Mekong River Connectivity Assessment and Toolbox

In 2022, Confluvio worked with WWF-US and WWF-Greater Mekong to conduct an updated free-flowing rivers assessment of the Lower Mekong basin.

We updated and created a series of datasets with the help of regional experts and developed a toolbox for Geographic Information Systems (GIS) to facilitate the Free-Flowing Rivers assessment.

Our free-flowing river assessment engaged a variety of stakeholders into a discussion of the importance of free-flowing rivers and river connectivity, their benefit and their vulnerabilities to local pressures, such as fragmentation.

The results of this project included

• Updated GIS geodatabase, including existing data river networks and network metrics; hydrologic connectivity information and attribute information.
• River maps for the study area, including maps of underlying metrics (i.e., degree of fragmentation, degree of regulation, sediment loss, road and urban development,water abstraction from rivers, and connectivity status index).
• Free-flowing status report, including statistical analysis of extent of free-flowing rivers (number, length, connectivity to ocean)
• Free-Flowing Rivers toolbox: accessible tool for GIS users to replicate and adapt analysis both in Lower Mekong, or other basins.
• Tutorial documents, including website with video guidance

The results of this assessment were also translated to an online interactive tool to explore the results in detail. The Lower Mekong Free-flowing River Atlas App provides data layers summarizing the six individual pressure indices, as well as the combined indices, including the Connectivity Status Index (CSI), the Free-flowing River status (FFR) and the Dominant pressure factors (DOM).

The user can interact with the map interface by zooming and panning, by filtering layers based on their attributes, and by clicking on river reaches and dams to receive key statistics.

Free Flowing River Assessment (FRA)

A Free-flowing Rivers Assessment (FRA) is an assessment to determine the connectivity status of rivers by taking into consideration both natural connectivity as well as fragmentation from infrastructure, such as dams, roads, urban areas, and water use.

A FRA produces a variety of results to characterize the free-flowing status of a river system. The main result is the Connectivity Status Index (CSI), which represents how well river stretches are still connected in the lateral, and in the upstream and downstream direction. Additional information is created that classifies river reaches into three free-flowing categories (free-flowing, good connectivity, and impacted) and identifies the dominant pressure indicators impacting rivers.

The results of a FRA are focused on river connectivity and are intended to be combined and supplemented with additional data layers, such as species information, water quality or fluvio-geomorphological information to, for example, further assess and identify high-value conservation areas.

Methodology

The methodology for conducting a free-flowing River Analysis is described in Grill et al. (2019) and datasets and source code is provided for replicating the global assessment.

In order to facilitate similar assessment more rapidly and user-friendly, we developed a toolbox for Geographic Information Systems (GIS) based on the source code we previously created for conducting a free-flowing rivers analysis. The toolbox is created for use in ArcGIS to make a user friendly graphical user interface for conducting a free-flowing river analysis.

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In addition to the toolbox, four datasets are required to conduct a free-flowing river analysis that represent a river network, benchmark rivers, barrier locations, and lake locations.

The river network consists of linear features representing river reaches within the study area. Benchmark rivers represent rivers in the river network that have been determined to befree-flowing by an expert. The benchmark rivers dataset is used as a form of validation to assess whether the tool is producing realistic results in line with export opinion. The barrier dataset indicates the locations of barriers to water flow in the stream network.

Results

The results of the free-flowing river analysis toolbox produces results as maps and tabular data. The map outputs are created in an ArcMap document to intuitively display the results graphically. Layers created by the free-flowing rivers analysis toolbox display the connectivity status index, the barriers included in the analysis, the dominant pressure indicators impacting river reaches, the free-flowing rivers status, and benchmark rivers.

The tabular results provide a variety of statics and insights into the free-flowing rivers assessment. The statistics cover a variety of aspects of the analysis, including summary statistics about the river reaches included in the analysis, the dominant pressure indicators impacting river reaches, statistics on individual rivers such as free-flowing status and connectivity to the ocean, and a list of rivers classified as free-flowing.

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Workshops and Outcomes

To launch the tool and to disseminate the results of the FFR analysis for the Mekong Region, Confluvio participated in a Regional Joint Workshop termed 'Rivers of the Lower Mekong Region', supported and organized by USAID, Stockholm Environment Institute, World Wildlife Fund for Nature (WWF), and the Asian Disaster Preparedness Center (ADPC).

The goal of this workshop was to bring together stakeholders from across the region to build knowledge and technical capacities, aid the development of new networks and partnerships that support the sustainable development and use of the rivers, and support the inclusion of those most impacted and least consulted when it comes to the development of the Lower Mekong Region.

Topics covered include learning about the importance of river connectivity and its threats, tools that can be used for river planning, guidance to address governance and transparency issues, and potential entry points for inclusion in decision-making and advocacy efforts for CSOs, INGOs, and research institutions.

At the workshop we introduced the free-flowing rivers Initiative, provided an overview of the methodology, and conducted a technical session to introduce our Toolbox for Geographic Information Systems (GIS).