Change Detection in Landuse/ Landcover of Abeokuta Metropolitan Area, Nigeria Using Multi-Temporal Landsat Remote Sensing

This research paper examined the changes in land use/ land cover of Abeokuta, Nigeria between 1984 and 2015 using Multi-Temporal Landsat Remote Sensing paired with Geographic Information System (GIS) techniques. The evaluation of the trend, rate and magnitude changes was the objectives of this study.  Five Landsat satellite images of different dates,  i.e., Landsat Thematic Mapper (TM) of 1984, 2001, 2006, 2011 and 2015 with spatial resolution ranging from 15, 30 and 60metres were obtained from National Aeronautics Space Administration(NASA),United State Geological Survey Website and  GIS facility of Sioux Falls Website  and quantify the changes  over a period of thirty-one (31) years. Supervised classification methodology was applied to the acquired multi-band raster imageries using maximum livelihood technique in ERDAS Imagine 9.3. The images of the study area were classified into three (3) classes namely; vegetation, water body and built-up area and were overlay with vector maps of the study area generated in ArcGIS 10. The results show that for the period of 31years (1984-2015), vegetation which covered 76.20% of the total area has decreased to 39.29%, water body decreases from 6.63% to 1.89% while the built –up area which initially was 17.14% as at 1984 increased to 58.82%. The study, however, recommended that there is a need for a timely Land use/ Land cover mapping of the entire Abeokuta and its environs in order to reduce the effects of undiscrimate land utilization in the area. This will also facilitate necessary Land use planning and forestall the rising sprawl not only in Abeokuta but also in other urban centres

Information technology and urban green analysis

It is well recognized that green area plays a pivotal role in improving urban environment, such as preserving water and soil, controlling temperature and humidity of air, preventing pollution, flood prevention, functioning as buffers between incompatible land uses, preserving natural habitat, and providing space for recreation and relaxation. However, due to pressures from new development both in urban fringes and urban centres, urban green and open spaces are seen to be rapidly declining in term of allocated spaces and quality. Without careful urban land use planning, many open spaces will be filled with residential and commercial buildings. Therefore, there is a need for proper planning control to ensure that the provisions of green spaces are adequately being conserved for current and future generations. The need for an urban green information system is particularly important for strategic planning at macro level and local planning at the micro level. The advent of information technology has created an opportunity for the development of new approaches in preserving and monitoring the development of urban green and open spaces. This paper will discuss the use of Geographical Information Systems (GIS) incorporated with other data sources such as remote sensing images and aerial photographs in providing innovative and alternative solutions in the management and monitoring of urban green. GIS is widely accepted in urban landscape planning as it can provide better understanding on the spatial pattern and changes of land use in an area. This paper will primarily focus on digital database that are developed to assist in monitoring urban green and open spaces at regional and local context. The application of GIS in the Klang Valley region or better known as AGISwlk developed since mid-1990's is currently being used by various organisations in the region. The focus of AGISwlk is not merely in providing relevant database to its stakeholders but more importantly, assist in making specific and relevant decisions with regard to spatial planning. It is also used to monitor the loss of green areas by using several temporal data sets. The method of classifying green and open spaces in the region is also being discussed. This paper demonstrates that GIS can be an effective tool in preserving and monitoring green and open spaces in an urban area. The contribution of urban green digital database in someway may leads toward landscape sustainability as to satisfy the ever changing society

Large scale mapping: an empirical comparison of pixel-based and object-based classifications of remotely sensed data

In the past, large scale mapping was carried using precise ground survey methods. Later, paradigm shift in data collection using medium to low resolution and, recently, high resolution images brought to bear the problem of accurate data analysis and fitness-for-purpose challenges. Using high resolution satellite images such as QuickBird and IKONOS are now preferred alternatives. This paper is aimed at comparing pixel-based (PIXBIA) and Geo-object-based (GEOBIA) classification methods using ENVI 4.8 and eCongnition software respectively, and ArcGIS 10.1 for map layout creation. It uses Aba main city in south-eastern Nigeria as a case study. The paper further evaluates the classification accuracies obtained using error matrix and then test the classifications’ agreement to geographic reality using Kappa Coefficient statistical analysis. Analyzing 2012 QuickBird image as a proof of concept, the study shows that the object-based approach had a higher overall accuracy (OA= 98.75%) than the pixel-based approach (OA=79.44%). With a Kappa Coefficient of K=0.97 (very good) for object-based approach and K=0.62 (good) for pixel-based, the object-based method showed a higher class separability between and among examined geographic objects such as water, bare-land and tree canopy as evidenced in the Golf Course under re-construction in Aba city. In addition, the object-based results also show a higher overall producer accuracy (PA=98.42% > PA=85.37) and user accuracy (UA=96.70 > UA=81.04%) respectively. The paper, therefore, recommends that object-based classification method be applied in analyzing high resolution satellite image. The approach is also recommended for mapping urban areas in developing countries such as Nigeria where the paucity of fund required in flying airplane for the production of orthophotos is a major challenge in large scale mapping.Keywords: Image Classification, Object-based Classification, Pixel-based Classification, Remote Sensing, Urban Planning and Mapping

