South Africa Reservoir Transparency

For the COVERED subset (~250 dams), DWS publishes weekly dam-level bulletins for all 9 provinces. Data is consistently published as structured HTML tables and weekly PDFs on the DWS website. The NIWIS portal provides supplementary CSV/Excel exports for surface water storage. The typical covered reservoir has weekly publication of percentage full, current storage, prior-week and year-ago comparisons.

For the COVERED subset, the dominant access mechanism is structured HTML tables requiring scraping. No public REST API or documented bulk download. The DWS NIAM register provides engineering metadata but is similarly HTML-only. NIWIS supports manual CSV/Excel export but no API. Automated daily ingestion requires HTML scraping of the weekly bulletins.

Conservative estimate — denominator includes thousands of private farm dams (South Africa has one of the largest concentrations of private farm dams globally; many medium-sized irrigation/livestock dams sit outside DWS NIAM coverage), traditional rural water-harvesting structures, mining/industrial slimes dams with non-trivial water storage, and small municipal impoundments not in the weekly bulletin. Methodology v1.3.0 (capacity-weighted). Covered capacity through the DWS Weekly Hydrology Report (250 dams) is approximately 31,000 hm³. A realistic national denominator including private farm dams and small municipal/industrial impoundments reaches approximately 34,400 hm³. Score = round(100 × 31,000 / 34,400) = 90. Every major water-supply, irrigation and hydropower reservoir above operational significance is captured weekly; the conservative discount reflects the well-documented long tail of South African private dam storage.

MEDIAN historical depth across the ~250 covered dams is approximately 10-15 years of online-archived weekly data. DWS archives weekly bulletins going back roughly 10 years online; some historical records extend further in non-machine-readable formats. NIWIS provides ~5 years of downloadable weekly time series consistently across the cohort. Long-record dams (Vaal, Gariep) have records spanning multiple decades but the median sits in the 10-20 year band.

For the COVERED subset, the typical cadence is WEEKLY publication, typically released on Tuesday or Wednesday. No daily or real-time data available at the national level. Weekly is the consistent cadence across all 250 reported dams.

For the COVERED subset, some methodology documentation exists and the NIAM register provides engineering dam data including capacity and design parameters. Quality control procedures are not prominently described for external users. Per-dam stage-storage curves and bathymetric survey schedules are not consistently published online.

English is an official language of South Africa and the primary language of the DWS portal. All bulletins, the NIAM register, and the NIWIS portal are in English. Interface is functional and accessible to international users.