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Journal of Science, Engineering and Technology 3(2), December 2014 81

INTRODUCTION

Calabar is a city that is located in the subequatorial

clima�c zone of south eastern Nigeria. By Nigerian

standards, it is an ancient city with a notable past. Ar-

cheological inves�ga�ons that were conducted in some

parts of the city in the first decade of the 21st

century,

have produced reliable and authen�c scien�fic evi-

dence that has suggested that, as a human se$lement,

the existence of Calabar is traceable to as far back as

the 5th

century AD (Eyo and Slogar, 2008).

In its earlier days (up to the end of World War II)

the only means of transport within the city were cycling

and walking. The major means of transport out of the

city was by water transport systems that operated from

the waterfront on the Calabar River. Although the city

also has an interna�onal airport (Margaret Ekpo Inter-

na�onal Airport) that predates na�onal independence

(in 1960) the contribu�on of the airport in terms of the

number of people who travel in and out of the city has

always been minimal.

With reference to the city’s present modes of inter

-city and intra-city transport, Calabar is a typical auto-

mobile –dependent Nigerian city. Calabar was pro-

pelled into the urban age that swept across Africa, fol-

lowing the African period of na�onal independence,

beginning from the second half of the 20th

century. In

1967 the poli�cal structure of Nigeria changed from a

federa�on of four regions to a federa�on comprising

12 states. In the course of these events Calabar was

transformed from a small provincial town

(headquarters) into the capital of the South Eastern

State (later named Cross River State) of Nigeria – a ter-

ritory that extended more than 300 kilometers to Obu-

du in the north, slightly more than 100 kilometers to

Journal of Science, Engineering and Technology 3(2), December 2014: 81-90.

UNDERSTANDING THE IMPACTS OF POOR INFRASTRUCTURAL

PLANNING ON URBAN SUSTAINABILITY: IKOT ANWATIM IN CALABAR

1Yaro, M. A.,

2Ukorebi, U. A.,

3Ugbong, I. A.,

4Obia, A. E.,

5Itam, E. B.,

6Ekeng, P. O.

1&3

Department of Urban & Regional Planning, 2,4,5&6

Department of Architecture,

Cross River University of Technology (Crutech),

Calabar, Cross River State, Nigeria.

Corresponding author: [email protected]

ABSTRACT

In Calabar (a coastal city with very heavy rainfall, located within the Subequatorial clima-c zone of

Nigeria), rapid urbaniza-on means rapid transforma-on of the urban landscape from natural eco-

systems into hard impervious surfaces. As this takes place, infiltra-on of rainwater into the subsoil

for the recharge of underground aquifers is curtailed; and stormwater management becomes a

significant problem in urban development. The Ikot Awa-m ecological disaster, the subject of this

study, emerged as a result of poor management of stormwaters that ensued out of the concrete

drain channels located on the sides of a newly constructed urban motorway in the early 1980s; but

the problems have con-nued to the present day. This study has shown that the stormwaters were

discharged into the shallow flat valley of Ikot Anwa-m, without the establishment of precau-on-

ary measures to enable the porous soils of the natural ecosystem to withstand the blas-ng forces

of the stormwaters that were being released. The result was gulley erosion that has ended up in

the destruc-on of the urban landscape, eradica-on of the poten-al of the valley for urban agricul-

ture and also in threats to buildings and property located in the vicinity. It has been shown that

with the applica-on of modern techniques in stormwater management (green infrastructure), this

disaster would have been averted. Furthermore, it has been shown that as the popula-on of the

city grows, urban agriculture emerges as a viable tool for addressing food insecurity and reducing

urban poverty. Thus, it has been argued that the destruc-on of ecologically produc-ve lands, by

reasons of poor management of stormwaters, acts in contradic-on to the desire for promo-ng the

sustainability of the city.

KEYWORDS: Calabar, rainfall, stormwater management, green infrastructure, urban agriculture.

ISSN-2315-6708

82

Ikot Ekpene in the west and more than 50 kilometers

eastwards to Ekang on the Nigerian/Cameroon border.

