Titan is the only body, beside the Earth, where liquid is present on the surface in the form of lakes and rivers. Moreover, observations reveal that the shorelines of some lakes have retreated by several kilometers. It means that there exist conditions necessary for evaporites formation. In fact, Cassini observations suggest the existence of organic evaporites deposits. One subject of the paper is thermal convection in regolith covered with evaporite deposits. The next subject is the convection below bed of a lake or a river. Some difference of convection in these cases are found, e.g. different convective pattern. The difference of pattern of convection in regolith could lead to different convection patterns in the lake which could be observable. The last subject is the interaction of flow with grains of sediments. It is indicated that the convection in regolith could trigger saltation or motion of sediments at the bedload.