Using the comprehensive governance degree to calibrate a piecewise sediment delivery ratio algorithm for dynamic sediment predictions: A case study in an ecological restoration watershed of northwest China

• Published in: Journal of hydrology (Amsterdam) Vol. 564; pp. 888 - 899
• Main Authors: Wu, Lei, Yao, Weiwei, Ma, Xiaoyi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2018
• Subjects: Comprehensive governance degree; Ecological restoration; Piecewise algorithm; Sediment delivery ratio; Sediment transport; Comprehensive governance degree; Ecological restoration; Sediment delivery ratio; Piecewise algorithm; Sediment transport
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2018.07.072

•A novel SDR algorithm was proposed to improve the accuracy of sediment predictions.•The algorithm had good reliability, few parameters, and high computation efficiency.•The annual SDR was less affected by rainfall erosivity but showed a decreasing trend.•The average SDR of 0.38 means the sediment was far less than erosion after governance. The sediment delivery ratio (SDR) is a bond of slope erosion and channel sediment transport but exhibits poor dynamic applicability, which makes it difficult to accurately identify the spatio-temporal evolutions of sediment yield in an ecological restoration watershed with different governance degrees. i) An innovative piecewise SDR algorithm considering the multi-stage effects of the comprehensive governance degree from 1991 to 2013 was embedded in a dynamic sediment yield model to solve the complex dynamic applicability problem of the SDR in sediment yield predictions. ii) The main advantages of the improved SDR algorithm over the existing models are small data requirements, dynamic mechanism, wide application range, reduced complexity, ease of use and better accuracy. iii) The erosion intensities of sloping farmland and orchards in the Yangou River watershed were both intensive at the early stage of governance in 1997. The trends in erosion and sediment yield were closely related to the watershed management measures. The soil erosion modulus in this watershed decreased from 5657 t/km2 in 1997 to 906.2 t/km2 in 2012, a total decrease rate of 84%. The sediment yield modulus decreased from 4500 t/km2 in 1997 to 51.9 t/km2 in 2012, a total reduction rate of 98.8%. iv) The annual dynamics of the SDR values were not completely affected by the random fluctuations in rainfall erosivity but showed an obvious decreasing trend from 0.932 in 1992 to 0.057 in 2012 due to the soil conservation measures. The annual average SDR in 1991–2013 was approximately 0.38, indicating that the average sediment yield after ecological restoration was significantly less than the average soil erosion in the Yangou River watershed. The results of this study may provide a better understanding of dynamic SDR studies and reveal the profound insights needed to guide watershed soil conservation planning.