The thesis is the first attempt of mapping impervious surface that offers a very simple and visual understanding of the health status of the watersheds within Kaduna metropolitan area. It examined the spatiotemporal growth of impervious surface areas in Kaduna metropolitan area, Nigeria in relation to the watersheds using the SAVI differencing approach. A supervised maximum likelihood algorithm was used to classify image derived from the SAVI differencing approach, for the time periods. A random sampling scheme was conducted to complete an accuracy assessment of the classification.
Results from the watershed categorization indicate it took 36 years to establish the first degraded watershed, this is from 1973 to 2009, going by the prediction in the analysis, it will take less years, i.e. 20 years to establish the next degraded watershed in the study area. This study demonstrates the feasibility of mapping and categorizing watersheds associated with impervious surface areas, through the combination of remote sensing data (LANDSAT and ASTER) with the help of a GIS software (ArcGIS).
Table of Contents
1. INTRODUCTION
2. LITERATURE REVIEW
3. METHODS
4. RESULTS AND DISSCUSION
5. CONCLUSION
Research Objectives and Focus
The primary aim of this research is to analyze the spatiotemporal growth of impervious surface areas within the Kaduna metropolitan watersheds in Nigeria, categorize these watersheds based on their impervious surface cover, and predict future degradation trends to support environmentally sustainable urban planning.
- Delineation of watersheds within the Kaduna metropolitan area.
- Evaluation of methods for mapping impervious surface areas.
- Categorization of watersheds based on the percentage of impervious surface cover.
- Prediction of future watershed degradation using spatiotemporal analysis.
- Application of remote sensing data (LANDSAT and ASTER) and GIS software (ArcGIS).
Excerpt from the Book
Impervious surfaces and urban watershed characteristic
Urban watersheds show greater surface runoff than comparable non-urban watersheds, and this is attributed to the differences in impervious surface cover in the two settings (Booth, 1991; Horner et al., 1999). Peak stream flows following storm events increase with urbanization while low flows between storms decrease because less water is able to infiltrate the ground (Leopold, 1968). Less infiltration means less ground-water discharge, that is, base flow, into any given stream channel. This subsurface flow of water to the channel is relatively slow. Urbanization disturbs the pre-urban equilibrium between hydrology and sediment yield and this results in geomorphic alterations of stream channels (Hammer, 1972; Morisawa and LaFlure, 1979; Pizzuto et al., 2000). The volume of sediment supplied to a stream changes as a function of the degree of watershed development, as suggested by Wolman (1967) and upheld by Chin (2006) and Grable and Harden (2006), occurring in three distinct stages: 1) a stable or equilibrium pre-urban stage; 2) a construction period exposing large areas of bare land; and 3) a final, new urban landscape dominated by impervious surfaces.
During the construction phase of development, large expanses of land are stripped and left bare for extended periods of time inducing widespread erosion of the surrounding landscape. This erosion supplies a greater volume of sediment to a stream than in the pre-urban stage, leading to short-term aggradation. Sediment yield during the construction phase has been shown to be as high as 40,000 times greater than pre-urban rates (Harbor, 1999). Deposition and bed aggradation result in overall channel capacity reduction as channel width and depth decrease. As land development continues, impervious surfaces begin to cover the majority of the landscape, through the construction of roads, buildings, parking lots, and other cultural features. Compared to pre-urban conditions, these impervious surfaces generate a larger amount of surface runoff, which is directed into the sediment choked stream channels as a greater discharge capable of eroding the recently deposited sediment.
Summary of Chapters
INTRODUCTION: This chapter introduces the context of rapid urbanization in developing countries, specifically Nigeria, and outlines the research objectives, hypothesis, and the scope of the study.
LITERATURE REVIEW: This chapter reviews established methods for mapping impervious surfaces and discusses the environmental impacts of urban development on watersheds, particularly regarding geomorphology and water quality.
METHODS: This chapter describes the technical framework used to map impervious surface areas, including data sources and GIS procedures for watershed delineation.
RESULTS AND DISSCUSION: This chapter presents the data analysis of impervious surface growth rates and compares watershed categories over the studied time periods to highlight spatiotemporal differences.
CONCLUSION: This chapter summarizes the research findings, addresses the limitations of the methodology, and provides recommendations for environmentally sustainable urban development.
Keywords
Impervious surfaces, Urbanization, Watershed, Spatiotemporal Analysis, Remote Sensing, GIS, Kaduna, SAVI, Land Cover, Surface Runoff, Environmental Health, Watershed Delineation, Urban Planning, Sustainability, Hydrology.
Frequently Asked Questions
What is the core focus of this research?
The work focuses on analyzing how the expansion of impervious surfaces affects the health and categorization of watersheds within the Kaduna metropolitan area over several decades.
What are the primary themes covered in this study?
The central themes include urban development, hydrological changes, impervious surface mapping techniques, watershed management, and the environmental consequences of rapid city growth.
What is the main research objective?
The primary objective is to identify impervious surface areas across three time periods, categorize watersheds based on this coverage, and predict which watersheds are likely to become degraded in the future.
Which scientific methods are utilized?
The study employs remote sensing (LANDSAT and ASTER data), the Soil Adjusted Vegetation Index (SAVI) approach, supervised classification, and GIS-based watershed delineation.
What is discussed in the main body of the work?
The main body covers the theoretical background of impervious surface impacts, the detailed procedural steps for satellite image processing and classification, and the resulting statistical analysis of watershed changes.
Which keywords best characterize this work?
The research is best characterized by terms such as impervious surfaces, urbanization, watershed management, spatiotemporal analysis, remote sensing, and environmental sustainability.
How does the study define an "impervious surface"?
Impervious surfaces are defined as constructed surfaces, such as rooftops, roads, and parking lots, that are impenetrable to water, thereby prohibiting infiltration into the soil and increasing storm water runoff.
What is the significance of the "first flush" mentioned in the research?
The "first flush" refers to the initial period of stormwater runoff during a rain event, which typically carries higher concentrations of accumulated pollutants from impervious surfaces into water bodies.
Why are watersheds categorized as Protected, Impacted, or Degraded?
This categorization, based on the percentage of impervious surface cover, serves as an environmental indicator to assess the health status of a watershed, where higher percentages correlate with increased degradation.
- Citation du texte
- Asadullah Muhammad (Auteur), 2014, Spatiotemporal analysis of impervious surface areas on the watersheds of Kaduna Metropolitan Area, Munich, GRIN Verlag, https://www.grin.com/document/514395
