Infrastructure Engineering - Theses
Permanent URI for this collection
Search Results
1 - 1 of 1
-
ItemThe investigation of land cover change and trends through the reconstruction of historical landscapes( 2012)The thesis presented on a new and novel method of reconstruction of historical landscapes for investigation of land cover change and trends. It also discusses and accentuate the importance of land cover change thus the reasons it should be known. Remote sensing and geographical information systems (GIS) method is the only available method for the land cover change investigations at present. This modern techniques method of remote sensing and GIS is reviewed and its inadequacies established. Its major problem is that it has only been available since 1972 therefore for periods that spans more than 40 years there is no satellite data. Then, since land cover change is a slow process, it is necessary to access evidence about the land cover conditions of past eras, data from 40, 50, 60 years ago and beyond. Therefore, it is imperative that a method is found that can be used to assess land cover change in the historical times. The major question is whether reconstruction of historical landscape can be used successfully for the land cover change investigation to fill up the gap where remote sensing is unavailable or inadquent. The proposal of this new method to counteract the inadequacies of remote sensing and GIS method is set forward. Its blue print (Table 3-2 and Figure 3-1) is submitted and tested against the well used, tested and trusted land cover change investigation method of remote sensing and GIS. The new method uses the elements of traditional ecological knowledge of oral history, songs, poems, praise singing and relics; archival data of maps, photographs and aerial photographs; written records and archeological research results. Since this approach does not rely on technology in its original data capture phase, it can be applied anywhere and long time after land cover changes has taken place. For the development and evaluation of the alternative method, test areas in Botswana were used because in these areas, it was possible to draw on the strong African tradition of oral history. The study was made between three time periods of – 1970-1979 – Sir Seretse Khama‟ Era, 1980-1990 – Sir Ketumile Masire‟ Era, and 1991-2003 – Festus Mogae‟s Era. Besides that, on the local setting of Botswana, three minor questions were asked: one was on the political landscape - how did Botswana come into being? And what were the political historical landscapes governing the southern African region? And whether these had any effect on shaping land use patterns and development as seen today? The other question was on population - What are the variability of population changes of Botswana within this period of study and their impact on its land use and therefore land cover changes? And the third question was on climate - What is the extent and variability of climatic changes in Botswana within this period of study and what assessment can be made by correlation of temperature/precipitation data with the years of drought and those of floods? The creation of land cover change maps by the new method followed some procedures. First, the informal data from the traditional ecological knowledge voice data recorded from interviews; the archival maps and photographs graphical data; the written records and the archaeological research findings text and tabular data were deciphered. Second, the epicentres of land cover change point of reference data of the areas were deduced from these data, which were then extracted, and tabulated. Third, the field visits to these points of reference were made and coordinates of their exact locations were measured using a global positioning system (GPS). Fourth, these single items, large scale field data was categorised into land cover classes similar to those seen from smaller scale satellite images of the same area. After these steps it was only then that these informal data were used to create databases which were then transformed and translated into land cover maps for different periods. The land cover maps of consecutive periods were then compared and from that change were detected land cover change map was formed. Other important findings were that for the two methods, that of remote sensing and that of the reconstruction of historical landscape sees the world differently. First it is about remote sensing and GIS intrinsic characteristics. Remote sensing sees the land cover surface from the above, a bird‟s eye view. Although it captures everything and is unbiased some details can be obscured by those above them and are missed out. It is also sees the Earth‟s phenomena from great distances above. Geostationary Operational Environmental Satellites (GOES) 8 orbit the Earth at 35 790 kilometres altitude, the latest of Landsat Earth resources group of satellites system, Landsat 7‟s orbiting altitude is 705 kilometres and the very high resolution IKONOS orbiting altitude is 681 kilometres. Consequently, the satellite data is always viewed as land cover class categories at small scale like built-up-area town/village, or field/forest/vegetation or river/lake/swamp not as single land cover items like a building or a tree or water. The view can change in incidence that depends on factors acting on the land surface; land change by the effects of seasons. The areas which can be viewed at one time are enormous. Good in showing the land cover change and what the land class has really changed to become and this is recorded and archived. Remote sensing views the world far beyond human eye; they utilize the visible electromagnetic spectrum as well as the infra red – they can even see heat; the microwave – RADAR satellites. But need trained people to interpret and analyze. Second, the natural way human beings see the world, the reconstruction of historical landscape method. The world is viewed piecemeal – large scale single item and in oblique, sideways fashion. Also what is viewed is the understory only. The items remain the same to the human mind, it does not change by season or by the way it looks. The world is categorized artificially into names, land uses, ownerships and governed by rules which sometimes has nothing to do with what is on the Earth‟s surface, the land cover its self. People also have the ability to know why something happed and also the ability to draw from their experience, rightly or wrongly. Therefore, as a consequence to that, if these two methods have to be used interchangeably a land cover class specification commensurate to the two methods has to be created. Third, besides all that, the remote sensing platforms and sensors have improved tremendously over the years. Consequently, land cover change from consecutive time period studied from data of satellite from different generation could be more pronounced not only on account of the changed landscape but also on account that better equipment are being employed. So, if a trans-generation satellite data has to be employed some form of standardization of the different generation data has to be made. Various elements of reconstruction of historical landscape subscribe to the land cover change investigation endevours at different levels which complement each other. The traditional ecological knowledge is the most effective giving information which could nearly complete the land cover change. Archaeology although it has brought life to the historical landscape is sporadic and falls apart by age and by space and it also depends on preservations. Others like the songs and the written records depend on whether they are available and also, the information they include is at the author‟s discretion. This thesis has sufficiently proved that the method of reconstruction of historical landscape for the investigation of land cover change can be applied to fill in the gap where modern technologyis inadequate or unavailable. And that indeed climatic change, population density and historical, political and economical landscape are factors that affect land cover change. This is, without any doubt, a welcome accomplishment for the field of engineering and will greatly facilitate further national and regional as well as global scientific undertakings of this nature.