Impact of Sand and Gravel Dredging on the Environment: a Case Study of the Lagos Bar Beach Coastal Area
CHAPTER ONE
OBJECTIVE OF THE STUDY
The main objective of this study was to ascertain the impact of sand and gravel dredging on environment. However at the completion of the study, the researcher seeks to achieve the following objectives:
- The impact of gravel dredging on the Lagos bar beach coastal area
- The impact of sand dredging on Nigerian waters
- To ascertain the consequences of gravel dredging in coastal area
- The challenges of dredging on Nigeria coastal area
CHAPTER TWO
REVIEW OF RELATED LITERATURE
INTRODUCTION
Soil is an important source of raw materials such as clay, sand, gravel and minerals. It is a non-renewable natural resource with potentially rapid degradation rates and extremely slow formation and regeneration processes (Mwangi, 2007). Sand is a cheap and heavy resource consisting of very small pieces of rocks and minerals, a result of weathering that forms beaches and deserts. Gravel is a heavy and cheap commodity made of small weathered stones used to make surface for paths and roads. The resource’s compressibility, plasticity and textural properties have been valued in construction for hundreds of years. The ability of soil to be moulded and its cohesion properties were the basis for using it to build the earliest houses (Goddard, 2007). Saviour (2012) defined soil as a mineral which protect the environment, buffer to strong tidal waves and storms, habitat for crustacean species and marine organisms. The mining of pit sand and gravel can be done on open areas, beaches, inland dunes, mountain sides while river sand is extracted from riverbeds and banks. Unscientific mining has led to degradation accompanied by subsistence and consequential mine fires, severe ecological imbalance around mining areas (Saviour, 2012). The practice is becoming an environmental issue as the demand for sand as an important mineral resource is increasing in the construction industry. Goddard (2007) realised that decisions on where to mine, how much and how often requires definition of reference state and sand budget. Reference state is the minimal acceptable physical and biological condition of a channel (Goddard, 2007). Though reference state is difficult to determine, a general knowledge of fluvial processes is necessary to minimise detrimental effects of mining. A sand budget for a particular extraction area for example a stream or open area should be done to first determine the amount of sand that can be removed without causing degradation and erosion. Before doing a sand budget, consider mining methods to be used, particle size, characteristics of the sand, riparian vegetation and magnitude as well as frequency of hydrologic events after disturbance.
Therefore minimisation of the negative effects of sand and gravel mining requires a detailed understanding of the response of site to these disturbances (Goddard, 2007). Hill and Kleynhans (1999) discussed various methods of mining sand and gravel. Dry pit mining is a method used when sand is extracted above water table from a dry stream bed and exposed bars using conventional bulldozers, scrapers and loaders. Wet pit mining involves extraction of sand and gravel from below water table stream channel or a perennial river using hydraulic excavator or dragline. Dewatering can be done in advance to allow easy excavation though this depends on deposit thickness, permeability of the ground as well as after use and restoration requirements. Bar skimming or scalping is a method used when only the top layer of soil is removed by scraping without excavating below summer water table which is the level of underground water in summer season (Hill and Kleynhans, 1999).
CHAPTER THREE
RESEARCH METHODOLOGY
INTRODUCTION
Ogili (2002) defined research as a process of finding out the solution to a problem. It is an activity with clear purpose in mind the result of which will contribute to or constitute the solution of a real problem. This chapter deals with the method used in collecting data required in carrying out this research work it explains the procedures that were followed and the instrument used in collecting data.
SOURCES OF DATA COLLECTION
Data were collected from two main sources namely; Primary source and secondary source.
primary source: These are materials of statistical investigation, which were collected by the research for a particular purpose. They can be obtained through a survey, observation questionnaire or as experiment, the researcher has adopted the questionnaire method for this study.
Secondary data: These are data from textbook Journal handset etc. they arise as by products of the same other purposes. Example administration, various other unpublished works and write ups were also used.
POPULATION OF THE STUDY
Ogili (2002) defined population of the study as “ a group of persons or aggregate items, things the researcher in interested in getting information from for the study” on analysis on the impact of sand and gravel dredging 100 staff of bar beach Lagos and 100 from Lagos coastal guard ; that is a total of 200 staff.
CHAPTER FOUR
PRESENTATION ANALYSIS INTERPRETATION OF DATA
INTRODUCTION
Efforts will be made at this stage to present, analyze and interpret the data collected during the field survey. This presentation will be based on the responses from the completed questionnaires. The result of this exercise will be summarized in tabular forms for easy references and analysis. It will also show answers to questions relating to the hypothesis for this research study. The researcher employed simple percentage in the analysis.
