Meeting Environmental Outcomes – A Planning Framework - Water and Agriculture: Sustainability, Markets and Policies - page 196

The frequency of natural and current flow conditions is provided in Table 1. This is
again derived from IQQM simulations. High flow events are substantially reduced under
current as opposed to natural conditions. The reduction is around 50 per cent for both
short and extended events. The reductions are less for flow rates at or below 30 gigalitres
a day.

Table 1. High flow events at the Wagga Wagga gauge -
current and natural modelled flow

Number of flood events in a 100 year period for events lasting at least:

15 days

1 day

Minimum flow
GL/day

Current Natural Current Natural

457 38

25

323 66

30 395 24

245 39

353 12

35

190 25

40 301 8

159 16

228 3

50

104 8

60 55 1

175 2

127 1

70

55 2

A planning framework

In this section an environmental planning framework that is intended to generate both
a well specified demand for environmental water and an optimal set of high flow release
rules is developed. Well defined demands imply that expected volumes of water required
and conditions of use are known. There are three characteristics sought within the design
of the framework: