Reclamation Measures For Gully Erosion Sites (A Case Study Of Obollo-Etiti, Udenu Local Government Enugu)

Description

ABSTRACT

The incidence of gully erosion in  Obollo-Etiti in Udenu Local Government  Area of Enugu State has assumed alarming proportions thereby gaining local government recongnition as an ecological disaster.

The aim of this study is therefore to determine and analysis the factors responsible for gully development and with preferring solutions. From my observation, the gully erosion for more than three to four years has been responsible for the loss of farmland, damage of roads, thereby rendering them farmless  for varying period of time and loss of livestock which majority of the population depends on for survival.

Congruently, the community have been working on it and even employing indigenous management strategies. However not much progress has been recorded with regard to combating the manace as both community and government carryout intervention measure almost exclusive of each other, with the information gotten is therefore  recommends among other things that the management strategies of local government  should be harmonized with that of the community with regard for the unique environment and social feature of the study area.

CHAPTER ONE

TABLE OF CONTENTS

ABSTRACT

CHAPTER ONE

1.0    INTRODUCTION

1.1   BACKGROUND OF STUDY

1.2   STATEMENT OF PROBLEMS

1.3   RESEARCH OBJECTIVES

1.4   RESEARCH QUESTION

1.5   RESEARCH HYPOTHESIS

1.6   SCOPE OF STUDY

1.7   SIGNIFICANCE OF STUDY

1.8   LIMITATION OF STUDY

1.9   DEFINITION OF TERMS

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF THE STUDY
• GEOLOGY OF NIGERIA
• PRINCIPLES OF GULLY CONTROL
• FACTORS AFFECTING GULLY FORMATION
• CRITERIA FOR THE SELECTION OF GULLY CONTROL MEASURES
• SELECTION OF GULLY CONTROL MEASURES
• CAUSES OF EROSION
• IMPACTS OF GULLY EROSION REVIEWED
• REVIEW OF POSSIBLE SOLUTIONS TO GULLY EROSION IN NIGERIA

CHAPTER THREE

• METHODOLOGY
• LOCATION OF THE STUDY AREA
• A BRIEF GEOLOGY OF THE AREA OF STUDY
• POPULATION OF STUDY
• INSTRUMENT OF DATA COLLECTION
• VALIDATION OF THE INSTRUMENT
• DATA ACQUIRED FROM SEMI-STRUCTURED

CHAPTER FOUR

4.1 RESULTS AND DISCUSSION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

Gully erosion is a highly visible form of soil erosion that affects soil productivity, restricts land use and can threaten roads, fences, buildings and human life [1]. Gully erosion enthrones deprivation in its process and this affects soils in many parts of the world [2]. It is a serious form of soil degradation often involving an initial incision in to the subsurface, by concentrated runoff along lines or zones of weakness such as tension and desiccation fractures [3]. Multiple on- site and off-site effects of gully erosion threaten sustainable development, which is especially evident in dryland environments [4].

Gully erosion often indicates extreme land degradation. Gully erosion is an cutting-edge stage of rill erosion where surface channels have been eroded to the point where they cannot be smoothened over by normal tillage works [5]. It reduces agricultural productivity by destroying valuable land resources, increases sediment concentrations, reduces water quality, and fills up reservoirs; its rehabilitation has proven to be challenging especially in the high-rainfall areas [6]. In the highlands of Ethiopia for instance, wide and deep gullies are common features, significantly affecting land used for agriculture [7]. The effect of soil erosion on bare and vegetated soil had been studied using rainfall simulation experiments by [8,9]. The results showed a negligible sediment yield, runoff and erosion in the vegetated soils, while the bare slope experienced remarkable runoff rates. In the Mediterranean countries, reservoir siltation is highly practiced to boost economic and agricultural development [10].

Population exploration as well as the attendants increasing human activities which include but not limited to deforestation, ever increasing developmental facilities and many other human factors/activities, have had negative impacts on the slope failures and subsequently resulted in gullying in many places, [11,12]. Recent efforts geared towards better understanding of the dynamics of gully erosion suggested that, the phenomenon could be further branded and studied using its relevant parameters like the mean equivalent width and depth and its length [13].

