By Daniel Collins
For the most part, droughts are natural events. Rainfall and river flows wax and wane, and there will be times when there just isn’t enough water to fully meet our needs, whether to grow crops or to quench a city’s thirst.
And when it comes down to it, that’s really the best definition of a drought: when water supply is insufficient to meet demand. If no rain falls on the land, and there is no-one there to go thirsty, is it a problem?
But there is a growing part of drought that isn’t natural. Increases in water use, beyond the capacity of the environment to supply the water, have led to what are called “demand-driven droughts”. Changing climate has been implicated in changing patterns of drought around the world (e.g., Dai, 2013), and this is expected for New Zealand in the future.
So how can we adapt to more frequent and more severe droughts?
One option being discussed in New Zealand lately has been to increase the drought relief from the Government, but the Government has indicated that farmers will not be able to rely on this.
Another option is to build more water storage reservoirs and siphon off some winter river flows for use in spring and summer. So long as this does not increase dependency during times of plentiful rain and is reserved as a form of insurance as a drought approaches, this is a possible option, depending on economics and environmental impacts.
But we shouldn’t become fixated on just one or two strategies. There are many to choose from and it is likely that the best approach will be a balanced portfolio of options, tailored to specific needs and adaptive capacities.
Here is a longer list. For more information, read the recent Ministry for Primary Industries (MPI) report on adapting to climate change. No option is favoured over any other, and important economic considerations are beyond our scope.
Around the house. Install dual-flush toilets and don’t flush every time. Switch to a front-loading washing machine. Take marine-style showers: turn the water off when soaping up. Plant your garden with drought-resilient species. Collect rainwater from the roof and stop watering when shortages loom. Sweep the path with a broom, not a hose. Buy food with a smaller water footprint, relative to the growing region’s climate, and reduce food wastage.
Around the farm. Increase water use efficiency. Match crops and livestock (number and species) to the available water. Accumulate feed reserves if seasonal weather forecasts indicate, and start de-stocking before the feed runs out. Build on-farm water storage or collaborate in large-scale reservoirs. Schedule irrigation based on short-term weather forecasts and distribute it based on soil moisture and crop conditions. Buy drought insurance with profits from more productive years.
Around the business. Use materials and products with a smaller water footprint, relative to the producing region’s climate. Reduce the water footprint of the manufactured products, adding value in the process. Identify parts of the supply chain that are more or less drought-sensitive and build in contingency plans based on climate forecasts. Seek drought insurance and relief. Adopt relevant actions from around the house or farm.
Around the town. Encourage water conservation through education, incentives, penalties or user-charges. Reduce reticulation leakage. Landscape green spaces with drought-resilient plants and cease irrigation when shortages loom. Secure alternative sources of water and protect existing supplies. Monitor weather and climate forecasts, and phase in voluntary or compulsory restrictions in advance. Develop long-term plans for residential and industrial growth that can be balanced by future water supplies.
Around the region and country. Develop policies and plans that account for the foreseeable impacts of climate change. Adapt water quantity limits as climate change projections indicate. Encourage personal and industrial water conservation through education, incentives, penalties or user-charges. Provide financial and logistical support for costlier adaptation options. Encourage the use and development of weather forecasts, both short-term and seasonal, among water users. Identify and develop new sources of water (e.g., inter-catchment transfers; inter-seasonal storage). Quantify the available water and how this may change in the future. Foster land covers that have higher water yields, particularly during times of low flow.
In the end, the only sure-fire way to drought-proof New Zealand is to live within our climatic means. Being resilient to some drought, however, may not be so bad. Both would require us to tailor our water demand to the vagaries of the climate, develop land uses and societal practices attuned to the water cycle, and build in flexibility to ramp usage up or down as variable water supplies dictate.
Dr Daniel Collins is a hydrologist and water resources scientist at NIWA.