Quantification of river bank erosion by RTK GPS monitoring: case studies along the Ningxia-Inner Mongolia reaches of the Yellow River, China

The Ningxia-Inner Mongolia reaches of the Yellow River suffer from bank erosion problems; in order to identify the bank erosion dynamics, Real Time Kinematic Global Positioning System (RTK GPS) was applied to monitor bank morphology at three sites: Taole Cropland (TC), Maobula Shrubland (MS), and Maobula Cropland (MC). The measured data were analyzed using the Geographical Information System (GIS) to quantify the volume and amount of bank erosion. To verify the feasibility of other means quantifying bank erosion including remote sensing image interpretation and Bank-Stability and Toe-Erosion Model (BSTEM) simulation, their results were compared with the directly monitored results by RTK GPS. Results show that the bank erosion moduli at the TC, MS, and MC sites are 12,762, 6681 and 44,142 t km^-1 a^-1 respectively based on RTK GPS measurements from 2011 to 2014, with the bank erosion amount varying between flood and non-flood seasons and among different years. The bank erosion quantified by remote sensing interpretation and BSTEM simulation agreed well with results from RTK GPS measurement. The main factors that influence bank erosion on the upper reaches of the Yellow River include land use in the bank area, bank height, and bank curvature. More rational land use along the Yellow River and stabilization of the river bank are required for this area. This study shows that RTK GPS monitoring is reliable and useful for bank erosion research, which has not yet been fully exploited. There is potential of applying remote sensing and model simulation to determine bank erosion of large rivers, while they should be combined and supported by field investigated data.