUREAU OF METEOROLOGY
SOUTH AUSTRALIA REGIONAL OFFICE

WARNING FOR MINOR FLOODING
For the Upper Onkaparinga River
Issued at 5:30 pm on Monday, 24 August 2009

1. FLOOD WARNING :
Heavy rainfall has been recorded in the upper Onkaparinga catchment during the
last six hours. This has resulted in rapid rises in the upper Onkaparinga River
and tributaries.

Minor flood levels are expected to be reached during the next hour [by 6:30 pm]
in Lenswood Creek at Lenswood, Inverbrackie Creek at the gauging station and in
the Onkaparinga River at Oakbank Ford.

River levels in the Onkaparinga River downstream at Verdun are not expected to
exceed the minor flood level at this stage.

Rainfall is forecast to ease to showers early this evening, and further rises
beyond minor flood levels are not anticipated.

People are advised to keep away from floodwaters.
Motorists are advised to avoid low level road crossings.

For information, contact the State Emergency Service 132 500

2. RAINFALL AND RIVER HEIGHT OBSERVATIONS :


Latest river height observations for MONDAY 24/08/2009 :

Onkaparinga R at Charleston 1.50 m steady at 5:13 pm Mon
Inverbrackie - Woodside 0.87 m steady at 5:17 pm Mon
Onkaparinga R at Woodside 1.21 m rising at 5:21 pm Mon
Western Branch at Tiers Road 1.45 m rising at 5:20 pm Mon
Lenswood Ck at Lenswood 0.77 m rising at 4:11 pm Mon
Onkaparinga R at Oakbank 0.55 m rising at 5:20 pm Mon
Aldgate Ck at Aldgate 0.37 m steady at 5:00 pm Mon
Onkaparinga R at SE F'way 0.63 m rising at 5:20 pm Mon
Cox Creek at Uraidla 0.30 m steady at 5:17 pm Mon
Houlgraves ALERT 3.44 m steady at 5:12 pm Mon
Clarendon ALERT 9.27 m steady at 5:09 pm Mon
Onkaparinga R - Clarendon 9.16 m steady at 5:20 pm Mon”

Same Place as Peak Flow, Pre-Winter 2010

The distance from where the photos are taken to the river bed is about 5-7 metres vertically.


Edited by Nazdeck (11/05/2010 15:55)
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#862769 - 11/05/2010 16:05 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
This is probably a better view.

Peak Flow 2, Winter 2009
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#862770 - 11/05/2010 16:06 Re: Streamflow Observations [Re: Seira]
bigwilly Offline
Weatherzone Mod and Photog

Registered: 25/09/2002
Posts: 6543
Loc: Junee - just north of the 'Bid...
Interesting stuff Naz! I enjoyed reading that and hope there's more to come.
_________________________
YTD Rainfall = 281.0mm (Avg to March 117.0mm)
MTD rainfall March = 34.7mm(Avg 41.3mm)
February 2011 total = 203.9mm (Avg 37.8mm)
2010 Rainfall: 759.3mm (Annual Avg: 521.5mm)

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#862772 - 11/05/2010 16:10 Re: Streamflow Observations [Re: bigwilly]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Lol, I just noticed:

"People are advised to keep away from floodwaters." laugh eek

Originally Posted By: bigwilly
Interesting stuff Naz! I enjoyed reading that and hope there's more to come.

Do you know where I can find daily evaporation observations for the Onkaparinga River?


Edited by Nazdeck (11/05/2010 16:18)
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#862868 - 12/05/2010 07:54 Re: Streamflow Observations [Re: Seira]
bigwilly Offline
Weatherzone Mod and Photog

Registered: 25/09/2002
Posts: 6543
Loc: Junee - just north of the 'Bid...
Hi Naz,

The BOM's climate section would be the place to go. You can search by location (Woodside - I don't know the region at all so wouldn't know which adjoining stations would suit) for monthly statistics, which should include pan evaporation.

