Environment and development in coastal regions and in small islands

Study lists causes of Ikoyi, Victoria Island floods

The Environment

The study, which was funded by UNESCO, revealed that the perennial flood problem in Victoria Island and Ikoyi are predominantly caused by excessive rains, faulty drainage designs and unsavoury habits leading to drainage blockages.

EXCESSIVE rainfall coupled with design defects of drainage channels have been blamed for the protracted flooding of the high-brow neighbourhood of Ikoyi and Victoria Island.

It was also disclosed, at a media and public forum on drainage and flood problems in Lagos last week, that when heavy rains coincide with high tides, tidal waters flow back into the channels through the outflows causing excessive flooding.

The study, which was funded by the United Nations Educational, Scientific and Cultural Organisation (UNESCO) on the platform of one of its divisions, the Coast and Small Islands (CSI) unit, also identified blockage of drainage channels by refuse and sediment, obstruction by buildings and lack of drainage heads to make them efficiently drain off storm waters.

The study was conducted by the Marine Geology/Geophysics Division of the Nigeria Institute for Oceanography and Marine Research, Lagos. The study examined the efficiency of some drainage channels in the face of tidal, sea level rise and other human activities.

Essentially, eight main drainage channels were surveyed to estimate their capacity to discharge storm water into the Lagoon. Analyses of historical tide gauge data to determine sea level rise variation; collecting and analysing meteorological data and storm surge data were conducted. The efficiency of the present channels was also determined during the study.

Results of the data collected show that flooding of the Victoria Island and Ikoyi is predominantly caused by excessive rains which are very prevalent during the months of June, July, September and October.

According to Mr. Larry Awosika, who presented the results on behalf of the study team, "analysis of historical tidal date shows that tides are predominantly semi-diurnal with two inequalities. Tidal range varies from one to 1.5m above the zero of the tide gauge while mean sea levels between 1992 and 1996 range from 1.7 to 1.9m above the zero of the tide gauge.

"However, the months of September and October are characterised by mean sea levels of about 2m above the zero of the tide gauge. Storm surges are experienced during the months of April, May, August and September. During these storm surges, high waters exceed 4m above low water resulting in flooding."

To alleviate the menace of these flood-prone neighbourhoods, the study recommended that some drainage channels must be re-routed to increase their efficiency; repair some of the concrete channels, while earthen channels have to be built with concrete; while screen bars should be installed along some drainage channels.

Others included fencing of some drainage channels to discourage people from using them as dump sites; increase the beach height along the Bar Beach above astronomical high tides; construct new channels and rehabilitate old ones with enough drainage heads; embark on a comprehensive survey of all drainage channels, and sustained public enlightenment to discourage residents from dumping their refuse into drainage channels.

In his comments, the UNESCO representative in Nigeria and the Economic Community of West Africa, Mr. Emmanuel Apea, went down memory lane, saying "my memories of Lagos during the rainy season is still very fresh; of the rivers and lakes' that cars and people have to swim through, of men with trousers folded knee high to wade through ankle deep pools of water after the rains; of agonizing 'go-slow' stretching for kilometres due to the effect of flooding of roads."

He described Lagos as the commercial nerve centre of Nigeria and even the whole of the west coast of the sub-region. The impact of any environmental catastrophe on commercial activities in Lagos, he reasoned, will have a rebounding effect on the entire economy of the sub-region.

He explained further, and said that is the reason Coast and Small Islands (CSI) division of UNESCO in its "programme for sustainable development of coastal regions, has recognized the importance of engaging in finding solutions to some of the coastal problems in Nigeria.

"The idea of a public campaign is very important because if we do not carry our people along in whatever plans we have for the environment we are not likely to succeed. Every member of the society ought to know his or her role in making where we live better. The roles of the people and the government should be complementary; each helping the other to achieve the best for the community, after all each is equally guilty for the state of affairs we have found ourselves in with respect to our environment.

"I am glad that UNESCO means business in Nigeria; there are currently major activities being carried out under the UNESCO-Nigeria special plan of action in its areas of competence and we are building upon the current democratic dispension to increase our activities in Nigeria."

Dr. H. Barah, another UNESCO official, disclosed that the CSI is a relatively new initiative within UNESCO which was launched in 1996, and seeks to assist UNESCO member states towards environmentally sound, socially equitable and culturally appropriate development of their coastal regions.

The Victoria Island, Ikoyi drainage is one of the 23 inter-sectorial pilot projects that have been established or co-sponsored involving some 60 countries. These projects cover topics ranging from the various dimensions of a ship breaking industry in India, to sustainable fishing activities in Haiti, to underwater archaeology in Egypt.

Tunde Atere, Housing & Environment Reporter, The Guardian - 19 June 2000