2. Assessment Procedure and Indicators

2-1 Assessment Procedure

It is extremely challenging to pursue a global-scale assessment of threats facing transboundary lake basins for the purpose of prioritizing potential management interventions at the international level. Such assessments would be substantially influenced by their widely differing locations and associated environmental conditions, varying lake volumes and basin surface areas, complex riparian situations, and other characteristics. In addition, because of the highly skewed nature of the available data, a range of assumptions and improvisations were introduced to address the above limitations and uncertainties, which included identification of transboundary lakes, delineation of their drainage basins, adoption of an academically-proven threat assessment methodology, access to various existing lake basin databases, development of a lake basin scenario analysis program, convening of regional expert group meetings, a lake basin questionnaire specifically designed for the purposes of the TWAP analysis, and reference to the knowledge mining capability of a specially-developed knowledgebase mining system (LAKES-III: see “5. Management Intervention Possibilities and Challenges” for details). The assessment framework ultimately developed consisted of: (1) Data Preparation and Refinement; (2) Scenario Development and Assessment; and (3) Parametric Sensitivity Analysis and Interpretation, as shown below.

Methodological Flow for Assessment of Alternative Lake Prioritization Scenarios

2-2 Assessment Indicators

Because of a scarcity of uniform data for the transboundary study lakes, it was not possible to evaluate the threats to the lakes on the basis of their in-lake conditions. Rather, the assessment approach for evaluating the relative threats to the transboundary lake basins was based on consideration of the characteristics of their surrounding drainage basins, utilizing a modification of the global-scale database derived by Vӧrӧsmarty et al. (2010) on the basis of 23 basin drivers, as shown below. These 23 drivers, were grouped under four major thematic areas, and were given relative weights highlighting their priority by identified expert groups, in terms of the magnitude of their potential impacts to the transboundary lakes, expressed as Incident Human Water Security (HWS) and Biodiversity (BD) threats. The definition of these terms was presented by Vӧrӧsmarty et al. (2010), and in the Technical Report, “Transboundary Lakes and Reservoirs: Status and Future Trends, Volume 2: Lake Basins and Reservoirs (2016)” ( Downloadable from “Data Download” page).

The analysis also considered the ability of transboundary basin countries to undertake investments in water infrastructure to address their transboundary water problems, as expressed in the form of the Adjusted Human Water Security (Adj-HWS) threat, which differs significantly between the developed and developing nations.

Thematic Groups and Assessment Indicators

Thematic Group Indicator Thematic Group Indicator
Catchment Disturbances Cropland Water Resources Development Dam Density
Impervious Surfaces River Fragmentation
Livestock Density Consumptive Water Loss
Wetland Disconnectivity Human Water Stress
Pollution Soil Salinization Agricultural Water Stress
Nitrogen Loading Flow Disruption
Phosphorus Loading Biotic Factors Non-Native Fish#
Mercury Deposition Non-Native Fish%
Pesticide Loading Fishing Pressure
Sediment Loading Aquaculture Pressure
Organic Loading
Potential Acidification
Thermal Alteration