You might have to do a bit of research to determine the relationship between pan evap. and creek/water body/soil evap.
_________________________
YTD Rainfall = 281.0mm (Avg to March 117.0mm)
MTD rainfall March = 34.7mm(Avg 41.3mm)
February 2011 total = 203.9mm (Avg 37.8mm)
2010 Rainfall: 759.3mm (Annual Avg: 521.5mm)

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#863779 - 18/05/2010 12:48 Re: Streamflow Observations [Re: bigwilly]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
A much clearer day-time view from 2005:

Peak Flow 3, 3rd September 2005


Edited by Nazdeck (18/05/2010 12:52)
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#865887 - 29/05/2010 22:10 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
“There is a non-linear relationship between rainfall and streamflow. That means any single unit reduction in rainfall in the Ranges is likely to lead to a 2–3 unit reduction in streamflow. Future projections are suggesting that there will be reductions in average rainfall from May to October, the most important period to generate runoff in the Mount Lofty Ranges. Modelling from Gillooly and Hutson (2005) of the Cox Creek catchment in the upper Onkaparinga catchment suggest that a 10% reduction in rainfall, the upper limit for projection by 2030, would cause a 24% reduction in stream flow. Such reduced average run-off rates could lead to a greater probability of the phenomenon of green droughts, where there is sufficient rainfall for crop and pasture growth but insufficient for run-off to fill dams and reservoirs. The quality of water could decline with reduced average flows, increasing evaporation, but with extreme erosive events increasing the sediment loads in streams. Such changes will have significant impacts on freshwater ecology (see page 26).

Work by SA Water has suggested that if a mid-point of the CSIRO projections is the eventual outcome, there will be on average a 10% reduction in in-flows, or approximately 20 GL less water, compared with current intake into Adelaide's reservoirs by 2025 (South Australian Government 2004). The 10–15% reduction in average annual rainfall in south-west Western Australia (WA) has led to an approximate halving of the amount of water flowing into Perth’s reservoirs since the 1970s (Pearcey and Terry 2005). Evaporation losses from reservoirs are also likely to increase in association with rises in temperature.

Urban and industrial water supplies in the AMLR region are partly provided from local resources and partly from Murray River water. During dry years, over 80% of Adelaide’s water can be supplied via pipelines from the Murray River. Projected climate change in the Murray Darling Basin is likely to result in reduced flows, and hence a reduced capacity to dilute saline groundwater accessions to the River. Climate change may also increase irrigated crop water demand in response to higher temperatures. Murray Darling Basin Commission (MDBC) has used CSIRO projections to produce indicative estimates of the impact of climate change over the Basin. This modelling suggests an 11% or 2550 GL reduction in flows and an average increase in salinity of 26 EC units at Morgan by 2023 (Andy Close, Water Resources Group MDBC). These levels of change in river condition could enhance conflicts of interest in the distribution of water resources and will continue to require careful anticipatory responses.”

Reference: Bardsley, D., June 2006, p. 18.


Edited by Nazdeck (29/05/2010 22:14)
Edit Reason: Correction
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#865970 - 30/05/2010 10:53 Re: Streamflow Observations [Re: Seira]
ROM Offline
Meteorological Motor Mouth

Registered: 29/01/2007
Posts: 6628
As I have posted elsewhere previously, agricultural researchers, acquaintances and friends of mine, at our large ag research institute, the Grains Innovation Park here in Horsham have been doing quite a lot of agricultural crop modelling using the CSIRO's climate models as base for their field crop forecasting research.
However very slight changes in the various versions of the CSIRO's climate models are throwing up large discrepancies in the forecasts and outputs of these CSIRO models.
The CSIRO was contacted by the researchers involved in the modelling as to why these large variations were occurring between versions of the same model.
No reply was forthcoming from the CSIRO.
So the same identical version of a CSIRO climate model was down loaded via the web and this "identical" climate model gave very different output to the supposedly same identical version that the researchers had.
Again no answer at all from the CSIRO as to why.

