Dry spells and their impacts on reservoir inflow in semiarid regions: hypothesis outline in a case study of Orós hydrographic basin, Ceará, Brazil

Veranicos e seus impactos na recarga de reservatórios em regiões semiáridas: delineando hipóteses em um estudo de caso para a bacia hidrográfica do Orós, Ceará, Brasil

ABSTRACT

The occurrence of subseasonal phenomena, such as dry spells and flash droughts, are potentially detrimental to the agricultural sector and water resources. The impacts on agricultural sector have been well explored by the technical-scientific community, attesting to the importance of subseasonal variability for this sector, especially for low-tech farming areas. However, when it comes to water resources, there is a large gap regarding the hydrological impacts of these phenomena, in a way that pertinent questions about the importance of subseasonal variability for water resources management remain still unexplored or poorly understood. This study evaluated the impacts of dry spells on reservoir inflow in semiarid regions, taking the Orós reservoir (Northeast Brazil) as a case study. The relationship between the dry spell index and the inflow of Orós reservoir during the rainy season was analyzed, as well as the daily time series of precipitation and storage volume during two long-term dry spells. The two formulated hypotheses suggest that dry spells are indeed capable of reducing the reservoir inflow efficiency in semiarid regions during rainy seasons. These hypotheses serve as a starting point for a deeper discussion on the impacts of dry spells on water resource management in arid and semiarid regions.

Keywords:
Dry spell; Semi-arid; Reservoir inflow; Subseasonal variability