Improved regionalization of streamflow by use of the streamflow equivalent of precipitation as an explanatory variable

SummaryRegionalization procedures are an important tool for estimating streamflow hydrography; however, there are difficulties associated with properly evaluating hydrological processes. This study aimed to propose a new explanatory variable for regionalization of the long-term average streamflow (Qlt) and permanent streamflow (present 95% of the time; Q95). The physical characteristic used was the drainage area (A), and the climatic variable considered was the annual rainfall, which was converted into the equivalent streamflow (Peq). Another explanatory variable was rainfall minus an abstraction value. This variable (Peq750) was also converted to streamflow. Use of Peq to replace A resulted in significant improvements in the statistical adjustment, particularly in the behavior of Qlt and Q95. The improvements were even more pronounced when using Peq750, which caused the distribution of specific streamflows to behave more consistently.

► A new explanatory variable for streamflow regionalization studies is proposed.
► Improvements in the statistical adjustment and in hydrologic behavior were observed.
► The use of the new variable resulted in more consistent hydrological behavior.
► The use of the new variable reduces the risks to the security of the water supply.