The surface geology, soil cover and prevailing environmental surface processes of an area greatly influence mechanism of gully erosion [14]. The efficacy of soils to function as a filter from polluting substances largely depends on the behaviour of pollutants in the soil and the hydrological transport processes as demonstrated by [15].

Earlier studies like that of [16], indicated that the nature of the underlying geology contribute significantly to the origin and spread of gullies. Their findings are summarized in Table 1. Most observations from gully erosion studies in Nigeria have also established that the menace principally occurs in the sedimentary landscapes of the country and in some cases, in areas where basement/sediment contact occur [14].

Although, the major causes of gully erosion are not well-understood; the dynamics involved in its progression and ruin are obvious [17].

For instance vegetation on land-side slopes protects embankments from erosion resulting from heavy rains or overtopping waves, particularly in many estuarine areas around the world [18]. Gullies can be categorized as active and inactive [14]. Active gullies move up in the affected site by head-cut movement [19].

The morphological evidences of past soil erosion can be easily inferred from the visible impacts of environmental variations in the landscape [20]. Most of the available erosion research could not provide adequate knowledge of gully erosion in the past as it concerned the gauging methods, creation of gully erosion models, and workable preventive and mitigating actions, which are certainly known challenges facing gully erosion research today [20].

Many parts in Nigeria, especially in the South- eastern region of the country are under serious threats of the gully erosion and its attendants consequences. The feasible causes of this unbelievable trait are traceable to both man- made and anthropogenic roots. However, the geology of the site where gully erosion is prevalent and the severity of attendant surface processes, are majorly the known causes. Study had proved that steep landscapes are commonly susceptible to slope failure under the influence of various factors already documented in this work [21].

Soil erosion is a major environmental problem in Nigeria. Obollo-etiti, udenu local government enugu is one of the cities in Nigeria that are worst hit by this ecological hazard. According to previous reports, gullying processes at some sites in Auchi have narrow incisions which are then broadened and extended by sidewall processes fractures as the gully erosion progresses [3]. The problem of soil erosion in Obollo-etiti has been on for more than 13 years. It had claimed over 20 lives, displaced more than 300 persons and has destroyed properties worth millions of naira.

As gullying is a serious menace and complex too, three-dimensional photo-reconstruction (PR) techniques as suggested by [22], is very apt for the production of high-resolution surface models for different applications and over different spatial scales. This straightforward image collection and processing approach can be of great benefit for non-expert users working on gully erosion assessment.

A holistic understanding of the formation and mechanism of gully erosion should therefore, involve collaborative inputs from experts in diverse fields like biologists, chemists, geologists, physicists, anthropologists, economists, engineers, medical professionals, military professionals, sociologists, and even artists amongst others as suggested by [23].

The objectives of this study therefore is to investigate the causes and impacts of erosion menace in Obollo-etiti community, map out erosion hot spots in the area, and recommend measures that will strengthen mitigation strategies and reduce risks.

1.1                              BACKGROUND OF THE STUDY

Disaster have been defined  and categorized in diverse by various scholars see for instance, Bates (2002). Hugo (2009), Naik (2009) and Keane (2004). Disaster which may occur from natural or man-made processes often involve large scale alternations of the areas they occurs and suffering of a sizeable number of persons. Human responses to disaster vary according to the nature of the disaster.

Advances in science and technology have aided the human race to stop the events, to predict the events and more out of the ways such disasters or discover ways of recovery after the events had taken place. However, some notable disaster which when they occur, death and loss of property usually result include, gas escapes earthquake, chemical spill oil, oil spills, forest fires, coastal floods  generally etc. landslide, causes of loss property death and population displacement when they occur in densely-settled area of the world s within Nigeria landslides occur as follows ups from deep gully incision (Mozie 2010). The most devastating gully erosion in Nigeria are found in South Easter Nigeria in the populated Enugu, Abia, Imo and Anambra State  and other lesser area is in Auchi in Edo State of Nigeria.

This project discusses the gully erosion control in Udenu Local Government Area of Enugu State, Nigeria.

