The two peninsular rivers in India that flow through troughs are the Narmada River and the Tapti River. These rivers have carved out deep valleys or troughs in the land as they flow through the Indian peninsula. The Narmada River flows through a rift valley known as the Narmada Rift Valley. This rift valley was formed due to tectonic activity, resulting in the creation of a deep trench-like depression where the river flows. The Tapti River flows through the Tapti Valley, which is also a trough-like depression in the landscape. This valley was formed by a combination of geological processes, including faulting and erosion, which created the distinctive landscape through which the Tapti River flows. Both the Narmada and Tapti Rivers are important water bodies in the Indian subcontinent, contributing to the drainage and water resources of the region.