简介:Amathematicalmodelforsimulatingmorphologicalchangesinspaceandtimeofthe124kmlongalluvialreachoftheKosiRiverbasedonthedataintheperiod1968-79isdeveloped.Equationsareobtainedtodescribethechangesofstreambedparameterssuchasminimumbedlevel,riverwidthandmaximumriverdepth.Fouriersineseriesareusedtofittherivercross-sectionsoverthestudiedreachfordifferentyears.Thegeneraltrendofastreamcross-sectioncanbemodeledsatisfactorilywiththeFouriersineseries.Temporalvariationsinbedlevelandwidthoftheriverhavetimeperiodsofabout7yearand3.2-4.3years,respectively,andarecontrolledbymeanannualdischargewithatimeperiodof13.9years.