Real-time prediction of the peak suspended sediment concentration and sediment yield of the Lao-Nung River during storms

摘要

Based on rainfall erosion of soil and suspended sediment transport in storm events,a method is proposed to predict peak suspended sediment concentration and suspended sediment yield in watersheds based on rainfall characteristics prior to peak rainfall intensity.The rainfall characteristics factors that dominate peak suspended sediment concentration C_p are rainfall erosion factor R_(ef), first peak rainfall intensity of area-average rainfall i_(p1) and antecedent precipitation index I_(ap);the rainfall characteristics factors that dominate suspended sediment yield Y_(ss) in storm events are total rainfall P,suspended sediment yield factor R_(sf) and antecedent precipitation index I_(ap).This research focuses on watersheds in Liau-Kwei observation station along Lao-Nung River in southern Taiwan as the research object,and adopts the PSED-model to simulate the discharge hydrograph, suspended sediment concentration hydrograph and suspended sediment yield in 11 storm events for analysis.The analytical results show that there is a good correlation between the above-mentioned rainfall characteristics factors and C_P as well as Y_(ss),thus enabling C_p and Y_(ss) to be predicted by using Expressions(13) and(14).These two expressions are utilized to predict C_P and Y_(ss) of Typhoon Morakot in 2009,and the results are compared with those from simulation by using the PSED-model.The result of comparison shows there is a good capability in predicting.For the watersheds where it is necessary to predict C_P and Y_(ss) of a storm event for the benefit of effective operation of water resource facilities,the aforesaid rainfall characteristics factors can be utilized to establish applicable models for prediction.