Attachment A Shoreline Management Plan Committee 15 March 2021 Comprehensive Report: Shoreline Management Plan Erosion and Inundation Hazard Maps 1 Background Coastal inundation is caused by sea levels increasing as a result of a number of oceanic processes which occur over both short time frames (hours to days), e.g. tides and storms, and long time frames, e.g. sea level rise. The different components of measured sea level include predicted astronomic tide, storm surge and sea level anomoly (see Figure 1). These processes vary between the Coromandel Peninsula’s east coast, that faces the Pacific Ocean, and west coast, within the Hauraki Gulf/Firth of Thames. Figure 1 The components of coastal inundation considered in the modelling Figure 2 The components of coastal erosion considered in the modelling 2 Discussion 2.1 Coastal Erosion Maps Coastal erosion maps have been produced for the following high risk locations for 2020, 2040, 2070 and 2120 (link to maps included in Attachment 1): For Thames Coast – Tararu, Te Puru, Whakatete Bay, Ngarimu Bay, Waoimu, Tapu, Te Mata, Waikawau and Kereta. For Coromandel to Kennedy Bay Coast – Papa Aroha, Oamaru, Colville and Kennedy Bay. For Whangapoua Harbour and Mercury Bay Coast – Whangapoua, Matarangi, Wharekaho, Buffalo Beach and Cooks Beach. For the South East Coast – Tairua, Pauanui and Whangamata. Some further modelling is proposed to provide more detailed information for Tararu, Te Puru, Colville, Buffalo beach and Whangamata South. Other areas of investigation should include Amodeo Bay/Waitete Bay. 2.2 Coastal Inundation Maps Coastal inundation maps have been produced for the following high risk locations (link to maps included in Attachment 1): For Thames Coast – Kopu, Thames, Tararu, Te Puru and Tapu. For Coromandel to Kennedy Bay Coast – Coromandel and Colville. For Whangapoua Harbour and Mercury Bay Coast – Whangapoua and Whangapoua Harbour, Matarangi, Whitianga and Cooks Beach. For South East Coast – Tairua Harbour and Whangamata. Further modelling is proposed to provide coastal inundation hazard lines in 20cm sea level rise increments to 1.4m for 1% (100-year) and 5% (20-year) AEP storm events and for king tide events. This will provide data on the likely increased frequency of flooding. Attachment 1 – Link to DRAFT Coastal Erosion and Inundation Maps https://www.tcdc.govt.nz/Your-Council/Council-Projects/Current-Projects/Coastal- Management/Shoreline-Management-Plans/.