Macau Matters | The need for water conservation?

Richard Whitfield

Around 70% of the world’s fresh water is used for irrigation and other food production purposes. Currently, global water demand can be met from the existing natural and man-made fresh water infrastructure, but with current population (and wealth) growth projections, it is predicted that there will be a 40% global shortfall in fresh water availability by the 2030’s.

Agricultural irrigation is generally very wasteful. Studies show that typically 50% of the water flowing through open irrigation channels “disappears” as evaporation and seepage into the nearby ground. Moreover, most farmers look at their plants to decide when to turn on the water flows, but again, studies show that more than half the time, measuring the soil moisture content proves that the water is not needed.

The Pearl River Delta has always been an important breadbasket for China but clearly much of the available farmland is being turned into factories, housing and roads. Rain falling on buildings and roads is not absorbed into the ground like it is in farmland, but is wasted into the sea through storm- water systems. And the local human population is greatly increasing and consuming more and more water. Thus, better water conservation is needed locally, and will become much more important in the future.

A study done for a Macau university that showed that collecting the rainfall over the campus could provide all the water we needed on-site without drawing from community water supplies as long as we had a large enough water storage capacity – the problem is that rainfall in not even throughout the year and we need to store rainwater during the wet season to use later in the dry season. This analysis leads me to believe that the local rainfall is adequate to support our population, but this is only true if we have adequate water storage reservoirs. In my wanderings around the Delta I have not seen many lakes and reservoirs and so I suspect that at a regional level we need much more investment in this kind of water infrastructure for the future.

Macau, like all cities, relies on its hinterland for water supplies and it is impossible to separate fresh water management in Macau from the rest of the region – the greater Pearl River Delta. I believe that we need to do a much better regional job of storing water, moving it around without wastage and using it effectively. A crucial element of this is making our water pricing realistic – now water in Macau is far, far too cheap. This imbalance means that investment to conserve water cannot be economically justified, but paying more for water could provide the money to invest in better infrastructure.

While better regional water infrastructure is crucial there are still things we can do in Macau. For example, I have always been pleased with the well planted roundabouts and road dividers in Macau, but then we waste the rainfall run-off from our roads. A case can be made to collect road rainwater run-off into tanks installed below roundabouts and road dividers and then use this water to subsequently irrigate the plantings. And, we should swap out the current sprinkler based watering systems and replace them with drip irrigation water soaking, with soil moisture sensors so that watering is only done when needed (and then, only in the evenings to minimize evaporation). Similar systems should be encouraged for our larger resorts and residential estates.

Come on Macau, let us significantly raise water prices and use the increased income to invest in improving our local and regional water conservation infrastructure, and make sure that our efforts are coordinated at a regional level.