GULLY EROSION A PRACTICAL LOOK AT THE CASE OF IMO STATE by Clement Udegbe
Gully erosion constitutes the major ecological problem in South Eastern Nigeria and requires adequate scientific and proper technical competence in the prevention and control of the menace.
An effective control of this phenomena may not be complete until the principles and mechanics underlying its behavior and distribution over time and space are fully understood.
A careful look at how gully builds up, will help us to understand how it can be managed controlled or checked by applying reverse steps to the very steps it took to grow.
Generally, the initiation and development of gully erosion is facilitated by natural processes, such as rainfall, topography, engineering-geological properties of soils, especially texture & structure, etc.
The the activities of man, especially road construction, the effects of water run offs from new building developments, depletion of grass and tree holder of flood, help gullies to grow.
Incorrect information, incomplete data or wrong concepts in the application of either methods of erosion control rather than help, have majorly aggravated gully erosion problems.
Globally, environmental issues have become major concerns to governments and citizens of various nations, including Nigeria.
The environment, which is at the heart of economic, social, cultural and human activities, has been disrupted by man’s neglect and abuse.
Deforestation, erosion, flooding, landslides, global warming etc are the aftermaths of this abuse in and on the ecosystem.
The location in the tropical latitudes, of Nigeria and Imo in particular with her soil types, rainfall regimes, and other physiographical units, have exposed the region to the destructive influences of climatically induced hazards including especially flooding and erosion. The general topography gives the force with which water runs which in turn creates gullies.
Gully erosion works in Imo State, have failed so far because of the Straight-Line, One-Method approach to its control and management primed by politicians to the chagrin of professionals.
Many of the erosion control measures put in place in Imo show that hydrological variables like runoff water, which constitute major factors in soil erosion, were not considered in the design and has resulted in deep gullies, instead of checking erosion.
Gully Erosion Development has become wild in Imo State due the combined effects of activities of man in creation of increased runoff, wrong management strategies, and lack of political will to develop multi -pronged control measures following the line of process of Gully development.
Gully is defined as a steep-sided channel, often with steeply sloping and actively eroding head scarp, caused by erosion due to the flow of water with strong force, usually during and immediately following heavy rains. Gully erosion is the final phase of a four-stage erosion process involving splash, sheet, rill, and gully ;
Erosion process begins by water falling as raindrops and flowing on the soil surface.
Splash erosion results when the force of raindrops falling on bare or sparsely vegetated soil detaches soil particles.
Sheet erosion in turn occurs when these soil particles are easily transported in a thin layer, or sheet, by flowing water.
If this sheet runoff is allowed to concentrate and gain velocity, it cuts rills and gullies as it detaches more soil particles. As the erosive force of flowing water increases with slope length and gradient, gullies become deep channels and gorges.
The greater the distance and slope, the more difficult it is to control the increasing volume and velocity of runoff and the greater the resultant damage.
At the final stage of gully, destruction of land farms, cutting of roads thereby limiting of transportation and movement, loss of houses and homes, and even evacuation and migration of entire communities become the biggest nightmare facing its victims.
At the stage, when it is almost too late, governments jump into reactive responses, with much political interests, building bridges and culverts that fail and create more hazards and havocs.
They build things that hardly survive three years of rainfall, and they throw blames all around, from contractors, consultants, to funds from Federal Sources.
When they write and speak, they quote figures of huge sums spent but that is not my look out now.
Examples of failed Gully management projects include, the Umuoza-Ugiri in Isiala Mbano, Umuaka – Njaba Gully; Umuhu Okabia Ubiri-Elem Gully in Orsu LGA, Omuomi Uzoagba Gully in Ikeduru, and especially, the Ogberuru- Acharaba Gully, Obibi- Asa Gully, Umuazalla -Okpiyi River Gully, and the Ihiteoweri -Ezize Asa Gully with the last four located in Orlu North Area. others are the Ogboko Umuma-Isiaku Link Gully, the Ikeduru Gully,and several others.
New approach which should not require rocket science is to apply control and management measures at all the first three stages of erosion development to prevent it from getting to the fourth devastating stage of Gully.
An original plan for each victim and flood water prone areas should be developed in three stages of quick and immediate term, medium term and long term management strategies with actions.
The immediate and quick term management strategies will involve a joint cooperation between victim or threatened communities and government. The purpose will be to put in place, constructions that will essentially aim at reducing the flood water from run off sheet erosion force, in order to reduce its chances of developing a gully.
The mustering of all resources available to prevent and or reduce to flow power or velocity of flood down slopes and leeward topographies in various affected communities will slow down gully development.
A properly articulated multi dimensional method of flood water movement force control, will not only prevent the development of gully it will put a stop to it over a period time of about three years.
This phase will concentrate on the construction of structures, that will guide or divert flood water, into holding points which may be many along any route and big enough to contain or hold enough water for one rainy season, at the least
The number of holding points will depend on the force of water and distance it has to move before joining the holding point. In some areas, these holding troughs, may become source of water for other needs of affected communities.
The affected communities will interface with government through a well designed financing and disbursement process that will provide integrity and safety to peoples money and the system.
When a Particular holding point project is agreed and designed, the communities can contribute an agreed proportion towards the quick and effective completion of the project. The community should participate all the way from design approval to construction supervision with corrective powers as each case may be. Labor from such communities could be monetized into the project as part of their contribution.
The mid-term strategy will involve plans to reduce most if not all the existing gully into a water holding contraptions by blocking the flow from the gully into any river or tributaries of rivers, near it.
This will halt the eating away or chopping off the sides of the gully that enhances its growth and expansion. Force or flood velocity is created by movement of water, over distance, and where the water runs into an existing gully through concrete channels, all harms can be prevented.
I think that this can be a wholly government project depending on what impacts the gully has, its extent and the threat posed by it to the nearby community.
Where a community desires to to be involved in this stage, same financial process will be adopted to achieve the goal of the community without any stories from government officials and politicians.
The long term strategies will include all existing Government failed Erosion control projects, which deserve complete review, revamping and resuscitation.
Tampering with Funds from Federal Government and international finance institutions especially the World Bank has remained the bane of Gully Erosion management in Imo State.
Governors have used and still use funding of or overlooking gullies development to punish or favor communities from where their perceived enemies or come from in addition to their many other idiosyncrasies.
The previous government of Okorocha deliberately ignored the entire Orlu North with over 7 live and growing Gullies. While Ihedioha wanted to begin to address some of them, his tenure was cut short.
Presently over 15 communities with over 50 houses are on the line to be consumed or swallowed up by gullies, from Uhualla Obibi near Acharaba to Ihite owerri.
Hundreds of millions Naira, of peoples investment in their homes and family land stand to be washed away if nothing is done quickly.
I am expectant that His Excellency will remember the youths who used to throng his ” Foot Ball Rallies ” at the County School in Obibi Ochasi when he was a Senator.
One can only pray and hope that he will write his name in the hearts of the Orlu North Communities and these youths, whose houses, and family homes are on the gully expansion lines.
His supporting the immediate strategies to reduce the velocity of flood water into the numerous gullies in the area, will bring relief, and make a great milestone, more so when the communities are ready and interested to work on a joint solution with the government in an agreed transparent, honest, disciplined process with integrity.