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LAND USE/LAND COVER CHANGE EARLY WARNING SYSTEM AND CLIMATE CHANGE IN THE QUA IBOE RIVER BASIN, NIGERIA

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Title: LAND USE/LAND COVER CHANGE EARLY WARNING SYSTEM AND CLIMATE CHANGE IN THE QUA IBOE RIVER BASIN, NIGERIA


1
LAND USE/LAND COVER CHANGE EARLY WARNING SYSTEM
AND CLIMATE CHANGE IN THE QUA IBOE RIVER BASIN,
NIGERIA
  • EKPENYONG, Robert Etim
  • Department Of Geography and Regional Planning
  • University Of Uyo
  • Uyo, AKS
  • Nigeria

2
Introduction
  • Studies have shown that information on land use/
    land cover is required for rational and
    sustainable allocation of land resources for
    development YANG and LO, 2003 EL-RAEY et.al.,
    2000 BRONSVELD et. al., 1994.
  • In the Qua Iboe River Basin, Nigeria, growing
    population densities, urbanization and poverty is
    leading to widespread changes in land use and
    land cover. The situation is so serious that food
    security, socio-economic development and the
    climate/microclimate of many areas are being
    threatened.
  • To effectively address these problems and ensure
    that future generations can enjoy the benefits of
    the earths resources, there is need for an early
    warning system for land cover change analysis and
    mapping.

3
LOCATION OF STUDY AREA
  • The Qua Iboe River basin is located within Akwa
    Ibom State which is situated in South Eastern
    Nigeria.
  • It lies between latitude 430 and 530N and
    long 730 and 815E (Fig.1)
  • The catchment area of the basin lies between the
    Imo and Cross Rivers and covers about 3266sq.km.

4
Theoretical Considerations
  • Generally, urban areas are made up of buildings
    and pavements which changes the natural landscape
    into townscape. The surface materials are mostly
    hard. This implies that, the thermal conductivity
    and heat capacity are greater than when the
    surface was mostly composed of vegetation.
  • Studies have shown that, the modification of the
    environment through the creation of cities
    represents a more extreme form of microclimate
    alteration Ojo 1977.
  • Transpiration from vegetation causes higher
    humidity. However, changes in vegetation cover
    from trees to grass usually decreases evaporation
    and transpiration losses and reduces the amount
    of rain and snow intercepted by foliage.
    Furthermore, temperature and wind speeds are
    lower within forested areas than in the open.
    Cities tend to have higher temperatures than the
    surrounding suburbs and they produce more haze
    and smoke MILLER et. al, 1970 OJO, 1977.
  • The foregoing underscores the importance of land
    use/land cover in climate change.

5
Materials and Methods
  • Data Acquisition, Database creation and Data
    Analysis
  • Maps of the area, mainly those showing relief and
    drainage, soils, vegetation, rainfall and
    temperature distribution, land capability/suitabil
    ity, land resource development areas etc.,
    published in 1982 by Cross River basin
    Development Authority at a scale of 1250,000
    were scanned, geo-referenced and digitized to
    create the early warning system baseline dataset.
  • Supervised classification was carried out to
    produce Land use/Land cover maps for the
    different time periods year 1984 and 2003.
    These are periods before the area was constituted
    into a State and the period 16years after State
    creation. Random test fields were located in the
    original image and in the field to perform
    accuracy assessment. An overall accuracy of
    82.11 was estimated. For change detection, the
    areas of the cover types were derived from the
    histogram of the respective classified imagery.
    YANG et al, 2002 SINGH, 1999 JENSEN, 1995
    LILLESAND et al, 1994. The image processing
    software used was ILWIS 3.3.

6
The Early Warning System
  • According to EWC 111 2006, a complete and
    effective Early Warning System comprises a chain
    of four elements
  • Risk knowledge-prior knowledge of the likely risk
    scenarios communities are faced with
  • Monitoring and warning services-monitoring
    capabilities for these risks and rapid and
    reliable decision mechanisms for early warning
  • Communication-dissemination of understandable
    warnings to those at risk
  • Response capability-knowledge and preparedness
    capacity to act by all partners of the
    information chain.

