The equatorial atmosphere harbours a large spectrum of waves that are trapped near and travel along the equator. These equatorially trapped waves interact nonlinearly with each other, with the extra-tropics and with the planetary-barotropic waves. Here, we consider advected shallow water equations that represent interactions of these equatorial waves, associated with the first baroclinic mode, with prescribed meridional-barotropic shears. We present three well-known numerical schemes for handling this system and discuss the risk of applying them crudely to equatorial waves. We study the properties of these waves, such as their phase speed and their trapping around the equator, using two approaches: linear analysis and the time evolutions of the system derived by meridional projection of the barotropic-first baroclinic system. We show that in the sheared environment the symmetric (anti-symmetric) equatorial waves excite other symmetric (anti-symmetric) equatorial waves of the same wavenumber and of different strengths.