The issue of gully erosion is of major concern in the south-eastern part of Nigeria. This study adopts Geographic Information Systems (GIS) as a tool to identify and study gully erosion hazards in Abia state. 171 gully erosion sites were coordinated using GPS receivers and overlaid on the soil and geological maps of the study area. Spatial database for erosion sites was created using relational database model. Additional 35 gully erosion sites were identified from the processed digital elevation model (DEM) and ground verification carried out. Result shows that gully erosion sites were well dispersed around false bedded sand stone geological formation. The slope characteristic was ascertained to be greater than 15 o which encourages gully erosion activities. An erosion hazard map was produced showing risk and vulnerability of settlements and infrastructure. This study shows that GIS is an efficient and effective tool in the study and mapping of gully erosions.

Soil erosion is of major concern in Abia State, Nigeria. This study adopts a combination of Geographic Information Systems (GIS) and Remote Sensing as a tool to study and map soil erosion menace in Abia State. For this research, several datasets that represent climate, soil, geology, topographic and anthropogenic factors were used as the basic requirements for environmental modeling of soil loss using Universal Soil Loss Equation (USLE) for 1986 and 2003. The results show that 1082.58 tons/acres were lost in 1986 and 1120.59 tons/acres in 2003 in the study area. Also, a negative correlation was found to exist between soil loss and NDVI (Normalized difference vegetation index) value. Soil erosion vulnerability index map as well as risk prone areas maps was produced. This study shows the integration of GIS with remote sensing as an efficient and effective tool in the study and mapping of soil erosions.

Flood disaster is considered a major natural hazard plaguing Lagosains due to its devastating effect on affected communities. Analytical Hierarchy Process (AHP) was adopted using Geographical Information System (GIS) to determine areas vulnerable to flood in Lagos for 1984 and 2013. This research considers the contribution of rainfall, elevation, land use, slope and soil to flood. AHP method was applied to these factors by means of ranking and pairwise comparison. This products a relative weight of 34.45% for slope, 19.58% for rainfall, 18.79% for land use, 18.61% for elevation, and 8.57% for soil. The consistency value was found to be reasonable with a consistency index of 0.0738 with a consistency ratio of 7%, these aids in flood vulnerability mapping. This reveals that the impact of flood is high for residential and socio-economic activities in Lagos, thus, this will assist decision makers on the menace posed by the disaster and mitigation measures to adopt.