COASTAL EROSION PROBLEMS IN THE GILBERT ISLANDS GROUP REPUBLIC OF KIRIBATI Richard D. Gillie SOPAC Secretariat March 1993 SOPAC Technical Report 167 Prepared for: South Pacific Applied Geoscience Commission (SOPAC) Coastal Program, Kiribati Project: KIA [3] TABLE OF CONTENTS i Page SUMMARY ........................................................................................................................................................... 9 ACKNOWLEDGEMENTS………………………………………………………………………………………………… 8 INTRODUCTION …………………………......................................................................................... ..........11 OBJECTIVES .................. ........ .. ................................................................................................. .......... 12 REVIEW OF LITERATURE ............................................................................................................................... 12 Geologici Origin and Tectonics ..............................................……. ................................................……. 13 Atoll Evolution and Reef Growth .. ........................................ …………………………......................….. .. 13 I Islet Formation and Evolution…. .............. .................. ........ .................... ..................... ...................14 Contemporary Coastal Processes and Engineering ..... ......... ..................... .................... ................ 1 5 Climatology, Meteorology and Oceanography .................. ... …. ... ...... … ....... … .... ... .. ............... 16 Climate Change, Sea Level Rise and Impacts ................... ...... ...... ..... ................. .... ... .................. 18 FI~LD ACTIVITIES AND METHODS Field Activities ......................................... ........... ......... ...... ... ..... ..... ........... .....................................19 Analysis of Maps and Air Photographs ............ ........ ..... ... ..... ..... ........ ......... ....... ..................20 Site Inspections ........................... .......... ........... ........ ...... ... ……………………... ....... .................. 20 Beach Profiles ............................ .......... ............ ........ ....... .. ..... .... ................... ……….. ...........21 Interviews .................................... .........…… .... ........ ....... ... ..... ..... ................. .. ……………………21 RESULTS ...................................... ................... .................................................. ....... .. ....................... 21 Eita District ................... …. ............. ................................................ .. ...... ..... ................... 22 Tabiteuea South Nikutiri Island ...................... ................ ..... ........................................................ .................. 26 Aranuka Island . ................... ................ ...... ....................................................... ................. 27 Maneaba at Nikutoru Village ......................................... ……. ............. …............................... 32 School at Tewai Island ........................................................... ............... ... ……………..........34 Onotoa Tabuarorae Village ............................................ ......... .............................................................................37 [TR167 - Gillie] [4] Nonouti Temotu Island, Site 1, Tebakauto Village ... ...........................................................................41 Temotu Island, Site 2, Tetabakea ................ ........................................................................... 44 Temotu Island, Site 3, Teitiaki ..................... .… .......................................................................45 Rotima Island, Site 1, Airfield Road .............. ...........................................................................48 Rotima Island, Site 2, West end of Airfield .... ...........................................................................49 Buariki Village ................................................ ...........................................................................54 Abemama Tanimainiku ......................... .................................................................................................... 56 Kuria Taubukintekira (East of Airfield) ................................................................................................60 Tanginimake (Causeway) ......................................................................................................... 65 GENERAL CONCLUSIONS AND RECOMMENDATIONS ........................................................................69! REFERENCES ........................................................................................................................................... 74 ! APPENDICES 1 Summary of Map Coordinate Data 2 Beach Profile Data 3 Beach Profile Bench Mark Descriptions 4 Foreshore Protection Construction Costs 5 Coastal Protection Alternatives [TR167 - Gillie] [5] LIST OF FIGURES Figure Page 1 Location of atolls visited ............................. ........................................................................10 2 Map showing location of two beach profile sites along lagoon shoreline of Eita District, Tabiteuea North .............................................................. 23 3 Eita District, Tabiteuea North. View north of beach profile location Eita-1 ...............................................................................................24 4 Eita District, Tabiteuea North. View south past location of beach profile Eita-1 .............................................................................................................24 5 Eita District, Tabiteuea North. View south in front of beach profile Eita-2 ............................................................................................................ 25 6 Eita District, Tabiteuea North. View south approximately 30 m south of Figure 5 ........................................................................................................25 7 Map showing location of three survey sites (Nikutiri, Aranuka and Nikutoru .........................................................................................................28 8 Nikutiri Island, Tabiteuea South. View north along lagoon shoreline at beach profile site ....................... .. ...................................................................29 9 Nikutiri Island, Tabiteuea South. View south to Nikutiri Island from causeway ............................................................................................. 29 10 Aranuka Island, Tabiteuea South. View northeast to lagoon shoreline .............................................................................................................................30 11 Aranuka Island, Tabiteuea South. View southeast along lagoon shoreline .................. .............................................................................................. 30 12 Aranuka Island, Tabiteuea South. View north along beach rock exposed on lagoon shoreline south of beach profile .................................................. 31 13 Maneaba at Nikutoru, Tabiteuea South. View northwest along lagoon shoreline .................................................................................................................31 14 Maneaba at Nikutoru, Tabiteuea South. View southeast along crest of beach .....................................................................................................................33 15 Map showing location of survey site at Tewai School on Tewai Island, Tabiteuea South ..................................................................................................... 35 16 School at Tewai, Tabiteuea South. View northeast along lagoon/channel shoreline ................................................................................................... 36 17 School at Tewai, Tabiteuea South. View southwest along inter-island channel shoreline ............................................................................................. 36 [TR167 - Gillie] [6] 18 Map showing location of survey site at Tabuarorae Village on the south end of Onotoa ................................................................................................ 38 19 Tabuarorae Village, Onotoa. View east along lagoon shoreline of village .................................................................................................. ...........39 20 Tabuarorae Village, Onotoa. View southeast from reef flat ........................................ ...........39 21 Onotoa, Tabuarorae Village. View southeast from reef flat ...................................... .. ......... 40 22 Tabuarorae Village, Onotoa. View east .............................. ....................................... .......... 40 23 Map showing location of survey sites on the island of Temotu, Nonouti ................................................................................................................. 42 24 Tebakauto Village (Site 1), Temotu Island, Nonouti. View southeast along ocean reef shoreline .................................................................................43 25 Tebakauto Village (Site 1), Temotu Island, Nonouti. View southeast ............................................................................................................................43