Kautilya's Arthashastra 4.3.7

4.3.7

kāṣṭhaveṇunāvaś copagṛhṇīyuḥ //

Villagers living on the banks of rivers shall, during the rainy reason, remove themselves to upcountries. They shall provide themselves with wooden planks, bamboos, and boats. They shall, by means of bottle-gourds, canoes, trunks of trees, or boats rescue persons that are being carried off by floods. Persons neglecting rescue with the exception of those who have no boats, etc., shall be fined 12 panas. On new and full-moon days shall rivers be worshipped. Experts in sacred magic and mysticism (máyáyogavidah), and persons learned in the Vedas, shall perform, incantations against rain.