Effect of Limestone Mining on Agricultural Land Use in Akampa Cross River State

Effect of Limestone Mining on Agricultural Land Use in Akampa Cross River State

CHAPTER ONE

AIM AND OBJECTIVES OF THE STUDY

The aim of the study is to assess the effect of limestone mining on vegetation cover in Akamkpa LGA of Cross River State. This aim was achieved through the following

objectives:

characterize the land-use /land-cover of the area in 1976, 1986, 2001, and 2011
determine the extent of vegetation cover in the area in 1976, 1986, 2001 and 2011
determine the land-use /land-cover change in the area between the study years
analyse the rate of vegetation change in the study area between 1976 to 2011
determine the extent to which mining has affected vegetation cover in the area between 1976 to 2011

CHAPTER TWO

CONCEPTUAL FRAMEWORK AND LITERATURE REVIEW

INTRODUCTION

This chapter is subdivided into two sections with the first part reviewing literature on the concept of mining, vegetation, Remote Sensing (R/S), Geographic information System (GIS) and Importance of R/S and GIS in Environmental Impact Assessment. The second section of this chapter deals with the review of previous works on the application of Remote Sensing and GIS in in detecting vegetation change in mining areas.

CONCEPTUAL FRAMEWORK

Mining

Mining generally refers to the extraction or removal of ore from the ground. According to Acheampong (2004), it is the removal of minerals from the earth crust in the service of man. It is the selective recovery of minerals and materials, other than recently formed organic materials from the crust of the earth. From the above definitions, it can be deduced that mining is a human activity that deals with the excavation and extraction of valuable materials from the earth crust other than agricultural products. Such materials mined by humankind are broadly grouped as fuels, metals, and non-metallic minerals. Metallic ores/minerals are those ores of the ferrous metals like iron, manganese, molybdenum, and tungsten, the base metals like copper, lead, zinc, and tin, the precious metals like gold, silver, the platinum group metals, and the radioactive minerals like uranium, thorium, and radium. The Non-metallic minerals also known as industrial minerals are the nonfuel mineral ores that are not associated with the production of metals. These include among others phosphate, potash, halite, trona, sand, gravel, limestone, sulphur. Fossil fuels also known as mineral fuels are the organic mineral substances that can be utilized as fuels, such as coal, petroleum, natural gas, coal bed methane, gilsonite, and tar sands among others (Adekoya, 2003; Kesler, 1994).

According to Akabzaa and Darimani (2001) the process of excavating the earth surface for valuable materials employs the use of two main methods which include Open cast and Underground mining. Open-casting or surface mining is a type of strip mining that involves the extraction of ore deposit that are located near the earth surface or ones that has a low stripping ratio. This method which excavate and extract ore/mineral deposits at a substantial underground depth necessitate the removal of layer upon layer of overburden as well as the creation of a pit that extends below the groundwater table. The removal of overburden usually involves logging of trees and clear-cutting or burning of vegetation above the ore deposit with the use of heavy machinery like bulldozers and dump trucks, this renders it as the most environmentally destructive type of mining, especially within tropical forests. Irrespective of its environmental destruction nature, open cast mining is however the predominant exploitation procedure used worldwide to excavate and extract almost all minerals excluding petroleum and natural gas (Fyles, Fyles & Bell, 1985; Akabzaa & Darimani, 2001; Aigbedion & Iyayi, 2007). According to reports of National Mapping Division, U.S. Geological Survey (1995), it produces about 85% in the United States with about 98% of metallic ores, 97% of non-metallic ores and 61% of coal. It major advantage over the underground mining method however includes high productivity, low operating cost as well as good safety conditions. This is the most common method used for mining limestone within the country in general and the study area in particular.

Underground mining on the other hand refers to any sub-surface vertical or horizontal excavations that are made for the extraction of minerals. This method has little effect on the vegetation and the ecosystem in general as a minimal amount of overburden is removed to gain access to the ore deposit. Access to ore deposit using this method is however gained through tunnels or shafts. Although underground mining is a less environmentally destructive, it is often more costly and entails greater safety risks than open-pit mining. While most large scale mining projects involve open-pit mining, many large underground mines are in operation around the world (Akabzaa & Darimani, 2001).

CHAPTER THREE

THE STUDY AREA AND METHODOLOGY

INTRODUCTION

This chapter looks into the general background of the study area as it relates to immediate environment. It also considers the methodology adopted for the study. The procedure adopted in this research work forms the basis for deriving statistics of vegetation dynamics and subsequently in the attainment of the set objectives.

THE STUDY AREA

Location and Extent

The Calabar river catchment is located in the southeastern part of Nigeria and precisely in Cross River State (Figure 1). Based on Köppen’s climatic classification, the area falls within the tropical rainforest climate. The original vegetation of the entire Calabar river catchment was the tropical rainforest. However, most of the original vegetation in the study area has been replaced as a result of agricultural, road construction, tree logging, industrial and residential activities. Though, the catchment can still be classified under the tropical rainforest, it is only in a few places that the structural organisation can be clearly distinguished.

