2015 National Water Week Event Launch of the WR2012 Website Water Resource Planning in South Africa : An Overview Protea Hotel, Centurion, 19 March 2015 Presented by: Dr. Ronnie McKenzie, WRP (Pty) Ltd

Distribution of surface runoff in SA D(Rem) 0,4% Notes: Due to the extreme variation in rainfall and evaporation, the distribution of runoff is highly skewed. Most runoff occurs in the East. Runoff drops markedly as you move towards the West. Not only is the runoff very unevenly distributed in space, it is also erratic with regards to time. In SA, many areas experience drought periods in excess of 10 years with the result that large surface storage reservoirs are needed to provide a reliable and continuous supply of water.

The results of climatic extremes Notes: During severe droughts, the reservoirs can experience shortages. The water resources in South Africa must be managed in order to survive the long drought events caused by the climatic extremes. Drought conditions can continue for up to 15 years in some areas. In order to overcome such extreme drought events, SA has developed a very complex system of water transfers to facilitate the movement of water from areas of surplus to areas of deficit.

Major transfers in South Africa Notes: As a result of the skewed distribution of water resources and the high demands in the central interior of South Africa, many inter-basin transfers schemes have been developed. Each arrow represents a transfer. The purpose is to move water from areas of surplus to areas of deficit. The transfer schemes are large and very expensive. It is expected that upon completion, Phases 1a and 1b of the Lesotho Highlands Water Project will cost in excess of $ 3 billion (at today’s prices).

Slide Courtesy Elias Nel from DWS : Hydrology Compiled by E A Nel Slide Courtesy Elias Nel from DWS : Hydrology

Slide Courtesy Elias Nel from DWS : Hydrology

Deepest Mine in the World at 4.5km deep Mopaneng Gold Mine Deepest Mine in the World at 4.5km deep

Produces >30% of SA’s Petrol/Diesel from coal Sasol Petrochemical Plant Secunda Produces >30% of SA’s Petrol/Diesel from coal Largest synthetic fuel plant in world

SA generates over 50% of electricity in Africa > 40 000 MW Power Stations SA generates over 50% of electricity in Africa > 40 000 MW

Vaalharts Weir and main canal

Origins of Models Based on ARSP Model from Acres of Canada – 1983 Prof Fontanne – Colorado State Prof Loucks – Cornell Prof Stedinger – Cornell Prof O’Connell – Newcastle Prof Pegram – Natal Prof Grieg – Colorado State Resource Software design by Rick Allan, Ronnie Mckenzie and Pieter van Rooyen Stochastic Software by Steffan van Biljon and Prof Pegram.

Yield and Planning Model Development Algorithms developed by Dr O Sigvaldeson of ACRES in Canada Originally designed for hydropower optimisation Original model had no stochastic capabilities Hydrology in Canada had short critical periods – no real need for stochastics Acres model selected after tour to identify world’s best practice

Software Development : Cont ARSP initially developed on VAX/780 Platform using VAX VMS operating system – 1982 In SA, first VAX mainframe was imported to SA from USA in 1984 Subsequent VAX 750 and Microvax computers imported by SA government for model use SA was first in world to run models on PC based computer – used Lahey Fortran compiler

VAX 780 (1980)

Microvax (1987)

Software Development : Cont First main system analysis was Vaal River System in 1985 Orange/Senqu River System Analysis commenced in 1987 and was first study to identify impacts of full 5 Phase LHWP on remainder of Orange/Senqu River Namibian Central Area Water Masterplan in 1993

Creating a System Model

Locality of the Caledon-Modder System

Network model of the Caledon-Modder System

Penalty Structure

Internal Node and arc network

Mokolo Catchment Crocodile Catchment Vaal Catchment Existing Transfer Schemes Proposed Transfer Schemes Mokolo Catchment Crocodile Catchment Vaal Catchment

Integrated Orange /Vaal system Thank You

Point out selected characteristics that will be referred to later in the presentation: Vaal Dam and Bloemhof Dam. Transfer to Crocodile via. Rand Water supply system. LHWP – Proposed Polihali Dam (upstream of Orange). Dilution in Vaal Barage (downstream of Vaal Dam).

Upper Orange Lesotho Hololo & Hlotse Metolong Makhaleng

Orange/Senqu System Model 87 Large Dams 279 Small Dams ± 1 250 Abstractions/Demand Centres 8 integrated subsystems and 8 stand alone subsystems ± 4 000 channels/arcs

Modelling Structure showing Yield and Planning Models

Stochastic yield analysis : why bother ?

Historical firm yields Why do they always seem to decrease ?

Basic Hydrology 1920 - 1990 Yield 18 24 29 40 28 30 33 42 51 100 24 120 28 29 40 30 60 50 45 24 29 40 59 29 81 72 63 59 45 63 50 40 60 18 40 Yield 18

Basic Hydrology 1920 - 2004 Yield 18 24 29 30 28 40 42 33 51 100 120 60 50 45 24 29 40 59 24 29 40 28 30 29 81 33 42 72 63 59 45 63 50 40 60 18 40 Yield 18

Basic Hydrology 1920 - 2014 Yield 15 24 29 40 28 30 33 42 51 100 24 120 28 29 40 30 60 50 45 24 29 40 59 24 29 40 28 30 29 15 33 42 72 63 59 45 63 50 40 60 18 40 Yield 15

Projected system volume trajectories

Percentage of sequence results exceeding given value Min % 5.0 % 25 % 50 % 75 % 95 % Max % Percentage of sequence results exceeding given value Results for sequences

Projected system volume trajectories

Projected system volume trajectories

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

THANK YOU