{"id":789,"date":"2020-09-21T06:21:41","date_gmt":"2020-09-21T05:21:41","guid":{"rendered":"https:\/\/cimafoundation.org\/2020\/09\/21\/the-role-of-evapotranspiration-in-driving-the-water-balance-during-droughts\/"},"modified":"2022-09-29T08:40:46","modified_gmt":"2022-09-29T08:40:46","slug":"the-role-of-evapotranspiration-in-driving-the-water-balance-during-droughts","status":"publish","type":"post","link":"https:\/\/www.cimafoundation.org\/en\/news\/the-role-of-evapotranspiration-in-driving-the-water-balance-during-droughts\/","title":{"rendered":"The role of evapotranspiration in driving the water balance during droughts"},"content":{"rendered":"\n

A study has shown how evapotranspiration, i.e., water used by vegetation or evaporated from the soil, drives the water balance during multi-year droughts. Vegetation water consumption during droughts is still a poorly understood topic, and these results will provide a starting point to improve our knowledge and consequently our predictive models<\/em><\/h4>\n\n\n\n

It is intuitive to think that water resources will be abundant during periods with high precipitation, while periods with low precipitation will translate into water shortages. However, the proportion between precipitation and the consequent water supply is not always as expected. In fact, scientists have already observed that, during multi-year droughts, water availability will generally be lower than one would expect. But why? According to a study<\/a> recently published in Hydrology and Earth System Sciences<\/em> and coauthored by one of the researchers of CIMA Research Foundation, this is because of plants, which require some extra time to adapt to droughts. <\/p>\n\n\n\n

An unbalanced balance<\/h4>\n\n\n\n

\u201cIn areas with a Mediterranean climate, i.e., those in which precipitation is larger in winter and lower in summer, multi-year droughts generally lead to a drop in available water resources. This decrease is even 30+ percent larger than you would expect,\u201d Francesco Avanzi, researcher in the Hydrology and Hydraulics Department<\/a> of CIMA Research Foundation and first author of the paper, explains. \u201cThis process is rarely reproduced by hydrological models. More precisely, these predictive models often overestimate the amount of water that will be available during a long period of drought. In this research, we investigated the mechanisms underlying this shift in the water balance, in order both to better understand the possible effects of drought and to improve the modeling.\u201d<\/p>\n\n\n\n

The study focused on a particular area of California,\na US state with Mediterranean climate that has been affected by four major and\nlong droughts since the 1970s. \u201cThe last one was in 2012 and lasted until 2016-17.\nIt has had very serious effects on crops, vegetation, ecosystems, and even water\nsupply for civil consumption. Vegetation across the Sierra Nevada is still suffering\nfrom the adverse effects of this drought\u201d, Avanzi continues. <\/p>\n\n\n\n

The first step of their researchers was to quantify\nthe shift observed during the four major Californian droughts; in other words,\nthey calculated how much less water there was compared to expected. Then, using\npast droughts as testbed, they investigated the predictive accuracy of the PRMS\nmodel, a tool that is widely used in operational hydrology across the US.\nFinally, they pinpointed the factors that most influenced the drop in\npredictive accuracy during droughts. Comparing observed data with those\nproduced by the model, they realized that the factor that was most affecting\nthe results was evapotranspiration<\/strong>, i.e. water used by vegetation and that\nevaporates from the soil.<\/p>\n\n\n\n

Plants with little elasticity<\/h4>\n\n\n\n

\u201cFor vegetation, adapting to changing environmental\nconditions is not immediate. On the contrary, in periods of drought, plants can\ninitially consume even more water than usual. This depends on several factors,\nnot least the fact that the recent drought has been associated with comparatively\nhigh temperatures\u201d, Avanzi explains. \u201cOnly after a certain period of time, a\nseries of adaptation processes take place: some plants reduce their water\nconsumption, others die, giving way to species that are more able to live in\ndrought, others are consumed by fires.\u201d<\/p>\n\n\n\n

Avanzi and coauthors called “climate elasticity\nof evapotranspiration<\/strong>” the capability of vegetation-water use to adapt\nto changes in environmental conditions. This factor is important in order to\nassess how much vegetation can affect water availability during droughts –\nincluding water needed by our societies.<\/p>\n\n\n\n

\u201cThis study helps us better understand the impact of multi-year droughts on the water balance, an important field of study, especially considering that climate change may affect the timing and frequency of droughts. It also allows us to work on improving forecasting models in a more targeted way, so that these models will be able to simulate all components of the water balance and not \u201conly\u201d those that have been traditionally important for our disciplines, such as streamflow. In other words, these studies will allow us to get the right answer for the right reason: this is what we are now doing with the Continuum<\/a> model, developed by CIMA Research Foundation\u201d, the researcher concludes.<\/p>\n","protected":false},"excerpt":{"rendered":"

A study has shown how evapotranspiration, i.e., water used by vegetation or evaporated from the soil, drives the water balance during multi-year droughts. Vegetation water consumption during droughts is still a poorly understood topic, and these results will provide a starting point to improve our knowledge and consequently our predictive models It is intuitive to […]<\/p>\n","protected":false},"author":1,"featured_media":986,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[12,124],"tags":[89],"class_list":["post-789","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","category-hydrology-and-hydraulics","tag-droughts"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/posts\/789","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/comments?post=789"}],"version-history":[{"count":0,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/posts\/789\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/media\/986"}],"wp:attachment":[{"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/media?parent=789"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/categories?post=789"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cimafoundation.org\/en\/wp-json\/wp\/v2\/tags?post=789"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}