The analysis of streamflow variability and flood wave characteristics on the two lowland rivers in Croatia

<p>Climate changes affect streamflow variability on the long-term and short-term temporal scale. Consequently, analysis of changes in hydrological regime, but also in intensity and frequency of short-time flood events, enables better understanding of hydraulic and geomorphological processes in rivers. Changes in streamflow variability and flood wave characteristics may lead to intensifying riverbed erosion and lowering infrastructure safety, such as bridges over rivers. The aim of the study is to analyse hydrological regime for historical data from the selected gauging stations on the two large lowland rivers in Croatia: the Sava River and the Drava River. Analysis of the magnitude, frequency, variability, and timing of streamflow is conducted. Additionally, deterministic and probabilistic approach to determination of metrics that describe hydrograph shape is performed for the different threshold levels. Results obtained from this study will help in exploring riverbed erosion processes which may entail the increased scouring around bridge piers and consecutively impair the infrastructure reliability in the changing climate.</p><p><strong>Acknowledgments</strong></p><p>This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046) and DOK-2020-01.</p>

A Paleo Perspective of Alabama and Florida (USA) Interstate Streamflow

Seasonal reconstructions of streamflow are valuable because they provide water planners, policy makers, and stakeholders with information on the range and variability of water resources before the observational period. In this study, we used streamflow data from five gages near the Alabama-Florida border and centuries-long tree-ring chronologies to create and analyze seasonal flow reconstructions. Prescreening methods included correlation and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that several regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with March–October streamflow, and stepwise linear regression was used to create the reconstructions. Reconstructions spanned 1203–1985, 1652–1983, 1725–1993, 1867–2011, and 1238–1985 for the Choctawhatchee, Conecuh, Escambia, Perdido, and Pascagoula Rivers, respectively, all of which were statistically skillful (R2 ≥ 0.50). The reconstructions were statistically validated using the following parameters: R2 predicted validation, the sign test, the variance inflation factor (VIF), and the Durbin–Watson (D–W) statistic. The long-term streamflow variability was analyzed for the Choctawhatchee, Conecuh, Escambia, and Perdido Rivers, and the recent (2000s) drought was identified as being the most severe in the instrumental record. The 2000s drought was also identified as being one of the most severe droughts throughout the entire reconstructed paleo-record developed for all five rivers. This information is vital for the consideration of present and future conditions within the system.