Land-use-mediated inconsistency of changes in the provision and delivery of soil erosion control services at the watershed scale.

Soil erosion control services (SECSs) are the benefits delivered to people derived from preventing the negative impacts of soil erosion, such as avoiding the loss in soil productivity and preventing the damage to infrastructures such as dams and roads. SECS is derived from the functions of the ecosystems and is delivered to people through physical processes and social activities. The land-use change (LUC) reshapes the SECSs supply capacity, the SECS flow over the landscape, and the related benefit people received. Numerous studies have revealed how LUC shapes the SECSs supply capacity. However, the SECSs flow to local communities, and the LUC-derived SECS flow dynamics remain unclear. This study quantified the SECSs delivered to local communities following a land-use-specific cascade mechanism and using the WATEM/SEDEM framework. The effects of on-site soil erosion and sediment delivery over the watershed were combined. The cultivated lands were considered as the conveyers of SECSs. The study revealed the inconsistency of temporal change in SECS provision and the actual SECSs delivery to local communities. The results illustrated the increased capacity for soil erosion prevention and sediment flow reduction and a consequent increase in SECS supply capacity. However, the total amount of actual SECSs delivered to the local communities was declined due to the land-use change featured in reduced cropland area. The results imply that changes in SECS provision capacity cannot directly indicate the changes in SECS delivery to local communities. Though the modeled SECSs did not cover all SECSs in this region, this study highlights the effectiveness of the land-use-specific cascade framework in describing the delivery of SECSs and the importance of addressing the delivery processes of ecosystem services from ecosystem to people.

Risk to residents, infrastructure, and water bodies from flash floods and sediment transport.

Intense rainfall-runoff events and subsequent soil erosion can cause serious damage to the infrastructure in residential areas in Europe countries and all over the world. In the Czech Republic, the Ministry of the Interior has supported an analysis dealing with the risks to residents, infrastructure, and water bodies from flash floods and sediment transport. A total of more than 150,000 risk points were identified by GIS morphology and land-use analysis. The threat, the vulnerability, and the resulting risk category were determined for each of these points. The WaTEM/SEDEM model was used to assess the threat with 10-m data resolution. The summarized vulnerability of real objects on individual runoff trajectories was combined with the threat of sediment transport, resulting in the overall risk represented by a 5-degree scale, from lowest (1) to highest (5). The output of the project lies stored in the WEB application. Nineteen percent of the sites in the Czech Republic, i.e., more than 23,000 sites, have been assigned to categories 4 and 5, with a high level of risk. Thirty-four percent of cadastral units are classified as the high risky (4416 cadasters, with a total area 24,707 km2). Approximately 30% of the population of the Czech Republic lives in high-risk cadastral areas. Four scenarios of protection were modeled. To reduce the high-risk and very high-risk sites (categories 4 and 5), the most effective solution is the implementation of technical measures or conversion to grassland within the contributing watersheds. This could reduce the number of high-risk sites from 23,400 to 3700.Methods of sediment transport modeling and risk evaluation, based on presented USLE input data and documented WaTEM/SEDEM model, can be used worldwide. Especially in post-soviet union countries with shared arable land development and erosion consequences.

Functions of traditional ponds in altering sediment budgets in the hilly area of the Three Gorges Reservoir, China.

The landscape pattern will affect the sediment transport process. The cluster of ponds is a common landscape, which has traditionally been used for irrigation in the hilly area of the Three Gorges Reservoir (TGR). However, little is known about how the landscape elements temporally changed over the past decades and if the ponds can be applied to function in balancing watershed sediments against soil erosion. The Jinglingxi watershed, covering 20.5 km2, was selected as the study area. The changes in pond number, surface area, and drainage catchment were analyzed with aid of high-resolution typographical map and unmanned aerial vehicles imagery. The spatial WaTEM/SEDEM model was developed to simulate watershed soil erosion and sediment deposition under the absence and presence of water bodies scenarios. Results from different simulation scenarios were compared and revealed the trapping effects of the multi-pond system. From 1983 to 2016, the number and total area of ponds roughly doubled. The density reached 30 ponds/km2. From 1983 to 2016, the total drainage area of ponds increased from 13.22% to 35.4% of the whole watershed. The sediments deposited at the bottom of ponds can indicate the past specific sediment yield (SSY) in drainage catchments. Our results suggest that the multi-pond system not only reduce watershed sediment export but also alter the sediment deposition in different land uses. The reduced sediments export is expected to prolong the service life of downstream reservoirs at the expectancy of ponds' storage capacities. The ecological compensation from downstream reservoirs' revenues to upstream regions should be established to drive dredging actions for the upstream ponds.