Cette table fournit des métadonnées pour l'indicateur réel disponible à partir des statistiques US les plus proches de l'indicateur SDG global correspondant. Veuillez noter que même lorsque l'indicateur global des ODD est entièrement disponible à partir des statistiques US, ce tableau devrait être consulté pour obtenir des informations sur la méthodologie nationale et d'autres informations sur les métadonnées spécifiques à un pays_adjectif.
Actual indicator available | |
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Actual indicator available - description | |
Date of national source publication | |
Method of computation | The GEMS/Water1 water quality index approach is used as a general model to calculate the index, in which measured determinand values are compared to guideline values (proximity to target approach): 1. Proximity-to-target (PTT) scores for each determinand at single monitoring sites are calculated as the difference between the temporal average (for the accounting period) of the determinand concentration and the target divided by the range between the (winsorized) minimum or maximum of the measured determinand concentration (for exceedance and non-exceedance targets, respectively) and the target. The PTT scores are scaled to the range between 0 and 100, where 100 indicates that the target is met and decreasing scores indicate an increasing distance from the target. 2. The water quality index (WQI) at site level is computed as the arithmetic mean of the site-level PTT scores for the selected determinands. The WQI scale can be divided into different water quality categories, ranging from very bad to excellent. The thresholds for these categories are country specific and should be reported in the monitoring system by the individual countries 3. For the spatial aggregation at the basin level and country level, the water bodies are divided into stretches of homogenous quality (between consecutive monitoring stations). 4. The final indicator is calculated from the proportion of the stretches with good quality compared to all water bodies assessed. |
Periodicity | |
Scheduled update by national source | |
U.S. method of computation | |
Comments and limitations | |
Date metadata updated | |
Disaggregation geography | |
Unité de mesure | |
Disaggregation categories | |
International and national references | |
Time period | |
Scheduled update by SDG team |