The CSIRO models are failing completely at the regional level with the various versions of these models often giving directly contrary climate forecasting results for the same identical regions.
That is the experience of these Ag researchers who have repeatedly run these models as a part of their infield crop research and who needless to say are now very scathing to say the least, about the claimed and purported accuracy of the CSIRO's climate models.

And that is exactly the type of modeled regional climate forecasting outlook that is needed by hydrologists to model and predict the flows from the various regions in the Murray / Darling basin.

After listening to these Ag research guys and their experiences with the CSIRO climate models, one of which is used in the 23 climate model suite used by the IPCC for it's climate forecasts, I would not in any way give any credibility to any flow and run off models or forecasts derived from or that used the CSIRO's or any other organisations climate models as a base to provide long term strategies and forecasts for water supplies for any region, particularly if those predictions supposedly extend for more than a half dozen years into the future and cost a huge amount of tax payers hard eared to implement.

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#865990 - 30/05/2010 13:40 Re: Streamflow Observations [Re: ROM]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Originally Posted By: ROM
As I have posted elsewhere previously, agricultural researchers, acquaintances and friends of mine, at our large ag research institute, the Grains Innovation Park here in Horsham have been doing quite a lot of agricultural crop modelling using the CSIRO's climate models as base for their field crop forecasting research. However very slight changes in the various versions of the CSIRO's climate models are throwing up large discrepancies in the forecasts and outputs of these CSIRO models.

I was actually trying to be informative and present some ideas which may raise some interests and/or questions for those interested in streamflow and surface-water hydrology. I acknowledge that very slight changes in various versions of the CSIRO’s climate models may throw up large discrepancies in forecasts and outputs of these models, however I believe such behaviours fall under scenarios involving sensitive dependence on initial conditions, which are a standard component in computer modelling and experimental analysis. That’s why multiple model scenarios are often considered, with the most likely of those, based on current, scientifically demonstrated knowledge, being the most indicative of what happens in the real world. A balance between being convincing and being sceptical is likely warranted.

Originally Posted By: ROM
The CSIRO was contacted by the researchers involved in the modelling as to why these large variations were occurring between versions of the same model.
No reply was forthcoming from the CSIRO.

Unless there is actual evidence demonstrating impropriety or some degree of angst towards those not involved in the development of CSIRO models, I would say that assuming there is something not right based on a lack of a reply may not carry as much weight as otherwise thought. There may simply be a misinterpretation carried in communication, or something else altogether. I am not making any suggestion about what may or may not being going on, I am simply saying evidence needs to be presented.

Originally Posted By: ROM
The CSIRO models are failing completely at the regional level with the various versions of these models often giving directly contrary climate forecasting results for the same identical regions.

Again, this would fall under sensitive dependence on initial conditions, which may be attributed to programming differences and human error.

Originally Posted By: ROM
After listening to these Ag research guys and their experiences with the CSIRO climate models, one of which is used in the 23 climate model suite used by the IPCC for it's climate forecasts, I would not in any way give any credibility to any flow and run off models or forecasts derived from or that used the CSIRO's or any other organisations climate models as a base to provide long term strategies and forecasts for water supplies for any region, particularly if those predictions supposedly extend for more than a half dozen years into the future and cost a huge amount of tax payers hard eared to implement.

Fair enough, if that’s how you see it smile. I believe that unless one has been in a climate modeller’s shoes and actually understands how the models they have developed work, down to the dotted “I” and crossed “T”, assumptions made about the validity and accuracy or otherwise usefulness of the outputs of climate models should be tempered.

