Assessment of Morphometric Characteristics and Gully Development Susceptibility in Itu Local Government Area Using Geographic Information System

Abstract

The intensification in urbanization and wrong termination of drains into ravine has resulted in gully development which has rendered people homeless and reduced agricultural and economic development. Consequently, this study assessed morphometric characteristics and gully development susceptibility in Itu Local Government Area using Geographic Information System. In conducting this study, measurement of the morphometric parameters of the identified gullies were carried out while the susceptibility extent of gully development was done using multi-criteria technique in GIS. In assessing the characteristics features of the gullies, Field surveys measurements of gully morphology and hydraulic variables were carried out by the researcher using Global Positioning System (GPS), measuring tape, ranging pole, etc. This help in determining gullied land volume and cross-sectional area. Result of the study shows that the measured gully depth varies from 6.4m at Obong Itam to 25.8m at Enen Atai, while the gully width ranges from 4.1m in Ikot Ekang to 9.3m in Ntiat Itam. The cross-sectional profiles ranges from 45.43m<sup>2</sup> to 165.12m<sup>2</sup>. Also, the cross-sectional profile of the area indicative of V-shape to U- shape, all with very narrow gully width and steeply sloping gully sides, which are features of gullies developed on very loose and incoherent soils that slump/collapse on exposure. On the other hand, the mean sand composition of the soil was 62.2% ranging between 55.3-70.1 while silt ranges from 17.7-25.2 with a mean of 20.2% and clay ranging between 10.0-21.9 with mean of 17.7%. The correlation matrix between the gully depth and cross- sectional area (0.84) and is significant at 99% confidence level, meaning that the retreat of gully sides take place at rates proportional to the rate of gully deepening. In assessing the susceptibility extent of gully development in Itu Local Government Area using multi-criteria Analysis technique, the summary of the map shows that 52.94% of the total study area are highly susceptible to gully development, 28.19% are moderately susceptible while 9.31% and 9.56% marginally and not susceptible respectively to gully development in Itu local government area. The study concludes that the poor soil quality attributes, soil conservation and management practices contribute to gully development in the area, hence, the need for government to enact laws against such activities that favour gully growth and initialization.