Analysis of Settlement Expansion and Urban Growth Modelling Using Geoinformation for Assessing Potential Impacts of Urbanization on Climate in Abuja City, Nigeria

This study analyzed the spatiotemporal pattern of settlement expansion in Abuja,

Nigeria, one ofWest Africa’s fastest developing cities, using geoinformation and ancillary datasets.

Three epochs of Land-use Land-cover (LULC) maps for 1986, 2001 and 2014 were derived from

Landsat images using support vector machines (SVM). Accuracy assessment (AA) of the LULC maps

based on the pixel count resulted in overall accuracy of 82%, 92% and 92%, while the AA derived from

the error adjusted area (EAA) method stood at 69%, 91% and 91% for 1986, 2001 and 2014, respectively.

Two major techniques for detecting changes in the LULC epochs involved the use of binary maps

as well as a post-classification comparison approach. Quantitative spatiotemporal analysis was

conducted to detect LULC changes with specific focus on the settlement development pattern of

Abuja, the federal capital city (FCC) of Nigeria. Logical transitions to the urban category were

modelled for predicting future scenarios for the year 2050 using the embedded land change modeler

(LCM) in the IDRISI package. Based on the EAA, the result showed that urban areas increased by more

than 11% between 1986 and 2001. In contrast, this value rose to 17% between 2001 and 2014. The LCM

model projected LULC changes that showed a growing trend in settlement expansion, which might

take over allotted spaces for green areas and agricultural land if stringent development policies and

enforcement measures are not implemented. In conclusion, integrating geospatial technologies with

ancillary datasets offered improved understanding of how urbanization processes such as increased

imperviousness of such a magnitude could influence the urban microclimate through the alteration

of natural land surface temperature. Urban expansion could also lead to increased surface runoff as

well as changes in drainage geography leading to urban floods.

Keywords: land-cover change; settlement expansion; support vector machines; urban growth

modelling; climate impact