RESEARCH METHODOLOGY

Reconnaissance survey

A reconnaissance survey was carried out in the area so as to enable the researcher familiarize with nature of vegetation and state of mining activities in the study area hence this knowledge is crucial in interpreting Remotely Sensed imageries.

CHAPTER FOUR

RESULTS AND DISCUSSION

INTRODUCTION

This chapter deals with presentation and analysis of result obtained from the research analysis. The presentation and analysis of data were carried out under the following subthemes: characterization of land-use/land-cover, extent of vegetation cover, land-use landcover change, trend, pattern and rate of land-use/land-cover change as well as the extent to which mining has affected vegetation cover within the study area. The results of the analysis were then discussed and appropriate inferences were made to assess the impact of mining activities on vegetation cover within the study area.

CHARACTERIZATION OF LAND-USE/LAND-COVER OF THE AREA

The characterization of the land-use/land-cover classes of Akamkpain 1976, 1986, 2001 and 2011 using satellite images was classified into five prominent land-use/land-cover classes including built-up, agricultural land, vegetated land, waste land and bare surfaces.

CHAPTER FIVE

SUMMARY, CONCLUSION AND RECOMMENDATIONS

INTRODUCTION

This chapter describes the summary of the major findings of this work, conclusion derived from the findings as well as recommendations for enhancing effective land-use/land-cover management within the study area in particular and the state in general.

SUMMARY OF FINDINGS

The study provided an insight on the effect of mining on vegetation cover in Akamkpa Local Government Area of Cross River State. The research revealed that vegetated land has continually reduced over the study period as the land-cover had percentage coverage of 42.22% in 1976, 36.13% in 1986, 31.42% in 2001 and 28.90% in 2011. This gradually reduction in vegetated land within the study area which is attributed to the fact that other landuse/land-cover types are gradually taking over places originally occupied by vegetation as at 1976 has led to vegetal clearance and deforestation of the area in the successive years.

This assertion is further buttressed by the fact that wasteland which was not seen in the study area in 1976, surfaced in 1986 owing to the introduction of mining within the area in 1980. This brought about a successive increase in the area coverage of the land-use (wasteland) as it increased from nothing in 1976 to 0.92 Km² in 1986, 1.2 Km² in 2001 and 1.24 Km² in 2011.

This finding indicates that portions of the study area that were originally occupied by vegetation cover have been subsequently taken over by wastelands.

The research further revealed that about 0.88km² of vegetation cover was displaced by waste land in 1986, 0.95 Km² in 2001 and 1.1 Km² in 2011. This means that a greater portion of vegetation has been displaced in 2011. This further explains the fact that mining activities have been on the increase within the study area as this has led to the increase in the displacement of vegetation cover within the study area in the latter study years.

CONCLUSION

This research work demonstrates the ability of using GIS and Remote Sensing for land-use land-cover change analysis. The results obtained from this study have shown that the study area has lost part of its vegetated land not only to settlement but also to mining activities as the inception of mining in 1980 has gradually given rise to the introduction and successive increase in waste land. It has also revealed that with the rehabilitation of the mine in 2004, there has been a changing increase in the land area occupied by mine waste especially from 2001-2011 as it records an increase of 0.22 Km² (21.09%) at a rate of 2.11% and an overall increase rate of 0.04 Km² between 1986 to 2011. If proactive measures are not put in place to checkmate this trend that is attributed to increase in mining activities, portions of the study area will be gradually degraded due to vegetal cover loss.

RECOMMENDATIONS

Based on the identified change in vegetation cover within the study area which has been attributed to mining activities, the following are recommended:

Proactive measure should be put in place by the management of the mining company, elders of Akamkpaas well as Cross River State Environmental Management Board for an effective and efficient management of various environmental challenges that might be associated with mining as being forearmed will help in urgently tackling any emergency environmental situation.
Stringent and rigorous efforts of re-afforestation and land reclamation aimed at restoring degraded lands should be intensified by the Company especially around the mine area so as to resuscitate lands that are devoid of vegetal cover. This could be done by using the mine spoils to fill up dug mine pits and the likes.
In order to deal with the changing nature of land-use/land-cover of areas within various developmental projects that are associated with such enormous long term effects, an urgent need for the use of Remote Sensing and GIS for proper monitoring and management of land within the state and the study area in particular is also recommended.
It is also recommended that further research should be conducted within the study area to determine whether there are intervention measures put in place by the company in order to tackle various environmental challenges that are associated with their operations and if there are any, the level of implementation and the success of such measures.

REFERENCE

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