NGT seeks Centre’s response on change in Floodplain Rules

Why in News? 

The National Green Tribunal (NGT) has sought the Centre’s response to a petition challenging the River Ganga (Rejuvenation, Protection and Management) Authorities (Second Amendment) Order, 2026. 

The amendment removes the general description of the Ganga’s floodplains as a “construction-free zone” and introduces risk-based floodplain categories. The NGT has not stayed the amendment. 

What is a Floodplain?

A floodplain is the low-lying area adjoining a river that becomes inundated when water exceeds the channel’s carrying capacity. Floodplains:

• Temporarily store excess floodwater
• Recharge groundwater and maintain base flows
• Trap sediment and pollutants
• Sustain wetlands, fisheries and biodiversity; and
• Reduce downstream flood peaks.

Consequently, construction on floodplains converts a natural “sponge” into an impermeable surface, increasing flood damage and transferring risk downstream.

What has Changed?

The 2016 Order broadly defined the Ganga floodplain with reference to the one-in-100-year flood and described riverbanks and floodplains as construction-free zones.

The 2026 amendment introduces three categories:

• Active Floodplain: Area inundated by a flood corresponding to a one-in-five-year return period.
• Regulatory Zone: Area inundated by floods with return periods ranging from five to 25 years.
• Warning Zone: Area inundated by floods with return periods ranging from 25 to 100 years.

A “one-in-100-year flood” does not mean that it occurs only once every century; it signifies an approximately 1% probability of occurrence in any given year.

The specific prohibition on structures in the river, its banks, tributaries and active floodplain remains. However, the amended notification does not clearly specify the nature of construction restrictions in the newly created regulatory and warning zones, producing legal ambiguity. 

Arguments Supporting Graded Zoning: 

• Provides scientifically differentiated regulation according to the intensity and frequency of flood risk.
• Clarifies the previously undefined concept of an “active floodplain”.
• May be more enforceable than a blanket prohibition across a densely settled river basin.
• Enables essential infrastructure and existing settlements to be managed through flood-proofing and conditional permissions.
• Broadly follows the risk zonation approach used in flood management planning.

Major Concerns: 

• Dilution of protection: Restricting the active floodplain to the five-year flood line may expose the wider 100-year belt to construction pressures.
• Climate non-stationarity: Climate change and extreme rainfall are making historical flood-return periods less reliable.
• Discretionary approvals: Replacing a clear prohibition with conditional regulation can encourage regulatory capture and piecemeal encroachment.
• Cumulative impacts: Individual projects may appear safe while collectively reducing flood storage and groundwater recharge capacity.
• Conflict with precedent: In 2017, the NGT declared a 100-metre belt along the Ganga between Haridwar and Unnao a no-development zone. 
• Disaster-risk transfer: Construction creates long-term public liabilities through recurrent relief, compensation and protective infrastructure.
• Social justice: Floodplain residents, informal settlements and downstream communities often bear the consequences of development permitted elsewhere.

Legal and Governance Dimensions: 

• Floodplain protection is supported by Article 21, Articles 48A and 51A(g), the public-trust doctrine, precautionary principle and intergenerational equity. Under Section 20 of the NGT Act, the Tribunal must apply sustainable development, precaution and polluter pays principles.
• Governance remains fragmented because river conservation involves the NMCG and the Union government, while land use, local planning and floodplain zoning substantially depend on States and urban local bodies. The limited adoption of the Model Flood Plain Zoning Bill, 1975 illustrates this federal implementation gap.

Way Forward: 

• Publish scientific justification and invite public consultation before altering ecological safeguards.
• Use updated climate projections, satellite imagery and basin-wide hydrological modelling.
• Explicitly list prohibited, conditional and permissible activities in each zone.
• Prohibit housing, industries and permanent critical infrastructure in high-risk areas.
• Subject projects to cumulative-impact and disaster-risk assessments.
• Make floodplain maps legally binding and publicly accessible.
• Restore wetlands and compensate landowners through conservation easements or transferable development rights.
• Establish an independent, basin-level authority to coordinate Union, State and local agencies.

Graded floodplain zoning can improve risk-sensitive planning, but only if it strengthens rather than weakens the river’s right to space. Development must adapt to the Ganga’s natural hydrology instead of compelling the river to conform to construction boundaries.