Vulnerability of freshwater lenses on Tarawa (the role of hydrological monitoring in determining sustainable yield.)

Outline of the presentation 1) HISTORY OF GROUNDWATER DEVELOPMENT. a) 1960’s investigations and findings b) 1999’s and 2000’s investigation and findings 2) DISCUSSIONS/CONCLUSION Lessons learnt

Brief on Kiribati

Map of Tarawa

Aerial Photo of Bonriki water reserves

Some basic facts about Climate Change By the year 2050 Sea level is likely to increase by cm Air temp between deg cent. Change in rainfall between –10.7% and 7.1 % ENSO – more of it.

WORLD BANK STUDY (2000) By the Year 2050 If the rainfall decreases by 10% If sea level rises by 0.4m If the island width is reduced by inundation Groundwater thickness would decrease by up to 38% US$0.7m to $1.4 million per year

Boreholes

History of groundwater development 1960’s and 1970’s Kirk, Grundy and Partners (1961) Wilton and Bell, Dobbie and Partners (1967) Mather in 1973 Wagner in 1977 To name a few

Findings Some (Richard etc) said that Bonriki could not sustain itself while others (DHC) said that Bonriki and Buota could supply 750m3/day and 250m3/day.

1990’s and 2000 Tony Falkland, Ian White and others Findings Bonriki and Buota could yield at least 1000 m3/day and 300 m3/day respectively.

Discussion/Conclusion A number of pacific countries rely on groundwater for freshwater Climate change will affect our groundwater Based on years of experiences, borehole monitoring is probably the best way to monitor groundwater

Initial Cost borehole: AUS$100,000 - $200,000 Cost due Climate Change: US$0.7m - $1.4 million