Banca de DEFESA: DIÓGENES FERNANDES DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DIÓGENES FERNANDES DOS SANTOS
DATE: 30/03/2020
TIME: 09:00
LOCAL: Sala 03 do LARHISA
TITLE:

DROUGHT AND ITS QUALI-QUANTITATIVE IMPACTS ON AVAILABILITY WATER RESERVOIRS IN THE SEMI-ARID REGION

KEY WORDS:

Standardized precipitation index. Dry. Public health. Water security. Semiarid.

PAGES: 59
BIG AREA: Engenharias
AREA: Engenharia Sanitária
SUMMARY:

Drought is a natural and recurring phenomenon, especially in the Brazilian semiarid region, which is vulnerable to interannual climate variability. In this sense, aquatic ecosystems, especially continental ones, as reservoirs, are increasingly susceptible to the actions of extreme events (severe drought, intense rains). Thus, the characteristics of semi-arid regions, such as the intermittency of rivers and high evaporation rates, combined with prolonged drought, tend to increase nutrient levels and the residence time of water sources, favoring the eutrophic condition and unviability the use of these for human activities. The objective of this study was to identify the occurrence and characteristics of drought, and how it is associated with the temporal variability of the water volume stored in the springs of the semiarid region. In addition, the study sought to assess the impacts of prolonged drought on the water quality of these sources, verifying whether there was a change in their trophic status during the occurrence of drought events. To this end, the study was carried out in two small reservoirs (~ 12.7 and 10.4 km²) in the Piancó-Piranhas-Açu River basin in the semi-arid region of the state of Rio Grande do Norte. To identify the periods and characteristics of the meteorological and hydrological droughts, the SPI (Standardized Precipitation Index) was used, calculated from a 57-year-old rainfall database (1963-2019), and the anomaly of the stored volume of water in the reservoirs during 19 years (2001-2019). The results showed that the 36-month SPI (SPI-36) was the best suited for the classification of meteorological droughts associated with water volume. The correlation between the SPI-36 and the monthly stored volume of the reservoirs was 0.89 and 0.87 (p <0.0001) for the Boqueirão (12.7 km²) and Passagem das Traíras (10.4 km²) reservoirs ), respectively. During the years 2001 to 2019, four meteorological droughts occurred, with different intensities and durations in the two reservoirs studied, with the Boqueirão reservoir (12.7 km²) presenting greater intensity and frequency, corresponding to ~ 22 to 11% of the total. events, while the reservoir of Passagem das Traíras (10.4 km²) moderate, severe and extreme droughts corresponded ~ 15, 11 and 9%, respectively. On the other hand, the hydrological drought is more intense in the reservoir of Passagem das Traíras. The most intense drought in both reservoirs lasted ~ 8 years (2012-2019). In the qualitative approach, during the years 2012 to 2019, the results indicated that there was an increase in chlorophyll-a, electrical conductivity, pH and turbidity due to the reduction in the water volume of the reservoirs. As well, when comparing the periods, it was verified a variation in the concentrations of total phosphorus and dissolved reactive phosphorus. In this sense, the study also demonstrated that the prolongation of drought had an impact on the intensification of eutrophication, changing the trophy status of Boqueirão de Parelhas, changing from mesotrophic to eutrophic. For the Passagem das Traíras spring, the permanence of the eutrophic state was evaluated, but with more intensified impacts, such as an increase in algal biomass confirming the hypothesis of the work. Understanding the impacts of drought on reservoirs, as well as the result of it on water availability, qualitative and quantitative, can be a facilitating means to better manage the region's water resources, as well as an important means in decision-making to mitigate the impact of drought in the population that depends on reservoirs for human supply, fishing, animal drinking and others.

BANKING MEMBERS:
Presidente - 1764855 - VANESSA BECKER
Interna - 052.716.174-83 - FABIANA OLIVEIRA DE ARAUJO SILVA - UFRN
Externo ao Programa - 2411669 - JONATHAN MOTA DA SILVA
Externo à Instituição - CARLOS RUBERTO FRAGOSO JUNIOR - UFAL