The drought conditions in Northland and other parts of the country last summer, have focused the minds of Federated Farmers in particular on the need for water storage.

Regenerating forest will complete the hydrological cycle.

Citing a number of cases in Hawke’s Bay and Canterbury, the farmers’ union pointed out the economic benefits of water storage, and have called on the government to make it a priority – in effect treating it as infrastructure, every bit as vital as railways and roads.

Water storage however is a more complex issue than simply building bigger dams.

The lack of rainfall this summer has been caused in part by climate fluctuation, which has in turn been interrupted by deforestation.

Rural Living recently caught up with Callum Coats, author of several books on the renowned Austrian Forester and Hydrologist, Viktor Schauberger.

“Trees attract rain in the exchange between upward evapo-transpiration and downward precipitation,’ said Callum.

“While water storage is certainly of benefit, the recreation of forest would do much to alleviate the present loss of rainfall, although this would not happen overnight, but gradually improve as the new forest grows.

“Such a forest should not be a monoculture, but as naturally mixed with native species according to altitude and location as circumstances permit.

“In terms of the current fears of global warming due to excess carbon dioxide, trees and vegetation generally are by far the best fixers of CO2, which would be another reason for large scale reafforestation.”

Callum pointed out that the large scale removal of the forest cover in a land as narrow as New Zealand, would certainly have been a factor in the highs and lows of precipitation.

Coupled with El Nino, and other, effects it was inevitable that the upward evapo-transpiration would be diminished with inevitable consequences.

“Trees are effectively standing columns of water, as well as being the greatest stabilisers of climate available. I remember reading in either Sahara Challenge or Sahara Conquest by Richard St.Barbe-Baker, a description of the result of planting a belt of trees (eucalypts I think) 70 odd miles long and 30 miles deep along the barren coast of Morocco.

“After these trees had matured slightly, rain fell in that area for the first time in living memory.”

Readers may recall that Richard St.Barbe-Baker was the founder of the Men of the Trees – now the International Tree Foundation (ITF) based in the UK.

The ITF continues the pioneering work of St.Barbe-Baker and has projects throughout the world for planting millions of trees.

The full hydrological cycle, in which water moves from subterranean regions to the atmosphere and back again continuously has been severely interrupted wherever humankind has cut down the trees.

Forest cover provides the retentive element within this cycle.

Roughly 15% of the rainfall will be absorbed by the vegetation and 70% will make its way into the aquifers.

Temperature is a crucial element in this cycle, and the forest has a natural cooling effect on the earth – notice how much cooler it is in a deep grove of trees on a hot day.

Rainwater will only penetrate if the receiving ground is cooler than the rain.

Where the land, and particularly slopes have been denuded of trees we have the half hydrological cycle.

Now increasingly warmer, the ability of the ground surface to absorb the rainfall has been reduced, or removed entirely, so the water drains away rapidly, increasing and exacerbating erosion.

The aquifers are not recharged, and the rainfall is wasted by surging away down streams and rivers (possibly normally dry) and through much faster evaporation.

In conclusion, we certainly need dams and water storage for our farming economy. But in order for those dams to be full we need to cultivate and promote the reality that trees and forest are an essential foundation.     

• Rural Living would like to thank Callum Coats for his assistance in the preparation of this article.