MANAGING FLUVIAL DYNAMICS AND ENVIRONMENTAL CRISES IN NIGERIA. BY A paper presented at the Workshop/Inauguration of Oshun State Chapter of Nigerian Environmental Society . Theme: Sustaining

1

MANAGING FLUVIAL DYNAMICS AND ENVIRONMENTAL

CRISES IN NIGERIA.

BY

J. E. UMEUDUJI

DEPARTMENT OF GEOGRAPHY & ENVIRONMENTAL MANAGEMENT,

UNIVERSITY OF PORT HARCOURT, PORT HARCOURT.

A paper presented at the Workshop/Inauguration of Oshun State Chapter of

Nigerian Environmental Society . Theme: Sustaining Environmental Best

Practices. Brymor Hotel, Ilobu Rd, Osogbo, 29thOct, 2013.

INTRODUCTION:

One very striking characteristic of nature is change and over time,

it is possible to detect a pattern or regularity as regards the course of

change. All features on the surface of the earth are variable, no matter

how massive and apparently stable they may appear at any given time.

A close and very critical look reveals that the change occurring on all

features and phenomena on the surface of the earth has a direction and

a pace which over time can also reveal a pattern or regularity.

An aerial view of any continent clearly shows an intricate pattern

of depression lines, which like arteries, conduct water, sediments and

other fluvial materials from elevated areas down to oceans, seas or

lakes. These are the river networks, which like every other phenomenon

2

on the earth’s surface, are constantly and inevitably evolving. The

activities which inherently circumscribe rivers are described as fluvial

and they are, by nature, dynamic.

Ordinarily, with respect to man, the environment refers to the

setting within which he optimally functions, or to the external

conditions inimical or favourable to his operation. Whenever any

changing phenomenon or feature assumes a critical state quite

deleterious to man, then we are talking of crisis in that regard. It is in

this light that we want to examine the changes associated with rivers in

Nigeria so as to understand and ameliorate their negative effects on

human survival.

WHAT RIVERS DO:

Apart from literally being intricate designs that beautifully adorn

the terrestrial landscape, rivers do a lot of work functionally integrated

into the mechanism that sustains the earth. As arteries, river through

their fluvial activities, relentlessly move topographic matter from high

land regions to lowlands and eventually into the sea. Much of the

transformation of surface configuration is a function of fluvial activities.

3

As a key component in the hydrological cycle, rivers conduct a

significant quantity of surface runoff to the oceans. However, rivers do

not just feed the oceans but also serve as inlet of the oceans into the

continent in the course of upward eustatic adjustment. Since rivers

create their own channels, it implies that over time, channel capacity

may gradually and automatically widen to accommodate increased flow.

Whenever a river’s adjustment to changes in related phenomena such

as sea level rise, increased precipitation through climate change or

topographic lowering comes too abruptly, the result could possibly spell

crisis to the environment in question. How to understand and safely

play along with the changes in river activities in such a way as to

minimize environmental crises is what we want to address using

Nigeria as a case in point.

OVER-VIEW OF RIVER SYSTEMS IN NIGERIA:

While presenting a fundamental work on the water resources

inventory of Nigeria, Ayoade and Oyebande (1983) aptly noted that the

country is well-drained with a close network of rivers and streams.

Many of the rivers including the Niger (and Benue), Ogun, Owena,

Cross, Imo etc empty directly into the Atlantic while a few such as

Hadejia and Jama’are empty into Lake Chad.

4

Fully aware of the role of rivers not just in the facilitation of the

efficient operation of natural systems on the topographic surface but

also its role in development, these numerous river systems have been

divided into Eleven River Basin Development Authorities (Fig.1). These

RBDAs are as follows: Sokoto-Rima, Hadejia-Jama’are, Lake Chad,

Upper Benue, Lower Benue, Cross river, Anambra-Imo, Niger, Ogun-

Oshun, Benin-Owena and Niger Delta.