Also this may help:

“There is a non-linear relationship between rainfall and streamflow. That means any single unit reduction in rainfall in the Ranges is likely to lead to a 2–3 unit reduction in streamflow [fact]. Future projections are suggesting that there will be reductions in average rainfall from May to October, the most important period to generate runoff in the Mount Lofty Ranges. Modelling from Gillooly and Hutson (2005) of the Cox Creek catchment in the upper Onkaparinga catchment suggest that a 10% reduction in rainfall, the upper limit for projection by 2030, would cause a 24% reduction in stream flow. Such reduced average run-off rates could lead to a greater probability of the phenomenon of green droughts, where there is sufficient rainfall for crop and pasture growth but insufficient for run-off to fill dams and reservoirs. The quality of water could decline with reduced average flows, increasing evaporation, but with extreme erosive events increasing the sediment loads in streams. Such [suggested] changes will have significant impacts on freshwater ecology (see page 26).

Work by SA Water has suggested that if a mid-point of the CSIRO projections is the eventual outcome, there will be on average a 10% reduction in in-flows, or approximately 20 GL less water, compared with current intake into Adelaide's reservoirs by 2025 (South Australian Government 2004). The 10–15% reduction in average annual rainfall in south-west Western Australia (WA) has led to an approximate halving of the amount of water flowing into Perth’s reservoirs since the 1970s (Pearcey and Terry 2005). Evaporation losses from reservoirs are also likely to increase in association with rises in temperature.

Urban and industrial water supplies in the AMLR region are partly provided from local resources and partly from Murray River water. During dry years, over 80% of Adelaide’s water can be supplied via pipelines from the Murray River [fact]. Projected climate change in the Murray Darling Basin is likely to result in reduced flows, and hence a reduced capacity to dilute saline groundwater accessions to the River. Climate change may also increase irrigated crop water demand in response to higher temperatures. Murray Darling Basin Commission (MDBC) has used CSIRO projections to produce indicative estimates of the impact of climate change over the Basin. This modelling suggests an 11% or 2550 GL reduction in flows and an average increase in salinity of 26 EC units at Morgan by 2023 (Andy Close, Water Resources Group MDBC). These levels of change in river condition could enhance conflicts of interest in the distribution of water resources and will continue to require careful anticipatory responses.”

Bold Added. [] Added.

-------------------------------------------------------------------------------------------------------

Also, I just have a query:

If level of certainty and accuracy about climate modelling by the CSIRO is questionable, how much scientific knowledge is require for us to have any reasonable degree of certainty about what’s going to happen in the future, and the potential impact of what’s happening now on those future outcomes?

Where do we draw the line about facts that are facts without constantly changing our position, and thus our standards of what constitutes enough scientific knowledge?

I invite anyone to put their thoughts forward on this.


Edited by Nazdeck (30/05/2010 13:46)
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#866002 - 30/05/2010 15:13 Re: Streamflow Observations [Re: Seira]
bd bucketingdown Offline
Meteorological Motor Mouth

Registered: 07/02/2008
Posts: 6033
Loc: Eastern A/Hills SA
My models suggest rainfall & stream levels will be back to normal higher levels from now on and is already in that process now from what I can see.
http://www.holtonweather.com/article2.htm

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#866025 - 30/05/2010 17:22 Re: Streamflow Observations [Re: bd bucketingdown]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Originally Posted By: Bucketing Down(BD)
My models suggest rainfall & stream levels will be back to normal higher levels from now on and is already in that process now from what I can see. http://www.holtonweather.com/article2.htm

I do not doubt there is some legitimacy and validity to what you have found, however, as I understand it, modelling streamflow, especially on a daily timescale, is a very complex and site-specific endeavour. This can likely be seen in the differences in stream behaviour evident across the Mount Lofty Ranges, where close-proximity streams within the same catchment can exhibit both perennial and ephemeral behaviours, meaning while one stream flows all year round without ever being dry (within its recorded history), another streams flow intermittently depending in several factors, including vegetation cover and osmotic processes, inflexion points of flow behaviour due to the nature of underground flow dynamics, and detention rates (which are likely dependent on the passage or atmospheric high- and low-pressure systems).

