Remote Sensing And Geographical Information System (Gis) Modelling Of Landuse/Landcover And Climate Change In The Derived Savannah Region Of Nigeria

ABSTRACT

The interaction of landuse/Landcover (LULC) and climate change, to a large extent, involves

anthropogenic activities. This interaction has brought about a complex global environmental

change which includes biodiversity loss, land degradation, deforestation, afforestation and

forest degradation among others. Such change is manifested through the dual nature of

landuse/landcover both as causal factor and as effect of climate change. LULC is initiated

through human activities such as forest harvesting for logging, fuelwood and charcoal

production without forest regeneration of these forest resources, bush fires, overgrazing, as

well as urban and agricultural expansion that tends to increase the concentration of

greenhouse gases (GHGs). This study was carried out in a delicate ecological zone where the

interaction of LULC and climate change could be well appreciated. The zone is an interface

between the forest and savannah zones experiencing drastic environmental change as it

impacts on desert encroachment and resource conflicts. The study evaluated coupled

interaction between LULC and climate change within the derived savannah zone of Nigeria.

It assessed the changes in the landuse/landcover patterns for the periods 1972, 1986, 2002

and 2010, and evaluated the variability in rainfall and temperature as the dominant climatic

parameters within the study area over the area from 1941 to 2010. In addition, an attempt was

made to predict the interaction between LULC and climate change and to estimate the

changes in carbon stock resulting from LULCC. The study further employed remote sensing

and GIS techniques to interpret and analyse Landsat satellite imageries for the period under

study while the multivariate statistical analysis was used to analyse the historical and

downscaled climate data for the present and future climates. In predicting the nature of

interaction between LULC and climate for future climate within the region, the study adopted

both statistical and Land Change Modeller (LCM) techniques. The study revealed that the

built up area, farmland, waterbody and woodland experienced a rapid increase of about

1,134.69%, 1,202.85%, 631.51% and 188.09%, respectively, while the forest cover, degraded

surfaces and grassland lost about 19.32%, 72.76% and 0.05% respectively between 1972 and

2010. The study thus confirmed the sinusoidal nature of the climatic pattern with 2.03mm

(0.02%) and 0.15mm (0.01%) increase per annum for mean annual rainfall and rainfall

anomaly respectively with annual mean rainfall of 1,316mm for the present climate. The

future climate was predicted to increase at a rate of 3.13mm (0.2%) per annum for mean

annual rainfall with an annual mean of 1,393mm. Also, the rainfall variability index during

the present climate ranges between 15 and 23% and 9 – 13% for future climate, which

indicated that rainfall will be more stable in the future climate, while temperature variability

indices range from 1.42 – 2.41% and 1.26 – 1.33% for both the present and future climates

respectively. Due to the short temperature range predicted for the future climate, temperature

will be more stable with higher intensity. Furthermore, the study predicted 40.28% and

37.84% reduction in the forested area between 1986 and 2050 and 2010 and 2050

respectively. In addition, the study estimated that about 298,767,040 tons of CO2 will be

emitted due to the deforestation and forest degradation induced by the interaction of LULC

and climate. The study concludes that climate parameters, especially rainfall will be the

major driver of LULC change within the study area and calls for further studies on the

implications of rainfall variability and change during future climate.