Sediment Reallocations due to Erosive Rainfall Events in the Three Gorges Reservoir Area, Central China

Abstract

Soil erosion by water outlines a major threat to the Three Gorges Reservoir Area in China. A detailed assessment of soil conservation measures requires a tool that spatially identifies sediment reallocations due to rainfall-runoff events in catchments. We applied EROSION 3D as a physically based soil erosion and deposition model in a small mountainous catchment. Generally, we aim to provide a methodological frame that facilitates the model parametrization in a data scarce environment and to identify sediment sources and deposits. We used digital soil mapping techniques to generate spatially distributed soil property information for parametrization. For model calibration and validation, we continuously monitored the catchment on rainfall, runoff and sediment yield for a period of 12 months. The model performed well for large events (sediment yield > 1 Mg) with an averaged individual model error of 7.5%, while small events showed an average error of 36.2%. We focused on the large events to evaluate reallocation patterns. Erosion occurred in 11.1% of the study area with an average erosion rate of 49.9 Mg ha À1 . Erosion mainly occurred on crop rotation areas with a spatial proportion of 69.2% for 'corn-rapeseed' and 69.1% for 'potato-cabbage'. Deposition occurred on 11.0%. Forested areas (9.7%), infrastructure (41.0%), cropland (corn-rapeseed: 13.6%, potatocabbage: 11.3%) and grassland (18.4%) were affected by deposition. Because the vast majority of annual sediment yields (80.3%) were associated to a few large erosive events, the modelling approach provides a useful tool to spatially assess soil erosion control and conservation measures.

Sediment Loss Patterns in the Sub‐Humid Ethiopian Highlands

“…In Kenya, catchments lose an average of 80% of their sediment in the largest 10% of flows and 41% of the mean annual sediment yield (SY) in the upper 1% of flows (Dunne, ). Other studies (Lamoureux, ; González‐Hidalgo et al ., ; González‐Hidalgo et al ., ; Krasa et al ., ; Stumpf et al ., ) have shown similar results entailing the strong impact of large events on annual sediment loads.…”

Impact of Land Use Change and Dam Construction on Soil Erosion and Sediment Yield in the Black Soil Region, Northeastern China

“…Land use changes and dams are two human-induced factors influencing sediment delivery to rivers. In decades, the importance of land use changes on the sediment flux in catchments has been well documented over the world (McIntyre, 1994;Olley & Wasson, 2003;Bakker et al, 2008;Chen et al, 2016;Stumpf et al, 2016), while the impacts of reservoirs, farm dams, flood-control ponds, water diversions and other water stores on sediment flux are less taken into account when the changed sediment delivery is explained by land use changes (Verstraeten & Prosser, 2008;Romero-Díaz et al, 2012;Licciardello et al, 2016). The main reason is that traditional field study does not allow simulating their respective contribution to sediment delivery.…”

On Landscape Patterns in Typical Mountainous Counties Middle Reaches of the Yangtze River in China

“…Across the study areas, evergreen and deciduous broadleaf mixed forests are the zonal vegetation, with dominant tree species such as Cinnamomum spp., Quercus spp., Schima spp., and Castanopsis spp. ( Figure 2 d–f) [ 3 , 57 ]. Thus, with this nature-based management strategy, local native broadleaf tree species should be introduced in the artificial coniferous plantations to form the broadleaf-dominant forests in this area.…”