Effects of Soil Properties on Erodibility and Infiltration; A Case Study of FUNAAB Hostel
Chapter One
Objectives of the study
The objective of this study is therefore to examine soils within Imo State to determine their erodibility factor (K) and ascertain areas prone to erosion. The data obtained from this study will form a reference for consideration in the design of conservation structures within the area of study.
CHAPTER TWO
REVIEW OF RELATED LITERATURE
Introduction
The review of the related literature based on the variables of the research objectives were presented in this chapter
The concept of soil erodibility
Early studies, such as Middleton (1930), suggested that soil properties affect soil erosion rates. Since then, many researchers have reported that the soil’s response to erosive factors can be related to soil properties, (Wischmeier, 1971; Wang, 2001). Soil erosion is linked to the influence of soil properties on several processes, such as aggregate breakdown, infiltration, sediment detachment and transport (Peters, 1993). The term “soil erodibility” has come to be used to represent the soil’s susceptibility to erosion processes (Sheridan, 2000). Middleton (1930) was the first to set up an index of erodibility. He showed that soils could be distinguished as “erodible” and “non- erodible” on the basis of the ease with which the soil would disperse, and the ease with which it would transmit moisture. It is generally accepted that soil erosion will increase with a high erodibility; while under similar conditions soils with low erodibility will have lower soil erosion (Hudson, 1995).
Soil erodibility is “a function of complex interactions of a considerable number of its physical and chemical properties which frequently vary within a standard texture class” (Wischmeier, 1978). There are several definitions of the term “soil erodibility” (Table 2.1) and it can be concluded that soil erodibility is a relative term that can be dependent on soil characteristics. All of the definitions displayed in Table 2.1 are relevant to the present research hypothesis that soil properties can be used as a predictor of the relative erodibility of the soils in the study area (Figure 2.1). Some researchers have been critical of the weakness of the erodibility concept. According to Poessen (1983) the concept is a “vague summarizing description of the differential behaviour of soils subject to erosion”. Bryan et al (1989) reported that soil erodibility has not been exactly defined. They stated that their own soil erosion studies in Canada have shown that most of the assumptions of the erodibility factor definitions are invalid. The concept fails to define several related forces such as erosive forces and soil conditions that may affect the factor, so, erodibility can only be defined for identified processes and erosive forces, while different properties determine soil erodibility for each erosional sub-process. Thus, the utility of the concept is limited and it is not possible to establish reliable, standard procedures to test erosivity forces. These researchers conclude that it is not possible to define soil erodibility uniquely by investigating a few soil properties. This is in agreement with Romkens (1996) who stated that the term is limited because it is used without describing its specific meaning in each case.
CHAPTER THREE
Data Collection
Soil Classification Map
The primary source of Soil map for the study area was generated from Nigeria Geological Survey, Centre. The co-ordinates (Longitude and Latitude) of the study area was used to extract the geological and mineral map from the enlarged soil map of Nigeria. Then the section extracted was imported into ArcGIS 10.1 and was geo-referenced under the WGS84 Cordinate System to give it a spatial attribute. The study area, Imo State was masked from it .Based on the digitized map, Imo State is divided into the following soil regions;
CHAPTER FOUR
RESULTS AND DISCUSSION OF FINDINGS
In this chapter, data obtained were analyzed using Pearson product moment correlation (PPMC), which was used to answer the research questions and to test the null hypothesis. The findings of the study are also discussed below:
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATIONS
This chapter presents a summary of the major findings, conclusion and recommendations of this study.
Summary of the Study
This research was conducted in order to examine …………… In order to carry out this study, specific research objectives were drawn
The review of literature was done using the variables of the research objectives. This was accomplished by employing past research works, academic journals and textbooks. The comparative survey, exploratory and secondary data, research designed were adopted in the study due to the nature of the research. The data collected was subjected to statistical analysis and the results of the analysis were all significant at 0.05 level. The findings were all discussed for agreement or disagreement with the findings of the past researchers.
Conclusions
From the K-Values obtained for all the locations, the locations with the highest K-values are Owerri West, Ideato North, Orlu and Ohaji Egbema which are 0.067, 0.066, 0.062 and 0.060 respectively, this concurs with the reconnaissance survey carried out within the study area depicting that those areas specifically have the highest incidences of gullies in Imo State. Okigwe, Ikeduru and Oguta showed moderate K-values of 0.039, 0.045 and 0.053 while Ehime Mbano showed the least K-value of 0.023. From the Table of standard erodibility indices all the soils fell into group 1, which implies that the soils in Imo State are permeable outwash well drained soils with permeable sub-strata. The data obtained from this study is a knowledge base reference for design of control structures which will be necessary for soil conservation and management practices within the study area.
References
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