Wilson, T.M.; Stewart, C.; Cole, J.W.; Johnston, D.M.; Cronin, S.J. 2009 Vulnerability of farm water supplies to volcanic ash. Lower Hutt, N.Z.: GNS Science. GNS Science report 2009/01 113 p.
Abstract: Volcanic ashfall can have serious impacts on water supplies. Freshly-fallen volcanic ash may result in short-term physical and chemical changes in water quality, increased wear and damage to water delivery systems and a high demand for water during cleanup operations. Modern farming operations are critically dependent on their water supplies, particularly dairying, which has very high rates of water consumption, particularly during summer months. The aim of this project was to characterise the vulnerability of farm water supplies in New Zealand to volcanic ashfall, and to make management recommendations to reduce this vulnerability. In this report, we have: reviewed the literature on the impacts of volcanic eruptions on rural water supplies worldwide; characterised the water use regimes and identified the vulnerability of the water supply systems of eight case study farms from across the North Island, New Zealand; devised a scheme to rate the overall vulnerability of each farm; reviewed international agricultural water quality guidelines; and finally, made a series of management recommendations for reducing vulnerability of farms to a volcanic eruption. (auth)