Inorganic town-planning, ill-managed drains and loss of lakes are among the unsustainable implications of rampant urbanization. Consequently, urban flooding has since then always posed an impending threat to the life-forms, their lifestyle and habitat. With the advent of climate change, the pattern and intensity of urban flash floods have since then only become more frequent and unpredictable. Under a Smart City concept, this environmental issue has since then opened avenues for monitoring the same with IoT based technologies as part of surveillance systems under the ambit of Disaster Mitigation and Management. Further introduction of this system into a traditional city, with site-specific amendments would be the way forward. In the present study, an earnest effort was undertaken to design and develop a low-cost simple and effective AI based prototype which would serve as an early-warning system to strengthen emergency response preparedness for even a non-smart city, in the event of any flash floods. The basic components of the fabricated prototype developed in this study encompasses hollow corrosion-resistant concentric cylinders weighing 2 kg with a white-painted stainless-steel frame, an ultrasonic sensor ranging module HC-SR04 for data acquisition, Arduino UNO microcontroller, camera for remote visual monitoring, filter-mesh to facilitate easy screening of any air-laden suspended impurities, and tapered funnel inlet etc. The real-time output (rainfall intensity, herewith expressed as mm/sec) is steadily received as an excel-file attachment viz. email to designated addressee for continuous monitoring towards any probable rapid influx. Statistical validation of the prototype under real-time and laboratory conditions was successfully accomplished using the Parametric ‘t-test’. It was found there existed no significant difference between the population means, therewith confirming the reliability of the device. Upon Commissioning at designated observatories, the functional prototype would serve to safeguard all life-forms and be most sought for applications by Disaster Monitoring Centre’s and Town Planning Authorities.