Forest resources has experienced natural and anthropogenic pressure various adverse effects manifested by their continued degradation over the years in the district of Gaoua. This degradation is continuing in spite of policies and many investments aiming at changing this dynamics on the basis of a diagnosis which determined its causes. Why is this regressive trend outstanding? Which solutions can be considered? The objective of this article is to contribute to a better understanding of land cover degradation dynamics in the district of Gaoua in revisiting degradation factor hierarchy to offer a new orientation for vegetation cover protection policy.
Remote sensing, spatial analysis, social surveys and field observations through toposequences were carried out.
We retain from this study that the degradation is and remains multifactorial and that the causes formerly identified are always actual: agricultural production system, climatic deterioration, using wood as main energy source, timber use in large scale craft production (building construction, production tool etc.).
What has changed is their respective contributions. Now firewood comes in first place among land cover degradation causes due to population growth and energy needs; efficiency of agricultural policies that have led to a gradual intensification of agricultural systems and new production tool importation.
Beyond the continuation of agricultural intensification, preservation of vegetation cover requires, in this context, to fundamentally review the issue of access to energy. The development of alternative energies such as biogas, solar energy, wind energy and improving energy consumption efficiency are required. It is therefore urgent to rethink the question of vegetation resource protection by mainstreaming, as in agriculture, population energy needs.
Aims: The potential of limestone ash for the improvement of some geotechnical properties of Laterite soils for construction purposes was evaluated. The assessment involved the determination of the engineering properties of Laterite soil in its natural state as well as when mixed with varying proportions of limestone ash.
Study Design: Experimental study was employed to achieve the aim of the study. The experiment was conducted in the geotechnical laboratory.
Place and Duration of Study: The study was conducted at Nsukka in Enugu State, South-Eastern Nigeria. Fieldwork was carried out for a period of one month while the laboratory experiments were conducted over a period of five months from June to December 2013.
Methodology: Lateritic soil samples were obtained from freshly exposed gully cuts to a depth of 1.5 m in Enugu, Nigeria. The soil samples were air-dried for two weeks after which the following parameters were tested for: Atterberg limits, grain size analyses, compaction characteristics, California Bearing Ratio (CBR) and compressive strength. Natural moisture content of the soil was determined by placing 38 g of the sample in an oven for a period of 24 hours in which the moisture content was obtained by subtracting the weight of the of dry soil from the weight of the wet soil and the container, multiplied by 100%. The geotechnical properties of the soil were determined both in the natural state and after stabilisation with varying percentages of limestone ash waste at a normal curing of 6 hours. Accelerated curing at 40°C, 60°C and 80°C for 24 hours was carried out for compressive strength tests for 4% and 6% respectively due to similarities in the values of both the CBR and compressive strength.
Results: The dry density and plasticity index decreased while liquid limit, plastic limit, compressive strength and CBR increased with increasing percentages of limestone ash. Maximum strength was achieved at 6% proportion of limestone ash for CBR and compressive strength respectively.
Conclusion: The results of this research indicate that limestone ash is comparatively suitable for the chemical stabilisation of Laterite soils as lime is, as reported by other researchers.
The work documents a vulnerability study of coastal aquifers based on Groundwater Pollution Potential Index (GWPPI). The parameters used in GWPPI include Lithofacies (L), aquifer thickness (b), Transmissivity (T), Storativity (S), Static Water Level (SWL), Total Dissolved solids (TDS), Chloride (Cl-), Nitrate (N03-) and Escherichia coli (E-coli). GWPPI is computed as the sum of the products of weights and ratings assigned over all the parameters. The GWPPI varies between 27 and 56 is divided into three classes; High (>40) Medium (30-40) and Low (<30). The results show that the most vulnerable areas are located in the southern part (zone 3) of the study area (GWPPI>40) which are mostly influenced by the nearness of SWL to the ground surface and biochemical pollution indicators (E-coli, NO3-, Cl-). The correlation matrices of parameters show moderate positive correlation between E-coli and No3- (r=0.642) and moderate negative correlation between E-coli and SWL (r=-0.624). The coastal aquifer is thus affected mostly by the influence of anthropogenic (human) activities based on the concentrations of NO3- (0.43–10.25 mg/l) and E. coli (1-50 counts/100 ml) in ground water than geogenic factors. GWPPI can be applied not only to Coastal Plain sandy environment but other sedimentary basins with similar conditions.
The present study is an attempt to find out the origin, occurrence and distribution of fluoride content in deep aquifers of Ambalapuzha river basin of Ambalapuzha Taluk. Comparison of the past tube well data with present data, at various localities of the study area shows a drastic increase in fluoride to hazardous level in recent years. Critical analysis of the data reveals that out of 15 tube wells, in all the 14 tube wells, fluoride is much above permissible limit. When cations and anions of the tube well samples were plotted in the piper diagram, replacement of K by Na is clearly indicated. Water type identified with in the study area is predominantly rich in sodium with sodium ion dominance. From ANOVA test, it is revealed that a significant effect of sodium, pH, TDS, Alkalinity, bicarbonate and chloride on fluoride. From the study it is found that the large scale withdrawal of groundwater from the clay bed resulted in increase of Na in groundwater. This in turn promoted leaching of fluoride bearing minerals such as flour apatite, apatite, hornblende etc in to the clay beds at deep sources and liberation of fluoride by the process of anion exchange and increased alkalinity which in turn results increase of pH. The study made it clear that the fluoride enrichment is insitu and it is better to avoid development of deep aquifers in Ambalapuzha taluk or it is to be utilized in a very judicious manner by the town planners and authorities of public water supply agencies.
This study investigated the impact of oil exploitation on wetland and livelihood sustainability in Ogbia Local Government Area of Bayelsa State, Nigeria. The objectives were to: carry out an expository study of the first oil well at Oloibiri; examine the vegetation and soil of the wetland; carry out an expository study of Kolo Creek as well as assessing the socio-economic and environmental impact of sand mining. Data were collected by Participatory Research Approaches which include focus group discussion, interview and field observation to elicit qualitative information on the issues involved in the wetland and livelihood sustainability. The result showed that the original mangrove forest have been replaced with secondary forest while the coastal ecosystems that was once a habitat for a diversity of flora and fauna have been lost. Kolo Creek which provided for navigation, fishing and cultural activities of the local people was taken over by water hyacinth invasion leading to the loss of fishes and other aquatic population and consequently, livelihood. The paper therefore, suggest the need for collaboration of all the stakeholders especially the oil companies operating in the area to ensure remediation and reclamation of the degraded wetland. All activities that degrade the wetland must be discouraged while encouraging those that promote sustainable use of resources.