Monitoring Urban Sprawl in the Federal Capital Territory of Nigeria Using Remote Sensing and GIS Techniques

Urbanization in Abuja and its environs was largely due to the movement of the Federal Capital Territory to Abuja in 1991 causing the influx of internal/national and international migrants and natural increase of birth rate over mortality. This increase has not only put pressure on the city (Abuja) but the surrounding settlements by posing a threat to the limited resources thereby resulting to high cost of living. Abuja city was planned for limited people as opposed to what is obtained now. The research set out to measure the changes in landmass or landuse/landcover and population increase in the study area. Multi-date Satellite images of 1987, 1999 and 2007 (Landsat TM, Landsat ETM and Nigeriasat 1) were acquired from National Centre for Remote sensing Jos and used in analyzing the physical expansion of the city overtime. Using supervised classification algorithm, the images were classified into built up, rock-outcrop, vegetation and water bodies and used to carry out change detection or time series analysis. In addition, coordinates of locations in the area were obtained using a GPS while figures from National Population Commission were used. Change detection analysis was carried out on the imageries to obtain the physical expansion of the area. Using change detection method, it was found that the builtup area increased from 8% in 1987 to 22% in 2007, rock-outcrop decreased from 74% to 37%, vegetation decreased from 40% to 17%, while the area occupied by water body has remained constant overtime. Also projection was done for population in the next nine years and 1,925,464.089 figures which are about 37% is expected. To support this increase in population and physical growth rate observed, constant monitoring of the urban growth is required to be sustained by anthropogenic activities.Key words: Monitoring, Urban sprawl, Urbanization, Remote Sensing, Geographic Information System (GIS), change detectio

An Efficient Method For Mapping Flood Extent In A Coastal Floodplain Using Landsat TM And DEM Data

An efficient and economical method for mapping flooding extent in a coastal floodplain is described. This method was based on the reflectance features of water versus non-water targets on a pair of Landsat 7 Thematic Mapper (TM) images ( before and during the flood event), as well as modelling inundation using Digital Elevation Model (DEM) data. Using limited ground observation, most flooded and non-flooded areas derived from this analysis were verified. Utilizingonly TM data, the total flooded areas in Pitt County, North Carolina on 30 September 1999 was 237.9 km2 or 14.0% of the total county area. This number could be low due to the underestimation of the flooded areas beneath dense vegetation canopies. To further investigate this underestimation, a subset of the area covering the four central topographic quadrangles, the Greenville area, in Pitt County was selected. Through addition of the DEM data into the flood mapping analysis of the Greenville area revealed that the total flooded area was 98.6 km2 (out of a study area of 593.9 km2 ) or 16.5%. In the Greenville study area, the three landuse and landcover categories most aVected by the flood were bottomland forest/hardwood swamps (32.7 km2 ), southern yellow pine ( 28.8 km2 ), and cultivated land (19.1 km2 ). Their total flooded areas were 80.6 km2 or 81.7% of the total flooded area within this study area. The DEM data helped greatly in identifying the flooding that occurred underneath forest canopies, especially within bottomland forest and hardwood swamps. The method was reliable and could be applied quickly in other coastal floodplain regions using data that are relatively easy to obtain and analyse, and at a reasonable cost. This method should also work well in areas of large spatial extent where topography is relative flat

Integrating Remote Sensing, GIS, Census, and Socioeconomic Data in Studying the Population–Land Use/Cover Nexus in Ghana: A Literature Update