I do not question so much that water could become more available (and evidenced by the potential for an intensification in the water cycle due not only to natural variations in climate, but also anthropogenic, including modifications of the landscape for agricultural and horticultural practices), it is more in what form it is available and where this is sourced from.

Weather systems do not necessarily have to become more or less frequent for impacts on streamflow to be witnessed on the ground. If, by land-use changes alone, the characteristic contributing behaviours of intermediary processes between weather systems and streamflow responses are modified or changed in such way that is not fully understood or appreciated in streamflow observations, the implications alone are that the intensity of weather events (as suggested by modelling of the relationship between saturation vapour pressure and temperature) has the capacity to alter streamflow behaviour.

If observations of the Onkaparinga River in the Central Adelaide Hills earlier this year, before significant rains, are anything to go by, the translation of rainfall into soil moisture over the last 20 years, and possibly longer, has not been going so well, the major floods of 1992, 1994 and 1996 not withstanding. The river is not even flowing yet (today), and we’ve had over 65 mm in the last week, some of which is still visible on the surface and hasn’t even soaked in. So the question is what kind of rainfall over what period, short of flooding the local neighbourhoods, will lead to streamflow? My current estimate is around 15 mm/hr over several hours, but that’s probably just a guess given how little we understand about underground systems compared to surface-water systems.

This from the same page as the previous quote:

Groundwater resource responses to climate change are less clear, partly because the hydrology of groundwater is not fully understood. While some groundwater resources are highly sensitive to rainfall changes, others are insensitive in the short-term. Reduced rainfall could lead to reduced rates of groundwater recharge and subsequent reductions in problems associated with waterlogging and secondary dryland salinity. On the other hand, reduced water-use efficiency may result from more unreliable and variable rainfall, and occasional extreme rainfall events could lead to large slugs of water penetrating through to replenish perched aquifers (Table 6).”

There is one thing in particular that seems to be apparent from rainfall events over the last few years: they have become much more concentrated in clusters of days, rather than spread out over days and weeks in a continuous fashion, .i.e. their reliability appears to have reduced, their variability increased. The passage of high- and low-pressure systems has also become somewhat more meridional (north-to-south oriented) and less zonal (less continuous passage of frontal systems within a given latitudinal range). I am by no means an expert on these things, however as rainfall represents the most significant and direct contribution to streamflow, it seems reasonable that an understanding of trends in weather patterns (and whether they are stationary or non-stationary trends, sinusoidal, have inflexion points, etc.) is critical to getting a better idea of how much quality water is really available in quantifiable terms, within the region.


Edited by Nazdeck (30/05/2010 17:25)
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#866026 - 30/05/2010 17:29 Re: Streamflow Observations [Re: bd bucketingdown]
ROM Offline
Meteorological Motor Mouth

Registered: 29/01/2007
Posts: 6628
No reflection on you in any way was mean't Nazdeck and you are way out in front of any knowledge base that I have when it comes to a lot of the info you post here.
But that does not mean we should just sit here and swallow what the expert's deliver as some of the experts are coming spectacularly undone quite frequently these days by ordinary people asking quite relevant questions or pointing out some salient and unacknowledged or deliberately avoided facts and data.
The web has seen to that!

Unfortunately so much of what we are now told must be correct because it is based on "models" and as you have posted, models are very, very subject to initial inputs and conditions.
And as is being commented on more and more by modelers themselves from professions other than climate modelling and something that is now acknowledged as being rife in climate modeling is that a modelers frequently select some input criteria that at best is fuzzy in it's accuracy and credibility and often they just select data inputs that are no more than guess work or because the data input "feels" right.
And there are cases where they are quoted as actually saying this.

