United Nations Office for Project Services (UNOPS) UNDP-Accra Environmental Sensitivity Map for Coastal Areas of Ghana. Volume II - Coastal Environment October 2004 Prepared for Environmental Protection Agency, Ghana by United Nations Office for Project Services (UNOPS) UNDP-Accra Environmental Sensitivity Map for Coastal Areas of Ghana. Volume II - Coastal Environment October 2004 Prepared for Environmental Protection Agency, Ghana Report no. Vol. II - Final Issue no. 1 Date of issue 30 October 2004 Prepared A.K. Armah, C. Biney S.Ø. Dahl and E. Povlsen Checked ERP/SDA/SHC Approved Steen Øgaard Dahl Environmental Sensitivity Map for Coastal Areas of Ghana 1 Table of Contents 1 INTRODUCTION 4 2 GEOGRAPHICAL BACKGROUND 5 3 PHYSICAL CONDITIONS 8 3.1 Climate 8 3.1.1 Rainfall 8 3.1.2 Evaporation 9 3.1.3 Temperature 9 3.1.4 Humidity 9 3.1.5 Wind 9 3.2 Hydrography 9 3.2.1 Temperature 9 3.2.2 Stratification of water masses (thermocline, halocline) 11 3.2.3 Tidal ranges 12 3.2.4 Salinity 12 3.2.5 Currents 12 3.2.6 Upwelling 13 3.3 Bathymetry and Sediments 14 3.3.1 The continental shelf and its extensions 14 3.3.2 Depth contours 15 3.3.3 Sediment types 16 3.3.4 Sediment balance 17 3.3.5 Littoral transport 17 3.3.6 Transport through tidal inlets 18 4 ECOLOGICAL CONDITIONS 19 4.1 Offshore Ecosystem 19 4.1.1 Introduction 19 4.1.2 Plankton 19 4.1.3 Fish 20 4.1.4 Shrimps and prawns 21 4.1.5 Shellfish grounds 21 4.1.6 Offshore benthic invertebrate fauna communities 21 Volume II – Coastal Environment, October 2004 Environmental Sensitivity Map for Coastal Areas of Ghana 2 4.2 Marine Coastal Ecosystems 22 4.2.1 Introduction 22 4.2.2 Sandy shores 23 4.2.3 Rocky shores 24 4.2.4 Coastal lagoons 26 4.2.5 Mangroves 31 4.2.6 Fringe forests 32 4.2.7 Estuarine wetlands 33 4.2.8 Depression wetlands 33 4.3 Birds 34 4.3.1 Songor Lagoon 35 4.3.2 Muni Lagoon 37 4.3.3 Sakumo Lagoon 37 4.3.4 Densu Flood Plain 39 4.3.5 Anlo-Keta Wetland 41 4.4 Endangered Species 43 4.4.1 Marine turtles 43 4.4.2 Manatees 44 4.5 Protected Areas 44 5 SOCIO-ECONOMIC CONDITIONS 50 5.1 Population and Settlements 50 5.2 Fishery 53 5.2.1 Introduction 53 5.2.2 Marine fisheries 54 5.2.3 Lagoon fisheries 60 5.2.4 Aquaculture 61 5.3 Oil and Gas Extraction 61 5.4 Salt Production 62 5.5 Industrial Development 63 5.6 Farming in Coastal Areas 63 5.7 Tourism 63 5.8 Historical Monuments 64 6 ENVIRONMENTAL DEGRADATION 67 6.1 Pollution 67 6.1.1 Municipal waste 67 6.1.2 Industrial waste 68 6.1.3 Chemical pollution from agriculture 68 6.1.4 Other chemical pollution 69 Volume II – Coastal Environment, October 2004 Environmental Sensitivity Map for Coastal Areas of Ghana 3 6.1.5 Oil spill events and threats 69 6.2 Coastal Erosion 70 6.3 Over fishing 71 6.4 Issues of Concerns in the Coastal Zone 72 6.4.1 Mangrove and wetland degradation 72 6.4.2 Sand and gravel mining in the coastal zone 72 6.4.3 Impact of inland drainage on coastal lands and waters 73 6.4.4 Endangered species 74 7 REFERENCES 75 Volume II – Coastal Environment, October 2004 Environmental Sensitivity Map for Coastal Areas of Ghana 4 1 Introduction Environmental Protection Agency of Ghana is the focal point for coastal zone management activities in Ghana and responsible for the National Oil Spill Con- tingency Plan. In order to strengthen the planning capabilities and support the Government of Ghana to perform sustainable coastal zone management, UNDP has supported the project ‘Environmental Sensitivity Map for the Coastal Area of Ghana’ with financial assistance from the Fund for Danish Consultancy Ser- vices administered by UNOPS. The aim of the project has been i) to develop a GIS based environmental plan- ning tool for coastal zone management, ii) to develop a management tool for use in planning and implementation of oil spill response, and iii) to train the EPA staff in operating the GIS system The project was carried out in 2003- 2004 by the joint venture of COWI and DDH Consulting both of Denmark with contributions from the national con- sultants, namely Charles Biney, A.K. Armah, Ernest Kusi-Minkah and George Botchie. The project has been anchored in the Environmental Protection Agency with the assistance of the core staff of Daniel Amlalo, Roger Leh and Wilson Tamakloe. The project has been reported in three volumes: Volume I - Atlas. The Atlas contains 96 maps (scale1:20.000) covering the entire coastline of Ghana. The maps illustrate geological, ecological and human use features