This Is AuburnElectronic Theses and Dissertations

Quantifying Flow and Sediment Yield of an Ungauged Catchment using a Combination of Continuous Soil Moisture Accounting and Event-based Curve Number Method




Tamang, Sagar

Type of Degree

Master's Thesis


Civil Engineering


A serious aggradation problem has been identified in the Soapstone branch, a tributary to Little Choctawhatchee River. A study of historical aerial imageries shows deforestation of the catchment by a significant amount in the period consistent with the first identification of the problem. The calculation of sediment yield from the catchment and its change during recent years require discharge data. However, due to the lack of any gauging stations and the difficulty of installing an area-velocity sensor to monitor discharge, parameter transfer for a hydrological model from a nearby donor catchment to the Soapstone branch was therefore investigated. However, due to the vast difference in the land cover composition of donor and soapstone branch catchment, event based curve number method was unfit for parameter transfer. Therefore, the soil moisture accounting, a continuous model available within HEC-HMS was used for the parameter transfer from a donor catchment after performing transfer validation process on an assumed ungauged receiver catchment. A continuous model of the Soapstone branch catchment was then built utilizing both transferred and locally developed parameters. This calibrated SMA model was used for calibrating locally developed curve number (CN) model of the catchment for a range of antecedent runoff conditions and for different years, i.e., 2011 and 2015. Calculations performed using calibrated CN model showed a significant amount of increase in sediment yield from 2011 to 2015. This study concluded that HEC-HMS SMA model can be effectively used for prediction in ungauged catchment using the spatial proximity approach. Also, a combination of the soil moisture accounting together with the event-based curve number method can be used for quantifying discharge and change in sediment yield of an ungauged catchment.