You might question the skills of the local Ag modelers that I have referred to but unlike the climate modelers these guys and a lot of gals nowadays, live and die professionally by their in field results that are a direct outcome of their modeling and then putting the output of that modeling into actual field conditions to verify those models and the predictions arising from that modeling.
No different to the way in which modeling is used in countless other professions from engineering to medicine to modeling the atomic structure of elements and the bosons, protons, quarks and etc and then verifying those predictions in the big nuclear particle colliders.
In the cases above, unlike climate modeling, the outcomes of that modeling can usually be verified within a short time frame and if the modeled outcome is different to reality then the necessary changes in the actual model and data inputs can be made before any serious damage is done to the subject that is being modeled.

And those Ag modelers use the CSIRO's models as supplied direct from the CSIRO as the basic climate forecasting tool on which to base a lot of their crop models and those CSIRO models are simply not consistent in their climate predictions particularly when it gets down to regional climate predictions and effects.
And that regional climate forecast part is critical for everybody as not many people will give a damn if the model says Australia will warm by x number of thousands'th of a degree in 20 years time.
Rather they will say, yeh! now how will it affect me in this patch?
And the CSIRO climate models simply can't do that forecast and if they try then they often give different and sometimes quite contrary results.

By it's very nature climate models can't be verified so it is pretty bloody stupid to bet the house on the predictions of usually years ahead climate and runoff flow based entirely on these climate models output.
Even less smart, in view of the experiences of our local modelers re the CSIRO's regional model predictions is to bet the farm on model predicted outcomes in the smaller scale regions, outcomes which may not be known for many years ahead.

A hell of a lot of damage and unnecessary angst can be caused by taking precipitous action based on these output of these climate models .
Stream flow predictions that are grossly wrong can lead to the wrong direction being taken by entire industries, housing and urban buildings and entire business precincts being placed in the wrong location, [ something that based on historical events well within my memory may have been done locally. will be interesting when we get the next really big a couple times a century floods. ] industries being set up on the basis of the models and enormous amounts of taxpayers money being frittered away on still born projects.

In the case of runoff and stream flows, better to just go back in history, written, oral and archeological and see what has happened in the past and build on that as the base for the decision making that is required for the future as nature has a habit of repeating herself regardless of puny mankind's intentions.

Modeling should be a case of "Trust but verify!" and if you can't verify then you do not trust in any way and that applies particularly to climate modeling and any other modeling that relies totally on the veracity of the climate models for their base data no matter what the climate models origin is.

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#866054 - 30/05/2010 19:14 Re: Streamflow Observations [Re: ROM]
bd bucketingdown Offline
Meteorological Motor Mouth

Registered: 07/02/2008
Posts: 6033
Loc: Eastern A/Hills SA
"There is one thing in particular that seems to be apparent from rainfall events over the last few years: they have become much more concentrated in clusters of days, rather than spread out over days and weeks in a continuous fashion, .i.e. their reliability appears to have reduced, their variability increased. The passage of high- and low-pressure systems has also become somewhat more meridional (north-to-south oriented) and less zonal (less continuous passage of frontal systems within a given latitudinal range). I am by no means an expert on these things, however as rainfall represents the most significant and direct contribution to streamflow, it seems reasonable that an understanding of trends in weather patterns (and whether they are stationary or non-stationary trends, sinusoidal, have inflexion points, etc.) is critical to getting a better idea of how much quality water is really available in quantifiable terms, within the region."(Quote Naz)