Fig. 1: Nigeria: Showing the Eleven RBDAs.

5

Technically, a river or drainage basin is a geomorphic or

hydrologic unit that supplies water, sediment and other fluvial

materials to a river channel or a network of channels. It is a

topographic space shaped in such a way as to slope towards a central

river hence enabling surface (and sub-surface) water to flow laterally

from the summit or interfluves to the central channel and subsequently

down and out through the outlet (Umeuduji, 2010).

Though delineating the eleven river basins did not follow the strict

technical definition, yet geographically the area within each basin has a

lot in common. Rather than population or ethnicity, geographical

parameters such as landscape morphology and drainage networks

played a critical role in defining each basin.

For optimal harnessing of the potentials of the rivers, it is

imperative to exhaustively explore their different attributes ranging

from an inventory of their numbers, drainage lengths, densities, stream

gradients to hydraulic parameters. With ample data on these

parameters over a considerable length of time, clearly predictable or re-

occurring regularities and irregularities about these rivers can easily be

isolated. If not foreseen and identified before hand, such fluvial

6

dynamics will obviously translate to serious environmental crises.

Details of such river- related problems capable of endangering life and

comfort will be examined in the subsequent section.

ENVIRONMENTAL PROBLEMS THAT STEM FROM RIVERS:

Fluvial dynamics or changes in the activities of river systems can

assume several forms. They can be noticed in the form of channel

elongation, channel widening, channel swinging, violent erosion,

excessive sedimentation/deposition before the outlet, inability to

efficiently transport or convey water hence resulting to flooding, among

others. These vagaries are often seen as abnormal but a careful analysis

of their frequencies over a long time can reveal a clear pattern in their

trend which means that they can actually be predicted. The earlier man

understands and foresees these changes, the more prepared he is to

encounter them and so the more minimal the effect on his economic

activities.

Since river flow is a function of rainfall, whenever there is

prolonged drought, the water in the channel becomes insufficient hence

impacting negatively on all life forms (including man) that depend on it.

7

For instance, Kumolu (2013) has argued that the creation of Eleven

RBDAs in 1976 by the Supreme Military Council was primarily a swift

response to the drought of 1972-74 in Nigeria.

It should be noted that rivers are both self-adjusting and sensitive

to external (especially human) interference. For instance, as we have

reported elsewhere (Umeuduji, 2000), a combination of intensive

cultivation on weakly coagulated soil setting and in-stream sand mining

or quarrying is what gives an impetus to accelerated soil erosion at the

head-water area of Mamu river (a tributary of Anambra river). Again,

much of the material removed at the yawning gullies of Agulu-Nanka is

what has exceeded channel capacity hence leading to braided stream

below the Niger-Anambra confluence at Onitsha.

However, the most dramatic and widely reported river activity is

when the channel capacity is exceeded leading to widespread flooding.

For instance, in the Zealand region of The Netherlands in 1953, a

combination of unusually high rainfall and spring tide caused the

channel capacity of IJssel, Rhine, Meuse and Schelde rivers to be

exceeded. This situation battered existing dykes in more than 500

locations, flooded about 200,000 hectares of land and leaving a trail of

8

terrible economic consequences in the region (Heer, Geurtsen and

Bijinsdorp, 2006).

Here in Nigeria, memories of the 2012 floods that ravaged up to

Twelve States (including Bayelsa, Rivers, Anambra, Delta, Kogi,

Taraba, Adamawa, Nasarawa, Edo, Benue, Jigawa, and Kebbi Fig. 2)

are still fresh. Again, the floods were attributed to a combination of

exceptionally high rainfall and the release of water from Lagdo Dam in

Cameroon.

PDNA (2013) reported that the most devastating effects of

the 2012 floods were on agriculture (food crops), livestock, fishery,

manufacturing, industry, commerce, oil industry, electricity, drinking

water supply and sanitation, transport and communication, housing,

education, health and nutrition. In Fig. 3, the photographs speak

eloquently for themselves and Table 1 gives more details of the effect on

housing.

