c=2;l=200;
modell={u'[z]==v[z], v'[z]== - c v[z] - u[z] (1 - u[z]),
u[0]==0.999, v[0]==-0.001};
loesung=NDSolve[modell,{u,v},{z,0,l}]; 
uu[z_]:=If[z>0,u[z]/.loesung[[1]],0.999];
abb=Plot3D[uu[x - c t],{x,0,100},{t,0,20},
PlotPoints->30,PlotRange->All,
ImageSize->{400,300},AxesLabel->{"x","t","w"}];