Give a detailed account of Harappans' town planning and evaluate the various reasons for its decline.

Grid-Based City Layout and Standardized Bricks

Cities like Mohenjodaro and Dholavira featured precise grid systems with streets intersecting at right angles and uniform baked bricks, showing centralized planning and resource management that ensured durable, uniform construction.

Advanced Drainage and Water Systems

Covered drainage connected to houses and water harvesting techniques, including wells and reservoirs, ensured sanitation and reliable water supply, crucial for sustaining dense populations in the semi-arid Indus valley.

Zoning and Public Utilities

Urban areas were divided into citadels and lower towns, with specialized structures like the Great Bath and granaries indicating organized communal functions and surplus food storage.

Climatic Change

A weakening monsoon and drying of the Ghaggar-Hakra river system caused agricultural decline and water scarcity, undermining the economic base.

Ecological Degradation and Natural Disasters

Over-cultivation, deforestation and flooding (evidenced by silt layers and collapsed structures at Mohenjodaro) disrupted urban life and trade routes, while tectonic shifts altered river courses.

Economic and Sociopolitical Factors

Decline in trade with Mesopotamia and the loss of central authority led to the abandonment of core cities for smaller settlements, though evidence of invasion remains inconclusive.

Heritage Conservation and Urban Planning

Initiatives like Heritage Corridors1 under PRASHAD and Swadesh Darshan, along with urban schemes like AMRUT2, integrate Harappan sanitation and water management principles to promote sustainable urban development.