Research

53 views

EFFECT OF LAND COVER CHANGE ON FRESH WATER ECOSYSTEM IN CALABAR MUNICIPALITY, CROSS RIVER STATE, NIGERIA

EFFECT OF LAND COVER CHANGE ON FRESH WATER ECOSYSTEM IN CALABAR MUNICIPALITY, CROSS RIVER STATE, NIGERIA
of 11
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Share
Tags
Transcript
  International Journal of Physical and Human Geography Vol.2, No.1, pp. 27-36, March 2014 Published by European Centre for Research Training and Development UK (www.ea-journals.org) 27 EFFECT OF LAND COVER CHANGE ON FRESH WATER ECOSYSTEM IN CALABAR MUNICIPALITY, CROSS RIVER STATE, NIGERIA . *Offiong, R.A. 1 , Offiong, V.E. 2 , and Ekpe, I.A. 1   1. Dept. of geography & Environmental Science, University of Calabar, Nigeria. 2. Dept. of Urban & Regional Planning, Cross River University of Technology, Nigeria. ABSTRACT: The study examined the resultant effects of land cover changes on Anwatim River  Located in Nkonib Clan, Calabar municipality. Anwatim River being a fresh water ecosystem that once served as a major source of drinking water and domestic water supply in the area is now lost due to land use and land cover changes. Data for the study was obtained from aerial photographs and was considered from 1980-2013. However, an interval of 10 years was used in determining the changes that have occurred alongside effects on the river size. Remote sensing and geographic information systems (Arc view GIS 9.3 software) technology was used in change detection analysis. From the study, it was revealed that from 1980-1989, the land cover was about 3,198,553.7 square meters with a river size of 883,463.5 square meters. Between 1990 and 1999, the land cover was reduced to 2,765,521.2 square meters which then reduced the stream size to 782,124.0 square meters. Similarly, in the years 2000-2009, further depreciation in land cover was observed to be 415,732.9 square meters. In 2013, land cover area of 72,390.4 square meters is now what is left with a corresponding river size reduction to 3677.9 square meters. Therefore, the total land cover loss of 3,126,163.3 square meters to built-up areas (housing and industrial development) have led to a total loss of 3,194,875.7 square meter of Anwatim River in size and extent.   KEYWORDS : Effects, Land cover Change, Stream loss , Anwatim River, Calabar Municipality. INTRODUCTION Land cover change is a conservation term that describes the gradual or swift removal of the natural vegetative cover of the earth surface. The purposes for which natural land covers are removed may include agriculture, mining or urbanization. This activity has great impact on the surrounding environment especially on nearby streams. According to Getachew and Melesse (2012) human health and welfare, food security and industrial developments are dependent on adequate supplies of suitable water; however, water resources are affected by many parameters. One of the parameters that affect the quantity of water flowing in a watershed is land use of the watershed area. Urban development near streams alters inputs (including nutrients, contaminants and sediment), flashiness of discharge, and temperature (Paul & Meyer 2001; Morgan & Cushman 2005). A study conducted by Mutie, Mati, Home, Gadain, & Gathenya (2006), showed that such anthropogenic activities reduced water  bodies’  areal extent by 47%. This is because Streams collect runoff, heat, and sediment from their watersheds, making them highly vulnerable to  International Journal of Physical and Human Geography Vol.2, No.1, pp. 27-36, March 2014 Published by European Centre for Research Training and Development UK (www.ea-journals.org) 28 anthropogenic disturbances that result into loss of ecosystem structure and services (Nelson, Palmer, Pizzuto, Moglen, Angermeier, Hilderbrand, Dettinger, & Hayhoe, 2009). Within the last two and a half decades, Calabar municipality has experienced unprecedented urban growth. This has led to alternation and alteration of several land uses. According to Atu et al (2012), in the past decade, the city’s built up area burst outward in an explosion of sprawl that consumed former agricultural land at a break-neck pace. Thousands of hectares of agricultural land are covered by concrete and asphalt as new roads are created and existing ones are extended. Over 5,200.09 hectares of the former agricultural land at Ekorinim, Esuk Utan, Edim-Otop, Anantigha, and Ikot Efanga have been converted to low density residential, commercial and industrial uses as these areas are merged with the urban areas. This development is consequent on the growth of the population of Calabar. For instance in 1991, the population of Calabar was 328, 876, with a density of less than a thousand person per square kilometer. In 2006, it was 375, 196. At present, the population of Calabar is estimated to be over 399, 761 (National population Commission 2010) while the population density is above 1,237 persons per square kilometer (Cross River State Economic Blueprint 2007-2008). One of the mostly affected streams as a result of increased urbanization in Calabar municipality is the Anwatim River. This served as source of drinking water to the nearby communities before the rapid trend of urbanization and the consequent land cover change around the area came to the fore. The effects of land cover change have caused the loss of fresh and portable water needs loss in the area alongside occupational dislocation. This is due to the fact that most of the inhabitants of the area were involved in fishing as a source of livelihood sustainability. In the same vein, the distance in which people travel to get water have also been on the increase, thus making water availability a problem in the area. In view of these, this study seek to evaluate the changes in land cover of this area and its resultant effects on physical attributes of Anwatim River vis-à-vis the resultant socioeconomic impacts on the inhabitants of the area. MATERIALS AND METHOD Study Area The study area is Ikot