Page 157 - Water Loss Control

Modelling W ater Losses 135

Problem-Solving Using BABE and FAVAD Concepts

Economic frequency Performance Infrastructure
of leakage control indicators condition
assessment
BABE and FAVAD
Nightflow concepts, local Annual water
analysis parameter values, balance and
and national data components
of losses

Night-day factor Pressure Pressure/leakage
management relationships

FIGURE 10.1 Range of problems which have been successfully modelled using BABE concepts.
(Source: Water Loss Control Manual, 1st ed.)

in much of the data used in the analysis. However, a component analysis or BABE
model is a very useful supplement to a top-down water balance because it provides
estimates of the volumes of real losses in different elements of the distribution infra-
structure. This is valuable data because it is required to develop the most appropriate
loss reduction strategy and it is essential for a robust determination of the economic
level of leakage (ELL) as discussed in detail in Chap. 9.
There are several commercial versions of these models (and many homemade ones)
available in the market today, most of them being extremely user friendly and flexible. If
using a commercial model, the operator must first fully understand what it is they wish
to perform and ensure that the commercial model has been suitably customized to the
local situation. If constructing a model in a spreadsheet it is vitally important that the
operator fully understands the concepts being used and their limitations. And users of
the models must be adequately trained if reliable results are to be obtained.
In order to arrive at an estimation of the loss situation, most statistical component
analysis models require
• Infrastructure and system data
• Coefficients and default values

10.5.1 Infrastructure and System Data
In most cases, the field data required for an annual component analysis model are leak
information by category over the audit period supplemented by flow data and pressure
data, which can also be used for the district component analysis. More information can
be found about the collection of field data in App. B. The BABE and FAVAD approaches
to modeling ensure that only a limited amount of specific data needs to be obtained,
and it is obviously important to collect the data as accurately as possible to ensure that
the estimation of loss is as close to the real situation as possible.
Typical infrastructure and system data needed for BABE and FAVAD models are
• Length, material, and diameter of mains
• Volume of service reservoirs/storage tanks