Thread: Hydrology - the real measurement???

Originally Posted by Utemad

Evaporation is a big problem in most of Australia.

You can get covers for dams to reduce evaporation but I imagine they are hugely expensive. Also why deep dams with minimal surface area are better than shallow dams with a high surface area.

It is possible to have more evaporation than rainfall as the evaporation is calculated not actual.

BOM does measure actual evaporation at some sites by means of a Class A Pan (see MEA | Products - Class A Evaporation Pan | Measurement Engineering Australia

At observation time water is added to bring the water level back up to a fixed point and the amount added is converted to an evaporation figure.

Stephen.

Although I agree with the foregone comments and accept the fact that we live in a 'dry' continent, the comparison of raifall and evaporation is not as bad as it may appear. If it was then Australia would be a much drier place than it is. eg Refer to Bushie's figures for a location only 10km from the coast.

When comparing evaporation and rainfall one must not overlook the area over which each occurs.
Whereas rainfall generally falls over a reasonably broad geographical area, the majority of evaporation occurs over the relatively (by comparison) small areas of 'stored' water.

In other words, to calculate total gain or loss, volumes (area x depth) must be considered and not merely 'depths'.

Roger

Originally Posted by Xtreme

The general farming practice for some time has been to channel runoff into a storage area (the farm dam) for future use.
However there is a guy in the Widden Valley who has channelled runoff away from the creek/river to spread out across his paddocks.
Apparantly it has proven quite successful and his property suffered very little during the drought.

Roger

Peter Andrews. Natural Sequence Farming Home
He started off by slowing the water flows in the creeks and depressions by reeds, weeds, trees, whatever.
Basically slowing the flows everywhere helped retain moisture where you wanted it. Makes sense to me.

His theory is that this is how the country and watercourses worked before whitefella came along and deforested everything including all the watercourses, creeks and rivers. Hell, 15 years ago SoilCon came along and ran a dozer right through the Pages River here (a tributary of the Hunter) to take out all the she oaks and weeds to speed up the flow. It also filled all the natural holes etc. (you can't swim anymore, all the hoples have gone.)
According to those that have lived here all there lives, the flows have never been the same since, but slowly the holes and trees, etc are reappearing.
His position is that drought is a natural and regular occurrence in Australia, maybe even more regular than rainfall. He ended up losing his farm (and his marriage ?) as he became obsessed with it, but Gerry Harvey became a convert (one of his studs is nearby)

Actually, it goes along with a comment supposedly made by a CSIRO scientist once at a grazing conference " there is no such thing as drought, only over stocking "

Originally Posted by rick130

Peter Andrews. Natural Sequence Farming Home
He started off by slowing the water flows in the creeks and depressions by reeds, weeds, trees, whatever.
Basically slowing the flows everywhere helped retain moisture where you wanted it. Makes sense to me.

His theory is that this is how the country and watercourses worked before whitefella came along and deforested everything including all the watercourses, creeks and rivers. Hell, 15 years ago SoilCon came along and ran a dozer right through the Pages River here (a tributary of the Hunter) to take out all the she oaks and weeds to speed up the flow. It also filled all the natural holes etc. (you can't swim anymore, all the hoples have gone.)
According to those that have lived here all there lives, the flows have never been the same since, but slowly the holes and trees, etc are reappearing.
His position is that drought is a natural and regular occurrence in Australia, maybe even more regular than rainfall. He ended up losing his farm (and his marriage ?) as he became obsessed with it, but Gerry Harvey became a convert (one of his studs is nearby)

Actually, it goes along with a comment supposedly made by a CSIRO scientist once at a grazing conference " there is no such thing as drought, only over stocking "

I exchanged a couple of emails with that bloke a few years ago.

While talking to someone about him, can't recall who, they suggested that there might be a problem with, I think, water sequestration.

Dunno I was pretty impressed.

Simon

Originally Posted by abaddonxi

I exchanged a couple of emails with that bloke a few years ago.

While talking to someone about him, can't recall who, they suggested that there might be a problem with, I think, water sequestration.

Dunno I was pretty impressed.

Simon

Possibly, as the water that falls on your land isn't owned by you but the state and you aren't allowed to stop, divert, etc, etc, yet all he's advocating is slowing it.
This is why farm dams over one megalitre have to be licensed in NSW. Department of Water and Energy: Harvesting runoff

P.A. Yeomans is also attributed with great solutions for conserving water in the land. He developed the keyline design system

Originally Posted by rick130

Possibly, as the water that falls on your land isn't owned by you but the state and you aren't allowed to stop, divert, etc, etc

It OK to change its route it as it flows through your property but you cannot change the point at which run-off exits your property.

Originally Posted by Bush65

P.A. Yeomans is also attributed with great solutions for conserving water in the land. He developed the keyline design system

Yes, and apparently his original demonstration farm at Nth Richmond or Kurrajong is under threat of development.
The FIL was a great Yeomans advocate, used his keyline system and vibrating ripper. (and told as often as he could )