CAUSES AND EFFECT OF EROSION

CHAPTER ONE

INTRODUCTION

1.1 Background To The Study

Erosion is recognized as one of the world's most serious environmental problems (Pimentel et al., 2005, Shiferaw and Holden, 2009). Globally, about 80% of the current degradation of agricultural land is caused by soil erosion (Angima et al., 2003). Erosion by water, at a global scale, is the main soil degradation process in agricultural areas (Bewket and Sterk 2002). It generates strong environmental impacts and major economic losses from decreased agricultural production and from off-site effects on infrastructure and water quality by sedimentation processes (Zinabu et al., 2002; Daba, 2003; Haregeweyn et al., 2005; Amsalu et al., 2007).

Erosion creates severe limitations to sustainable agricultural land use, as it reduces on-farm soil productivity and causes food insecurity (Tadesse, 2001; Sonneveld, 2002; Beshah, 2003, Moges and Holden, 2006, Bewket, 2007). In most developing countries human activity triggers these losses (Mohammad et al., 2001, Belyaev et al., 2004, Bewket and Sterk, 2005, Hurni et al., 2005). This is associated with rapid population growth, inadequate attention to the basic natural resources (soils, water and vegetation), and the need to maximize production to meet the needs of the growing population (Shiferaw and Holden, 2009, 2000, Bewket, 2002, Feoli et al., 2002). This situation is more serious in poor developing countries where subsistence production predominates. The average farmer who cultivates one hectare of food crops and keeps some livestock, is nowadays dependent on natural conditions and cannot tolerate further deterioration of soil productivity (Sonneveld and Keyzer, 2003). Increasing population, intense land cultivation, uncontrolled grazing, and deforestation often lead to, or exacerbate, soil erosion (Tadesse, 2001 and Bewket, 2002). These factors undermine agricultural productivity and frustrate economic development efforts, especially in developing countries where there is heavy land dependence (Shiferaw and Holden, 2000) in low external-input farming systems.

1.2 Statement Of The Problem

Erosion is considered as one of major land degradation process in Ovia North East Local Government Area of Edo State which is also the main source of environmental deterioration. It creates negative impacts on agricultural production, infrastructure and water quality (Vrieling, 2006).  Erosion is also the natural phenomenon (geological process) which is caused by natural force; it can be more accelerated when the process is influenced by human activities (human-induced erosion). It is considered that the accelerated erosion is a serious global problem and widely recognized (de Graaf, 2006). With the accelerated erosion, it can affect agronomic/biomass productivity (on-site effect) and flooding, sedimentation of reservoirs, siltation of agriculture field and decrease of water quality downstream (off-site effects). The two important agents of erosion are wind and water (Hudson, 2006).

The study area is located in Ovia North East Local Government Area, Edo State. This area is an intensive agricultural areas in Edo State for years now. The conversion of the tropical rain forest to agricultural system has been taking place. With the increasing population, the cultivation in the mountainous area has been taking place. The primary forest is replaced by the maize, plantain, paw-paw, yams, and other crop types. The removal of natural forest and vegetation cover in steep slope and followed by improper land use practices have led to the various land degradation problems in the area. Each year during the rainy season a lot of topsoil is eroded and the agricultural lands are affected. On the other hand; the eroded soil and sediments which are transported by the surface runoff affect the downstream cultivation land.

1.3 Purpose Of The Study

The purpose of this study is to have clear understanding of the causes and effect of erosion in Ovia North East Local Government Area, Edo State.

The specific objectives are:

1) To identify the practices that accelerates erosion in the study area.

2) To discuss the perception of the people in relations to the effect of erosion on the agricultural potentials and performance of the communities in Ovia North East.

1.4 Research Question

(i)  Do agricultural activities lead to erosion?

(ii) Does deforestation lead to erosion?

(iii) Does improper soil management cause erosion?

(iv) Is urbanization a major effect on erosion processes?

(v) Does climate change contribute to erosion problem?

1.5 Significance Of The Study

This study helps to know the extent at which the resident of Ovia North East participate in unhealthy activities that lead to erosion in the area. It will also provide the information about the major causes of erosion in the study area.

It will enlighten the general public on the ways erosion can be control/reduced in the study area.

It will serve as a source of information to government and the ministry of environments on steps to take in tackling the menace of erosion in the study area. It will also provide information to the local government authority on the causes and effect of erosion and ways to solving the problem of erosion in Ovia North East.  

1.6 Scope Of The Study

The study is set out to determine the causes and effect of erosion in Ovia North East Local Government Area of Edo State. Therefore, the study is restricted to five communities in the area of study. The communities include: Ekiadolor, Ovbiogie, Iguedaiken, Iguikhinmwin and Iyowa community. Respondents include farmers, students, teachers, civil servants, youths, and drivers.

1.7 Definition Of Terms

Soil Erosion:- “The wearing away of the land surface by physical forces such as rainfall, runoff water, wind, ice, temperature change, gravity.

Wind erosion: Is a major geomorphologic force, especially in arid and semi-arid regions.

Exfoliation: Is a type of erosion that occurs when a rock is rapidly heated up by the sun.

Vegetation: Is the interface between the atmosphere and the soil.

Deforestation: The continuous felling of trees without replanting.

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