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Good practice Imported

That Luang Marsh — Vientiane's flood-buffering urban wetland under development pressure

Laos · Vientiane · See the Laos profile · See the Vientiane profile

Evidence: Observational / pre–post Top 76% 33/100 · Ask Evidence Copilot about this practice

Vientiane's That Luang Marsh, part of a ~2,000ha wetland system draining the capital, removes an est. 117±13 t of nitrogen and 3.9±0.8 t of phosphorus a year and generates ~US$5m/yr in flood-buffer and livelihood value — even as a 365ha SEZ converts part of it.

2,000 hectares
Combined wetland system area
5 US$ million (just under)
Estimated annual economic value
40 %
Direct-use benefits share of total value
117±13 megagrams/year
Nitrogen removed per year (2023)
3.9±0.8 megagrams/year
Phosphorus removed per year (2023)
365 hectares
Special Economic Zone carved from marsh

Details

Promoter
National University of Laos & WWF Lao PDR (wetland valuation and monitoring)
Period
2004–2023 (valuation study 2004; hydrology study 2023)
Keywords
urban wetlands, flood mitigation, water quality, nutrient retention, urban planning

Context

Vientiane sits in a shallow basin; the That Luang Marsh and neighbouring wetlands (roughly 2,000 hectares combined) intercept stormwater and wastewater from the city before it reaches the Mekong, acting as the capital's main natural flood buffer while also supporting fishing, rice and vegetable-growing livelihoods for surrounding communities.

Results

A wetland ecosystem valuation cited in a UN Convention on Biological Diversity/TEEB case study put the marsh's annual economic value at just under US$5 million, with direct-use benefits such as fish and water spinach accounting for around 40% of that total, and a 2023 peer-reviewed hydrology study in the journal Water (MDPI) measured the marsh removing on the order of 117±13 megagrams of nitrogen and 3.9±0.8 megagrams of phosphorus per year from water passing through it, while linking encroaching urban land use in the catchment to declining purification capacity.

Conclusions

The marsh is also a cautionary case: a 365-hectare stretch of it was carved out and designated the That Luang Lake Special Economic Zone for real-estate development, and UN reporting on Laos has framed the site as 'the paradox of urban development' — the wetland's documented flood-control and livelihood value has not stopped incremental infill and land conversion.

Implementation
Indicative cost
Low (< €50k) — No investment or management cost is reported; sources document ecosystem valuation and monitoring, not programme spending.
Time to results
Long (> 3 years) — Valuation study (2004) and hydrology study (2023) span roughly two decades of documentation of a wetland under continuing development pressure.
Staffing & skills
National University of Laos research team, WWF Lao PDR monitoring partners

Conditions for success

  • Legal protection of wetland boundaries against incremental land conversion
  • Continued hydrological and nutrient-removal monitoring to track purification capacity as the catchment urbanises

Common failure modes

  • A 365-hectare stretch of the marsh has already been converted into a Special Economic Zone despite its documented flood-control and livelihood value
  • Encroaching urban land use in the catchment is linked to declining purification capacity

Where it fits

Governance type
national/municipal land-use authorities with academic and NGO monitoring
Scale
city-wide wetland system (~2,000 ha)
Income level
lower-middle-income

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Data sources

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