Anwatim in Calabar Municipality. Calabar has a land area of about 30,355 square kilometers and a total population of 503,819 according to 2006 population census (Cross River State development project 2007). It is located on latitude 5 0 00 ’ N and 5 0 10’and longitude 8 0 19’ and 8 0 20’E. Calabar municipality  is bounded to Odukpani L.G.A in the north, Akpabuyo L.G.A, to the south by the Atlantic Ocean and west by Calabar River. Calabar is affected by the weather conditions due to its unique coastal location and high rainfall associated with the tropical rainforest. It is characterized by rainfall which starts from the month of April to October, reaching its climax in the month of June and September. The remaining four month make up the dry season with the Harmattan wind blowing over the area. The rain falls averagely at 172mm with temperature of 29 0 C at warmest and 17 0 C at coldest (www.google.com Calabar weather report 2011). The vegetation of the study area is mainly riparian and fresh water swamp forests. Also, a few derived savanna vegetation, cultigens and ornamental/avenue tree/shrub species are present in the area. The dominant soil type is the clayey- loamy soils. The topography of the study area is the low lying coastal plain of the Calabar River and Great Kwa River. It is relatively undulating  International Journal of Physical and Human Geography Vol.2, No.1, pp. 27-36, March 2014 Published by European Centre for Research Training and Development UK (www.ea-journals.org) 29 with a few hills and valleys running east-west wards. Several rivers/streams exist in the area and are basically drained by the aforementioned rivers. The Geology of the area is mainly sand stone. Procedure for data collection Data was collected using stratified sampling. This was based on 10 years interval. This was done through the aid of aerial photographs of the area, obtained from the department of Geography and environmental science cartography unit, university of Calabar, Calabar. Furthermore, the remote sensing and the geographic information system (GIS) technology and applications were applied in the determination of the land cover changes. The stepwise methodology was also used for careful examination of aerial photographs, development of an interpretation key, plotting of the stream area boundary, geo-referencing of digital data, interpretation of data, collecting of ground truth data, editing, finalizing of maps and extraction of statistical data for the different land cover (Njungbwen and Njungbwen, 2011;, Singh and Loshali, 2005; Gourmelon et al., 2004, Acevedo et al., 2003, Ashbindu et al., 2001 and Geomatics International Inc. 1996). However, the Arc view GIS 9.3 software was used for the analysis of topology which was established among the lines and polygons and the coding of the various land cover. Appropriate colours were given to the different land covers. Layouts were developed for them and the final maps produced. Quantitative data for the different land cover for the different time periods were then extracted. The change detection analysis was carried out. This was done by subtracting the values of the previous inventory data from the current one and the rate of the changes was determined by calculating their respective percentage values (Woodwell et al. 1984, Williams 1984). Data Analysis The obtained was analyzed using tables and maps. The size and area of the land cover changes were calculated and represented in square meters. The rationale for these was based on the total size of the study area, being a small unit of the biophysical environment in Calabar Municipality. RESULTS AND DISCUSSION Sequel to the general objective of this study, it was generally observed that there was an exponential growth in the city which have led to the quest for land, housing and other facilities/infrastructures that have given rise to changes in land cover, thus, reduction and loss of the Anwatim fresh water stream as shown in Table 1.  International Journal of Physical and Human Geography Vol.2, No.1, pp. 27-36, March 2014 Published by European Centre for Research Training and Development UK (www.ea-journals.org) 30 Table 1: Land Cover Change in the Study Area S/N Year Land Cover (Sq.M) Built-up Area (Sq.M) River Size (Sq.M) Total River Loss (Sq.M) 1 1980-1989 3198553.678 0.0 883463.516 0.0 2 1990-1999 2765521.165 433032.513 782124.000 101339.516 3 2000-2009 415732.945 2782820.733 39571.895 843891.621 4 2013 72390.387 3126163.291 3677.953 3194875.725 Source: Author’s Computations (2013)  Between the years 1980-1989 it was observed that the natural land covers (vegetation components) was 3,198,553.7 square metres while the built up areas around the water body was almost 0.01 square metres. Also, the size of the Anwatim river was 883,463.5 square metres with a near zero loss as at the year of data collection. Considering urban expansion between the years 1990-1999, it was observed that there were changes in the land cover on the reducing end, and corresponding increase in built-up areas. Hence, the land cover of the area was reduced to 2,765,521.2 square metres, while the built up area increased to 433,032.5 square metres with a reduction in the size of the river to 782,124.0 square metres leading to a total loss of 101,339.5 square metres. Between the years 2000-2009, the land cover was further reduced to 415,732.9 square metres with a corresponding increase in built-up area with a value of 2,782,820.7 square metres. This increase thus, posed a significant effect on the size of the river as it further depleted to 39,571.9 square metres with a total area loss of 843,891.6 square metres as shown in figures 1-3.  International Journal of Physical and Human Geography Vol.2, No.1, pp. 27-36, March 2014 Published by European Centre for Research Training and Development UK (www.ea-journals.org) 31 Fig.1: 1980  –   1989 Land cover change
Advertisement
Related Documents
View more
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks