However, though WP is a framework well-suited to systems where water use is directly attributable, particularly via depletion, to definitive benefits, the suitability of the approach becomes questionable when these conditions are not met, such as in multiple use systems with high re-use and non-depleting uses.
The opportunity costs inherent in the existing multiple-use system must also be accounted for to give a replacement cost for the wetland.
The replacement cost of a wetland converted from a multiple-use system to a single-use flood recession agricultural system is based on the loss of pastoral resources, wild foods and medicinal plants, construction materials and biodiversity.
Using these estimates and the replacement costs calculated in Table 14, a total value for the conversion of Tamourt Goungel from a multiple-use system to a single-use system is calculated (Table 17).
The data presented in this paper have shown that despite investing over 24 million UM (>92,000 Euro based on 2002 conversion rates) in developing a wetland for agriculture, production from the new system could never equal the production and replacement costs of the existing multiple-use system.
Table 20 Comparisons of annual revenue from Goungel under multiple-use and single-use systems (based on 1999 market prices) Multiple-use system - 1999/2000 productiona Single-use system - revenue 1b Single-use system - revenue 2b Single-use system - revenue 3b 236,527,739 UM 17,745,000 UM 28,665,000 UM 36,400,000 UM 908,046 €68,124 €110,047 €139,742 €2 € aFrom Table 10; bfrom Table 19.
Two types of suction-catheter systems are available: the open, single-use system, and the closed, multiple-use system.
The comparison of multiple-use and single-use systems has shown the superior performance of multiple-use systems in Sahelian conditions.
The study assesses the benefits of multiple-use systems compared to such single-use systems through economic valuation of production from the respective systems.
Arable agriculture, livestock rearing and botanical and other natural resources are valued in the case of multiple-use systems and compared to arable production from single-use systems.
