We derive a Lagrangian based approach to study the compatible Hamiltonian
structure of the dispersionless KdV and supersymmetric KdV hierarchies and
claim that our treatment of the problem serves as a very useful supplement of
the so-called r-matrix method. We suggest specific ways to construct results
for conserved densities and Hamiltonian operators. The Lagrangian formulation,
via Noether's theorem, provides a method to make the relation between
symmetries and conserved quantities more precise. We have exploited this fact
to study the variational symmetries of the dispersionless KdV equation.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and
pplications) at http://www.emis.de/journals/SIGMA
