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Project Documents
Up one levelThis section has all NWSAS project documents, like the Aquifer system, SASS programme, SASS micro model, Digital model. Exploratory simulations, Forecast Simulations, Concertation and Project conclusions.
The Aquifer System (Main Basins Aquifers)
Throughout the Sahara-Sahel region, there are great sedimentary cross-border basins containing shared aquifer systems.
The SASS Programme
This document was adopted by the countries at the meeting on September 8-10, 1997 in Tunis where they also entrusted the OSS with the task of raising external funds and act as "overseer" for the execution of the programme. After wide-ranging efforts, the OSS managed to obtain funding from the FIDA, the DDC-Switzerland and the FAO and finalize the procedures at the meeting in Rome, on April 29-30, 1998.At the meeting in Rome in May 1999, it was decided that the official launch of the SASS project would be planned for July 1st 1999.
SASS Micro Module
Data on the harmful consequences and risks to the water obtained during exploratory simulations showed the limits to the "pure simulation" approach in defining a NWSAS development strategy. Hence it was decided that another way must be found to define joint and acceptable solutions using a miniature or micro model based on an optimisation-simulation approach.
Digital model
The overall design of the model must meet two seemly contradictory requirements that are actually complementary: a) Abide by the overall guidelines used in the main studie [CI-Kiklah, CT-Upper Cretaceous] in order to optimise expertise from the system accumulated over the last thirty years. This means ensuring the regional coherency and adaption of the main decisions concerning the general distribution of transmissivity [CI, CI-Kiklah] and storage; the overall shape and the distribution of runoff at the regional level, the nature and position of boundary conditions especially in the recharge and outlet areas and the respect for rough figures on various elements in the assessment. b) Replace the IC vs TC concept used up to now by a multilayer representation that the Conceptual Model shows is the only approach that can combine the three hydrogeological systems, more specifically the Algerian and Tunisian systems with the Libyan system.
Exploratory Simulations
The aim is to explore the capacity of the system and of NWSAS to achieve the countries' development aims. The exploratory simulations are run for 50 years, the initial reference being the state in the year 2000 as reproduced by the model. The simulated flow rate is constant throughout the period.
Forecast Simulations
Manipulations on the micromodel during the Tunis workshop (1-2 April 2002) led to a certain number of scenarios that met development objectives and, at the same time, by respecting vital restrictions, minimised risks of resource degradation. After the scenarios had been defined on the micromodel they were simulated on the digital model which produces more complete results and can give a more precise evaluation of the degree of goal attainment and respect for restrictions.
Concertation
Consultation mechanisms have been carried out on how the Sahara aquifers can be exploited beyond their recharge rates by pumping in the accumulated reserves, without jeopardizing sustainable development.
Project's Information System
Data structuring is essential for the NWSAS project whose aim is to optimize all the information compiled in the region to date. The collection of this information is a prerequisite to updating the assessment of knowledge on the basin's resources.
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