21 Sep 2023
 | 21 Sep 2023
Status: this preprint is currently under review for the journal HESS.

Climate-change impact on reservoir evaporation and water availability in a tropical sub-humid region, north-eastern Brazil

Gláuber Pontes Rodrigues, Arlena Brosinsky, Ítalo Sampaio Rodrigues, George Leite Mamede, and José Carlos de Araújo

Abstract. The potential effects of climatic changes on water resources are crucial to be assessed, particularly in dry regions such as Northeast Brazil (1 million km2), where water supply is highly reliant on open-water reservoirs. This study analyses the impact of evaporation (by the Penman method) on water availability for four scenarios based on two regional climatic models (Eta-CanESM2 and Eta-MIROC5) under the Representative Concentration Pathways 4.5 and 8.5. We compared the water availability in the period of 2071–2100 with that of the historical period (1961–2005). The scenarios derived from the Eta-CanESM2 model indicate an increase in dry season evaporative rate (2 % and 6 %, respectively) by the end of the century. Unlike the above scenarios, the ones derived from the Eta-MIROC5 model both show a decrease in dry season evaporative rate of −2 %. Consequently, for a 90 % reliability level, the expected reservoir capacity to supply water with high reliability is reduced in 80 %. It is reasonable to state that both patterns of future evaporation in the reservoirs may prove to be plausible. Because model-based projections of climate impact on water resources can be quite divergent, it is necessary to develop adaptations that do not need quantitative projections of changes in hydrological variables, but rather ranges of projected values. Our analysis shows how open water reservoirs might be impacted by climate change in dry regions. These findings complement a body of knowledge on estimation of water availability in a changing climate and provide new data and insights on water management in reservoir-dependent drylands.

Gláuber Pontes Rodrigues et al.

Status: open (until 27 Dec 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-189', Maarten Krol, 23 Nov 2023 reply

Gláuber Pontes Rodrigues et al.

Gláuber Pontes Rodrigues et al.


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Short summary
The research focused in a four-million-inhabitants tropical region supplied by a network of open-water reservoirs whose dry season lasts 8 months (Jun−Dec). We analysed the impact of four climate change scenarios on the evaporation rate and the associated availability (water yield distributed per year). The worst-case scenario shows that by the end of the century (2071−2099) the evaporation rate in the dry season could increase by 6 %, which would reduce the stored water by about 80 %.