Transboundary basins are basins of transboundary waters, that is, of any surface waters (notably rivers, lakes) or groundwaters which mark, cross or are located on boundaries between by two or more states. For the purpose of the calculation of this indicator, for surface waters, the basin is the extent of the catchment area; for groundwater, the area considered is the extent of the aquifer.
Arrangement for water cooperation: a bilateral or multilateral treaty, convention, agreement or other formal arrangements, such as a memorandum of understanding) between riparian countries that provides a framework for cooperation on transboundary water management. Agreements or other kinds of formal arrangements may be interstate, intergovernmental, interministerial, interagency or between regional authorities.
Operational: For an agreement or other kind of formal arrangement (e.g. a memorandum of understanding) for cooperation between the riparian countries to be considered operational, all the following criteria needs to be fulfilled:
- There is a joint body, joint mechanism or commission (e.g. a river basin organization) for transboundary cooperation
- There are regular formal communications between riparian countries in the form of meetings
- There is a joint or coordinated water management plan(s), or joint objectives have been set
- There is a regular exchange of data and information.
Step 1 Identify the transboundary surface waters and aquifers
While the identification of transboundary surface water is straightforward, the identification of transboundary aquifers requires investigations. If there are no transboundary surface waters or groundwaters, reporting is not applicable.
Step 2 Calculate the surface area of each transboundary basin and the total sum
Commonly at least the basins of the rivers and lakes have been delineated through topographic maps and the basin area is known or easily measurable.
The total transboundary surface area in the country is the sum of the surface areas in the country of each of the transboundary basins and aquifers (expressed in km2). Transboundary areas for different types of systems (e.g. river basin and aquifer) or multiple aquifers may overlap. The area of transboundary aquifers, even if located within a transboundary river basin, should be added to be able to track the progress of cooperation on transboundary aquifers.
The calculations can most easily be carried with Geographical Information Systems (GIS). Once generated, with appropriate tools for spatial analysis, the shapes of the surface catchments and the aquifers can be used to report both disaggregated (for the surface water basin or aquifer) and aggregated (agreement exists on either one).
Step 3 Review existing arrangements for transboundary cooperation in water management and verify which transboundary waters are covered by a cooperation arrangement
Some operational arrangements for integrated management of transboundary waters in place cover both surface waters and groundwaters. At the end of this step, it should be known which transboundary basins are covered by cooperation arrangements (and their respective areas).
Step 4 Check which of the existing arrangements for transboundary cooperation in water management are operational
The following check-list allows determining whether the cooperation arrangement on a particular basin or in relation to a particular co-riparian country is operational:
- existence of a joint body, joint mechanism or commission for transboundary cooperation
- regularity of formal communication in form of meetings
- existence of joint or coordinated water management plan(s), or of joint objectives
- regular exchange of information and data If any of the conditions is not met, the cooperation arrangement cannot be considered operational.
Step 5 Calculate the indicator value, that is, the area share by adding up the surface area in the country of those transboundary surface water basins or aquifers that are covered by an operational cooperation arrangement and dividing it by the total summed up area in the country of all transboundary basins (including aquifers), multiplied by 100 to obtain a percentage share.