Which of the following Harappan sites is known for a unique water harnessing system and storm-water drainage?

The correct answer is Dholavira.

Step-by-Step Explanation:

1. Overview of Dholavira:
Dholavira is an ancient Harappan (Indus Valley Civilization) site located on Khadir Bet island in the Rann of Kutch, Gujarat, India. It is one of the five largest Harappan sites and is renowned for its remarkable urban planning and sophisticated engineering.

2. Unique Water Harnessing System and Drainage:
Unlike many other Indus Valley sites located along major perennial rivers, Dholavira was situated in an arid region with scarce rainfall. To adapt to this harsh environment, Harappan engineers built an extraordinary water management system:
- A series of massive reservoirs excavated out of living rock were constructed around the city to harvest rainwater.
- Sophisticated dams were built across seasonal streams (Manhar and Mansar) to divert water into these storage reservoirs.
- An intricate, city-wide underground storm-water drainage network was created to collect surface runoff and channel it efficiently into the reservoirs, preventing flooding while ensuring a reliable supply of fresh water throughout the year.

3. Analysis of Other Options:
- Lothal: Famous for its artificial brick dockyard and maritime trade.
- Kalibangan: Famous for its ploughed agricultural field evidence and fire altars.
- Banawali: Known for evidence of barley grains and high-quality terracotta models of ploughs.

Hence, Dholavira is uniquely recognized for its sophisticated water harnessing system and storm-water drainage.