One Dimensional Sediment Transport Model to Assess Channel Changes along Olteniţa-Călăraşi Reach of Danube River, Romania

Sediment budget of thelower part of theDanube River haschangedduringthelastdecades, mainlyduetotheconstruction of damsanddykes. The objective of thisstudyistoassessthe sediment budget andmorphologicalchangesalongOlteniţa - CălăraşiDanube River reach, withtheuse of a one dimensional hydraulicand sediment transport model. The river schematic networkwasextractedfrom a Digital Terrain Model, builtwithtopobathimetric data, using HEC-GeoRAS. The hydrodynamic model wasbuilt, calibratedandvalidatedwiththe 1D HEC-RAS software underunsteadyflowregime, withhydrologicand sediment data fromthe period 2008-2011 at thetwoupstreamanddownstreamgaugingstations. Measured sediment discharge data wereusedtocomputethesuspendedloadwithdifferent transport functions. The functionthatrepresentsthebest fit for theobservedvalues of suspendedload in 2008 wasusedto model thehydromorphologicalbehaviour of theriverreach for the period 2009-2011. Computed sediment dischargevalueswerefoundtofollowthetendency of previousdecades. The model wasalsousedtoassesspossiblechanges of thechannelbedbyaggradation or degradationalongthestudyreach, over theanalysed period.