Regional Regression Models of Mean Annual Streamflow and Design Flow in a Tropical Region of Colombia.

Sammanfattning: A responsible and sustainable water resources management is important. It is also crucial to take the presence of watercourses into account during design of hydraulic structures such as small dams and bridges. Doing this requires knowledge of estimates of annual streamflow and extreme flows to be used for design purposes. This study is divided into two parts, both focusing on the departments of Santander and Norte de Santander in Colombia where a tropical climate dominates. Both studies treat the creation of regression models using statistical tests to secure their reliability. The first study creates models for estimation of mean annual streamflow by relating streamflow to geomorphic and climate characteristics. Models are created for each individual department as well as for smaller, hydrologically homogeneous regions. The majority of the results show remarkably good fits with adjusted R2-values ranging from 86.1-99.3 % and VIF-values in the range of 1.00-3.20. The second study creates regression models for estimation of design flows, with return periods of 10, 20, 50 and 100 years, using geomorphic variables. It is found that watershed area, elevation and slope result in the best fit giving adjusted R2-values in the range of 72.8-75.7 % and a VIF-value equal to 1.536.