DATA ANALYSIS
The data collected from the respondents were analyzed in tabular form with simple percentage for easy understanding.
A total of 160 ( one hundred and sixty) questionnaires were distributed and 140 questionnaires were returned while others were not accounted for due to not on seat and busy schedule syndrome of the sector. Some got lost entirely.
However, the researcher considered a return of about 88% not so bad and so decided to settle with the 140 respondent 50 of these represented the male secretaries while 90werefemalesecretaries.
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATION
INTRODUCTION
It is important to ascertain that the objective of this study was to analyze the impact of sand and gravel dredging on the environment.
In the preceding chapter, the relevant data collected for this study were presented, critically analyzed and appropriate interpretation given. In this chapter, certain recommendations made which in the opinion of the researcher will be of benefits in addressing and evaluating the negative impact of sand and gravel dredging on the environment
SUMMARY
The study on impacts of sand and gravel dredging in Lagos coastal area and surrounding areas revealed both positive and negative effects. It highlighted the views of affected people through questionnaires and interviews. Majority of the respondents were not happy with environmental degradation, accidents caused, waste disposed by dredgers, threats from illegal dredging and general damage to the ecosystems. The research justified that there are both positive and negative environmental impacts to sand and gravel dredging. It revealed that river sand is the soil component mined most in construction industry because of its strength as a resource and has many uses which include building strong structures, plastering, making foundations and bricks. The researcher discovered that pits at extraction sites were increasing on every visit while rivers at sampled areas were widening and deepening. There are two main methods of loading being used by dredgers which are the use of front end loaders by licensed dredgers while illegal dredgers mostly prefer the cheaper way of hiring manual loaders who use shovels.
CONCLUSION
Sand and gravel represent the highest volume of raw material used on earth after water. Their use greatly exceeds natural renewal rates. Moreover, the amount being mined is increasing exponentially, mainly as a result of rapid economic growth in Asia (UNEP and CSIRO, 2011). Negative effects on the environment are unequivocal and are occurring around the world. The problem is now so serious that the existence of river ecosystems is threatened in a number of locations (Kondolf, 1997; Sreebha and Padmalal, 2011). Damage is more severe in small river catchments. The same applies to threats to benthic ecosystems from marine extraction (Krause et al., 2010; Desprez et al., 2010; Boyd et al., 2005). A large discrepancy exists between the magnitude of the problem and public awareness of it. The absence of global monitoring of aggregates extraction undoubtedly contributes to the gap in knowledge, which translates into a lack of action. As this issue is truly a major emerging one, there is a need for in-depth research. The implementation of a monitoring mechanism regarding global aggregate extractions and trade would shed light on the magnitude of this issue and bridge the current data and knowledge gap (Velegrakis et al., 2010). This would also raise this issue on the political agenda and perhaps lead to an international framework to improve extraction governance, as the current level of political concern clearly does not match the urgency of the situation
RECOMMENDATION
Haven successfully complete the studies, the following recommendation were made:
- There should be effective and efficient control measure to control dredging
- Adequate legislation should be made to control the dredging business in other to check any inadequacy in the dredging system
- Only licensed company should be allowed to dredge as the will be covered under the tax net, there by generating revenue for government
- There should be a limit to the quantity of sand and gravel extracted from a particular water
REFERENCE
- Aromolaran AK 2012: Effects of Sand Mining Activities on land in Agrarian Communities of Ogun State. Continental Journal of Agricultural Science, 6, 1
- Bagchi P 2010: Unregulated Sand Mining Threatens Indian Rivers. The Journal India Together, 21, 7-9.
- Central Statistics Office Botswana 2011: Population and Housing Census Information: Preliminary Results Brief. Available at: https://www.cso.gov.bw
- Chimbodza P 2012: Mineral Sands Mining in the Ruckomechi and Chewore Rivers. http://www.victoriafalls-guide.net
- Chimedza C 2003: Statistical Methods in Geography. Harare: Zimbabwe Open University.
- Department of Mines Annual Report 2001: Gaborone: Government Printers.
- Department of Mines 2005: Reclamation/Rehabilitation Guidelines for Sand and Gravel Mineral Concession Operators Document. Gaborone: Government Printers.
- Department of Mines 2007: Mining Licence and Mineral Permits Application Requirements Document. Gaborone: Government Printers.
- Disele S 2011: Sand Mining in Moshupa. Mmegi Newspaper, 41. 18.
- Draggan S 2008: Encyclopedia of Earth. Sand and gravel.
