Climate Sense

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bserving

, P

redicting

and

rojecting

limate

onditions

timescales in conjunction with corresponding operational, tacti-

cal, and strategic management functions

• Questions remain on the scientific basis for validating predictive

skills of climate models and their utility for water management

• Water managers do not make routine use of climate predictions

• There is a need for the climate community to quantify uncertain-

ties in climate predictions and for water managers to explore

how probabilistic climate products can be used more routinely

• A project concept and plan for facilitating the use of appropriate

climate information by water managers was developed.

The meeting also provided inputs to the concept of pilot projects

to facilitate national hydrological services in meeting the new

expectations that have emerged due to climate change awareness.

Two pilot projects were initiated in Mexico and Egypt. Based on

the experience gained thus far, it is clear WMO, working as it does

with both the climate scientific and hydrological communities, is

in a unique position to provide support to facilitate this multi-

stakeholder activity.

Water engineers, and most of the agencies in charge of water

management do not yet rely on forecasts that extend normal

weather models by using ENSO and other type indicators, because

of the large uncertainties. It is the engineers that are responsi-

ble for the planning and design water projects, rather than the

hydrologists, climate forecasters or meteorologists. Recent arti-

cles testing the predictive skill of hydrological forecasts at short

timescales demonstrate large uncertainties.

This is one principal

reason why water managers and engineers, who make

project decisions, and are accountable for the conse-

quences, do not have full confidence in the predictions

and forecasts over a range of timescales derived from

climate and hydrological models.

Many hydrological modelling tools are being devel-

oped to model hydrological processes at an appropriate

range of temporal and spatial scales,

in parallel to

the development of global/regional/mesoscale climate

models. Links between the climate and hydrological

models may facilitate physically-based and scien-

tific short-to-medium-term climate and hydrological

information and predictions, of more practical use to

water managers. Identical physically-based climate

models are now used at temporal scales from short-

term weather forecasting to century scale climate

change modelling. Likewise physically-based hydro-

logical models, linked with climate models, are being

tested for forecasting and prediction at a range of time

spans.

Such multi-model ensembles and downscal-

ing techniques might improve prediction skills and

reduce the current large uncertainties within the next

25 years.

To validate climate and hydrological models,

ongoing monitoring and data storage, quality assur-

ance and analysis needs to be maintained to at least

their current levels.

Irrigation systems on the Canterbury Plains, New Zealand

Image: Alan Porteous, NIWA