MANAGEMENT OF SMALL AND LARGE WATER STORAGE INFRASTRUCTURE IN WATERSHEDS WITH IRRIGATION AND HYDROPOWER DEMANDS

Código

XXVI-SBRH0147

Autores

Julieta Augusto Nhampossa, Guilherme Fernandes Marques, Ana Paula Dalcin, AMAURY TILMANT, FILIPE SAMPAIO CASULARI PINHATI, LINEU NEIVA RODRIGUES

Tema

A - Planejamento e Gestão de Recursos Hídricos e Segurança Hídrica

Resumo

Water storage infrastructure allows mitigation of water availability imbalances and can be developed at both large and small scales. However, these developments are often uncoordinated, leading to trade-offs from expanding small reservoirs to large ones with multiple uses. The integration of small- and large-scale water storage is still not properly addressed in the literature, which is either focused on water balance and hydrologic simulation, which lacks explicit representation of important economic objectives and management rules to attain them, or large-scale system optimization, which lacks finer detail in the representation of local storage. This paper contributes to filling this gap with an integrated explicit stochastic modeling framework that combines small and large reservoirs in a system with competing economic uses (hydropower and irrigation) and an evaluation of economic trade-offs. The approach uses a hydroeconomic model based on Stochastic Dual Dynamic Programming (SDDP). The results for a study area in Brazil indicate that small reservoirs can increase water access by 14.2%, 90% of the time, especially in critical months at the beginning of the irrigation season and reduce supply variability (uncertainty) by over 83% to local irrigation. On average, irrigation deficit is reduced by about 8.5%. This comes at the expense of delayed refilling and earlier depletion of large reservoirs, resulting in energy trade-offs of 201.6 GWh/year, 90% of the time, a 27.6 % reduction. Results are useful to integrate energy, irrigation and water policies with infrastructure expansion investment and operations at both watershed and local scales, avoiding economic losses and conflicts.