Following its transforma�on from a small provin-

cial town into the capital of one of the 12 newly creat-

ed states of the federa�on (in 1967) there followed

significant structural changes in the transport systems

of the city. Roads were constructed to link human

se$lements located to the east, west and north. Auto-

mobile transport began to assume a dominant role,

while water transport began to fade [into history]. Cal-

abar has never been part of the railway network of

Nigeria. Calabar evolved very rapidly into an automo-

bile-dependent city and the construc�on of road infra-

structures received the most significant a$en�on. The

Murtala Mohammed Highway, which provides the de-

sired links to the territories located to the northern and

eastern sec�ons of the state, is by all accounts, the

most major of the urban roads of Calabar. The con-

struc�on of this highway (referred to as the Western

Motorway in the city master plan of 1970) began in the

1970s. The overriding importance of this motorway is

underlined by the fact that it was the first dual-carriage

motorway that to have been constructed in the city

and un�l the early 1990s it was also the only one in

existence. Thus, to all intents and purposes, the con-

struc�on of Murtala Mohammed Highway was consid-

ered to be a top priority urban development project.

However, as this research study has revealed, the eco-

logical considera�ons associated with this top-priority

project did not receive adequate a$en�on.

Ikot Anwa�m is located at 2.7 kilometres’ distance

north of the Millennium Park in Calabar. Calabar-Zero,

the point adopted as the origin for the calcula�on of

road distances in every direc�on out of Calabar is locat-

ed at the Millennium Park. In the early 1970s Ikot

Anwa�m was a virtually unknown se$lement located

on the peri-urban regions of Calabar, but today it is

part of the inner city. In the 1970s the development of

road infrastructures throughout this area was accom-

panied by the incorrect management of stormwater.

Today Ikot Anwa�m is the scene of a major ecological

disaster in Calabar. This ecological disaster, which has

spanned more than three decades in the city, is the

subject of this research study.

BACKGROUND

The Landforms at Ikot Anwa0m.

The physical characteris�cs of the landform of the ur-

ban sector within which Ikot Anwa�m is situated, are

peculiar to this part of the country. Prior to any devel-

opment, the landform consisted of a shallow valley that

sloped gently approximately from east to west, with

other gentle slopes forming the hillsides on the north

and south. Calculated along the centre line of the Mur-

tala Mohammed Highway, the land rises steadily to

south for nearly 1 kilometre and also for several kilo-

meters to the north. In the residen�al district located

to the east of the highway in this urban sector, the land

also rises steadily to the east for more than 1 kilome-

tre. The original vegeta�on of Calabar and environs

had been tropical rainforest. In its pris�ne state the

territory of Ikot Anwa�m together with its immediate

environs collected the stormwaters that rolled natural-

ly towards it, facilita�ng the gradual percola�on of the

stormwaters into the subsoil for recharge of the under-

ground aquifers. In the process a fer�le valley evolved

and provided the inhabitants with the means of a sus-

tainable livelihood in ar�sanal agriculture within the

tropical rainforest enclave. Thus, prior to the advent of

rapid urbaniza�on in Calabar, Ikot Anwa�m had been a

small farming se$lement located a short distance be-

yond the northern limits of urban Calabar (Tesco-Koz�

1970).

In Nigeria, since na�onal independence in 1960,

the rates of popula�on growth have been phenomenal

(Brown et al 1999; O'Meara 1999). This has resulted in

rapid urban growth in many parts of the country; in

circumstances in which the mechanisms for the man-

agement of the concomitant rapid changes in land use

are obselete (Okosun et al 2010). The rapid urbaniza-

�on that began to spread over Calabar in the early

1970s quickly integrated the environment of Ikot

Anwa�m into the urban structure of the city. The

spread of urbaniza�on throughout the territory led to

the rapid replacement of natural forest lands with im-

pervious surfaces; and, in turn, the spread of impervi-

ousness all over the territory, resulted in very signifi-

cant increases in the volumes of stormwaters that en-

sued during and aIer the rains. Poor management of

the stormwaters that were directed towards Ikot

Anwa�m resulted in an ecological disaster of immense

magnitude that has persisted for several decades, since

the early 1980s to the present day.

Rainfall.

