Effects of Small Reservoirs on Hydrological Droughts

Código

III-END0016

Autores

Udinart Prata Rabelo, Jörg Dietrich, Alexandre Cunha Costa, Max Nino Simshäuser, Fernanda Elise Scholz, Tam V. Nguyen, Elahe Fallah-Mehdipour, Pieter van Oel, IRAN EDUARDO LIMA NETO

Tema

12. Estiagens e Secas

Resumo

The combination of strategic large reservoirs with many small reservoirs in dryland catchments generates a High-density Reservoirs Network (HdRN) that should improve water security but can modify streamflows during dry and wet periods. The understanding of HdRN dynamics is extremely important for the management of water resources in drylands since a system of small reservoirs can influence hydrological processes at catchment scale. However, most studies use highly simplified models to represent small reservoirs in hydrological networks. Their horizontal connectivity and interaction with large strategic reservoirs are not represented in detail, which may lead to misinterpretation of the role of small reservoirs. To assess the impact of small reservoirs on the streamflow and its influence on hydrological drougths, this research aims to evaluate the annual flows generated at the outlet of a dryland watershed for scenarios with different number of small reservoirs per area. A detailed representation of a watershed, including large and small reservoirs, was modeled in SWAT, with the development of two scenario approaches, one of them considering or not the presence of small reservoirs and the other considering several hypotheses of densities of small reservoirs in the catchment. The water retention can reach up to 30% for dry years in future scenarios with higher densities of small reservoirs and the increase in the number of small reservoirs may intensify the period of extended droughts. The methodology proposed is highly transferable for catchments worldwide and may help water resources agencies to better prepare for future periods of droughts.