Groundwater Resources Recharge Faster than Previously Estimated

Research sheds light on the recharge rate of groundwater resources, which has important implications for the sustainable use of underground aquifers.
By Paolo DeAndreis
Jan. 17, 2023 15:13 UTC

New research pub­lished in the Geophysical Research Letter Journal sheds light on the con­nec­tion between ground­wa­ter and sur­face water fluxes. The results show that ground­wa­ter resources replen­ish at a sig­nif­i­cantly faster rate than pre­vi­ously thought.

The find­ings also hint at the sig­nif­i­cant role played by ground­wa­ter resources in evap­o­tran­spi­ra­tion and stream­flow. Such knowl­edge should improve cur­rent and future ground­wa­ter assess­ment.

Groundwater resources play a cru­cial role in sus­tain­ing farm­ing activ­i­ties and drink­ing water avail­abil­ity around the globe.

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The team of American and European sci­en­tists noted that the rate at which pre­cip­i­ta­tions replen­ish ground­wa­ter stor­age directly impacts sus­tain­able ground­wa­ter use.

Groundwater is an invalu­able global resource, but its long-term via­bil­ity as a resource for con­sump­tion, agri­cul­ture and ecosys­tems depends on pre­cip­i­ta­tion recharg­ing aquifers. How much pre­cip­i­ta­tion recharges ground­wa­ters varies enor­mously across Earth’s sur­face, yet recharge rates often remain uncer­tain,” the researchers wrote.

To mea­sure ground­wa­ter resource recharge rates, the researchers designed a cal­cu­la­tion model based on avail­able regional ground­wa­ter mea­sure­ment data from six con­ti­nents. That model showed how cli­mate deter­mines ground­wa­ter recharge rates, espe­cially arid­ity and pre­cip­i­ta­tion.

Using the cli­mate arid­ity para­me­ter, the sci­en­tists found that the global recharge rate of ground­wa­ter resources hap­pens twice as fast as pre­vi­ously esti­mated.

The paper’s authors explained that their find­ings show a higher-than-esti­mated per­cent­age of ground­wa­ter return­ing to the sur­face via river flow or when used by veg­e­ta­tion.

The higher recharge rates sug­gest that nat­ural phe­nom­ena, such as evap­o­tran­spi­ra­tion and stream­flow, depend on ground­wa­ter much more than pre­vi­ously thought. This result is espe­cially evi­dent when com­pared to the con­tri­bu­tion of other sur­face fluxes, such as over­land flow, shal­low sub­sur­face flows and soil-mois­ture-fed evap­o­tran­spi­ra­tion.

Consequences of the study could include the abil­ity to assess the impacts of cli­mate change on ground­wa­ter recharge, which is con­sid­ered highly uncer­tain and has not been glob­ally quan­ti­fied by cur­rent mod­els.

Strengthening the ground­wa­ter con­nec­tion to sur­face fluxes in these mod­els is essen­tial, given that mod­els are the foun­da­tion of our under­stand­ing of our planet and under­pin present-day envi­ron­men­tal sci­ence and pol­i­cy­mak­ing,” the authors wrote.

Finally, the sci­en­tists warned that their find­ings do not dis­re­gard the cur­rent under­stand­ing of ground­wa­ter overuse and the risk it rep­re­sents for global water secu­rity. Groundwater overuse results in stor­age deple­tion and declin­ing water lev­els that have been robustly doc­u­mented in (…) arid areas across the globe,” they wrote.


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