9

Fig.2: Nigeria: Showing Per capita damage in the 12 most affected

states (Source: PDNA,2013).

10

Figure 3: Aerial View of Submerged Housing in Delta, Anambra,

Bayelsa, and Rivers State. (Source, PDNA, 2013).

Table 1: Number of Totally and Partially Destroyed Houses in the Most-

Affected States.

States

Traditional

Sandcrete

Total

Number

Affected Number

Totally

Destroyed

Number

Partially

Damaged

Total

Number

Affected

Number

Totally

Destroyed

Number

Partially

Damaged

Total

Number

Affected

Adamawa 117,829 36,134 153,963 23,401 23,401 177,364

Anambra 16,186 6,719 22,905 95,394 95,394 118,299

Bayelsa 79,730 26,577 106,307 26,577 26,577 132,884

Delta 84,834 4,465 89,299 89,299

Edo 13,153 14,249 27,402 27,402

Jigawa 11,623 5,230 16,853 282 282 17,135

Kebbi 103,048 52,555 155,603 155,603

Kogi 124,085 3,102 127,187 16,259 16,259 143,446

Nasarawa 16,326 136,049 152,375 5,750 5,750 158,134

Rivers 36,999 4,111 41,110 10,121 192,290 202,411 243,521

Taraba 81,688 32,675 114,363 114,363

Total 685,501 321,866 1,007,367 10,121 359,962 370,083 1,377,450

(Source: PDNA, 2013).

11

The losses enumerated above are the primary effects of flooding, in line

with O’Connor and Costa (2004), who classified the magnitude and

severity of flood losses into primary, secondary and tertiary. The

secondary effects are experienced much later after the flood incident, for

example, in the form of disease outbreak as drowned humans and

animals decay and contaminate drinking water. In the same manner,

there can be tertiary or long term effects which may be expressed in

form of a general difficulty for man and other biological entities to

overcome the immanent impact of a past flood. This can lead to an

economic melt down in the long run.

Recounting the environmental, economic and social losses

sustained from unforeseen adjustments in the fluvial system is not of

much use instead, understanding and managing the dynamics can be a

noble intellectual venture.

MANAGEMENT OPTIONS:

Generally, the starting point for managing or controlling any

natural phenomenon is to understand and key into its operation. To

passively accept and bear any natural event as an “act of God”, is in

12

itself, defeatist. In other words, a change of attitude is required right

from the onset that it is possible to understand the working of nature in

such a way as to control it.

Secondly, though most natural occurrences are characteristically

random, yet ironically there may be little or nothing random about such

occurrences in that when properly analyzed over a considerable length

of time, clear trends and predictable patterns can emerge. Fluvial

dynamics, apparently seen as irregular, may actually be underlain by a

striking regularity. This can only be realized through a rigorous

scientific analysis of related details or background information.

It is important to take an inventory of the gamut of fluvial

activities as well as their spatial manifestation and features associated

with them. For instance, given the geological and geomorphological

setting, specific channel activities such as erosion or deposition should

be clearly associated with specific stretches of the river channel.

Fluvial activities should also be seen in conjunction with related

causative phenomena. For instance, fluctuations in stream flow can be a

function of climatic and marine dynamics. Rivers act as conduit for

13

conveying surface water that came from precipitation. It implies that

meteorological or climatic vagaries will directly translate to

corresponding variations in stream flow. Rainfall is cyclic and clearly

exhibits return periods. As we have stated else where (Umeuduji, 2010),

the return period defines the length of time after which the event in

question is expected to occur again. Smaller rainfalls that generate

smaller floods are more frequent in occurrence while exceptionally

higher rainfall events which generate exceptionally widespread floods

occur less frequently. So, understanding rainfall regimes can throw

some light on river flow and floods.