1.2                                                  PROBLEM STATEMENT

This project work is seen in the aftermath of the gully development, which includes the destruction of the profile and the topography of the area, thereby hindering development around it. The downstream sedimentation is causing damage to the vegetation of area and a kind of sediment transfer to discharge outlet is being seen effected by the overland flow that originates from the watershed. All these problems will be tackled when this work is successfully completed. The justification of this project work is also seen in the earnestness of the control. This is because the cost of reclamation and control is increasing on daily basis due to the continuous deepening of the gully by run off action and detachment by rain drop action.

1.3                                                     AIM OF THE STUDY

The aim of this study is therefore to determine and analysis the factors responsible for gully development and with preferring solutions.

1.4                              OBJECTIVES OF THE STUDY 

1. To determine the cause of the gully erosion in the Obollo-Etiti, Udenu L.G.A. gully site.
2. To construct maintain and unrest in the study are unfrustural works like roads, water schemes and gradual transfer of these to benefiting communities to engage in other activities that will increase agricultural production in the soil.
3. To design appropriate soil erosion control structures for gully erosion site.

1.5                                                  RESEARCH QUESTIONS

1. What is gully reclamation?
2. How do you test gully erosion?

• How can we control gully erosion?

1. In which area gully erosion is important?

1.6                                          RESEARCH HYPOTHESIS  

The following Null Hypotheses are tested and advanced in the course of this study.

H₁: gully erosion has negative effects in our environment

H₀ : gully erosion has no negative effects in our environment

1.7                                                      SCOPE OF STUDY

The gully erosion results loss of farmland, damage of roads, thereby rendering them farmless the gully erosion for more than three to four years has been responsible for the loss of farmland, damage of roads, thereby rendering them farmless for varying period of time and loss of livestock which majority of the population depends on for survival.

Because of more prevalence of gully erosion in the southeastern part of the country as earlier noted, the region has attracted more attention of a number of researchers to unravel the causes of gully erosion. Therefore, the works from this area are overwhelming in the literature.

Gully erosion can be caused in a number of ways, having different mechanisms, modes and conditions of formation; some of which are directly related to the underlying geology and the severity of the surface processes operating on the surface geology and soil cover. Ezechi and Okagbue (1989) summarized the types of gully erosion with respect to their modes and conditions of formation, and common advance mechanism. Their study indicated that the nature of the underlying bed (or geology) has a bearing on the initiation and propagation of gullies. Observations have also shown that gully erosion, in Nigeria, is more predominant in the sedimentary terrains and perhaps in the basement/sediment contact areas.

1.8                                                      SIGNIFICANCE OF STUDY

This study has help us to understand current knowledge of gully erosion; to assess how hydrology, especially subsurface flow, together with topographic factors determine the vulnerability of valley bottomlands to severe gully erosion; and to identify deficiencies in existing rehabilitation measures

1.9                                                       LIMITATION OF STUDY

There are different studies about gully erosion, but this study focus fully on techniques that can be used to tackle gully erosion. This study discusses gully erosion: causes and impact.

1.10                                                    DEFINITION OF TERMS

Gully erosion: Gully erosion is the removal of soil along drainage lines by surface water runoff. Unless steps are taken to stabilise the disturbance, gullies will continue to move by head ward erosion or by slumping of the side walls.

Erosion – The wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Also, detachment and movement of soil or rock fragments by water, wind, ice, or gravity. The following terms are used to describe different types of water erosion.

Erosion and Sediment Control – Any temporary or permanent measures taken to reduce erosion, control siltation and sedimentation, and ensure that sediment-laden water does not leave a site.

Erosion and Sediment Control Facility – A type of drainage facility designed to hold water for a period of time to allow sediment contained in the surface and storm water runoff directed to the facility to settle out so as to improve the quality of the runoff.

Erosion Control Blanket – Blanket made from straw, coir, excelsior, or synthetic material and enveloped in plastic or biodegradable netting. Use to stabilize disturbed or highly erosive soils while vegetation is established.

Biodegradable – Able to decompose when exposed to biological agents and soil chemicals.

Bioengineering – Combination of vegetative and structural practices to prevent erosion or stabilize slopes or stream banks.