Land is a very important asset and a means to sustain livelihood. In the face of a rapidly growing global population, increase in technological capacity, and affluence, the earth’s land cover has been transformed, especially in developing countries. At the same time, social organisation, attitudes, and values have also undergone profound changes. In contemporary times, issues of sustainabledevelopment, pollution prevention, global environmental change and related issues of human-environment interaction have been a major concern globally. This concern has largely been sparked by the phenomenon of global warming and its consequences, which are threatening the very existence of humans on the surface of the earth. Remotely sensed data (mainly from aerial photographs and satellite images) in combination with Geographical Information Systems(GIS) have been observed to have potential scientific value for the study of population-environment interaction. This paper provides an account of how Remote Sensing, GIS, census (mainly population and agricultural) and socioeconomic (household, district and regional) survey data have been integrated in studying the population land-use/cover nexus in Ghana. It also identifies the major methodological challenges, and solutions

Comparison of the Landsat-7ETM+ and NigeriaSat-1 Imagery for the Revision of 1: 50000 Topographic Map of Onitsha Metropolis, Anambra State, Nigeria

Topographic maps are needed almost in every aspect of public and private sector activities, including general engineering and construction works, economic and physical planning regulation, environmental management, general planning and as a base map for land use/land cover mapping. Most of the topographic maps available in Nigeria are outdated including that of Onitsha and its environs. Consequently, they cannot be used for the desired needs. This study focused on the use of Remote Sensing and Geographic Information System (GIS) in revising and analyzing 1:50000 topographic map of Onitsha metropolis. Two satellite images (Landsat-7 ETM+ and NigeriaSat-1) of the same date (2006) were used respectively to revise 1964 topographic map of Onitsha metropolis. The two imageries which have been georeferenced, in UTM Coordinate System of WGS 84 Zone 32 were sub mapped using the bounding coordinate of the study area. The NigeriaSat-1 and the digitized and georeferenced topographic map of the study area were co-registered to the 28.5m resolution of Landsat-7 ETM+ using ILWIS 3.3 software. The satellite imageries were classified and the classified images were vectorized in ArcGIS 9.3 Software and integrated with contour generated from SRTM data of 2000 to produce revised topographic map of Onitsha Metropolis (2006). The SRTM data of 2000 was used despite the difference in years (6years), because a sample survey revealed that the topography has not changed significantly between 2000 and 2006 within the study area. Pixel-based image analysis revealed that NigeriaSat-1 has better descriminability than landsat-7ETM+ based on the overall classification accuracy obtained from each image; 86.90% for NigeriaSat-1 and 85.77% for landsat-7ETM+. The NigeriaSat-1 was recommended to be used in revising Medium-Scaled topographic maps of Nigeria. The study recommends among others that Medium-scaled topographic map coverage of the entire country should be carried out without further delay. Furthermore, the study recommends that Nigeria should now adopt topographic map of scale 1:25000 as the base map for the whole country. Keywords: Topographic Map, GIS, Remote Sensing, Satellite Imager

Remote Sensing Information Sciences Research Group, Santa Barbara Information Sciences Research Group, year 3

Research continues to focus on improving the type, quantity, and quality of information which can be derived from remotely sensed data. The focus is on remote sensing and application for the Earth Observing System (Eos) and Space Station, including associated polar and co-orbiting platforms. The remote sensing research activities are being expanded, integrated, and extended into the areas of global science, georeferenced information systems, machine assissted information extraction from image data, and artificial intelligence. The accomplishments in these areas are examined

Impact of coastal inundation on ecology and agricultural land use case study in central Java, Indonesia

Focusing on the regional scale, this study provides information concerning the existing ecological problems associated with coastal inundation in the northern part of coastal area in Central Java Province, Indonesia. The objectives of this paper are to map the coastal inundation, to investigate the impact of coastal inundation on coastal environment and ecology, and to assess the impact of inundation on agricultural land use. An integration of techniques, namely neighborhood analysis, iteration operation, and superimposed analysis method has been applied to generate the digital map and to analyze the impact of inundation. Fieldwork measurement has been done using cross-profiling in order to observe the impact of inundation on the coastal ecosystem. Based on the scenario of 100 cm and 150 cm of inundation, the affected area is about 15 207.6 Ha and 16 687.31 Ha, respectively. Fishpond, dry farming and paddy field are the most affected agricultural areas due to coastal inundation