Short-term bank gully retreat rates in Mediterranean environments

摘要: Abstract In this study, short-term headcut retreat was monitored from 46 active bank gullies, selected in the Guadalentin and Guadix basin Southeast Spain. The measurements were carried out manually using an orthogonal reference system fixed by erosion pins around gully heads, between April 1997 1999 with a 1-year interval. average volumetric rate for all gullies 4.0 m 3 year −1 , corresponding linear of 0.1 but more took place during first (1997–1998) compared to second (1998–1999). An interplay spatial variations rainfall distribution tension crack activity is assumed be responsible important difference annual retreat, small amounts. Statistical analysis showed that present drainage-basin area ( A p ) most topographical factor explaining rate, both terms eroded volume V e R l ), expressed power relationships =0.04 0.38 2 =0.39) =0.01 0.23 =0.39). – relationship original o total (Vol), i.e. Vol=1.71 0.60 =0.65). importance runoff generation drainage shown positive correlation curve number (CN), representative conditions basin. High CN values tend coincide higher volumes effect not observed (Vol). Stepwise multiple regression relevant environmental parameters retreat. equations, explained largest part variation. as another common parameter. Height variable volume, indicating role energy transfers undercutting at headcut. Linear further slope area, representing decreasing transmission losses increasing flow velocity steeper catchment slopes, sand content, cohesion soil material, promoting fall Spatial extrapolation measured revealed heads contribute up 6% sediment yearly filling Puentes reservoir. Estimated ages (i) based on ergodic principle, (ii) actual rates past, range 63 years 1539 64 1720 years, respectively. high estimated two methods attributed fact have reached evolutionary stage significantly declining rates. Since medium-term are dependent obtained represent maximum values, assuming land-use climate prevailed over last millennia.