Vulnerability of farm water supply systems to volcanic ash fall

Abstract

Agriculture is critically dependent on continuity of water quality and quantity. It is well-established that even small quantities of volcanic ash can disrupt municipal water supplies, with known impacts to quality including: acidification, increases in turbidity and ionic concentrations. In addition, delivery systems may be blocked or damaged by hard and abrasive suspended ash and related ash-cleanup operations place extra stress on water reserves. The aim of this study was to characterise the key areas of vulnerability of farm water supplies to volcanic ashfall, and to identify management recommendations to reduce these. From literature review and case studies of farms impacted by the 1991 Pinatubo (Philippines) and 1991 Hudson (Chile) eruptions, key issues were: sedimentation of irrigation ditches and drinking water ponds, turbidity induced abrasion of sprinkler nozzles and water pumps, and damage to electric pumps (by ash on air-intakes). Building on this, we characterised the water-use regimes and water supply system vulnerability of eight case-study farms from across the North Island, New Zealand. From this, we propose an index system to evaluate the vulnerability of farm water supply systems. The key contributors to the vulnerability index include: water source, storage capacity, reliance on electricity, independence/interconnectedness of system elements, volume of water use and other load factors. These allow identification of key strategies for mitigating water supply vulnerability during prevention, preparation, response and recovery phases of a volcanic eruption.

Impacts to agriculture and critical infrastructure in Argentina after ashfall from the 2011 eruption of the Cordón Caulle volcanic complex: an assessment of published damage and function thresholds

“…These are based on previous experimental and theoretical studies and were compiled as part of the UN-ISDR Global Assessment Report on Disaster Risk Reduction. Additionally, ashfall thickness thresholds, which can also be compared to CC-VC, have previously been placed on expected agricultural impacts by using a range of case studies (Wilson et al 2009). These were developed based on field trials and numerous case studies.…”

“…When assessing agricultural losses due to the 2011 CC-VC ashfall using DDS (Jenkins et al 2014) and impact thresholds (Wilson et al 2009), the national park region performed much better than expected given the large thicknesses received (>300 mm). This is demonstrated by both current schemes (Fig.…”

“…Categorise the interview data collected using a range of DDS schemes (e.g., Jenkins et al 2014;Neild et al 1998;Wilson et al 2014a;Wilson et al 2009). Assign the same DDS based on the ashfall thicknesses received.…”

The size range of bubbles that produce ash during explosive volcanic eruptions

“…Volcanic ash represents a significant hazard to the airline industry and operation of global commerce (Casadevall 1994;Casadevall et al 1996;Prata 2009;Durant et al 2010), water quality (Stewart et al 2006;Stewart et al 2009;Wilson et al 2010), agriculture (Cronin et al 1997;Wilson et al 2010), stability of local infrastructure (Wardman et al 2012a;2012b;Wilson et al 2012), and human health (Baxter et al 1999;Horwell et al 2003aHorwell et al , 2003bHansell et al 2006;Hincks et al 2006;Horwell and Baxter 2006). Because ash can be transported for great distances regardless of the total volume of material actually erupted, it represents one of the farthest reaching volcanic hazards.…”

Interdependence and dynamics of essential services in an extensive risk context: a case study in Montserrat, West Indies

“…Ruapehu, New Zealand, 1995-1996andMt. Hudson, Chile, 1991 (Johnston, 1997;Johnston et al, 2000Johnston et al, , 2004Leonard et al, 2005;Stewart et al, 2006;Sword-Daniels et al, 2011Wilson et al, 2009Wilson et al, , 2010. Ashfall impact studies have included aspects of structural loading, electrical power networks, water and wastewater systems, telecommunications networks, aircraft, land transportation, heating ventilation and air conditioning (HVAC) systems, and laptop computers.…”