The development of models for prediction of gully growth and head advancement A case study: Queen Ede gully erosion site, Benin city, Edo state, Nigeria

This paper examines gully growth and head advancement at the Queen Ede gully site, Benin city. This is achieved by observing gully growth and head advancement between the year 2000 and 2012 using eld surveys, aerial photographs and geographical information. Also, experimental models such as Thompson [1], [Thompson, J.R. \Quantitative eect of watershed variables on the rate of gully head advancement", Trans ASAE, 7, pp. 54-55 (1964)]. the American Soil Conversation Service, SCS (I) and SCS (II), and FAO models, were used for estimating migrating headcuts over a study period. Results obtained revealed that the gully width varied from 15.6 m to 99.5 m, while the depth varied from 0.5 m to 13.8 m. The volume of soil loss was 372, 775 m3 over an area of 104.4 m2. A mathematical model is proposed for gully growth (GA) and head advancement (RA), which is hereby presented as: (i) GA = 0:15R0:2679L0:0873 a L0:09179 w E0:009860P0:06773: (ii) RA = 0:15A0:5328S0:14P0:6778E: The model has been tested against the best existing theories and found to give the same order of error.