Preprints
https://doi.org/10.5194/hess-2021-225
https://doi.org/10.5194/hess-2021-225

  10 Jun 2021

10 Jun 2021

Review status: this preprint is currently under review for the journal HESS.

Evaluating and developing a model of specific degradation using geospatial analysis for sediment erosion management in South Korea

Woochul Kang1 and Pierre Y. Julien2 Woochul Kang and Pierre Y. Julien
  • 1Department of Land, Water and Environment Research. Korea Institute of Civil Engineering and Building Technology (KICT)., Goyang-si 10223, Gyeonggi-Do, Korea
  • 2Dept. of Civil and Env. Engineering, Colorado State Univ., Ft. Collins, CO 80523

Abstract. The South Korean Peninsula is subject to hydrological extremes, and 70 % of its terrain is mountainous, with sharp ridges and steep valley flanks. Recently, rapid urbanization has created an emerging demand for large-scale water resources, such as dams and reservoirs. Accordingly, complicated sediment-related problems have become an issue, with abundant soil loss during typhoons transported to the reservoirs, and downstream, riverbed degradation is caused by intercepting sediment. Thus, a reliable approach is required for predicting sediment yields of soil erosion and sedimentation. In this study, the specific degradation (SD) of 62 stream-river watersheds and 14 reservoir watersheds were calculated from field measurements of sediment concentration and deposition. Estimated SD ranged between 10 and 1,500 tons·km−2·yr−1. Furthermore, existing empirical models of sediment yield are insufficient for predicting specific degradation upstream of the reservoirs; therefore, a new model was developed based on multiple regression analysis and model tree data mining of 47 watersheds (~75 % national land cover). Accuracy of the developed model was enhanced with the following significant parameters: (1) drainage area, (2) mean annual precipitation, (3) percent urbanized area, (4) percent water, (5) percent wetland and water, (6) percent sand at effective soil depths of 0–10 cm, (7) slope of the hypsometric curve, and (8) watershed minimum elevation. Additionally, erosion maps from the revised universal soil loss equation (RUSLE) were generated to validate model variables and further understand the sediment regime in South Korea. The gross erosion results for 16 ungauged watersheds were used to validate the empirical model by comparing sediment delivery ratios of other references. The modeled meaningful parameters were examined via remote sensing analyses of satellite and aerial imagery and revealed the features affecting erosion and sedimentation with an erosion loss map at 5-m resolution. Vulnerable areas of soil loss, including construction sites, and croplands, as well as sedimentation features, such as wetlands and agricultural reservoirs, were highlighted.

Woochul Kang and Pierre Y. Julien

Status: open (until 05 Aug 2021)

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Woochul Kang and Pierre Y. Julien

Woochul Kang and Pierre Y. Julien

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Short summary
This study examined the specific sediment yield (SSY) of 62 stream-river watersheds and 14 reservoir watersheds. New models based on regression analysis and data mining were developed for predicting SSY, and 16 ungauged watersheds were used to evaluate the models. Also, erosion loss maps, satellite images, and aerial photos were used to represent the geospatial features affecting erosion and sedimentation. These methodologies could be helpful for erosion and sediment management.