function g = deltah1(q)
global m n rho mu grav
h0=15.0; beta=0; gamma=2000;
Di=[0,0.3,0.2,0.2,0.2,0.1,0.1,0.1];
L=[0,100,50,60,70,70,30,100];
eps=1e-5*ones(1,m);
for i=1:m
 if (i!=1) 
  u=q(i)/(pi*Di(i)*Di(i)/4);
  Re=u*Di(i)*rho/mu;
  ff=friction(Re,eps(i)/Di(i));
  g(i)=-ff*L(i)/Di(i)*abs(u)*u/(2*grav);
 else
  g(i)=h0-beta*q(i)-gamma*q(i)*q(i);
endif
endfor
endfunction