7
The Land Cover Change Early Warning System
  • The land use/land cover change early warning
    system comprised a personal computer system with
    intel Pentium 4 processor 3GHz, 200GB HDD, 1024GB
    RAM and 21 color monitor, a variety of GIS and
    image processing software ILWIS 3.3, ArcGIS 9,
    GPS Utility 4.2, Global mapper, LCCS 2.4.5,
    SURFER 32, JT Maps etc and database. It is
    located in the Department of Geography and
    Regional Planning, University of Uyo, AKS-Nigeria
    where it is used for capacity building. To
    enhance its capabilities, the system is
    frequently updated as new theory, models and/or
    data become available. Also advantage is often
    taken of the free GIS/Image processing software
    and landsat data available in the internet.
  • The early warning system is capable of providing
    information on the likely risk scenario that
    communities may face but the challenge now is to
    build partnerships that can support its
    monitoring, communication and response
    capabilities.

8
Manipulation and Analysis of Data for Early
Warning Purpose
  • Fig. 2 and Fig 3 are land use/land cover maps of
    lower Qua Iboe River Basin for 1984 and 2003.
    They were produced using landsat TM. A summary of
    the changes in land use/land cover is given in
    table 1.

9
Table 1 Qua Iboe Basin Land Cover Type Coverage
Area
LAND COVER TYPE AREA IN 1984ha AREA IN 2003ha
Bare soil 2,504.133 38.817
Beach sand 35.946 127.539
Fallow land/grassland 26,939.05 32,074.48
Mosaic farmland/oilpalm forest 8,464.60 18,662.29
Freshwater swamp forest 9,922.95 7,545.29
Mangrove forest 3,739.45 3,644.91
Rivers/Natural water bodies 8,192.99 10,721.20
Urban/Industrial/built-up 895.995 1028.115

Source Histograms of classified imageries for
1984 and 2003
A critical examination of the images reveals the
facts that, much of the farmland and fallow land
were encroached upon by urban centers. This has
serious implications on sustainable
agriculture/food security, climate etc.
10
Impact of Urbanization
  • Urbanization refers to the process in which an
    increasing proportion of an entire population
    lives in urban and suburban areas. Historically,
    this has been closely connected with
    industrialization and the discovery of petroleum
    in Nigeria. New job opportunities in urban areas
    spurred the mass movement of surplus population
    away from the rural communities Yang and Lo,
    2003 El-Raey et.al., 2000.
  • In Akwa Ibom state where the Qua Iboe river basin
    is located there were only 10 urban centres as
    at 1987 when the state was created. Of this
    number, five were within the river basin. With
    the creation of new Local Government Areas, the
    number of urban centres in the State increased to
    31. Of this number, 16 are within the catchment
    of the Qua Iboe River basin.
  • The population of people attracted to these urban
    centres continues to increase because of the
    important industries and socio economic activity
    centres located within and or close to them. For
    instance, Uyo is a capital city and the sit of
    Government of Akwa Ibom State. It grew in size as
    a result of urbanization from 125.595ha in 1984
    to 242.262ha in 2003table 2.
  • Two other areas within the basin Eket and Mkpanak
    also expanded in size. Eket expanded from 23ha to
    27ha while Mkpanak expanded from 7ha to 33ha
    table 2.

11
Table 2. Urban/Industrial/Built-Up Area Land
Cover type coverage Areas
PLACE NAME AREA IN 1984ha AREA IN 2003ha
Uyo 125.595 242.262
Eket 23.472 27.567
Mkpanak 6.912 32.697
A critical visual interpretation of the 1984
images of Uyo, Eket and Mkpanak reveals the fact
that, the settlements were surrounded by
agricultural land i.e. mosaic farmland/oil palm
forest and bush fallowing/grassland land cover
types. This implies that, the growth of the
urban areas in 2003 have encroached on valuable
agricultural land. This is a serious threat to
agriculture/food security in the area under study.
12
Images Showing Land Cover Change in Uyo Capital
City
13
Climate Change
  • There is no doubt that a city modifies its own
    climate. It is however difficult to separate the
    influence of the city from that of other factors
    such as relief, drainage, or water bodies within
    or near the city, which independently affect
    climate OJO 1977 MILLER et.al 1970.
  • However, of all the climatic elements, the only
    one that changes quite often within the area is
    rainfall.

