Hydrological modelling in small ungauged catchments

Area of Science:

• Hydrology
• Water Resource Management
• Environmental Science

Background:

• Accurate assessment of low flow events is vital for mitigating socioeconomic and ecological impacts.
• Brazil's limited streamflow measurement network leaves small (<300 km²) basins ungauged.
• Severe droughts in 2014-2016 highlighted water supply challenges in Minas Gerais.

Purpose of the Study:

• To evaluate the performance of the Silveira Method (SM) for estimating low flow in small, ungauged basins.
• To assess the suitability of SM for predicting local low flow rates during dry seasons.
• To analyze the water supply scenario in the São Bartolomeu river basin.

Main Methods:

• Utilized the Silveira Method (SM), a rainfall-runoff model tailored for dry season flow estimation in small ungauged basins.
• Applied SM to the São Bartolomeu river basin, a representative small ungauged basin in Minas Gerais, Brazil.
• Tested eleven scenarios varying drought period timing and duration for model parameterization.

Main Results:

• The best SM scenario underestimated low flow rates (Q95) by 31%, indicating suitability for local prediction.
• The model identified a potential imbalance between granted water concessions and available river flow during dry seasons.
• Results suggest a risk of unsustainable water supply in the São Bartolomeu river basin.

Conclusions:

• The Silveira Method (SM) demonstrates capacity as a valuable tool for assessing water potential in small, ungauged basins.
• Findings highlight the need for careful water resource management to prevent future supply shortages.
• The study underscores the importance of hydrological modeling for informed water governance.