MINIMUM RIVER FLOW ESTIMATIONS � TUNDZHA RIVER, BULGARIAN CASE STUDY

Abstract

River hydrology is a key component in river resources planning and river engineering. Our recent study is focused on flow metrics that best describe the registered flow regime and hydrological characteristics of rivers within the Tundzha watershed located in South Bulgaria. The flow regime will be described using 5 broad categories: magnitude of river flow; frequency; duration; timing and rate of change. A special attention in the research was given to the low flows. Thirteen hydrometrics stations were selected for the analysis. Data were obtained from the monitoring network of the National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Bulgaria. A flow duration analysis was done for each station in Tundzha River basin in order to estimate the probability of occurrence of different flows. Low flow frequency analysis was conducted. Baseflow indices were calculated to estimate the relative contribution of ground flow or baseflow. Regional regression equations were calculated between flow metrics and drainage basin area. Hydrological analyses play an important role not only in water resources projects but also in instream flow and fish habitat studies. Furthermore, we believed that such a regional characterization of river hydrology will help water resources managers to better deal with water issues.