Date(s) - 03/10/2017
6:00 pm - 7:30 pm
Join us to hear about how to use water more efficiently and how we can protect this valuable resource.
Speakers: Brent Clothier, Plant & Food Research, Palmerston North & Chris Teo-Sherrell, ex-city Councillor, Water protection Society, Palmerston North
The soil and plant-based ecosystems which cloak the lands of our Earth are the planet’s critical zones. They provide valuable ecosystem services. Through these soil and plant systems on the earth’s surface, there are massive fluxes and storages of mass and energy. These flows and storages provide valuable ecosystem goods and services. Water is the prime natural capital stock. Water is the world’s most valuable natural asset. We are vitally dependent on the myriad of ecosystem services that water delivers to us via our plants and soils.
There is only much water on earth as there was when the world began. Yet, there is far greater competition for it nowadays.
There is already great pressure of our water resources. Furthermore, this is being exacerbated by the intensification of our primary production systems, rising population numbers, and climate change.
In thinking about the sustainability of our water resources, it is of heuristic value to consider the three water colours of green, blue and grey. Blue water is that which is in the surface bodies of our streams, rivers and lakes, along with that contained in our groundwater reserves. Green water comes from the rain that falls onto the earth’s surface and is stored there, either to be used by plants, evaporated from the soil surface, or drained through the vadose zone to receiving waters. Grey water is the water that leaves our soils with a changed quality due to dissolved or entrained substances, or it is that can be that which is discharged, with, or without, treatment from urban sites or industrial processes.
The imperative is to minimise abstraction from our blue water reserves and seek to use this water to achieve the best outcome for the least use. Efficiency is a flawed metric when considering blue water use. Further, we need to ensure that we make the best use of our green water resources, and this is especially so for the developing world where there is not the infrastructure to enable the use of blue water. As for the grey water discharged as leachate from farms and orchards, we need to develop sustainable land-management practices to protect the quality of the water in our blue-water reserves. Where the grey water is discharged from cities or factories we need to ensure that its treatment protects groundwater and surface waters, and preferably enables its re-use. Examples of all of these are given: from New Zealand, through the Middle East, to Africa.