Angelos N. FINDIKAKIS 1 , T. EL AFTI 2 and James L. STEPHENS 3
1 Bechtel National, Inc., 50 Beale Street, San Francisco, California, USA, anfindik@bechtel.com
2 Direction Générale de l’Hydraulique, Rabat, Maroc, afti@mtpnet.gov.ma
3 Nexant Ltd., 161 Hammersmith Road, London, United Kingdom, jlstephe@nexant.com
The paper presents an approach for the evaluation of the reliability of water resources developed in support of the study of the new National Water Plan for Morocco, accounting for the uncertainty associated with recurring and prolonged drought cycles and the possible impact of climate change on water resource availability. The approach used so far for planning new projects in the country has been based on the application of deficit criteria expressed in the form of the acceptable frequency of supply deficits defined as a percentage of a preset demand level. Such criteria were applied for both domestic water supply and irrigation. The approach presented in this paper is based on the concepts of stochastic hydrology and provides a probabilistic assessment of the available development and management options. The results of these simulations are analyzed to develop curves giving the base yield from storage dams as function of the target draft at different probability of exceedance levels. The same data are used to derive probability of exceedance curves for the firm yield of each reservoir. The present work introduces firm yield curves that define the volumes that are guaranteed at different levels of service, i.e. all the time, 9 out of 10 years, 4 out of 5 years, etc. The approach is illustrated through an example.