Ion, diversion, and storage of flow alter rivers worldwide. In this context, minimum flow regulations are applied to mitigate adverse impacts and to protect affected river reaches from environmental deterioration. Mostly, however, only selected instream criteria are considered, neglecting the floodplain as an indispensable part of the fluvial ecosystem. Based on essential functions and processes of unimpaired temperate floodplain rivers, we identify fundamental principles to which we must adhere to determine truly ecologically-relevant environmental flows. Literature reveals that the natural flow regime and its seasonal components are primary drivers for functions and processes of abiotic and biotic elements such as morphology, water quality, floodplain, groundwater, riparian vegetation, fish, macroinvertebrates, and amphibians, thus preserving the integrity of floodplain river ecosystems. Based on the relationship between key flow regime elements and associated environmental components within as well as adjacent to the river, we formulate a process-oriented functional floodplain flow (ff-flow) approach which offers a holistic conceptual framework for environmental flow assessment in temperate floodplain river systems. The ff-flow approach underlines the importance of emulating the natural flow regime with its seasonal variability, flow magnitude, frequency, event duration, and rise and fall of the hydrograph. We conclude that the ecological principles presented in the ff-flow approach ensure the protection of floodplain rivers impacted by flow regulation by establishing ecologically relevant environmental flows and guiding flow restoration measures.

“The water runs the river.” This chapter focuses on the river flow as the fundamental process determining the size, shape, structure, and dynamics of riverine ecosystems. We briefly introduce hydrological regimes as key characteristics of river flow. Hydrological regimes are then linked to habitats and biotic communities. The effects of flow regulation as a result of human activities such as water abstraction (irrigation and hydropower), river channelization, land use, and climate change are demonstrated. Finally, methods to assess the environmental flow, the flow that is needed to maintain the ecological integrity, are described, and examples of successful flow restoration presented.

Rivers have all too often been considered as two-dimensional elements of terrestrial landscapes neglecting their own internal structure and heterogeneity. But rivers exhibit certain characteristics, which should grant them a special position in connectivity conservation. With habitat fragmentation causing dramatic losses in global aquatic biodiversity, ecological research put much effort into conservation measures for maintaining and restoring connectivity of riverine habitats. To make use of the full mitigation hierarchy, the implementation of both avoidance (e.g. large-scale planning) and mitigation measures (e.g. facilities for up- and downstream migration) should be aspired.

Hydropower (HP) is an important renewable energy source contributing 65.7% to Austria's national electricity generation. However, HP is also associated with ecosystem degradations jeopardizing the aims of the EU Water Framework Directive (WFD) and Habitats Directive. Based on the EU Renewable Energy Directive (RED), the Austrian Energy Strategy has defined goals to further increase HP production by 3.5 TWh until 2015. Because national strategies for HP development are widely missing, hydropower plants (HPPs) are planned and approved on a local and regional level, often neglecting the overall optimum for energy supply and ecology. Therefore, a decision support tool (Hy:Con) was developed to integrate the energy-economic characteristics of planned HPPs and conservation needs of ecologically sensible river stretches. Based on 102 planned HPPs in Austria, Hy:Con identified HPPs with high economic attractiveness and low conservation concerns. The results show that owing to the already high HP exploitation in Austria, only a minor number of projects are without conservation conflicts. Upgrading of existing HPPs was associated with least ecological impacts, while HPPs with reservoirs are favoured over run-of-river plants. Cumulated ecological effects of numerous small HPPs are significant, whereas their contribution to overall energy production is comparatively small. Hy:Con represents a strategic instrument that can help decision makers to govern the implementation of the RED and WFD in a transparent way to pinpoint the limitations of future HP development and to avoid conflicts and stranded investments. © 2015 The Autors. River Research and Applications Published by John Wiley & Sons Ltd

In today’s intrinsically connected world, the Water–Food–Energy–Climate Nexus (WFEC Nexus) concept provides a starting point for informed and transparent decision-making based on the trade-offs and synergies between different sectors, including aquatic ecosystems, food security, energy production, and climate neutrality. The WFEC Nexus approach is particularly applicable in regions requiring transboundary water management, such as Central Asia. Unfortunately, this region with unevenly distributed water resources—consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan—is characterized by data scarcity, which limits informed decision-making. However, open-source geodata is becoming increasingly available. This paper aims to fill Central Asia’s WFEC Nexus data gap by providing an overview of key data. We collected geodata through an integrated survey of stakeholders and researchers, stakeholder consultation, and literature screening. Sixty unique datasets were identified, belonging to one of six thematic categories: (1) climate, (2) hydrology, (3) geography and topography, (4) geomorphology, (5) ecology, and (6) anthropogenic uses. For each dataset, a succinct description, including a link to the online source, is provided. We also provide possible applications of using the presented datasets, demonstrating how they can assist in conducting various studies linked to the WFEC Nexus in Central Asia and worldwide.

Europäische Fließgewässer stehen unter starkem Nutzungsdruck. Dabei zählen Eingriffe in die Hydromorphologie im Rahmen energiewirtschaftlicher Nutzung oder durch Hochwasserschutzmaßnahmen zu den stärksten Belastungen. Heute gibt es nur noch wenige verbleibende natürliche oder naturnahe Gewässerstrecken. In Österreich befinden sich derzeit nur 15 % der Wasserkörper in einem „sehr guten“ und 22 % in einem „guten“ ökologischen Zustand. Um die Ziele der EU-Wasserrahmenrichtlinie zu erreichen, sind im Nationalen Gewässerbewirtschaftungsplan Maßnahmen definiert, mittels derer der gute Zustand der Wasserkörper erreicht werden soll bzw. künftige Beeinträchtigungen und Verschlechterungen des Zustandes verhindert werden sollen. Gleichzeitig gilt es, die Ziele der EU-Erneuerbare-Energien-Richtlinie zu erreichen. In Österreich spielt dabei insbesondere der weitere Ausbau der Wasserkraft eine wesentliche Rolle. Um sowohl Schutz- als auch Nutzungsziele zu erreichen bzw. um eine transparente Abwägung unterschiedlicher Interessen zu gewährleisten, ist eine strategische Planung notwendig. Im hier vorlegenden Artikel werden diesbezügliche Empfehlungen, Leitlinien und ausgewählte methodische Ansätze zusammengefasst. Anhand von drei methodisch aufeinander aufbauenden Fallbeispielen wird außerdem detailliert vorgestellt, wie Schutzpriorisierungen von Gewässerstrecken als Pre-planning-Instrumente herangezogen werden können. Außerdem wird eine Methodik vorgestellt, die bei bereits bestehenden Kraftwerksplanungen auf (über-)regionaler Ebene durch die Integration gewässerökologischer, naturschutzfachlicher und energiewirtschaftlicher Aspekte einen wesentlichen Beitrag bei der Entscheidungsfindung leisten kann.