We still believe that the drainage basin provides a standard

spatial framework for appraising fluvial dynamics. Fluvial activities are

only functional in the setting of a spatially definable basin. Therefore,

understanding both the structure and function of the drainage system

can help us better explain fluvial dynamics. The actual creation of

RBDAs in Nigeria is a step in the right direction but making sure that

the RBDAs fulfill their mandate is another and more important thing.

Recently, it was reported that the Federal Government has stated

that there was imminent need for the privatization of the RBDAs and

14

their assets across the country in order to better achieve the objectives

for which they were established (Nnodim, 2013). As the issue is with the

National Assembly, whether the private sector or the Government runs

the RBDAs is a purely political decision, but what is of interest to us is

that the river basin framework should not be abrogated. In fact, what is

needed is real integrated river basin management. There are so many

interrelated and potentially mutually enhancing components of the

drainage basin. It is a fact that the more precise and holistic our

appreciation of the parameters, the better the derivable benefits.

Finally, a key management option we must mention is the issue of

land use zoning. This zoning should be based on detailed and accurate

morphological and hydro-meteorological data. For instance, data on

rainfall return periods should be used to delineate the morphology of

the floodplain into say, 5-year, 10-year, 20-year, 50-year or 100-year

floodplains. Since flood losses are correlated with the degree of human

activities, it means that the more the human activities, the more the

losses. Land uses should therefore be consciously zoned on the

floodplain. For example, Hillsdale County (2008) recommended the 100-

year floodplain as the safe and acceptable limit for development

15

involving heavy capital outlay (such as urbanization and

industrialization).

The major challenge in Nigeria is to use meteorological and runoff

data to mark out the different floodplains of long return periods and

then force developers to abide by the stipulated safe limits for each

human activity.

CONCLUSION:

Having examined fluvial dynamics in terms of changes in the activities

and resulting forms associated with the river system, it is clear that a

lack of understanding of the key issues has greatly contributed to

environmental crises in Nigeria. We have argued that with relevant,

adequate and detailed information, what appears to be a random

process or event may actually be underlain by a discernible and

predictable regularity. With particular reference to flooding, we

strongly believe that we can competently and convincingly explain such

unusual occurrences and in fact, be in a position to make some safe

predictive statements. Fluvial dynamics constitute a series of normal

and inevitable fluctuations in activity and form which are necessary for

16

progressive evolution of the river system. A good understanding of these

fluvial dynamics is therefore required for effective management of

environmental crises stemming from or relating to river systems.

REFERENCES.

Ayoade, J.O. and Oyebande, B.L. (1983): “Water resources”. In:

Oguntoyinbo, J.S, Areola, O.O and Filani, M. (eds.): A Geography

of Nigerian Development. Heinemann, Ibadan. Pp. 71-88.

Heer, R.J, Geurtsen, G.H and Bijnsdorp, H. (2006): Southwest

Netherlands: Field Trip to the Delta Works. UNESCO-IHE, Delft.

Hillsdale County (2008): Hillsdale County Community Centre.

htt://www.hillsdalecounty.info/planning.edu010.asp

Kumolu, C. (2013): “River basins: How unending policy reversals abet

inefficiency” Vanguard, 22 Oct, 2013.

Nnodim, O. (2013): NASS rejects river basins privatization plan”.

Punch, 26 May 2013.

O’Connor, J.E. and Costa, J.C. (2004): The World’s Largest Floods:

Their Cause and Magnitudes. Circular 1254. Washington D.C.

PDNA (2013): Nigeria Post-Disaster Needs Assessment (PDNA) 2012

Floods: A report by The Federal Government of Nigeria (NEMA).

Umeuduji, J.E. (2000): Principles of Fluvial Geomorphology. Jodigs,

Minna.

Umeuduji, J. E. (2010): Drainage Basin Dynamics. Emhai Books, Port

Harcourt.