Developing solutions for sustainable water management

This policy brief, published by the International Project Office of the Global Water System Project and produced to inform the UN Conference on Sustainable Development (Rio+20), outlines how scientists and policymakers can advance water security by focusing on interdisciplinary research, and ensuring that all stakeholders are involved in developing sustainable solutions to water problems.

Rio+20 is an opportunity to strengthen commitment to integrated and sustainable management of water resources, which are coming under increasing pressure, say the authors. Water stress is a reality in many parts of the world and human activities are changing the global water system without adequate knowledge of the consequences.

Scientists can offer knowledge, information and technical tools. But this is only part of the solution: governments must set up frameworks for better water management, and many other stakeholders — including decision makers, managers and technical personnel — must be involved to foster commitment and facilitate conflict resolution. 

As water crosses natural and political boundaries, governments must consider the water needs of all sectors. Better information will help to evaluate needs and prioritise water allocations between them. But the unavoidable compromises and trade-offs should be assessed based on scientific evidence — not influenced by lobbying and pressure groups.

Water management should be integral to climate change adaptation, and vice versa. 


To ensure water use stays within the planet's natural limits, interdisciplinary science should be complemented by ethical water governance and management practices. 

Research shows that good governance depends on having multiple centres of control, effective legal frameworks, reduced inequalities, free access to information and meaningful participation by stakeholders. In turn, good governance can help attract needed funds for clean water and sanitation.

The future should be seen through a water 'lens', say the authors. They conclude that, in order to develop solutions for sustainable water management, it is important to go beyond technical solutions to understand the complexities of the global water system — including the social and political dynamics, as well as human behaviours related to water use. This is a huge challenge, say the authors, but it is the only way forward.

This policy brief was compiled by the International Project Office of the Global Water System Project based in Bonn, Germany. It was commissioned by the international conference Planet Under Pressure: New Knowledge Towards Solutions.

Link to full article in Planet Under Pressure

Fuente: UN Conference on Sustainable Development (Rio+20)
SciDev

Natural sediment may shield groundwater from arsenic

Contamination of deep groundwater with arsenic from shallower sources may not be as serious as feared — if pumping deep water is limited to domestic use, a study has found.

Exposure to arsenic-contaminated groundwater has been linked to almost one in every five deaths in Bangladesh, and some 100,000 deep wells have been constructed to pump deeper, cleaner water. 

Recent modelling studies have suggested that these cleaner water sources are also being contaminated — from shallower water seeping down to replenish deeper wells.

But a study published in Nature Geoscience yesterday (9 October) found that natural adsorption of arsenic by sediment — sand in the aquifers — reduces contamination risk in most areas.

"Deep groundwater in Bangladesh is at risk from contamination by arsenic from shallow groundwater seeping downwards if not carefully managed," Yan Zheng, who co-authored the study while she was a senior scientist at Columbia University, United States, told SciDev.Net. 

"The risk is higher if deep groundwater is used for irrigation, which consumes a lot more water than [use for] domestic purposes."

Modelling studies have suggested that the contamination of deep groundwater results from shallower water seeping down to replenish pumped deep water. 

But these studies did not consider the influence of sediment, which can adsorb arsenic, Zheng and her team say.

They  tested this adsorption in the field in Bangladesh, and used their results to estimate the vulnerability of deep groundwater to arsenic pollution from shallower water seeping down.

They found that sediment removes around 70 per cent of arsenic within a day, reducing the risk of contamination of deep groundwater in most, but not all areas; and more so when the water is pumped for domestic use only, rather than irrigation. 

This suggests that current contamination of deep wells is either natural or comes from individual cases of badly designed wells that allow more seepage, Zheng said.

She added that the recommendation for the policymakers "is not to use deep groundwater for irrigation", and to regularly and systematically monitor water quality in the areas identified as more vulnerable to contamination.

Zheng also said that the agricultural sector should urgently look for sources of surface water to use for irrigation instead of groundwater.

Wais Kabir, executive chair of Bangladesh Agricultural Research Council, agreed that irrigation leads to higher risk of arsenic contamination of groundwater and said that Bangladesh needs to "change its food habits" and produce crops that need less irrigation.

S M Ihtishamul Huq, the Department of Public Health Engineering's superintendent engineer, told SciDev.Net: "We have to be more cautious while using groundwater for irrigation where the presence of arsenic is much higher."

He suggested changing crop patterns to reduce dependency on groundwater for irrigation. 

For example, he said: "We cultivate paddy during the winter using the groundwater irrigation. If we instead produce wheat [in] that period we do not need to irrigate much."

Link to full paper in Nature Geoscience

Syful Islam
SciDev

Plastic bottles could clean arsenic-contaminated water

Chopped up plastic bottles covered in a common chemical may be a simple and inexpensive method for removing arsenic from drinking water.

A team of chemists at Monmouth University, United States, found that bits of plastic coated with cysteine, a common molecule found in foods, bind to arsenic.

http://pampawater.blogspot.com/p/plastic-bottles-could-clean-arsenic.html