|Computer software of SANEX: Description of procedure and
The purpose of this computer program is to support decision makers and
project beneficiaries in identifying feasible alternatives and in evaluating the
adequacy of these alternatives with respect to community circumstances. The
three questions which the program attempts to answer are:
- Which sanitation technologies are relevant to rural and urban communities in
- Which are the relevant criteria to evaluate the appropriateness of these
- How can these criteria be incorporated into a decision aid that can be
applied by decision makers to concrete projects?
This model features two distinct evaluation stages (Diagram A). During the
screening stage, infeasible alternatives are eliminated based on mainly
technical criteria. Subsequently, during the comparative stage, the remaining
alternatives are compared with regard to the indicators implementability and
sustainability. Apart from technical issues, this stage considers numerous
sociocultural objectives. Implementability expresses the probability that
sanitation facilities can be constructed within the period and with the
financial resources usually required in favourable conditions. Sustainability
expresses the probability that facilities serve beneficiaries according to their
design throughout their design life.
Diagram A: Screening evaluation is symbolised by the screen
(1) which lets only technically feasible options (represented by the smaller
spheres) pass. Comparative evaluation is symbolised by the horizontal bar graph
(2), indicating performance for each feasible option.
A major obstacle to formulation the comparative component of the algorithm
was the amalgamation of numerous criteria outcomes. The application of
conventional methods, such as the arithmetic mean, would have resulted in a
diminishing effect of the individual criterion. In order to preserve the effect
of criteria, a new method for amalgamating criteria on multiple levels was
developed, which would also allow the simultaneous application of various
methods like the arithmetic and the geometric mean. The combined advantages of
multi-level amalgamation are reflected in more plausible evaluation results.
Costing of Sanitation Alternatives
Assuming the planners in developing countries usually have sufficient access
to financial expertise, no criteria to assess the affordability of sanitation
systems were formulated. Instead, it was decided to develop a costing model that
would enable the proposed decision aid to estimate the capital as well as the
recurrent costs of all alternatives. Further, a simple method based on the local
residential building cost was developed to convert these estimates to costs in
local currency units, as they would occur in the project area.
The above work resulted in an evaluation model for assessing the
implementability, the sustainability and for costing sanitation alternatives in
developing countries. In 1998, in order to validate this model, a second journey
was undertaken to Southeast Asia and to Europe. Based on the application to nine
case studies, several modifications emerged to be necessary.
The expert system software SANEX© was developed for the MS Windows operating
environment. The knowledge base of this software contains more than 80
sanitation alternatives, which are combinations of the technologies outlined in
the table below, and uses around 50 technical, sociocultural and financial
criteria for their assessment. The costing component employs approximately 50