River Flow Alterations Caused by Intense Anthropogenic Uses and Future Climate Variability Implications in the Balkans

Christina Papadaki,Elias Dimitriou

doi:10.3390/hydrology8010007

Abstract

River flow alterations, caused by climate variability/change and intense anthropogenic uses (e.g., flow regulation by dams) are considered among the main global challenges of which hydrologists should be dealing with. For the purpose of this study, environmental flow and potential hydrological alterations are made for the extended Drin river basin, with limited historical hydrological information available. To overcome this limitation environmental flow assessment is made using simulated streamflow data from a watershed hydrological model. Descriptive statistics applied to streamflow values indicate that median monthly flows with no anthropogenic uses are consistently greater than those with anthropogenic uses by 0–37.4 m3/s in all subbasins. Moreover, an investigation of potential climate variability/change impact on river flow regime is made using streamflow simulations from a global hydrological model. Results indicate that hydrologic alteration is intense between nonregulated and regulated streamflow conditions. More specifically, for all Global Circulation Models and Regional Climate Models combinations, and both regulated and unregulated streamflow conditions, the minimum discharge values had statistically significant decreasing trends, except one combination (RCP 4.5–RCA4/ECEARTH) for unregulated conditions. Finally, results from this preliminary analysis could enhance the necessary conversations among all relevant stakeholders to discuss and decide on sustainable water resources management issues for the development of a Drin Basin Management Plan in the future.

Highlights

Maximum flow conditions in the Ohrid subbasin have evident differences between baseline and post−baseline streamflow indicating a possible overexploitation of instream flows by anthropogenic uses
These results indicate increased water uses in the study area
The differences in maximum flows between the two flow scenarios are relatively small for all subbasins, excluding Ohrid which implies that the winter anthropogenic abstractions are not significant in relation to the discharge outflow

Summary

Introduction

Environmental flows represent the water required to sustain freshwater and estuarine ecosystems, and the human livelihoods that depend on these ecosystems [1,2]. River water designated for environmental outcomes can be either flow remaining in the river protected from abstraction, or actively released water from storages to achieve desired ecosystem outcomes [3]. All components of a flow regime influence the river ecosystems [4]. River flow alterations may be caused by numerous factors; including climate variability/change and flow regulation by dams [3,5]. Hydromorphological pressures may cause alteration to the natural flow regime of rivers [6]. There is an urgent need to develop sustainable environmental flow management guidelines [7], especially in areas where flow—ecology relationships have not been well established

Methods

Results

Discussion

Conclusion