Sources of information by country
* The data presented here only represents a summary data available. For more detail, or to change the format of the data, please visit the Main AQUASTAT Country database.
Global maps on water resources
Water resources assessment methodology
AQUASTAT collects statistics on water resources and data on water resources obtained from national sources are systematically reviewed to ensure consistency in definitions and between countries sharing the same river basin. A methodology has been developed and rules have been established to compute the different elements of a country's water resources. The methodology is described in the article Key Water Resources Statistics in AQUASTAT. The calculation rules are provided in the country "Water Resources Sheets", which can be accessed through the first drop-down menu above.
With the assistance of Mr. Jean Margat, expert in global water resources assessment, a comparative analysis of available country water resources data is carried out at regular intervals. On that basis, AQUASTAT compiles and updates its best estimates of the main elements of the water resources for each country.
Note 2: The overlap between surface water and groundwater should be deducted from the sum of surface water and groundwater.
Note 3: The "Surface water: outflow secured to treaties" is deducted in order to obtain the total external renewable water resources.
Note 4: See the glossary for definitions and calculation rules of the variables and terminology used in AQUASTAT.
Water resources updates
For the past few years, AQUASTAT has been improving the way that information on water resources is treated. The methodology being used now introduces several new steps that allow for more meticulous note taking and error checking. At its heart, the change can be explained by tracking individual river points of international significance. Flows at these points are kept in a specific database, along with relevant metadata, comparison with data of the Global Runoff Data Centre (GRDC) data, location information, etc. From there, data can be automatically compiled into a global matrix of international flows. At the matrix level, data and metadata can be better evaluated and compared to national sources. After an acceptable level of quality has been accomplished, the data are transmitted to the Main AQUASTAT Country database, where they can be displayed online in the database results page, as well as in the automatically generated Water Resources Sheet PDF files (see first dropdown at the top of this page).
Visually, the process looks something like this, where black arrows denote the flow of information, and blue arrows denote the iterative quality control steps:
In the above, the Point database and the Matrix are the centerpoints that ultimately drive the entire process. Explaining further:
Point database (1)
While at a first glance this approach looks unnecessarily complex, it is important to consider that countries report data at varying levels of aggregation, from river-level to full national-level values. More than any other variables, having a system that allows AQUASTAT to keep all data and notes in the correct "box" ultimately results in increased data quality, more metadata being revealed, and ultimately reduces the workload to process new data.
In addition, more substantial changes to the way water resources are reported by AQUASTAT are currently under discussion with experts. When these discussions have concluded, a report documenting the rationale will be released
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