Calabar is located in the subequatorial clima�c zone of

south eastern Nigeria: at la�tude 04.58 degrees north of

the Equator and longitude 08.21 degrees east of the

Greenwich Meridian (see Plate 2). The annual average

rainfall is about 300 mm. The heaviest rainfall occurs in

the months spanning from July to September; and the

average rainfall for these four months is slightly above

400 millimetres (about 405 millimetres). The maximum

rainfall is recorded in June: about 440 millimetres on

average (see Plate 3). ) Thus, on average in Calabar, the

amount of rainwater that would pour over one hectare

of land in each of the four months spanning from June

to September, would be in the order of 4.1 cubic metres

(100 x 100 x 0.41 = 4.1 x 103 m

3). This quan�ty of water

has great poten�al in providing vast ecological and agri-

cultural benefits to the city if properly harnessed; but it

also has the poten�al for inflic�ng grave ecological dam-

age if mismanaged. Thus, in Calabar, physical develop-

Yaro, M. A. et al: Understanding the Impacts of Poor Infrastructural Planning on Urban Sustainability...


ment calls for good judgment and appropriate ecological

awareness; because in respect of physical development

and the concomitant demands for stormwater manage-

ment in this city, the developer is faced with a dilemma.

The Rise in Ecological Awareness.

In the corporate context global a$en�on began to fo-

cus on the deteriora�ng human environment towards

the end of the third quarter of the 20th

century. The

United Na�ons Conference on the Human Environment

was convened in Stockholm, Sweden in 1972

(Stockholm 1972). The notable outcomes of the confer-

ence include: the Ac-on Plan for the Human Environ-

ment and the Declara-on of the United Na-ons Confer-

ence on the Human Environment (UNEP 1972). The

next landmark event occurred in 1987, following the

publica�on of the report of the World Commission on

Plate 1: Ikot Anwa�m ecological site in Calabar is located about 2.7 kilometres north of the Millennium Park. The inscrip�on

“Ikot Anwa�m erosion site” has been added to the map by the authors. (Source: Google Earth Imagery of January 20, 2011)

Plate 2: Loca�on of Calabar in Nigeria (Source: Wikimedia Commons)

Plate 3: Average monthly rainfall figures for Calabar

84

Environment and Development (WCED), Our Common

Future (also known as the Brundtland Report of 1987).

This report is famous for its exposi�on on the concepts

of sustainable development and also for its contribu-

�ons in fixing the no�ons of sustainability in the human

consciousness globally (WCED 1987). In 1992 (3-14

June) the United Na�ons Conference on Environment

and Development – UNCED (also known by the infor-

mal name Earth Summit) was convened at Rio de Janei-

ro in Brazil. The Summit’s key message was “that noth-

ing less than a transforma�on of our aRtudes and be-

haviour would bring about the necessary changes” (UN

1997). The Earth Summit produced very notable docu-

ments which further helped in establishing a global

consciousness for sustainability; Agenda 21 and others.

Follow-up conferences to Rio 1992 (Rio+10 held in Jo-

hannesburg, South Africa in 2002, and also Rio+20 held

again in Rio de Janeiro, Brazil in 2012) have con�nued

to elaborate further on the key subject of sustainabil-

ity.

Since 1972 the rise in global environmental con-

sciousness has been very notable.. The concept of sus-

tainability has permeated virtually every facet of hu-

man society; and due emphasis has been placed on the

management of stormwater and wastewater. Nigeria

has also always been a full par�cipant in all the events

that have been associated with this global environmen-

tal consciousness [since Stockholm 1972]. However, the

applica�on of the concept of sustainability to storm-

water management has not yet begun to mature in

Nigeria.

THE THEORETICAL FRAMEWORK

The Meaning of Sustainability

In an ecological age stormwater management should

be guided by the principles of sustainability or sustaina-

ble development. In “Towards Sustainable Develop-

ment” , Chapter 2 of the Brundtland Report (of 1987),

sustainable development is defined as: “development

that meets the needs of the present without compris-

ing the ability of future genera�ons to meet their own

needs” (WCED, 1987). Furthermore, according to the

United States Environmental Protec�on Agency

(USEPA), from the agency’s Execu�ve Order 13514 of

October 5, 2009 the term sustainable has been cited as

follows:“Sustainable means: to create and maintain

condi�ons, under which humans and nature can exist

in produc�ve harmony, that permit fulfilling the social,

economic, and other requirements of present and fu-

ture genera�ons” (USEPA, 2012).

The Classical Concept of Stormwater Management

As far back as 5000 years ago, in the classical days of

urban development in the ancient Babylonian Empire,

systems of stormwater management had already been

in opera�on. The systems relied on drainage channels

that collected stormwater and wastewater within the

urban space and transported it away for discharge into

water bodies (Chocat et al 2004; Chocat et al 2007).

