Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Meeting growing water demands in an uncertain future: a case study of current and future groundwater supply challenges and opportunities for Honiara, Solomon Islands (351)

Shaun Kies-Ryan 1 , Samantha Kies-Ryan 1
  1. Earth Water People, Highgate Hill, QLD, Australia

Currently, groundwater bores and springs make up the total water supply source for Honiara. Current demand is starting to overcome supply, with reliance on aging or under-performing assets and spring supply shortages due limited treatment capacity of high turbidity in high rainfall periods. By 2050, water demand is projected to double to around 80 ML/day 1.

The work presented is a situational analysis of current and future challenges, as part of work for the water utility, Solomon Water, on bore field performance and feasibility studies to secure further groundwater supplies for Honiara in alignment with the utilities 30-year Strategic Plan. 

Honiara has two aquifers, the deep confined fractured rock aquifer and the semi-confined alluvial Guadalcanal Plains Aquifer. Much of the conceptual understanding of the aquifers has been developed through old, discontinued, government programs 2 or via major donor projects on development of Honiara’s water supplies in 1997 and 2013 3,4. To date, the boundaries of the aquifers and inputs and outputs of the system are loosely defined or are not defined. However as is a common challenge in many Pacific nations, monitoring and understanding of the overall capacity of the aquifers has not been adequately funded, leading to incremental and reactionary developments.

In terms of Honiara’s bore water supply, the majority of bores are constructed within the confined fractured rock aquifer, with bore fields spread across the city. Four out of six bore fields are producing less than 65% of their target yields. Ongoing work is showing that the reduced yields are a combination of well interference and screen clogging.

The semi-confined aquifer has not been developed extensively for Honiara’s water supply. Honiara sits on the western edge of the 40 km wide Guadalcanal Plains, which consists of deep unconsolidated sediments (up to 200 m thick) 2. This area has potential for further development as indicated by many privately-owned bores already drilled here. Given the current level of monitoring and understanding about Honiara’s groundwater resource, a precautionary approach is required.

Having a broader understanding of groundwater systems can lead to better responses to these challenges , such as stronger water policy, more effective water sector collaboration and skills capacity building. This in turn will help build climate change resilience in the Solomon Islands.

  1. 1. Hunter H2O. 2017. Solomon Water 30 year Strategic Plan. Main Report. February 2017.
  2. 2. Lekelalu, I. 1998. Guadalcanal Plains, Solomon Islands, Groundwater Availability Guide. SOPAC Training Report 77.
  3. 3. JICA 1997. Improvement of Water Supply Facilities in Honiara. Japanese International Cooperation Agency.
  4. 4. JICA 2013. Improvement of Water Supply and Wastewater Systems for Honiara and Auki. Japanese International Cooperation Agency.