Raw Water Availability in the Integrated Vaal River System Presented to:WSF Presented by:Kobie Mare Date:25 May

1.Background 2.Description of IVRS 3.IVRS Operating Analysis 4.Factors Influencing Dam Levels 5.Historical Storage Levels 6.Current Dam Levels 7.Typical Interventions During Scarcity 8.Conclusion 2

 IVRS Definition  IVRS Management  IVRS vs SA Storage Capcity  IVRS Yield 3

 The following slides show a map and a schematic of the IVRS  It consists of the Upper, Middle and Lower Vaal River system as well as the raw water transfer schemes that supplement it with water from adjacent catchments  The IVRS consists of 14 main dams with a combined storage capacity of million cubic meter (11.1 cubic km)  This is equal to 33% of all the dams in South Africa and Lesotho 4

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 DWS determines the level at which restrictions (curtailments) are required  It varies over time due to the changing relationship between storage, yield and use  The 2016\17 Vaal River System Annual Operating Analysis System Operation Forum meeting is scheduled for 31 May 7

 Climate ◦ Temperature ◦ Rainfall  Geography ◦ Mean Annual Runoff (MAR) vs Mean Annual Precipitation (MAP) ◦ MAP vs Catchment Area  Usage ◦ Active and productive use ◦ Losses and Wasteful Use - this is normally the first target for water demand reduction and restrictions 8

 The following slides give an indication of the time, duration, extent and severity of previous droughts in the IVRS region ◦ 1990’s Restrictions ◦ 2000’s ◦ Future???? 9

Historical reservoir levels Levels below which curtailments are imposed Restrictions imposed Restrictions lifted

Levels below which curtailments are imposed Worst drought on record for IVRS

12 2 nd worst drought (has not ended) 3 rd worst drought

13 Start Drought End Drought VolumeTime Out Max Vol Out Max % Out Average Vol Out Coun t Years RAN K m3-weeksm3 % of FSCm3Years Apr-91May % Mar-02Mar % Jun-06Jan % May-11 May-16 +???? %

 The May 2016 dam levels were 61% which was just above the 59.4% restriction level  The worst drought in the IVRS region to date occurred in the early 1990’s. It lasted for 6 years  During that drought a maximum of Mm3 was lost from storage  This means that 72% of the then FSC of Mm3 was out of storage, leaving only 28% in storage  The current drought has already lasted for 5 years since the last time the system was full. It is highly probable that this will continue for at least the next 5 winter months, making its duration longer than the previous drought  During the current drought a maximum volume of Mm3/a was out f storage, representing 39% of FSC and leaving only 61% in storage 14

 It can be concluded that the current drought is less extensive and less intense than the worst one but, because it is still in progress and will probably last longer, it can lead to a larger total loss in volume in storage  Luckily for us, the current storage capacity of Mm3 after the first phase of the LHWP, is much higher than the Mm3 in the 1990’s  However, the increased current IVRS demand of Mm3/a (27% of FSC equivalent to 3.7 years of storage) is so much higher than the Mm3/a in the 1990’s (30% of FSC equivalent to 3.3 years of storage) that we have ended up in a similar shortage situation 15

 Awareness and education  Request for voluntary reductions  Gazetted curtailments by DWS  Penalty raw water tariffs by DWS  Quotas by Rand Water  Water loss reduction measures by all (water board, municipality and end users)  Penalty potable water tariffs by Rand Water  Sliding scale retail water tariffs by municipalities 16

17 Worst drought on record for IVRS (included restrictions and penalty tariffs) Uncertainty regarding current drought ?????

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