Why In News?

Authorities initiated a comprehensive rejuvenation project across eight grama panchayats in Kerala's Kasaragod district to restore traditional underground water tunnels known as Surangams. 

What is Surangams?

Surangams (also known as surangas, thurangams, or thorappu) are traditional, gravity-fed underground water harvesting structures.

●        Prominent in the Kasaragod district of Kerala and parts of Dakshina Kannada in Karnataka, as well as parts of the Western Ghats.

●        Structure: Hand-dug horizontal tunnels (or tunnel wells) excavated into porous laterite hillocks.

●        Function: They intercept natural groundwater seepage and channel it outward via gravity into a storage pit, open tank, or dug well without using electric pumps or motors.

●        Placement: They are cut just above the impermeable lithomarge clay layer inside lateritic formations. 

●        Length: Varies widely from 3 meters to 300 meters (some extend further depending on the aquifer).

●        Layouts: Can be a single straight tunnel, criss-cross networks, or diversion tunnels. Air shafts are built into longer tunnels to maintain atmospheric pressure. 

●        Origins

○        Global Analogues: Closely resemble the Qanat system of Persia (Iran/Mesopotamia) and Afghanistan’s Karez system.

○        Spread: Historians suggest similar underground gravity tunnel concepts traveled via ancient trade routes. 

Advantages

●        Recharge: Monsoon rainwater infiltrates the sponge-like laterite hills, recharging underground reserves that steadily feed the surangam through the dry summer months. 

●        Zero Energy Cost: Operates purely via natural gravity percolation (no electricity or fossil fuels required).

●        Eco-Friendly & Low-Cost: Minimal disturbance to surface ecology compared to deep borewells or large dams.

●        Community Resilience: Empowers local traditional artisans and rural communities with decentralized water security during dry spells.

Source: THEHINDU