Naz, the only part I was commenting on was like is in this paragraph(I am not into the rest of the post enough to comment, as my dealings are only with the more major Murray system forecasting wise)...But that is exactyly my point, past weather or persistence is a very poor forecasting tool. The weather and rainfall run in cycles & some are sinusoidal, yes, and all the past and currentccycles imo suggest that we will return to a more "normal" whatever that is, rainfall pattern. Systems of pressure and weather again imo will return to more what we have been used to before the last 10 years of dryness. It is all cyclic, and nothing to do with global warming, it is mainly caused by solar effects which rule the long term weather and rainfall trends, again imo from years and years of research. And 2010 is startying to well bear out what I am saying...even the past week
eg
Weather News & Web Pages of Interest:
^^^ Lots of Australian wild, stormy, floody, heavy & record breaking rains in the past week!
http://www.weatherzone.com.au/news/biggest-downpour-in-years-soaks-was-southwest/14430
http://www.weatherzone.com.au/news/destructive-winds-smash-into-nsw/14452
http://www.weatherzone.com.au/news/flooding-isolates-tasmanian-residents/14437
http://www.weatherzone.com.au/news/gippsland-watches-rising-rivers/14454
http://www.weatherzone.com.au/news/storms-dump-rain-across-sa/14416
http://www.weatherzone.com.au/news/storms-rip-into-the-nt/14445
http://www.weatherzone.com.au/news/tasmania-awash/14444
http://www.weatherzone.com.au/news/wettest-day-in-weeks-for-south-australia/14419
http://www.weatherzone.com.au/news/wettest-may-day-on-record-for-moomba/14412
http://www.abc.net.au/rural/content/2010/s2912346.htm?site=southeastnsw

Cheers Ian PS Nice rains we are having here at Nairne and you as well I guess Naz at Woodside...We have had 40mm so far and its still thickly raining here, almost all day long!

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#866082 - 30/05/2010 21:38 Re: Streamflow Observations [Re: bd bucketingdown]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Originally Posted By: ROM
But that does not mean we should just sit here and swallow what the expert's deliver as some of the experts are coming spectacularly undone quite frequently these days by ordinary people asking quite relevant questions or pointing out some salient and unacknowledged or deliberately avoided facts and data.
The web has seen to that!

In many respect I agree with you one those points :), particularly in relation to the use and abuse of internet resources. I agree that more transparency in scientific practices is mostly probably warranted, and that the knowledge and experience base of those who see things happening first-hand in the field should not be considered merely as a supplementary source of information in mathematically-dominated modelling practices. Given that without that knowledge and experience, input into mathematical models would be on rather poor foundations, I think it is very important. I also think there should be more stringent criteria against which hypothetical and theoretical ideas must be tested before they can pass as valid.

Originally Posted By: ROM
Unfortunately so much of what we are now told must be correct because it is based on "models" and as you have posted, models are very, very subject to initial inputs and conditions.

I would say initial model input data and boundary conditions need to be rather stringent, given the output of models is only representational.

Originally Posted By: ROM
And as is being commented on more and more by modelers themselves from professions other than climate modelling and something that is now acknowledged as being rife in climate modeling is that a modelers frequently select some input criteria that at best is fuzzy in it's accuracy and credibility and often they just select data inputs that are no more than guess work or because the data input "feels" right. And there are cases where they are quoted as actually saying this.

Lol re: "feels" right, couldn’t agree more :), hence the term “representational” above.

Originally Posted By: ROM
You might question the skills of the local Ag modelers that I have referred to but unlike the climate modelers these guys and a lot of gals nowadays, live and die professionally by their in field results that are a direct outcome of their modeling and then putting the output of that modeling into actual field conditions to verify those models and the predictions arising from that modeling.

Your point (concerning bias data input) above cleared that up a bit for me, thanks smile. Additionally, to clarify, I was not actually questioning the skills of modellers, more the interpretation of information in communication between the group you identified as “feels” right, and the local agricultural modellers, as you pointed out.

Originally Posted By: ROM
In the cases above, unlike climate modeling, the outcomes of that modeling can usually be verified within a short time frame and if the modeled outcome is different to reality then the necessary changes in the actual model and data inputs can be made before any serious damage is done to the subject that is being modeled.

And those Ag modelers use the CSIRO's models as supplied direct from the CSIRO as the basic climate forecasting tool on which to base a lot of their crop models and those CSIRO models are simply not consistent in their climate predictions particularly when it gets down to regional climate predictions and effects.

