The Sydney duricrusts: their terminology and nomenclature

Two main duricrust types - laterites and ferricretes - and their underlying materials are mapped and described for the northern parts of the Sydney district, New South Wales. Laterites are by far the more widespread, being found both in the Wainamatta-Shales and in the Hawkesbury-Sandstone areas, particularly on the broad hilltops and interfiuves of the major divide between the three drainage systems - the north-flowing Hawkesbury-Broken Bay, the south-flowing Parramatta-Port Jackson and the east-flowing Pacific Ocean systems. The ferricretes occur mainly in the drier parts of the northwest, especially in the conglomeratic river gravels of the Maroota area. The two materials have similar profile characteristics but they are different in hand specimen, in textural and structural characteristics, and also in mineralogical composition. The duricrusts and their profiles have been widely destroyed and differentially truncated, so that their various zones and subzones are presently exposed at different places. These materials, especially in respect of laterites, are classified from field and laboratory evidence, according to their recognised, or assigned, position in the typical deep weathering profile. Names are assigned, depending on the area where the best examples were found

Downstream morphologic characteristics of the alluvial section of lower river Ogun, Nigeria

Rivers constitute an important focus of attention in surface water studies because of their dynamic nature. Therefore, natural rivers develop a wide range of channel forms whose characteristics vary as a function of the position within the fluvial systems. This study examined the river channel morphologic parameters along the alluvial section of River Ogun in South western Nigeria. Data on the channel morphologic variables were collected through field measurement of the bankfull cross sectional characteristics of the river from where the longitudinal characteristics were defined. 48 cross sections were randomly established at bankfull stage along the river channel stretch of 90 km. Bankfull depth and width at each of the cross sections were determined using sonar (electronic sounding machine) that was mounted to a boat. Velocity was measured with the aid of a current meter, while other morphological parameters were estimated from the field data. Analysis of variance revealed that downstream morphological characteristics of the river varies distinctively at each cross section with bedslope as the most significantly varied among all other morphologic parameters (F=91.18; P=0.00). Pearson product moment correlation technique revealed that bankfull width had a correlation of 0.8 and 0.9 with wetted perimeter and cross sectional area respectively while bankfull depth (maximum) had correlations of 0.9, 0.8 and 0.78 with hydraulic radius, wetted perimeter and cross sectional area respectively. The research also revealed that gradient affects the discharge with a positive correlation of 0.9. The study ascertains the extent of variability in the morphologic characteristic of River Ogun which provides scientific basis for river maintenance and management

Downstream Morphologic Characteristics of the Alluvial Section of Lower River Ogun, Nigeria

Rivers constitute an important focus of attention in surface water studies because of their dynamic nature. Therefore, natural rivers develop a wide range of channel forms whose characteristics vary as a function of the position within the fluvial systems. This study examined the river channel morphologic parameters along the alluvial section of River Ogun in South western Nigeria. Data on the channel morphologic variables were collected through field measurement of the bankfull cross sectional characteristics of the river from where the longitudinal characteristics were defined. 48 cross sections were randomly established at bankfull stage along the river channel stretch of 90 km. Bankfull depth and width at each of the cross sections were determined using sonar (electronic sounding machine) that was mounted to a boat. Velocity was measured with the aid of a current meter, while other morphological parameters were estimated from the field data. Analysis of variance revealed that downstream morphological characteristics of the river varies distinctively at each cross section with bedslope as the most significantly varied among all other morphologic parameters (F=91.18; P=0.00). Pearson product moment correlation technique revealed that bankfull width had a correlation of 0.8 and 0.9 with wetted perimeter and cross sectional area respectively while bankfull depth (maximum) had correlations of 0.9, 0.8 and 0.78 with hydraulic radius, wetted perimeter and cross sectional area respectively. The research also revealed that gradient affects the discharge with a positive correlation of 0.9. The study ascertains the extent of variability in the morphologic characteristic of River Ogun which provides scientific basis for river maintenance and management

Synthesis of existing literature in the urban sector in Nigeria

3.1 Introduction As explained in chapter 1, a survey of existing literature on the urban sector in Nigeria was carried out. The survey revealed that there is a substantial volume of such literature. In all, about 1,747 entries were assembled (see appendix VI). These are classified under sixteen major sub-themes (see table 3.1). The highest number of entries was recorded under housing. Next, in descending order, were spatial analysis, environment, economy, transportation, administration and ma..

The future prospects of urban research in Nigeria

5.1 Introduction In spite of the significant roles cities play as engines of national development, and in spite of the increasing magnitude of problems in the urban centres generally, the urban sector has continued to suffer neglect and to lack adequate attention. In the last two decades, the urban sector, in particular, has been accorded very low priority by both government and donor agencies. Consequently the various institutions engaged in urban research cannot conduct effective research d..

Urban research environment and funding in Nigeria

4.1 Introduction As shown in chapter three, urban research in Nigeria is undertaken essentially by academics in universities and other institutions of higher learning. Appendices I-V contain lists of organizations, NGOs, firms and institutions in Nigeria with research, academic and professional interest in the urban sector. The research environment can, therefore, best be defined in relation to what is happening in these places. When these institutions were well funded and properly managed, e..

Urbanization and urban problems in Nigeria

2.1 Introduction Available data reveal that the population of Nigeria has been increasing at an alarming rate. Our towns and cities are growing rapidly. In 1921, the population of Nigeria was only 18.72 million (table 2.1). In 1952, it rose to 30.4 million and in 1963 to 55.67 million. The preliminary census data for 1991 (although the 1991 census figure is still controversial) indicated a population of 80.5 million while the projection for the year 2000 AD suggests a doubling of the populati..

Introduction

1.1 Research Background Nigeria is one of the most urbanized African countries south of the Sahara. Some of Nigeria's urban centres have a history which dates back to antiquity. Indeed, a great deal of research exists on the urban environment in Nigeria, but it has never been compiled into a comprehensive reference book. The bulk of studies done on the urban environment is in the form of journal articles and university-based theses and dissertations or government reports. As a result, knowled..