Look what’s swelling the sea...Rising Waters : A study says evaporation and precipitation of groundwater is responsible for a fourth of the annual sea level rise of 3.1 mm. File photo

Groundwater is becoming important to sustain agriculture, industry and drinking water. But as we exploit aquifers, more water becomes part of the hydrological cycle. A recent study shows evaporation and precipitation of groundwater is responsible for a fourth of the annual sea level rise of 3.1 mm.

The study,  to be published in Geophysical Research Letters, employed a global hydrological model run with 44 years (1958-2001) of data of precipitation, temperature and evaporation.

The researchers found that the contribution of groundwater to sea level rise is 0.8 mm per year. They were taken aback because this is surprisingly large when compared to the current annual rise in sea levels, which the Intergovernmental Panel on Climate Change estimates at 3.1 mm.

“We redid calculations several times because we did not believe it at first,” said Marc Bierkens, lead researcher and faculty of Geosciences at Utrecht University in the Netherlands. Groundwater, unlike surface waterbodies, is not susceptible to evaporation. Hence Bierkens and his team took into account the rate of groundwater depletion.

The model showed that the rate at which groundwater stocks are shrinking has more than doubled in the past four decades, increasing the amount of groundwater lost in a year from 126 cubic km to 283 cubic km. Most of the depleted groundwater ends up in the ocean and is in excess of the current hydrological cycle, they concluded.

Dinesh Kumar, groundwater expert and director of the Institute for Resource Analysis and Policy in Hyderabad, suggested a careful scrutiny because the study results contradict government data.

For instance, Kumar said, the paper suggests several regions in India such as the northeastern region show high groundwater recharge despite unfavourable conditions. But as per the water ministry’s groundwater maps, groundwater recharge is nearly zero in the northeastern region.

Bharat Lal Seth
Down To Earth Feature Service

Centre to study endosulfan effect

Union Minister of State for Environment Jairam Ramesh announced the panel after meeting Kerala forest minister Benoy Viswam recently.

Kerala had pressed the Centre to endorse a global ban on the pesticide before the sixth meeting of the Persistent Organic Pollutants Review Committee (POPRC) in Geneva in October.

Viswam and Kerala Chief Minister V S Achuthanandan had written to the MoEF before the meeting, but India did not support the ban.

Despite India’s opposition, POPRC recommended a ban to the Conference of Parties of the Stockholm Convention that will meet in April next. The convention is a global treaty to protect public health and environment from persistent organic pollutants.

Savvy Soumya Misra
Down To Earth Feature Service

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