30    std::unique_ptr<SimplifiedElasticityModel> simplified_elasticity =
 
   31        std::make_unique<RigidElasticityModel>();
 
   32    if (
auto const simplified_elasticity_switch =
 
   36        DBUG(
"Using simplified_elasticity for the Richards flow equation");
 
   37        if (*simplified_elasticity_switch == 
"uniaxial")
 
   39            DBUG(
"assuming local uniaxial deformation only.");
 
   40            simplified_elasticity = std::make_unique<UniaxialElasticityModel>();
 
   42        else if (*simplified_elasticity_switch == 
"hydrostatic")
 
   44            DBUG(
"assuming constant hydrostatic stress locally.");
 
   45            simplified_elasticity =
 
   46                std::make_unique<HydrostaticElasticityModel>();
 
   48        else if (*simplified_elasticity_switch == 
"user_defined")
 
   50            DBUG(
"using user defined elasticity model.");
 
   51            simplified_elasticity =
 
   52                std::make_unique<UserDefinedElasticityModel>();
 
   54        else if (*simplified_elasticity_switch == 
"rigid")
 
   56            DBUG(
"using user defined elasticity model.");
 
   57            simplified_elasticity = std::make_unique<RigidElasticityModel>();
 
   60    return simplified_elasticity;