Integration of DSM interventions into bulk water supply strategies

South Africa suffers from water-scarcity and uneven water distribution. Water transfer schemes are therefore spread across the country. They utilise large dams and energy intensive pump stations to supply water where needed. Water schemes are regulated by water supply strategies and annual operating rules. Load shifting is a mature demand side management practice in South Africa. Its implementation at these pump stations (PS), within water transfer schemes WTS, requires the investigation of the interaction between two processes; load shifting and the annual operating rules. Load shifting necessitates pump station operation aimed at reducing peak loads. Annual operating rules require uninterrupted supply and balanced dam draw-down. The inter-process interactions are evaluated through simulations and a case study. The simulations provide a set of key performance indicators for actual pre-, and approximated post-DSM scenarios. They are compared with measured indicators for the performance assessment period of actual load shift projects at sites. The results show that energy neutral, daily scaled load shifts will not negatively impact either process's goals. It was, however, found that if load shifts are not followed by sufficient comeback loads, transfer deficits may occur. The study concluded that there exists an optimum range of daily average transfer rates for which maximum DSM savings are achievable. Outside this range, DSM savings were below maximum. If they were enforced however, it would be detrimental to the operation of the pump station and water scheme.