Over �me, especially in the 19th

century, significant

changes occurred in engineering prac�ce towards the

perfec�on of this concept; but the key paradigm re-

mained the same: “that stormwater and other

wastewater should be collected in urban areas and

disposed outside of the urban environment as quickly

and as completely as possible” (Chocat et al 2004). In

the course of the last few decades some compelling

factors have dictated changes in the concepts of urban

water management; leading to a departure from an

age- long enduring paradigm. Some of these compel-

ling factors or driving forces for change have been enu-

merated in Granger et al (2010):

Urban water management must adapt to the

city and its evolu�on; the driving forces are

numerous with a diverse range of origins: social

evolu�on (increasing expecta�ons regarding

levels of service), societal evolu�on (increasing

complexity of regula�ons and ins�tu�ons,

which make urban water management more

complex), environmental evolu�on (climate

change and its consequences, etc.), technologi-

cal evolu�on (including new monitoring possi-

bili�es), economic evolu�on (global markets,

share of costs between stakeholders) (Granger

et al 2010: 1).

In addi�on to all the above, there is also the key factor

of the accelerated pace of urbaniza�on since the se-

cond half of the 20th

century, together with its impact

on the water cycle (Granger et al 2010; Cunningham,

Cunningham and Saigo 2007; Chocat et al 2004; Nebel

and Wright, 2000).

The Green Scenario for Stormwater Management

In Chocat et al, 2004 the term green scenario has been

adopted to refer to a variety of hard and soI technolo-

gies that have been evolved for stormwater manage-

ment in the ecological age. The term green scenario is

apt in that it refers to systems that have been classified

under a variety of terms in various parts of the world:

Sustainable Urban Drainage Systems (SUDS), Best Man-

agement Prac�ces (BMP), Low-Impact Development

(LID), etc. The essence of all these systems is that they

emphasize source control. Stormwater is recycled back

into nature (through infiltra�on into the subsoil for the

recharge of underground aquifers) at the point where

it occurs on the urban landscape. By this means it

would be possible to leapfrog some of the piTalls that

have been associated with the classical system: distor-

�on of the water cycle of nature, destruc�on of urban

landscape, pollu�on and destruc�on of urban aqua�c

ecosystems etc. This is a$ained through the applica�on



of diverse ecological technologies, collec�vely de-

scribed as green infrastructure (USEPA 2014).

The Ikot Anwa0m Episode

The Remote Origins of Ikot Anwa�m Episode: At Ikot

Anwa�m ecological problems arose following the com-

ple�on of the Murtala Mohammed Highway in the

1970s. With this development imperviousness increased

in the vicinity of Ikot Anwa�m and (being the lowest

point of the highway in this territory) large volumes of

Plate 4a: Ikot Anwan�m ecological site (Source: Google Earth Imagery of January 20, 2011)

Plate 4a: Ikot Anwan�m ecological site (Photo: U. A. Ukorebi, 2014).

Plate 4a: Ikot Anwan�m ecological site (Photo: U. A. Ukorebi, 2014).

86

stormwaters were directed to this loca�on from the

north, south and east; resul�ng in the flooding of the

highway in the event of heavy rainfalls. Between the

months of June and September, heavy rainfalls occur

very oIen in Calabar (see Plate 2). By the early 1980s the

floods had undermined the sub-base of the highway,

resul�ng in several lateral cracks across the highway in

the vicinity of Ikot Anwa�m. Thus the need arose for the

resolu�on of the problems of stormwater management

in the vicinity of Ikot Anwa�m on the Murtala Moham-

med Highway.

The method that was adopted was a modified ver-

sion of the classical system of stormwater management.

The stormwater was collected from drain channels locat-

ed on the eastern side of the highway, transported across

the highway by means of underground channels and re-

leased (a few metres away from the western edge of the

highway) into the shallow valley of Ikot Anwa�m (see Figs.

4a, 4b & 4c). Probably it was hoped that the stormwaters

would roll down harmlessly along the shallow valley, per-

cola�ng gradually into the subsoil for the recharge of the

underground aquifers. This did not happen, however! The

consequence of this method turned out to be completely

contrary to all the expecta�ons of the project developers

– deep gully erosion (see Plate 5a).

