The Global Centre for Risk and Innovation (GCRI)
Wetlands, rivers and lakes cover a small part of the Earth's surface yet hold a large share of its species, and freshwater species are consistently reported among the most threatened. These systems store floodwater, filter pollutants, recharge groundwater and hold large stocks of carbon in peat. This page sets out how watershed and wetland resilience is observed, how pressures propagate along river networks, and what the evidence means for the authorities that manage water and land.
Wetlands and freshwater · Wetland complex · Accounting year 3
| Water level regime | 0.6 | 0.5 | 1.0 |
| Native vegetation cover | 0.6 | 0.7 | 1.0 |
| Invasive species pressure | 0.5 | 0.5 | 0.0 |
| Connectivity | 0.3 | 0.4 | 1.0 |
Fig.Ecosystem condition account. Design wireframe with placeholder names and illustrative values, not a record or a live system.
Wetland loss is the drainage, conversion or degradation of marshes, swamps, peatlands, floodplains, lakes and rivers. These systems hold a large share of species for their area, store floodwater, filter pollutants, recharge groundwater and hold carbon in peat. Pressures travel along river networks, so what happens upstream shapes downstream habitats.
Mountain ranges, deserts, wetlands, glaciers and reefs, and how remote each division is from large cities, shown for Mozambique and Malawi as an example geography for this subject.
Watershed and wetland resilience. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Wetlands are drained for agriculture, settlement and infrastructure, and peatlands for plantations. Drained peat oxidises and subsides, releasing carbon and raising flood risk, and the loss is slow or impossible to reverse.
Dams, weirs and abstraction change the timing and volume of flow and block fish migration. Floodplains cut off from their rivers stop receiving the floods that sustain spawning grounds and wetland vegetation.
Nutrients, sediment, pesticides and untreated wastewater move through the river network. Excess nutrients drive algal blooms and oxygen loss in lakes, estuaries and coastal waters far from where they entered.
Healthy floodplains and wetlands absorb flood peaks and sustain dry-season flow. As they are lost, floods and droughts reach towns and farms faster and harder, and the cost moves to infrastructure owners, insurers and households.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Wetland | An area of marsh, fen, peatland or water, natural or artificial, permanent or temporary, including marine water up to six metres deep at low tide, in the Ramsar Convention's definition. |
| Ramsar site | A wetland designated as internationally important under the Ramsar Convention. |
| River connectivity | The degree to which water, sediment and organisms can move along and across a river system without barriers. |
| Peatland rewetting | Raising water levels in drained peat to stop carbon loss and restore wetland function. |
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Wetland Extent Trends index | index relative to a baseline | periodic | Compiled wetland area time series | ESTIMATED |
| Surface water extent | square kilometres | monthly | Optical and radar satellites | OBSERVED |
| River connectivity status | connectivity index per river reach | periodic | Barrier inventories on river networks | MODELLED |
| Environmental flow compliance | percent of months meeting the agreed regime | annual | Gauges against the agreed regime | OFFICIAL |
| Water bodies with good ambient quality | percent of assessed water bodies | periodic | National monitoring reported under SDG indicator 6.3.2 | OFFICIAL |
| Freshwater species extinction risk | count of species by Red List category per basin | per assessment | IUCN freshwater assessments | OFFICIAL |
| Drained and rewetted peatland | hectares | periodic | National inventories and satellite mapping | ESTIMATED |
| Lake chlorophyll-a | micrograms per litre | monthly | Sampling and satellite water-colour retrieval | OBSERVED |
The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.
Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| Ramsar Sites Information Service | Wetlands of international importance, their boundaries and reported changes | Public records, terms of use |
| JRC Global Surface Water | Surface-water occurrence, change and seasonality from Landsat | Free and open, attribution |
| HydroSHEDS, HydroATLAS and the Free-flowing Rivers dataset | River networks, catchment attributes and connectivity status | Free, attribution and terms |
| Freshwater Ecoregions of the World | A biogeographic frame for comparing freshwater assessments | Free, attribution |
| Global Peatland Database and Global Peatland Map | Peatland extent and status from national and remote sensing sources | Terms per dataset |
| GEMStat (UNEP GEMS/Water) | Water quality measurements from national monitoring programmes | Terms per data provider |
| Copernicus Land Monitoring Service lake products | Lake surface temperature and water quality from satellite | Free and open, attribution |
Biodiversity Nexus prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Ramsar administrative authorities and environment ministries | Whether a designated wetland's ecological character is changing and what response is required | Extent and condition trends against the site description, with driver evidence |
| River basin organisations and water regulators | What flow regime and barrier removal sustain fisheries and wetlands | Environmental flow compliance, connectivity status, species distributions |
| Land-use planners and agriculture agencies | Where drainage or conversion should be refused and where rewetting has most effect | Peatland and floodplain maps with their carbon and flood-storage function |
Freshwater ecologists and hydrologists share a set of core questions.
Freshwater ecosystems are organised by flow. The seasonal pattern of high and low water cues spawning and migration, moves sediment, and reconnects floodplains to rivers. Dams, abstraction and channelisation flatten and shift that pattern; levees cut floodplains off; drainage converts wetlands to farmland or development. Each change removes habitat and also changes how water moves through the landscape, often increasing flood peaks downstream and lowering dry-season flows.
Water quality is shaped by what enters from the land. Excess nutrients from fertiliser and wastewater can drive algal blooms and low-oxygen conditions; sediment from eroding land smothers riverbeds; chemicals accumulate in food webs. Because rivers concentrate the effects of everything upstream, the condition of a catchment, including its forests and wetlands, determines the risk faced by communities and infrastructure below it.
Gauges and models from hydrology and water science estimate flows and how wetlands modify them. Gauging networks are thin in many regions and models need local calibration.
Radar and optical imagery map open water and inundation over time. Vegetated and seasonal wetlands are often under-mapped.
Indicator invertebrates, fish surveys and environmental DNA reflect ecological condition. Methods and reference conditions vary between regions.
Grab samples and sensors measure nutrients and pollutants. Short events such as storm runoff are easily missed.
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.