EVALUATION OF THE EFFECT OF LAND SCOPE ON SOIL LOSS FROM EROSION SITES
Abstract
Soil loss is as a result of detachment and transportation of soil particles from one place to another due to rainfall. The rate of soil erosion has been of great concern to the government and people of Enugu state as regards to farm land and environmental degradation. This work analyzed the soil samples collected from two erosion sites namely, IMT campus I and Campus III and the soil loss for the samples which is the mainstay of this project was determined using a rainfall simulator. It was observed that IMT campus I recorded the highest soil loss of 190.3g and Campus III with a soil loss of 178.0g both at 9% slope. In terms of steepness of slope, Campus I has the steepest slope of 1/253.3 which led to a greater volume of runoff and resulted to the highest soil loss. Recommendations were made on how best to reduce soil loss in Institute of Management and technology Enugu and in Enugu State at large.
CHAPTER ONE
INTRODUCTION
Background to the Study
Soil is a natural body consisting of layers (soil horizons) that are primary composed of minerals from the weathering away of rocks. It can also be defined as the top layer of the earth’s crust. It is formed by mineral particles, organic matter, water, air and living organisms. It is also unconsolidated or loose covering. It is infact an extremely complex variable and living medium. It is the interface between the earth, the air and the water. Soil is a non-renewable resource which performs many vital functions. Food and other biomass production, storage, filtration and transformation of many substances including water, carbon and nitrogen.
Soil has a role as a habitat and capable of supporting life. It serves as a platform for human activities, landscape and heritage and acts as a provider of raw materials. Soil is also known as earth. It is the substance form which our planet takes its name. its important is too many to mention. The life we are living today depends on the soil. Soil is also known as earth, it is the substance from which our planet takes its name. its important is too many to mention. The life we are living today depends on the soil. Soil is a critical component in the mining and construction industries. Soil serves as a foundation for most construction projects. Massive volumes of soil can be involved in surface mining, road construction and construction of other structures. Soil is critical to the environment of other structures. Soil is critical to the environment, as well as food and fibre production. Soil provides plants with minerals and water. Soil absorbs rain water and releases it through evaporation, preventing and controlling both flood and drought respectively. Soil is also the natural dwelling place for earth micro and macro organisms. Also houses water for man’s use.
These functions are worthy of protection because of their socio-economical importance as well as environmental importance. Erosion, loss of organic matter, compaction, salinization, landslides, contamination and sealing are evidence of soil degradation. Soil degradation is accelerating with negative effects on human health, natural ecosystems and climates change, as well as on our economy. Today, one of the most serious environmental problems facing our nation and the world in general is he loss of top soil layer through the process of detchament and transportation caused by the impact of raindrop and the resulting overland flow. Soil erosion is the process by which the surface of the land is attacked, resulting to gullies in valleys, cliffs and hills and it is completely washed into water bodies. It is composed of many factors which is a function of intensity, duration, infiltration, susceptibility including soil detachability and transportability. When water is applied into the soil continually in the form of irrigation or rainfall, it filters downward into the soil at a certain time, the soil will be saturated then the excess above infiltration capacity will result to surface runoff above infiltration capacity will result to surface runoff thereby leading to transportation of detached particles and erosion.
The basic causes of erosion have been classified into three factors.
i. Climatic factors
ii. Geological factors and
iii. Human activities
i) The climatic factors: The climate factors that influences erosion are rainfall amount, intensity and frequency. During the period of frequent rainfall, a greater percentage of the rainfall will become runoff this is due to high soil moisture or saturated conditions. ii) The Geologic factors: This is caused as result of the action of the wind, water, ice and gravity in wearing away rock to form soil and shape the ground surface. iii) The Human Activities: Human causes most soil erosion when strip the natural vegetation from the steeper slopes and do not put back a cover of healthy grass of other vegetation. This leads to the worse erosion. Take for instance in Enugu state, high annual rainfall helps in speeding up soil erosion including river bank and sediment transportation. The geology of an area is a useful index for gauging the erodibility of that particular place. In Enugu metropolis precisely, soil erosion has a focus on the human activities as the primary cause of erosion, a good cover of vegetation, including grass shields the soil from the impact of raindrops. It also binds the soil together, making it more resistance to runoff and filters sediment. A cover of vegetation is one of the best protections against erosion.
Objectives of the study
Specifically, the objectives of the study are
1)To collect soil samples from two erosion sites in the Institute of Management and Technology (IMT) Enugu namely, Campus I and III.
2) Selection of different rainfall intensities
3) To determine the Plastic limit test, grain size analysis, moisture content, shear strength, and soil conditioning test.
4) To determine the rate of soil loss in IMT campus I and III.
5) Relate land slope to erosion.
Justification of the Study
In our country Nigeria today, erosion has spreaded generally through out the nation and has been an environmental problem seriously causing ecological problems by destroying lives and properties, Agricultural land and social infrastructures. Outside the destruction of form land through removal of top soil, houses, road, bridges, telecommunication, electric power and railway lines are being washed away. Also, the erosion of arable land is a threat to food productions and agro-industrial raw materials. Erosion produces load of silts and other particles which pollutes our inland water and cause siltation of dams, reservoirs thereby reducing their storage capacity and useful life span of structures. The pollution of water by silt is known to have caused serious damage to our aquatic lives. Therefore urgent measures are needed to control erosion in other to avoid termination of lives and endangering structures.
