Town planning, architecture and water management

Detail

Citadel-Lower Town layout

• Standard bipartite plan: smaller, higher Citadel (western, mud-brick platforms, walled) + larger, lower Lower Town (eastern, also walled).
• Dholavira: unique three-part division (Citadel, Middle Town, Lower Town), stone used extensively in foundations (unlike baked brick elsewhere). Entire settlement fortified with additional internal walls dividing sectors. UNESCO inscribed (2021) recognises Dholavira for "multifaceted achievements in urban planning, construction techniques, water management, social governance" [2].
• Lothal: entirely fortified, but Citadel not separately walled off — only raised on a platform, distinguishing it from Mohenjo-daro/Harappa pattern.

Planning-first evidence

• Platforms preceded construction: houses/structures built only atop pre-raised mud-brick platforms.
• Estimated 4 million person-days of labour for foundation-platform construction alone at Mohenjo-daro — indicates centralised labour mobilisation/planning authority.
• Streets laid on grid pattern, intersecting at right angles; sequence was streets/drains first, house construction after — drainage channels predate habitation, not retrofitted.

Standardised bricks

• Uniform ratio 4:2:1 (length:breadth:height), sun-dried or kiln-baked.
• Standardisation held across the entire geographic spread — Jammu to Gujarat — evidencing shared technical/administrative norms without a single identifiable political centre.

Domestic architecture

• Courtyard-centric plan, rooms arranged around central courtyard.
• Privacy-oriented design: no windows facing the street at ground level; entrances angled so passersby cannot see into the courtyard.
• Individual brick-paved bathrooms with drains connecting to street drains.
• Staircases indicate second storeys or roof access.
• Wells within houses — Mohenjo-daro alone had roughly 700 wells, among the earliest evidence of dedicated water-supply infrastructure at this density.

Drainage system

• Nearly every house connected to street drainage.
• Main channels: brick-set-in-mortar, covered with removable bricks (sometimes limestone slabs) for cleaning access.
• Flow path: house drain → sump/cesspit (to trap solid waste) → street drain; sumps positioned at intervals along long channels.
• Mackay's assessment: "the most complete ancient system as yet discovered."
• Present even at smaller settlements — Lothal had mud-brick houses combined with burnt-brick drains, showing the drainage standard was not reserved for major cities.

Citadel structures at Mohenjo-daro

• Warehouse: brick lower portion survives; wooden superstructure decayed and lost.
• Great Bath: rectangular tank, ~12 × 7 m, corridors on all four sides, staircases from north and south. Made watertight with bricks-on-edge and gypsum mortar; bitumen layer also used along tank sides to prevent seepage [2]. Rooms on three sides, one housing a large well (likely the Bath's water source) [2]. Outflow connects to a large corbelled drain [2]. Adjacent block of eight bathrooms opens onto a lane.
• Interpretation: ritual/special bath, not a public utility bath — inferred from its uniqueness and Citadel location; ordinary bathing needs were served by individual house bathrooms.
• Dated to the mature Harappan phase (3rd millennium BCE) [2].

Water harvesting and management

• Dholavira: at least six large reservoirs, stone-built or rock-cut, interconnected via underground drains; largest reservoir ~73 m long. Reservoirs fed by two seasonal streams channelled into the walled city, plus wells, tanks and a dam — a comprehensive system built to survive an arid, water-scarce island environment [2][3].
• Wells widespread at Mohenjo-daro.
• Possible canal irrigation attested only at Shortughai (Afghanistan) — no confirmed canal evidence within the Indian core zone.
• Reservoirs interpreted as also serving agricultural water storage needs.

Note: scaffold states reservoirs are "stone or rock-cut"; UNESCO documentation additionally describes wells, tanks, drains, and a dam as part of the same integrated system at Dholavira — this extends rather than contradicts the scaffold [2][3].

Prelims Hooks

• Mohenjo-daro Great Bath dimensions: ~12 m × 7 m; waterproofed with gypsum mortar + bitumen.
• Brick ratio standard across Harappan sites: 4:2:1 (length:breadth:height).
• Only Dholavira had a three-part town division (Citadel, Middle Town, Lower Town).
• Lothal's Citadel was raised but not separately walled — exception to standard Citadel-Lower Town model.
• Mohenjo-daro had ~700 wells.
• Dholavira: minimum six reservoirs; largest ~73 m long; UNESCO World Heritage Site (inscribed 2021).
• Foundation platforms at Mohenjo-daro alone required ~4 million person-days of labour.
• Only confirmed possible Harappan canal irrigation site: Shortughai (Afghanistan).
• Mackay described Harappan drainage as most complete ancient system known.
• Great Bath had rooms on three sides, one with a large well; adjoining block of eight bathrooms.

Mains Points

• Scale of platform labour (4 million person-days) and cross-regional brick standardisation imply strong centralised planning/authority despite absence of identifiable palaces or kings — key debate on nature of Harappan political organisation.
• Water management variability (Dholavira's reservoir-dam system vs Mohenjo-daro's well-drainage model) shows adaptive engineering responding to local ecology (arid island vs riverine plain) — usable for GS-I "civilisation and environment" linkage.
• Uniform private sanitation (individual bathrooms/wells) alongside a singular ritual Great Bath suggests social values placed on cleanliness/ritual purity distinct from public monumental religion — contrast with contemporary Mesopotamian temple-centric urbanism.
• Drainage-before-housing sequencing is central evidence against theories of unplanned organic urban growth, supporting the "planned city" thesis over "gradual accretion" thesis.