Effects, urban design and the RMA: 2

I'm on a (one person) quest to better define urban design effects as part of RMA processes. I have started by looking at how effects might be defined, before looking at urban design effects. I ended my first post on the topic with the following effects 'equation':

The scale of an effect is a combination of:

Persistence of effect * magnitude of effect * extent of the effect * probability of the effect * consequence to receiving environment * possible mitigation (reduction) * plan weighting.

I am not sold on the above equation, but it is a start.

If you think the above is a bit complex, then look at the following. This is from Department of Conservation’s guidance on policy 13 of the New Zealand Coastal Policy Statement (which in turn is drawn from a regional policy statement).

The following guidance aims to help with determining the extent to which an adverse effect is ‘significant’.

Status of resources: The importance of the area—locally and regionally. (Effects on rare or limited resources are usually considered more significant than impacts on common or abundant resources).

Proportion of resource affected/area of influence: The size of the area affected by the activity will often influence the degree of impact (i.e. affecting a large area will generally be significant). Affecting a large proportion of a limited area or resource will tend to be significant.

Persistence of effect: The duration and frequency of effect (for example, longterm or recurring effects as permanent or long-term changes are usually more significant than temporary ones. The ability of the resource to recover after the activities are complete is related to this effect).

Sensitivity of resources: The effect on the area and its sensitivity to change. (Impacts to sensitive resources are usually more significant than impacts to those that are relatively resilient to impacts). Reversibility or irreversibility: Whether the effect is reversible or irreversible.

Irreversibility will generally be more significant (depending also on nature and scale), and reversibility the converse.

Probability of effect: The likelihood of an adverse effect resulting from the activity. Unforeseen effects can be more significant than anticipated effects. (Adopting a precautionary approach may reduce the likelihood of adverse effects occurring).

Cumulative effects: The accumulation of impacts over time and space resulting from the combination of effects from one activity/development or the combination of effects from a number of activities. Cumulative effects can be greater in significance than any individual effect from an activity (for example, loss of multiple important sites).

Degree of change: The character and degree of modification, damage, loss or destruction that will result from the activity. Activities that result in a high degree of change are generally more significant.

Magnitude of effect: The scale and extent of possible effects caused by an activity (for example on the number of sites affected, on spatial distribution etc). Activities that have a large magnitude of effect are generally more significant.


I think this list can be re arranged to match my equation, as follows:

DM rating	DoC
Persistence	Persistence of effect:
Magnitude	Magnitude
Extent	Proportion of resource affected/area of influence
Probability	Probability of effect
Consequence	Degree of change Irreversibility Sensitivity of resource
Possible mitigation
Plan weighting	Status of resources:

The DoC list doesn’t have mitigation in it. It does have cumulative effects in it. More on that below.

As another example, Environmental Impact Assessment (which is where the idea of Assessment of Environmental Effects comes from) can have a fairly complex list of things to look at when considering impacts. For example:

Characteristics of Impact:
• the extent of the impact (geographical area and size of the affected population);
• transfrontier impact;
• magnitude and complexity of impact;
• probability of impact;
• duration, frequency and reversibility of the impact.

Transfrontier impacts refers to whether the impact crosses country borders or other boundaries.

Again some similarities come through in terms of the dimensions of an effect.

Once the components of effects has been considered, how do you express the product of the equation? I wonder if the scale for urban design effects should be related to people’s reactions to or acceptance of change to an urban environment, given that cities are all about people, but also constant flux and change. For example, effects are:

1. Not discernible
2. Negligible
3. Tolerable
4. Undesirable
5. Detrimental
6. Intolerable.

These might be described as follows:

Overall rating	Description
Not discernible	Within the normal range of effects / rate of change as currently experienced, generally not perceptible
Negligible	Effect may be noticed against 'background levels', but would be so small or unimportant as to be not be worth addressing. It would not change day to day activities in any material way
Tolerable	Effect would be noticed and may change behaviour / routines, but within the ability of people to adapt. The effect may be bearable
Undesirable	Effect would be noticeable and negatively  impact on people’s day to day routines. It would be objectionable or unpleasant. The effect might be able to be mitigated or potentially traded off for other much bigger benefits
Detrimental	Effect would be visible and be felt. It would be harmful or damaging. People would need to be take deliberate action to avoid the effect which would reduce the overall utility of the environment to support urban activities
Unbearable	Level of effect is excessive and would negatively impact on a wide range of people and lead onto other spill over effects that cannot be managed. The effect would be calamitous and destructive to an urban environment.

The above categories of effects can be related back to the threshold / procedural tests of the RMA as follows:

Rating	Degree of ‘minorism’	Degree of significance
Not discernible	Less than minor
Negligible	Minor
Tolerable	More than minor
Undesirable		Significant, but maybe 'tradeable'??
Detrimental		Significant, best avoided
Unbearable		Significant, avoid

Having said all that, I am not convinced that the above deals with the issue of small, incremental changes to urban areas. Many urban design matters involve small scale changes to the built environment, and most often are not changes to a highly valued environment. One tall fence on the front boundary of a 'normal' residential site might not seem so bad, a whole street of high fences is a problem, but getting from one to many high front fences usually involves numerous small steps. Is the first tall fence an 'unbearable' effect?

As a different example, the area or number of people affected may be relatively small, with only a minor portion of an urban area subject to the effect. A formula which talks about nature and extent of change might imply that changes that affect 100s of hectares are much more important than changes that affect one or two sites. As a result the small changes should get a low 'relative' impact rating.  But of course only one in twenty cases may affect 100  hectares, but 19 cases may affect 5 sites each.

This is the cumulative effects issue; an issue which goes round and round without resolution.

One guide says that cumulative effects become significant when these impacts on the environment:
• “occur so frequently in time or so densely in space that they cannot be assimilated or
• combine with effects of other activities in a synergistic manner” .

In other words, cumulative effects may be additive (accumulate) or synergistic (amplify other effects). Someone has also pointed out that cumulative effects could also be neutralizing (the effects cancel each other out). The issue with accumulative effects is their frequency.

It is the accumulative form of cumulative effects which are perhaps most relevant to urban design. It is common for assessment guides to note that there are thresholds where additional (small scale) disturbance can result in significant deterioration of resources or ecosystems. Cumulative effects become apparent when such thresholds (tipping points) are breached.

But if the effect is at the start of the sequence of potential repetitions, and no threshold has been reached, then a cumulative effect has not yet technically occurred. Even if there is a clear sequence occurring, identifying the tipping point is not easy, and is often only apparent in retrospect.

Cumulative effects can be related to the concept of the "tyranny of small decisions".  Overtime, big changes can occur as a result  of many steps, each small in their individual size, time perspective, and in relation to their cumulative effect. In economic terms, the tyranny of small decisions means that a series of apparently free, individually welfare-maximizing 'purchase' decisions can so change consumer tastes and the context of subsequent choices that desirable alternatives are cumulatively and irreversibly destroyed.

There is no straight forward antidote to the tyranny of small decisions, except to say that someone needs to keep the bigger picture in mind.  But just saying that cumulative effects should be taken into account in the effects equation doesn't really help much.

Plan weighting maybe one way to address small scale, insignificant in isolation but potentially damaging additive cumulative effects. Another way to address cumulative effects may be to introduce another step into the effects equation, covering the likely prevalence or recurrence of the effect - does the effect come up often, or is a rare or unusual effect? So should the equation be:

Persistence of effect * magnitude of effect * extent of the effect * probability of the effect * likely recurrence of the effect * consequence to receiving environment * possible mitigation (reduction) * plan weighting.