(2) Tapti Explanation: Tapti river empties into the Gulf of Cambay of the Arabian Sea, forming an estuary. It is fed by monsoon rains. The mean flow rate is about 600 cu m per sec, with the maximum in the summer. The Tapti is navigable by small craft for a distance of 50 km from the mouth. In some places it is used for irrigation. The seaport of Surat is located in the estuary. 45. (3) Deserts take up about one third (33%) of the Earth's land surface. Hot deserts usually have a large diurnal and seasonal temperature range, with high daytime temperatures, and low nighttime temperatures (due to extremely low humidity).