14
Table 3 Rainfall Pattern in Uyo Capital City
Years Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Total (mm) Ave mm)
1984 0 0 147.8 100.6 217.6 400.2 244.2 170.2 225 223.7 149.4 0 1878.1 156.5
1985 63.5 0 157.5 191.2 281.7 213.6 274 392.7 226.4 239.8 84.6 7.6 2132.6 177.7
1986 1.05 63 207.9 99.8 198.8 154.4 313.6 107.8 399.3 296.3 63.2 0 2132.6 177.7
1987 0 42.9 225 165 419 205.8 188.6 300.9 329.4 289.7 26.6 58.5 2251.7 187.6
1988 5.5 3 143.9 228.5 198.4 233.4 310.9 251.3 475.1 213.6 18.3 33.1 1915.1 159.6
1989 0 0 39.1 200.7 261.6 223.8 553.2 331.6 453.7 442.8 82.2 0 2631.7 219.3
1990 22.6 1.5 27 158.7 308.6 113.1 456.2 417.9 152.3 204.5 124.3 41.1 2032.8 169.4
1991 0 29.5 41.2 395.3 207.9 319.6 383.8 405.2 78.2 239.9 69.4 76.7 2243.7 186.9
1992 7.5 0 113.3 115.9 248.5 307.6 470.8 383.1 322.8 116.9 165.7 4.7 2276.8 189.7
1993 2 0 121.8 130.4 141.4 339.9 352.5 468.4 324 252.1 97 0 2229.6 185.8
1994 7.2 6.2 153.3 167.6 300.5 315.4 456.6 380.9 463.6 294.8 122.6 0 2668.7 222.4
1995 4.4 26.1 168.9 82.4 316.8 221.4 428.6 313.7 234.7 339.5 122.9 5 2264.4 188.7
1996 34.8 112.4 124 240.9 398.2 295.2 275.5 407.9 409.6 220.4 1.8 0 2117.6 176.5
1997 17.5 0 113.4 120.8 195.2 237.5 345.4 326.6 151.7 314.7 81.2 17.3 1957 163
1998 26.5 1.8 81.5 131.9 144 303.2 302.7 253 300.4 178.6 241.7 68.5 2033.8 169.5
1999 60.4 85 224.2 275 177.2 154.9 211.1 327 468.6 420.9 95.1 9.1 2509.5 209.1
2000 31.5 0 106.5 125.3 320.4 146.2 254 262.7 281 172.5 95.1 45.6 1840.7 153.4
2001 0 8.6 229.9 219.3 339.7 503.2 219 182.6 270.6 225.6 118.3 0.4 2317.2 193.1
2002 0 10.8 135.1 261.4 312.4 255.8 205 347 320 414.9 30.1 9 2341.5 195.1
2003 20 43 104 223.5 235.6 181.6 202.4 218.6 340.6 207.8 116.7 1 1894.8 157.5
2004 2.1 57 24.2 165.8 218.1 363.8 357.1 288.9 362.3 280.9 79.4 22 2221.6 185
2005 22.4 97 156 284.8 186.7 325.6 637.7 325.1 279 505.5 207.1 3.6 3030.5 252.5
2006 3.7 60.8 277.8 296.8 370.8 592.7 419.3 360.5 566.8 374.9 49.6 0 3373.7 281.1
SOURCE Department of Meteorological services,
station Number 050705B, University of Uyo.
Uyo,AKS, Nigeria
SOURCE Department of Meteorological services,
station Number 050705B, University of Uyo.
Uyo,AKS, Nigeria
15
Climate Change
  • Table 3 shows the yearly variations of rainfall
    between 1984 and 2006 for Uyo Capital city.
  • Relatively high rainfall of more than 2500mm
    occurred in 1989, 1994, 1999, 1005 and 2006
    whereas, unusually low rainfall of less than
    1900mm was recorded in 1984, 2000 and 2003.
  • Compared with the mean annual rainfall of 189.4mm
    for Uyo, the years 1989, 1994, 1994, 1999, 2001,
    2002, 2005 and 2006 were years with rainfall
    above the average.

16
Climate Change
  • As can be observed from table 3, more than 80 of
    the annual rainfall occurs between March and
    October of each year, while less than 20 of the
    rain falls between November and February.
  • However, a lot of variations occur from year to
    year in the monthly distribution of rainfall. For
    example, the highest rainfall in 1984 and 2006
    occurred in June whereas in 1985, 1987, and 2002,
    it occurred in August, May and October
    respectively.

17
Conclusion
  • This study confirms reports of destruction of
    vegetation cover in the Qua Iboe River Basin.
    Since studies have shown that losing vegetation
    cover in any area can affect climate, there is
    need for the land use/land cover Change early
    warning system.
  • The results of this study shows that, with the
    land use/land cover change early warning system,
    it is possible to among other things, monitor and
    manage urban growth to ensure food security and
    a stable climate regime in any area.
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