A proper environmental impact assessment would

have revealed that the release of large volumes of

stormwaters (with the associated high momentum) on

the loose fer�le agricultural soils of Ikot Anwa�m

would most certainly have the poten�al of dislodging

the soil par�cles and destroying the soil structure.

Thus, the outcome of this project (deep gully erosion)

should have been foreseen. The actual reason, which

caused this unexpected outcome for project develop-

Plate 5a: Ikot Anwan0m: by reason of poor management of stormwaters, an ecologically produc�ve land has been replaced

by this barren valley; thus foreclosing all possibili�es of use of this land for urban agriculture. (Photo: U. A. Ukorebi)

Plate 5b: Ikot Anwan�m: while erosion is constantly wearing away the sides of the valley, the risk of landslide is not yet fully

appreciated and new buildings are s�ll springing up close to the edge of the precipice. (Photo: U. A. Ukorebi)



ers, was the omission of a very cri�cal phase of project

planning – a pre-construc�on environmental impact

assessment. By such means various environmentally-

friendly op�ons of stormwater management would

have been proposed.

Response and Remedia�on: Almost two decades aIer

the erup�on of the ecological disaster in the early

1980s, Ikot Anwa�m was revisited in the early years of

the 21st century for the purpose of implemen�ng eco-

logical remedial works. The ecological remedial works

took place in the form of construc�on of concrete

channels for transpor�ng the stormwaters from the

point of inflow (see Plate 4c), through the base of the

gully to some distant loca�ons, somewhere on the far

west – “Out-of-sight-out-of-mind?” (Chocat et al 2004).

There is also evidence of slope-stabiliza�on works to

secure the sides of the gully in posi�on. However, ob-

serva�ons made on the project in early 2014 have re-

vealed that several sec�ons of the sides of the gully

have already started caving in (see Plates 5a & 5b). The

inference is that more effec�ve techniques of slope

stabiliza�on s�ll need to be adopted for this project.

The fact that the Ikot Anwa�m ecological site was

not revisited un�l two decades aIer the erup�on of the

environmental crisis is indeed a sad commentary on

the level of environmental consciousness that is cur-

rently in existence in the state. Ikot Anwa�m is the

most visible ecological site in Calabar. It is located on

Murtala Mohammed Highway, the principal motorway

that conveys people into as well as out of Calabar. It is

therefore curious that a major ecological disaster that is

situated on this loca�on did not a$ract appropriate

a$en�on for remedia�on un�l two decades later. The

aRtude of urban governance towards this ecological

disaster has also leI much to be desired. In Plate 5a, a

cluster of buildings can be seen located very close to the

edge of the gully; there is no evidence available to sug-

gest that the urban authori�es have addressed the issue

of the dangers that the collapsing sides of the gully pose

to the safety of the occupants. The most amazing fact is

that there is an on-going building development that is

proceeding very close to the collapsing walls of the gully

(see Plate 5b). If indeed there was any statutory approv-

al issued for the construc�on of this new building in this

loca�on (in spite of the extant ecological crisis on this

loca�on), then it would appear that the approval must

certainly have been issued in error.

Stormwater, Urban Agriculture and Sustainability: In

the place of the ecological disaster that has been al-

lowed to occur, the stormwaters that were directed to

Ikot Anwa�m valley ought to have been collected in

ponds which, in turn, would have been directed to-

wards the promo�on of urban sustainability in two

principal ways. Firstly, with �me, the water in the

ponds would have percolated through the subsoil for

the recharge of the underground aquifers. Scholars

have shown that directly or indirectly, ground waters

cons�tute the source of freshwater for a very large

percentage of humanity (Cunningham, Cunningham

and Saigo 2007; Sheehan 2001; Nebel and Wright

2000; O'Meara 1999). Secondly, the water in the ponds

could have been used for suppor�ng urban agriculture

– the produc�on of crops and vegetables.

The popula�on explosion of the 20th

century ac�ng

in tandem with the concomitant intensifica�on of ur-

baniza�on has brought a new understanding in urban

development - the concept of ecological footprints of

ci�es. Modern ci�es depend on goods that are brought

in from distant places to meet the regular needs of city

dwellers – food, materials for housing development,

etc. While the ci�es of the developed world are capa-

ble of bearing the costs of goods brought in from dis-

tant places, the reverse is the case with the ci�es of the

developing countries (Rees 1992). In the developing

world, where transport systems (from conveying urban

food quotas from distant places) are not very dependa-

ble, food is becoming closely �ed up with urban sus-

tainability. The transport of food from distant loca�ons

is linked with the uncertainty in the price of fossil fuels,

which results in infla�on in the price of food. Essen�al-

ly urban agriculture seeks to address the food supply in

ci�es by avoiding the logis�cal problems associated

with the transport of food from outside of the city.

