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Good practice Imported

Green Riyadh — Treated-Wastewater Urban Afforestation Without a Published Delivery Record

Saudi Arabia · Riyadh · See the Saudi Arabia profile · See the Riyadh profile

Evidence: Observational / pre–post Top 96% 20/100 · Ask Evidence Copilot about this practice

Riyadh's US$11bn programme targets 7.5m trees by 2030, irrigated by treated wastewater. No cumulative delivery figure has ever been published, and peer-reviewed Landsat studies found no vegetation gain and no cooling through 2022-23.

7.5 million
Target trees by 2030
US$11 billion
Programme investment
0.771% to 0.674%
Vegetation coverage change 1993-2023
56.73°C to 59.89°C
Mean summer land surface temperature rise (1993-2023)
Green Riyadh — Treated-Wastewater Urban Afforestation Without a Published Delivery Record

Details

Maturity
Scaling
Promoter
Royal Commission for Riyadh City (RCRC)
Period
2019-2030 (ongoing)
Keywords
urban greening, urban forestry, urban heat island, treated wastewater reuse, arid cities

Context

Green Riyadh, launched 2019 by the Royal Commission for Riyadh City, targets 7.5 million trees and about 9% green cover by 2030 at roughly US$11 billion, irrigated by treated wastewater.

Results

No cumulative delivery figure has ever been published. Peer-reviewed Landsat studies (Imam 2023; Miah et al. 2026) found no net vegetation gain and no cooling effect through 2022–23, and a 2025 peer-reviewed paper found current monitoring methods too imprecise to verify programme progress.

Implementation
Indicative cost
Very high (> €5M)
Time to results
Long (> 3 years)
Staffing & skills
Royal Commission for Riyadh City programme management, treated-wastewater distribution network contractors

Conditions for success

  • contracted and operating effluent-transmission pipeline sized to demand
  • species-appropriate, evapotranspiration-based irrigation management
  • published, verifiable cumulative planting records

Common failure modes

  • no cumulative delivery record ever published
  • peer-reviewed remote sensing found no measured greening or cooling through 2022-23
  • effluent pipeline lot not yet contracted years before the 2030 target

Commonly funded by

National / regional programmes

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Data sources

Where this practice's information was retrieved from, and when.

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