relevant in coastal zone management and in oil spill combat. Each map sheet includes a short description of the main features and indicates the ranking of the coastline in terms of sensitivity to oil spills Volume II - Coastal Environment. The Coastal Environment Report de- scribes the geological-, hydrographical-, ecological- and socio-economical con- ditions mapped in the Atlas. Volume III - Oil Spill Sensitivity Ranking. The Oil Spill Sensitivity Ranking Report describes the ranking system and the assessment of the sensitivity of the ecological and human use features to oil spill. Volume II – Coastal Environment, October 2004 Environmental Sensitivity Map for Coastal Areas of Ghana 5 2 Geographical background Ghana lies along the Gulf of Guinea in West Africa, within longitudes 3° 5’ W and 1° 10’ E and latitudes 4° 35’ N and 11°N. It covers an area of about 239,000 km2. The country is bordered by Togo to the East, Côte D’Ivoire to the West and Burkina Faso to the North. The coastline of Ghana is about 550 km long. Coastal plain Behind the coastline is a low lying coastal plain. The coastal plain is broad in the east and west, where it stretches over 80 km inland, and narrow in the mid- dle near Winneba and Accra. In this area it does not extend more than 16 km inland from the sea (Dickson & Benneh, 1980). There are two main vegetation zones on the coastal plain. In the Western part from the frontier with Côte d’Ivoire to Cape Coast the coastal plain is dominated by semi-deciduous and evergreen secondary tropical forest. The area from Cape Coast to the eastern border with the Republic of Togo comprises a relatively dry zone with low- lying thickets and savannah-grassland to the east (Armah and Amlalo, 1998). Coastline and conti- Around 70 percent of the 550 km long coastline consists of sandy beaches. The nental shelf continental shelf (200 m depth limit) varies in width along the coast of Ghana, from 20 km off Cape St. Paul in the east to about 90 km at the expanded por- tion between Takoradi and Cape Coast in the west. Ghana’s offshore area (50- 200 meter depth) is estimated at 8,500 km2 and comprises soft (muddy and sandy-mud), hard and sandy bottoms. The coastal zone is dotted with over 90 coastal lagoons, most of which are very small and less than 5 km2 in surface area (Armah, 1993). The largest lagoon, the Keta Lagoon, however covers an approximate surface area of 350 km2 (Ababio, 2001). The Ghanaian coastal zone may be divided into three geomorphologic zones (see Figure 2.1); the West, Central and East Coasts (Ly, 1980). • The West Coast covers 95 km of stable shoreline and extends from Ghana's border with Côte d’Ivoire to the estuary of the Ankobra River. It is basically fine sand with gentle beaches backed by coastal lagoons. • The Central Coast shoreline is 321 km long and extends from the estu- ary of the Ankobra River near Axim to Prampram, located to the east of Accra. It represents an embayed coast of rocky headlands, rocky shores and littoral sand barriers enclosing coastal lagoons. Volume II – Coastal Environment, October 2004 Environmental Sensitivity Map for Coastal Areas of Ghana 6 • The East Coast, which is made up of 149 km of shoreline, extends from Prampram eastwards to Aflao, at the border with Togo. It is character- ized by sandy beaches with the deltaic estuary of the Volta River situ- ated halfway in-between. The Volta River is the largest river in Ghana with a regulated flow of about 850 m3/s due to damming upstream. The East Coast has a significant proportion of its land area covered by the Keta Lagoon, the Volta Estuary and the Songor Lagoon. Figure 2.1. Map showing the coastal zone of Ghana Rivers The major rivers, which drain the coastal area, are, from the west, the Tano, Ankobra, Butre, Pra, Kakum, Amisa, Nakwa, Ayensu, Densu and Volta. Some of these such as the Amisa, Nakwa and Ayensu flow into the sea through la- goons. Three of these, the Ankobra, Pra and the Volta are among the largest and flow all year round. Peak discharges occur in June and July with low flows in February. For the Ankobra and Pra rivers, the mean discharge rates for the peak months are in the order of 110 and 480 m3/s respectively. The discharge rate for the low flow periods for the Ankobra River is about 4 m3/s and the Pra River 70 m3/s. The largest river in terms of catchment area and volume is the Volta, which was dammed in 1965 for hydroelectric power generation.