| چکیده انگلیسی مقاله |
The Loess Hilly-Gully Region contains area showing the most severe soil and water loss in the world, however, gully land consolidation projects have been established in this region since 2010. Therefore, quantifying how these projects influence the erosional processes in the highly managed small watersheds remains an issue of general concern. For this reason, a scale mode was developed based on erosional dynamics and similarity theory for the purposes of simulating the evolution of erosional environment. Similarity scales were provided to include the similarities of geometry, rainfall, runoff, eroded sediment and pollutant transportation, which have rarely been addressed before. These scales were tested on the Kangjia watershed scale model, which has a 90% management coverage. Compared with the unmanaged conditions, significant influences on the production and confluence mechanisms were found. Not only was the amount of sediment and the discharge peak greatly reduced by 50%~90% but the peak propagation time order was also reversed. Further research showed that the critical land consolidation proportion value ranged between 0.85%~1% for the highly managed small watersheds. These results indicate not only that the production and confluence mechanisms of small watersheds under high-level management had changed greatly but also that a critical value exists at the scale of gully land consolidation projects. When the critical value was exceeded, erosion and sediment production obviously increased, which led to a decrease in the governing benefits. These findings are highly significant for land consolidation projects in highly managed watersheds under the condition of ensuring ecological security. |
