Transboundary Water Systems: Crosscutting Status and Trends


The Global Environment Facility (GEF) approved a Full Size Project (FSP), “A Transboundary Waters Assessment Programme: Aquifers, Lake/Reservoir Basins, River Basins, Large Marine Ecosystems, and Open Ocean to catalyze sound environmental management”, in December 2012, following the completion of the Medium Size Project (MSP) “Development of the Methodology and Arrangements for the GEF Transboundary Waters Assessment Programme” in 2011. The TWAP FSP started in 2013, focusing on two major objectives:

(1) to carry out the first global-scale assessment of transboundary water systems that will assist the GEF and other international organizations to improve the setting of priorities for funding; and

(2) to formalise the partnership with key institutions to ensure that transboundary considerations are incorporated in regular assessment programmes to provide continuing insights on the status and trends of transboundary water systems.

The TWAP FSP was implemented by UNEP as Implementing Agency, UNEP’s Division of Early Warning and Assessment (DEWA) as Executing Agency, and the following lead agencies for each of the water system categories: the International Hydrological Programme (IHP) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) for transboundary aquifers including groundwater systems in small island developing states (SIDS); the International Lake Environment Committee Foundation (ILEC) for lake and reservoir basins; the UNEP-DHI Partnership – Centre on Water and Environment (UNEP-DHI) for river basins; and the Intergovernmental Oceanographic Commission (IOC) of UNESCO for large marine ecosystems (LMEs) and the open ocean.

The five water-category specific assessments cover 199 transboundary aquifers and groundwater systems in 43 small island developing states, 204 transboundary lakes and reservoirs, 286 transboundary river basins; 66 large marine ecosystems; and the open ocean, a total of 756 international water systems. The assessment results are organized into five technical reports and a sixth volume that provides a cross-category analysis of status and trends:

Volume 1 – Transboundary Aquifers and Groundwater Systems of Small Island Developing States: Status and Trends

Volume 2 – Transboundary Lakes and Reservoirs: Status and Trends

Volume 3 – Transboundary River Basins: Status and Trends

Volume 4 – Large Marine Ecosystems: Status and Trends

Volume 5 – The Open Ocean: Status and Trends

Volume 6 – Transboundary Water Systems: Crosscutting Status and Trends A Summary for Policy Makers accompanies each volume.

Volume 6 presents a unique and first global overview of the contemporary risks that threaten international water systems in five transboundary water system categories, building on the detailed quantitative indicator-based assessment conducted for each water category. The report is a collaboration of the five independent water-category based TWAP Assessment Teams under the leadership of the Cross-cutting Analysis Working Group, with support from the TWAP Project Coordinating Unit

Key messages

This novel assessment provides a first indicator-based look at the broad global patterns of risk to transboundary water systems and dependent human populations across the five water system categories – Aquifers, Lakes & Reservoirs, River Basins, Large Marine Ecosystems (LMEs) and the Open Ocean. Key directional indicators (indicating good to bad ecosystem states), addressing thematic (i.e. biophysical, socioeconomic and governance) conditions of transboundary waters, are chosen from each of the five water system category-based assessments, and are used to show broad patterns of relative risk.

Risk is defined as the likelihood of failure to sustain the ecosystem services that transboundary waters provide for planetary and human wellbeing. It is assessed at five color-coded risk levels from highest risk (red) to lowest risk (blue) using individual indicators and their averages. The results are geographically organized to allow for comparisons of risk across water system categories and themes in 14 regions of the world. The 14 regions are based on the UN sub-continental regions, with the smaller areas like Northern, Southern and Western Europe being grouped together as a region, to optimize the regional aggregation and comparison of transboundary water systems. The Transboundary Waters Assessment Programme (TWAP) crosscutting analysis covers 89% of the global total of currently identified transboundary aquifer surface area and 87% of transboundary lake surface area for 204 lakes considered in the assessment. For transboundary river basins, LMEs and the Open Ocean, spatial coverage is 100%

. • Risk is generally lower in developed regions (Australia, North America and Europe) and higher in SubSaharan Africa and South and South East Asia. However, there are high and low risk systems in all regions, indicating the need for attention to transboundary water systems across the planet.

• Risk appears spread across the three thematic areas - biophysical, socioeconomic, governance - and signifies the need for policy and management interventions to address the integrated nature of risk in order to effectively sustain ecosystem health and human wellbeing.

• There is a tendency for risk to increase ‘downstream’ from aquifers and river basins to LMEs, with the exception of transboundary governance arrangements for aquifers, which are largely absent.

• The assessment of governance arrangements and architecture is a novel aspect of this assessment, but does not yet reflect how effective the governance responses are in sustaining ecosystem health and human wellbeing. Subsequent assessments should focus on measuring effectiveness.

• Spatial data coverage for transboundary aquifers and lakes should be improved. Across all five transboundary water categories, there is a serious need for long-term time-series data, including those that quantify and track rates and magnitudes of linkages between water systems, for transboundary management to become effective.

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