According to Halloran (2011), “Providing food to ci�es

is a major logis�cal challenge. Addi�onally, market

changes, associated with high oil prices, as well as infla-

�on of the price of food are other systemic challenges

that must be addressed.” Within this context making

room for agriculture in the city (urban agriculture)

helps in posi�oning the city appropriately in the aspira-

�on of enabling the city to produce some of the food

that is demanded by the numerous city dwellers; this

has now been accepted as an indica�on of the sustain-

ability of the city. The use of stormwater for growing

crops has been found to be a useful strategy for coping

with the level of stormwater; thus urban agriculture is

considered to be part of the green infrastructure for

stormwater management (Freshwater Society 2013).

Urban agriculture is defined as:

An industry located within (intra-urban) or on

the fringe (peri-urban) of a town, a city or a me-

tropolis, which grows and raises, processes and

distributes a diversity of food and nonfood

products (re-)using largely human and material

resources, products and services found in and

around that urban area, and in turn supplying

human and material resources, products and

services largely to that urban area (Halloran

2011: 5).

According to Rosenburg and Yuen (2012), urban agri-

culture “does not refer exclusively to large ci�es but

88

widely applies to all agricultural sites in proximity to

densely se$led places. Scholars agree that no clear

boundary dis�nguishes urban from rural.”

In the case of the Ikot Anwa�m episode, there was

the need and the possibility of harnessing the storm-

water for the purpose of urban agriculture. The failure

to apply ecologically recommended approaches to

stormwater management has resulted in the washing

away of all the ecologically produc�ve land that had

existed in this loca�on for several previous genera�ons.

In the place of the ecologically produc�ve land that had

once covered the Ikot Anwa�m valley (an ecological

asset for innumerable genera�ons), there is today a

barren landscape, remaining as an ecological burden

for future genera�ons. For a city that is labouring under

the pressure of rapid popula�on growth, it would be

sound logic to encourage urban agriculture. This would

produce a desirable means of curtailing the ecological

footprint of the city of the future (Rees 1992;

Wackernagel 1994). The benefits of urban agriculture

include “improved nutri�on, heightened food security,

ecological restora�on, the crea�on of open spaces, and

opportuni�es for educa�on and job skills train-

ing” (Rosenburg and Yuen 2012). In the case of Ikot

Anwa�m, the principal benefits would be ecological

restora�on and the development of open spaces.

DISCUSSION

The Ikot Anwa�m episode is a man-made ecological

disaster that could have been avoided. The rise of glob-

al ecological consciousness, following the United Na-

�ons Conference on the Human Environment held in

Stockholm, Sweden in 1972 (Stockholm 1972) had al-

ready set the agenda for a proper understanding of the

environmental impacts of development projects. Ac-

cording to Chocat et al (2007), in the ecological age,

stormwater management demands a change in levels

of compression. It is significant to observe that the said

change in levels of comprehension advocated by

Chocat et al (2007) actually re-echoes the key message

of the Earth Summit of 1992 (Rio 1992); to wit that the

desired change demands “nothing less than a transfor-

ma�on of our aRtudes and behavior” (UN 1997).

At Ikot Anwa�m the prevailing concept was to col-

lect the stormwaters in the drainage channels created

along the sides of the highway and to release them at

some convenient posi�ons into the urban landscape.

The [convenient] logic that was applied was that water

finds its own level. This was understood to mean that

stormwaters, released at some convenient points on

the urban landscape, would find their ways to the near-

est urban surface waters or percolate through the sub-

soil to replenish the underground aquifers.

However, this concept of stormwater disposal

failed, and resulted in a barren gully that has remained

an ugly scar on the urban landscape. It has also pro-

duced a fragile landscape that will con�nue to require

large sums of money for remedia�on as well as stabili-

za�on of its sides to forestall landslide. The need for

changes in levels of comprehension in stormwater

management is thus confirmed. There exists a vast

array of green infrastructural facili�es that could pro-

vide useful solu�ons in situa�ons such as this, for ex-

ample: deten�on/reten�on ponds and also infiltra�on

trenches. Green infrastructural facili�es are not, by any

means expensive or unaffordable (Parkinson 2003).

