Spatial Analysis of Gully Erosion Patterns and Community Impact in Kaduna South, Kaduna State, Nigeria

Abstract

This study assessed the spatial patterns and socio-economic factors influencing gully formation in Kaduna South Local Government Area of Kaduna State. Gully erosion sites numbering eighty eight (88) were identified in planned and unplanned areas, coordinates of all the spatial locations of gullies are collected using hand held GPS Garmin 78s and the area was mapped using ArcGIS 10.5. Shape files were used to generate Base Map for the period of 20 years (2001-2020) at 5 years interval. Data on gullied areas were obtained from places where gullies are more prevalent like Kurmin Mashi, Kakuri Gwari, Tudun Nupawa and Kabala West through survey, interviews, measurements and ground trothing exercise. The highest number of gullies identified was 21, Kabala West having the most of the gullies and Makera having the lowest. Several roads identified to be affected by gully erosion like Kajuru road and Alagbado Street in Kabala West as well as Birnin Kudu Road in Tudun Nupawa were investigated, While building infrastructures were also affected by gully development at Tudun Nupawa LEA, River close in Kurmin Mashi, Lungu (pipeline) in Kakuri Gwari which eventually became a criminal hiding points. Base Map of Kaduna South LGA for the years 2005, 2010, 2015 and 2020 was obtained with the coordinate of the gully locations superimposed. From the Base Map, the year 2005, 2010, 2015 and 2020 had 33, 18, 20 and 16 gullied points respectively. Mean length, Width, Depth and year of formation for each gullied site was obtained and the rate of advancement per annum was calculated. Kajuru and Alagbado roads in Kabala have the highest rate of advancement of 6.6m per annum which is due to slope and inadequate drainage. Captain Road in Kurmin Mashi has the lowest rate of advancement of 0.2m per annum which is due to community effort put in place by using sacks of sand as a way to mitigate and reduce the effects of the gully. There was community participation in different areas in trying to mitigate the effect of gully in their communities, as evidenced at Abuja road, Kurmin Mashi and Kajuru Road at Kabala West, where residents use old car tires and sacks filled with sand across the gullied region to stop further advancement of the gully on the road side. An action that helped in ameliorating the advancement of gully overtaking the available access roads. From the results obtained it can be concluded that gully formation can occur in any area whether planned or unplanned. Factors discovered to be responsible for the development of gullies in the study areas clearly shows that the socio economic status of the residents contributed in their formation where residents were found to have abandoned their houses because they cannot remediate the effect of gully presence. However, relevant government authorities need to enlighten the communities about the dangers of gullies in the society and finding lasting solutions to gully effects. Also, state and local government authorities need to provide required engineering solutions to the places affected by the gully(s) like retaining walls, embankments and proper drainages.