Europe

Using Technology and Old Photos to Map Erosion in Jaén's Olive Groves

Researchers from the University of Jaén have developed a tool to more precisely monitor soil erosion. It may help growers to estimate future damage and put in place preventive measures.
Photo courtesy of the University of Jaén.
Jul. 1, 2020
Paolo DeAndreis

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A new method for ana­lyz­ing soil ero­sion and its impact on olive groves has been devel­oped by the researchers at the Uni­ver­sity of Jaén.

A bet­ter under­stand­ing of how the groves’ soil changes over time – its com­po­si­tion, vol­ume, shape and other char­ac­ter­is­tics – may offer grow­ers a new set of tools to plan their oper­a­tions.

Con­sid­er­ing these find­ings, we sus­pect that an accel­er­a­tion in the soil ero­sion process is on its way, prob­a­bly due to the effects of infra­struc­ture, dif­fer­ent poli­cies in the man­ag­ing of the ter­ri­tory as well as the chang­ing rain­fall.- Tomás Fer­nán­dez, researcher, Uni­ver­sity of Jaén

The team, from the uni­ver­si­ty’s cen­ter for advanced stud­ies of Earth sci­ences, energy and envi­ron­ment, stud­ied aer­ial pho­tographs taken over sev­eral decades to eval­u­ate the chang­ing soil con­di­tions of the olive groves. 

The aer­ial pho­tographs col­lected either by con­ven­tional air­craft plat­forms or drones were cou­pled with LiDAR (Laser imag­ing detec­tion and rang­ing) data to make dig­i­tal sur­face mod­els,” Tomás Fer­nán­dez, one of the authors of the study, told Olive Oil Times.

See more: Research News

He added that these dig­i­tal ele­va­tion mod­els (DEMs), are accu­rate rep­re­sen­ta­tions of the ground heights.”

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By com­par­ing DEMs obtained from decades of aer­ial pho­tographs and LiDAR, a whole new set of data was cre­ated 

In Spain, we’ve had peri­od­i­cal aer­ial flights over the ter­ri­tory since 1956. Since 2004, this has hap­pened every two or three years, and drone flights can be oper­ated when needed,” Fer­nán­dez said.

There­fore, we could com­pare DEMs from dif­fer­ent dates and the result of this com­par­i­son, the dif­fer­en­tial DEMs, allows us to iden­tify areas in which the ground sur­face decreases – the ero­sion areas – and loca­tions where the ground sur­face increases – the depo­si­tion areas,” he added.

By quan­ti­fy­ing these areas and the ero­sion or depo­si­tion heights asso­ci­ated with them, researchers were able to eval­u­ate the vol­umes of mate­r­ial involved in the chang­ing soil shapes.

We have cal­cu­lated an increase of two inches per year in some sec­tors of the gul­lies from 1984 to present, and soil losses of 50 tons per year for every 2.5 acres, almost twice the esti­mated annual aver­age losses in the province of Jaén,” Fer­nán­dez said.

The researchers also deter­mined that dur­ing peak peri­ods, when soil ero­sion accel­er­ated, such as from 2009 to 2010, the rate of ero­sion reached 20 inches per year with a total loss of 450 tons per year for every 2.5 acres, a ten­fold increase when com­pared to the aver­age losses that were esti­mated by experts and farm­ers before this study was com­pleted. 

Those are val­ues to be taken into account because they cause very sig­nif­i­cant losses of fer­tile soil, as well as very sig­nif­i­cant dam­age to crops and infra­struc­ture,” Fer­nán­dez said.

Researchers also found a cor­re­la­tion between soil ero­sion in olive groves and peri­ods of increased rain­fall – a find­ing with a twist.

The researchers noted that soil ero­sion in peri­ods of heavy rain­fall had a more notice­able impact in recent years, such as from 2009 to 2013, when com­pared to sim­i­lar rain­fall pat­terns from ear­lier time peri­ods, such as from 1996 to 1998.

Con­sid­er­ing these find­ings, we sus­pect that an accel­er­a­tion in the soil ero­sion process is on its way, prob­a­bly due to the effects of infra­struc­ture, dif­fer­ent poli­cies in the man­ag­ing of the ter­ri­tory as well as the chang­ing rain­fall,” Fer­nán­dez said.

While the study was con­ducted in a spe­cific olive oil pro­duc­ing region, the method devised by the researchers can be applied to other rel­e­vant ter­ri­to­ries as well.

The tech­nique can poten­tially be applied every­where, at least where aer­ial pho­tog­ra­phy of the ter­ri­tory and LiDAR data can be made avail­able,” Fer­nán­dez said. Should these data not be avail­able, a his­tor­i­cal inves­ti­ga­tion is not pos­si­ble.”

Still, actual and future evo­lu­tion in the soil ero­sion can be addressed by means of drone flights or ter­res­trial pho­togram­me­try and LiDAR,” he added.

Their study could help bet­ter under­stand what the researchers believe is a cur­rent major prob­lem at the global level, which has a rel­e­vant impact in Mediter­ranean coun­tries and, locally, in the olive groves of Jaén.”

A prob­lem, they said, which may crit­i­cally increase in the com­ing years.”





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