AN ITEGRATED ApPLICATION OF REMOTE SENSING, GLOBAL POSITIONING SYSTEM AND GEOGRAPHIC INFORMATION SYSTEM TECHNIQUES IN ASSESING THE IMPACT OF GULLY DEVELOPMENT ON FARMLANDS IN FARIN LAMBA, RIYOM LGA, PLATEAU STATE, NIGERIA.

Abstract

Gully erosion is responsible for significant soil loss from catchments areas ofRiyom Local Govt Area. Vast lands in Farin Lamba ofRiyom Local Govt. area are dissected by .. ~. gullies, destroying farmland, thus contributing to downstream sedimentation. The study involve's an assessment of the impact of gully development on farmlands in Farin Lamba area. It also involves mapping and measurements erosion parameters which were employed on aerial photographs, satellite imagery of different periods and previous lands degradation reports. The above objectives were achieved by employing GPS, scanning of analogue maps/photographs at a resolution of 400 dpi and digitization. However, a mosaic of the scanned aerial photographs was created to show the area at a glance for better working condition. Land use interpretation was based mostly on cover data provided by photo interpretation keys and farming pattern. A drainage map was obtained from the topographical map and contours for generation of digital elevation model of the area. Using the software ILWlS, delineation of gully areas was possible by digiti sing the aerial photo which were characterised into partial, completely eroded, bare surfaces etc. The fieldwork carried out was able to supplement the age of the photo/satellite data. Similarly the satellite image was classified. To allow GIS to play its role, a database was created. The analysis was r.arrled out using the same software to obtain histograph, slope, flow direction etc. The land use/cover map from the 1981 photos shows an increased vegetation cover of agricultural practice on the reclaimed area on the slopes. Gully erosion is seriously devastating farmlands and it is a threat to farmers in Farin Lamba such that in the next 10 decades, if nothing is done to avert the situation, the available land would be taking over or consumed by gullies