Evaluating the Effectiveness of Spatially Reconfiguring Erosion Hot Spots to Reduce Stream Sediment Load in an Upland Agricultural Catchment of South Korea

Abstract

Upland agricultural expansion and intensification cause soil erosion, which has a negative impact on the environment and socioeconomic factors by degrading the quality of both nutrient-rich surface soil and water. The Haean catchment is a well-known upland agricultural area in South Korea, which generates a large amount of sediment from its cropland. The transportation of nutrient-rich sediment to the stream adversely affects the water quality of the Han River watershed, which supports over twenty million people. In this paper, we suggest a spatially explicit mitigation method to reduce the amount of sediment yield to the stream of the catchment by converting soil erosion hot spots into forest. To evaluate the effectiveness of this reconfiguration, we estimated the sediment redistribution rate and assessed the soil erosion risk in the Haean catchment using the daily based Morgan–Morgan–Finney (DMMF) model. We found that dry crop fields located in the steep hill-slope suffer from severe soil erosion, and the rice paddy, orchard, and urban area, which are located in a comparatively lower and flatter area, suffer less from erosion. Although located in the steep hill-slope, the forest exhibits high sediment trapping capabilities in this model. When the erosion-prone crop lands were managed by sequentially reconfiguring their land use and land cover (LULC) to the forest from the area with the most severe erosion to the area with the least severe erosion, the result showed a strong reduction in sediment yield flowing to the stream. A change of 3% of the catchment’s crop lands of the catchment into forest reduced the sediment yield entering into the stream by approximately 10% and a change of 10% of crop lands potentially resulted in a sediment yield reduction by approximately 50%. According to these results, identifying erosion hot spots and managing them by reconfiguring their LULC is effective in reducing terrestrial sediment yield entering into the stream.

Impacts of Landscape Changes on Water Resources

“…The papers in this Special Issue describe the applications of a variety of observational and modeling tools and techniques to evaluate the impacts of landscape changes on water resources. The studies can be categorized into four subject areas: (1) impact assessment due to implementation of management practices [12][13][14][15], (2) impact of landscape on stream and soil temperature [16,17], (3) landscape and river meandering [18], and (4) landscape for flood inundation [19].…”

“…This Special Issue presents studies [12][13][14][15][16][17][18][19] that describe the application of a variety of observational and modeling tools and techniques to evaluate the impacts of landscape changes on water resources in watersheds. Landscape changes included change due to agricultural best management practices (BMPs), low impact development (LID) in urban settings, conservation agriculture practices, conversion of erosion hot spot cropland into forest, and others.…”

Combining Soil Erosion Modeling with Connectivity Analyses to Assess Lateral Fine Sediment Input into Agricultural Streams

“…Sediment delivery from agricultural landscapes to adjacent watercourses is highly dynamic in space and time, depending on various factors that determine lateral sediment connectivity in fluvial systems [21][22][23]. These include erosion, transport and deposition processes [24,25], weather events [26], artificial drainage pathways [27][28][29], land use type, spatial pattern of land use within a watershed, management practices, soil type, and slope [30][31][32][33][34].…”