A new approach for assessing natural patterns of flow variability and hydrological alterations: The case of the Spanish rivers

Ensuring water is available for human use usually requires dams and reservoirs that severely affect river ecosystems. Hydrological alteration by river damming represents one of the most prominent human impacts on freshwater ecosystems. This paper presents a methodological approach to assessing the natural patterns of flow variability and hydrological alterations in Mediterranean rivers. The methodology first defines the admissible range of flow variability under a natural flow regime. Then, the methodology measures the environmental impact of flow regulation according to the inferred hydrological alteration and classifies rivers into homogeneous groups according to the magnitude, frequency, duration and seasonality of the impacts. This paper applies the proposed methodology to thirty-three river segments below large reservoirs located in the three largest Spanish watersheds (Duero, Ebro and Tajo). For each segment, this study evaluates the general impoundment characteristics and geographical contexts and calculates the flow impacts and the divergence between the circulating flows and the reference area of admissible flow variability on a daily basis for the period 2000 2010. This assessment of dam regulation impacts provides a reference to plan measures for mitigating these impacts. The advantages of this flow regulation impact analysis over other analyses are discussed in terms of the implementation of environmental water costs as suggested by the European Water Framework Directive. This approach expands the current understanding of water environmental costs and represents a practical management tool for decreasing the environmental impacts of flow regulation and for increasing water-use efficiency. (c) 2018 Elsevier Lt

Water pricing: are 'polluters' paying the environmental costs of flow regulation?

River ecosystems are severely affected by dams and reservoirs. The Water Framework Directive states that polluters should be financially responsible for the caused environmental damage. Nevertheless, the environmental costs associated to flow regulation often are not fully paid by water users. This study presents an approach to value the environmental costs of flow regulation based on the "polluter pays" principle, i.e., the amount to be paid should be proportional to the caused environmental impact. The procedure includes three major steps: (i) assessing the admissible range of regulated flow variability based on flow data during the pre-dam period, (ii) estimating the daily environmental impact of regulated flows according to the resulting hydrological change in terms of the intensity, duration and frequency of the impact, and (iii) calculating the environmental costs of flow regulation subject to spatiotemporal characteristics. This paper applies the proposed methodology in the Luna River, Spain. The advantages over other water cost valuation methodologies are discussed. The approach enlarges the current recognition of water environmental costs and represents a simple and practical management tool for achieving the objectives of the Water Framework Directive

Indicators of river system hydromorphological character and dynamics: understanding current conditions and guiding sustainable river management

The work leading to this paper received funding from the EU’s FP7 programme under Grant Agreement No. 282656 (REFORM). The Indicators were developed within the context of REFORM deliverable D2.1, therefore all partners involved in this deliverable contributed to some extent to their discussion and development

Flow regime patterns and their controlling factors in the Ebro basin (Spain)

Natural intra-annual flow fluctuations vary between rivers, being a determining factor for aquatic insects, fish and riparian communities which are adapted to the habitat conditions and different flows throughout the seasons. Moreover, restoration of seasonal flow patterns plays an important role in achieving good ecological status of rivers, through the preservation and/or recovery of components and processes of natural river ecosystems. In this work we: (a) classify fluvial segments in the Ebro basin (North-Eastern Spain) according to the intra-annual variability of flows under natural conditions using statistical cluster analysis of monthly mean flow data; (b) characterise the resulting flow typologies according to several ecologically important hydrological variables; (c) analyse the relationships between flow regimes of fluvial segments and physical variables from their catchments; and finally (d) predict the most probable natural flow regime using logistic models based on the most determinant physical characteristics. Fifteen natural flow typologies were described in the Ebro basin, which were characterised in terms of flow fluctuation through the year as well as timing, flow ratio and duration of the maximum and minimum flows. Precipitation, biogeography and geology of catchments showed the highest correlations with flow regimes. Basin size, mean elevation and slope were also correlated. The logistic model we developed had a prediction success of 72% in the Ebro basin. The definition of the natural hydrological conditions (to which the biological communities are tailored), even when flow data are not available, is an important support in the management of river ecosystems. It is especially suitable for setting goals in aquatic ecosystem conservation or restoration projects

A review of assessment methods for river hydromorphology

The work leading to this paper has received funding for the EU’s FP7 under Grant Agreement No. 282656 (REFORM

Classification of river morphology and hydrology to support management and restoration

The work leading to this paper has received funding from the European Union’s FP7 programme under Grant Agreement No. 282656 (REFORM

River Restoration in Spain: Theoretical and Practical Approach in the Context of the European Water Framework Directive.

River restoration is becoming a priority in many countries because of increasing the awareness of environmental degradation. In Europe, the EU Water Framework Directive (WFD) has significantly reinforced river restoration, encouraging the improvement of ecological status for water bodies. To fulfill the WFD requirements, the Spanish Ministry of the Environment developed in 2006 a National Strategy for River Restoration whose design and implementation are described in this paper. At the same time many restoration projects have been conducted, and sixty of them have been evaluated in terms of stated objectives and pressures and implemented restoration measures. Riparian vegetation enhancement, weir removal and fish passes were the most frequently implemented restoration measures, although the greatest pressures came from hydrologic alteration caused by flow regulation for irrigation purposes. Water deficits in quantity and quality associated with uncontrolled water demands seriously affect Mediterranean rivers and represent the main constraint to achieving good ecological status of Spanish rivers, most of them intensively regulated. Proper environmental allocation of in-stream flows would need deep restrictions in agricultural water use which seem to be of very difficult social acceptance. This situation highlights the need to integrate land-use and rural development policies with water resources and river management, and identifies additional difficulties in achieving the WFD objectives and good ecological status of rivers in Mediterranean countries

Consideraciones sobre el estado actual de las riberas de los principales cauces fluviales de la Cuenca del Rio Segura (S.E. de España)

The composition and structure of riparian vegetation of the Segura, Mundo and Guadalentín Rivers are studied in relation to different topographic and human variables. River Mundo presents the highest species diversity along the course, with values relatively high and nearly constant until its mouth. The Tajo-Segura Transfer reduce its natural summer low-flows and has a beneficia1 effect on the riparian community. Species diversity in Segura and Guadalentín Rivers is lower and decreases from head to the mouth, showing a good correlation with length river and altitud, respectively. Agricultura1 in the the Segura valley and grazing in Guadalentín basin seem to be the main causes degrading riparian ecosystems.En el presente trabajo se describe algunos aspectos de la composición y estructura de la vegetación de especies leñosas y helófitos de las riberas de los ríos Segura, Mundo y Guadalentín, analizando su relación con ciertas variables fisiográficas y de influencia humana que determinan su estado actual. El río Mundo es el que presenta mayor diversidad de especies en todo su recorrido, teniendo un marcado efecto el Trasvase Tajo-Segura al reducir su estiaje natural. Los nos Segura y Guadalentín presentan una diversidad decreciente aguas abajo, altamente correlacionada con la longitud de recorrido del río, en el primer caso, y con la altitud en el segundo. La agricultura y la ganadería extensiva, respectivamente, resultan ser las principales causas de su degradación

Un système hiérarchique multi-échelle et des indicateurs pour les processus et formes hydromorphologiques

The research objective for Deliverable 2.1 is to develop a process-based, multi-scale, hierarchical framework to support river managers in assessing the hydromorphological character of rivers, exploring the causes of hydromorphological problems, and devising sustainable management solutions