Ok, I see your point – I was probably thinking more case- and site-specific. I am mostly sceptical of the inputs and outputs to and from any computer model that has not been scientifically validated within a given range of uncertainty, and which does not have specific boundary conditions.

Originally Posted By: ROM
A hell of a lot of damage and unnecessary angst can be caused by taking precipitous action based on these output of these climate models.

Agreed.

Originally Posted By: ROM
In the case of runoff and stream flows, better to just go back in history, written, oral and archeological and see what has happened in the past and build on that as the base for the decision making that is required for the future as nature has a habit of repeating herself regardless of puny mankind's intentions.

Practically, I would say a potential first step would be to construct comprehensive streamflow records from that we already have and know.

Originally Posted By: Bucketing Down(BD)
Naz, the only part I was commenting on was like is in this paragraph(I am not into the rest of the post enough to comment, as my dealings are only with the more major Murray system forecasting wise)...

Thanks for clarifying smile.

PS, I was actually competing (sport) out in this stuff today lol. Will endeavour to post rainfall totals soon in other thread.
_________________________
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#867389 - 06/06/2010 12:55 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
To be honest, I'm not sure about the impact of AGW on streamflow, because there doesn't seem to be a clear trend (other than stationary) that reflects AGW in Adelaide Mount Lofty Ranges rainfall records.
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#868183 - 13/06/2010 12:20 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
I have done a bit of a statistical analysis for several areas in the Mount Lofty Ranges using data made available to the public by the DWLBC. The results for the rainfall and streamflow look fairly interesting and there are two things I have noted in particular:
  • The closer the rainfall site, the higher the correlation – this is not necessarily true, and
  • The higher the correlation between rainfall and streamflow, the more predictable streamflow is – this is not necessarily true.
_________________________
*Kindness is our ally.

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#868448 - 15/06/2010 12:18 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Originally Posted By: Bucketing Down(BD)
The weather and rainfall run in cycles & some are sinusoidal, yes, and all the past and currentccycles imo suggest that we will return to a more "normal" whatever that is, rainfall pattern. Systems of pressure and weather again imo will return to more what we have been used to before the last 10 years of dryness. It is all cyclic, and nothing to do with global warming, it is mainly caused by solar effects which rule the long term weather and rainfall trends, again imo from years and years of research.

I’m a little sceptical about the weather and climate patterns in the southern hemisphere “returning to normal,” just as I’m sceptical of exaggerated claims of AGW. There are two apparent trends which are pretty clear to me after reading a report from the BoM, for Adelaide. Credit: R. J. Szkup and B. H. Brooks.

The first is that there were a greater number of heatwave events in the earlier part of last century from roughly 1890 to 1940 in Adelaide, which was consistent stationary or near-stationary high-pressure systems in the Indian Ocean, which likely blocked the passage of numerous frontal systems during that period. After 1940, these synoptic situations seemed to have become less frequent or dominant, up until about the years 1990, before beginning to rise again by the year 2000. Indeed this may be evidence of cyclic climate behaviour, over periods of several decades. However, given the recent slight increases in heatwave conditions since 2000 the question is, even if this is a natural cyclic or sinusoidal trend, when does the dominance of the high-pressure synoptic systems in the Indian Ocean return, or is it beginning to already?

The second apparent trend, or rather lack of trend, has to do with ENSO events (El Niños and La Ninas). The above mentioned heatwave events, judging from the BoM report, do not align strongly with the onset of ENSO event (out of all significant events 1890 to 2000, 3 of 12 Heatwaves aligned with El Niños, and 4 of 12 aligned with La Ninas).
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*Kindness is our ally.

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#868450 - 15/06/2010 12:36 Re: Streamflow Observations [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6808
Loc: Adelaide Hills.
Sorry, 3 of 12 La Nina, 4 of 12 El Nino, my blue.
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