!	==================================================================================
!	 计算断面几何要素的子程序
!	==================================================================================
	subroutine sub_sect(	NRIVER				,&
							NSECT				,&
							MRIVER				,&
							KRC					,&
							NDATA				,&
							river               ,&
							Is					,&				
							Zs					,&
							ds					,&
							bd					,&
							zd					,&
							sm 					,&
							rough				,&
							Bs					,&
							As					,&
							Rs					,&
							Cs					)

	INTEGER::NRIVER
    INTEGER::NSECT
    INTEGER::MRIVER
    INTEGER::KRC
    INTEGER::NDATA

	integer River
    ! section
	REAL::ds(mriver,nriver),bd(nsect,nriver),zd(nsect,nriver),&
		sm(nsect,nriver), rough(nsect,nriver)
    ! BARC
	REAL::Bs,As,Rs,Cs

!    ----------------------------------------------------------------------------------
!    Bs、As、Rs、Cs——相应于水位Zs的断面要素（梯形断面）
!    ----------------------------------------------------------------------------------
	h=Zs-zd(Is,river)
	Bs=bd(Is,river)+2.0*sm(Is,river)*h
	As=(bd(Is,river)+sm(Is,river)*h)*h
	Sl=bd(Is,river)+2*h*sqrt(1+sm(Is,river)**2.0)
	Rs=As/Sl
	Cs=Rs**(1.0/6.0)/rough(Is,river)
	return
	end