Compared with the economic costs of remedia�on of

an ecologically devastated urban landscape (such as

Ikot Anwa�m) the costs of green infrastructural facili-

�es are negligible.

Reten0on Pond

A typical reten�on pond is constructed out of natural

materials to emulate the structures of natural ponds; a

recommended version for the situa�on in Flo$ow-

enweg in Germany is shown in Plate 6. Stormwaters

held here gradually percolate downwards through the

subsoil towards the recharge of the underground aqui-

fers. In the process the stormwater is filtered before

reaching the levels of underground aquifers (USEPA

2014). In the case of Ikot Anwa�m valley (before the

ecological devasta�on), a reten�on pond developed in

the forested model shown in Plate 6 could have been

made to serve dual func�ons, namely: (i) an urban

amenity for recrea�on; (ii) a green infrastructure for

safely recycling stormwaters back into nature.

Infiltra0on Trench

A typical infiltra�on trench is, to some extent, similar in

construc�on and opera�on to a soak-away pit that is

widely used for sewage disposal in Nigeria. It differs

principally in some materials and specifica�ons. The

depth of the trench is between 0.9 and 3.7 metres,

while the surface area is determined through specific

computa�ons made on loca�on. It is filled with stone

aggregates usually in the order of 2.5 to 7.5cm to pro-

vide a void space of about 40 per cent. The immediate

area surrounding the trench is constructed in the form

of a vegetated buffer used for extrac�ng solid par�cles

from the stormwaters directed into the trench. Infiltra-

�on trenches have been shown to have the capacity

to purify stormwaters before releasing them into the

subsoil towards the recharge of the underground aqui-

fers. A 150mm perforated pvc pipe makes it possible to

monitor the flow of stormwaters from the infiltra�on

trench into the subsoil (see Plate 7 and Table 1) (USEPA

1999).

It has been observed that the aRtude of the urban

governance agencies towards this ecological disaster

has been worrisome. The buildings located on the side

of the gully are clearly in danger; but it would appear

that appropriate measures have not been taken to

forestall the incipient danger. The most curious devel-

opment is the fact that a new construc�on is currently



proceeding within the same danger zone (see Plate 5b).

CONCLUSION

The ugly scar that the Ikot Anwa�m episode has leI on

the urban landscape of Calabar is a painful reminder of

the perils that could occur if urban infrastructural projects

are not planned and executed in a holis�c manner. The

interplay between the project and its environment must

always be placed in view throughout the lifespan of the

project. In this project, the en�re emphasis was placed on

the crea�on of the highway for easy movement of urban

traffic; no considera�on whatsoever was directed towards

the resolu�on of the environmental impact of the storm-

water that would follow an increase in imperviousness.

Within the realms of urban governance in Calabar, rapid

response to ecological disasters has been found to be

exceedingly lacking and therefore in need of comprehen-

sive re-thinking. In the early 1980s the Ikot Anwa�m eco-

logical site resulted, from a cri�cally important urban

project; yet it took two decades for its ecological remedia-

�on to receive official a$en�on. Two decades is enough

�me for an ecological disaster site to deteriorate beyond

remedy! Even today, some three decades later, statutory

regula�ons have s�ll not been put in place to restrict

building developments on the sides of the Ikot Anwa�m

gully, in spite of the very obvious dangers.

Fig. 6: Reten�on pond in Flo$owenweg in MiRngen, Kries Steinfurt, North Rhine-Westphalia, Germany. Source:

"Regenrueckhaltebecken Flo$owenweg MeRngen" by J.-H. Janßen - Own work. Licensed under CC BY-SA 3.0 via Wiki-

media Commons - h$ps://commons.wikimedia.org .

Table 1: Typical pollu0on removal efficiency

of infiltra0on trenches

S/No

Pollutant

Typical percent-

age removal rates

1 Sediment 90%

2 Total phosphorous 60%

3 Total nitrogen 60%

4 Metals 90%

5 Bacteria 90%

6 Organics 90%

7 Biochemical Oxygen

Demand (BOD)

70-80%

Plate 7: Source: USEPA, 1999 Source: Schueler, 1992, cited in USEPA, 1999.

90

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