India, Nov. 3 -- In the drought-scorched heart of Karnataka's Kolar district, residents of Keeluholali village once lived at the mercy of unreliable rains. Year after year, they watched crops wither and wells run dry as borewells sank ever deeper. "Farming had become a gamble," says Ganesh K V, a smallholder who once ferried buckets of water on his motorcycle just to keep his four coconut saplings alive.

In 2014, determined to change their fate, residents pooled their labour under the Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGS) to build a check dam that would capture rainwater. It was meant to provide irrigation through the dry months, but the plan failed. The structure could not hold the water, which simply seepe...