Effects of flow regime alteration on fluvial habitats and riparian quality in a semiarid Mediterranean basin

Abstract The Segura River Basin is one of the most arid and regulated zones in the Mediterranean as well as Europe that includes four hydrologic river types, according to their natural flow regime: main stem rivers, stable streams, seasonal streams and temporary streams. The relationships between flow regime and fluvial and riparian habitats were studied at reference and hydrologically altered sites for each of the four types. Flow regime alteration was assessed using two procedures: (1) an indirect index, derived from variables associated with the main hydrologic pressures in the basin, and (2) reference and altered flow series analyses using the Indicators of Hydrologic Alteration (IHA) and the Indicators of Hydrologic Alteration in Rivers (IAHRIS). Habitats were characterized using the River Habitat Survey (RHS) and its derived Habitat Quality Assessment (HQA) score, whereas riparian condition was assessed using the Riparian Quality Index (RQI) and an inventory of riparian native/exotic species. Flow stability and magnitude were identified as the main hydrologic drivers of the stream habitats in the Segura Basin. Hydrologic alterations were similar to those described in other Mediterranean arid and semiarid areas where dams have reduced flow magnitude and variability and produced the inversion of seasonal patterns. Additionally, the Segura Basin presented two general trends: an increase in flow torrentiality in main stems and an increase in temporality in seasonal and temporary streams. With the indirect alteration index, main stems presented the highest degree of hydrologic alteration, which resulted in larger channel dimensions and less macrophytes and mesohabitats. However, according to the hydrologic analyses, the seasonal streams presented the greatest alteration, which was supported by the numerous changes in habitat features. These changes were associated with a larger proportion of uniform banktop vegetation as well as reduced riparian native plant richness and mesohabitat density. Both stream types presented consequent reductions in habitat and riparian quality as the degree of alteration increased. However, stable streams, those least impacted in the basin, and temporary streams, which are subject to great hydrologic stress in reference conditions, showed fewer changes in physical habitat due to hydrologic alteration. This study clarifies the relationships between hydrologic regime and physical habitat in Mediterranean basins. The hydrologic and habitat indicators that respond to human pressures and the thresholds that imply relevant changes in habitat and riparian quality presented here will play a fundamental role in the use of holistic frameworks when developing environmental flows on a regional scale.

[1]  I. Schnauder,et al.  Flow in a tightly curving meander bend: effects of seasonal changes in aquatic macrophyte cover , 2012 .

[2]  James J. Butler,et al.  Patterns of Tamarix water use during a record drought , 2010, Oecologia.

[3]  C. Nilsson,et al.  Alterations of Riparian Ecosystems Caused by River Regulation , 2000 .

[4]  G. Quinn,et al.  Experimental Design and Data Analysis for Biologists , 2002 .

[5]  Jeffrey H. Braatne,et al.  Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon , 2007, Environmental management.

[6]  David P. Braun,et al.  A Method for Assessing Hydrologic Alteration within Ecosystems , 1996 .

[7]  Wayne D. Erskine,et al.  River rehabilitation from the hydrogeomorphic impacts of a large hydro‐electric power project: Snowy River, Australia , 1999 .

[8]  Anna Zimmer.  New water uses in the Segura basin: conflicts around gated communities in Murcia , 2010 .

[9]  Brian Richter,et al.  ECOLOGICALLY SUSTAINABLE WATER MANAGEMENT: MANAGING RIVER FLOWS FOR ECOLOGICAL INTEGRITY , 2003 .

[10]  F. Magilligan,et al.  Changes in hydrologic regime by dams , 2005 .

[11]  Jorge de las Heras,et al.  Assessment of regulated rivers with indices based on macroinvertebrates, fish and riparian forest in the southeast of Spain , 2010 .

[12]  D. Noble,et al.  Combining surveys of river habitats and river birds to appraise riverine hydromorphology , 2007 .

[13]  J. Casas,et al.  Riparian vegetation of two semi-arid Mediterranean rivers: Basin-scale responses of woody and herbaceous plants to environmental gradients , 2007, Wetlands.

[14]  N. Poff,et al.  Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows , 2010 .

[15]  Nick Davidson,et al.  Biodiversity impacts of large dams , 2001 .

[16]  Susan K. Jenson,et al.  Mapping the response of riparian vegetation to possible flow reductions in the Snake River, Idaho , 1995 .

[17]  W. Erskine,et al.  Complex response of a sand‐bed stream to upstream impoundment , 1991 .

[18]  D. Merritt,et al.  Shifting dominance of riparian Populus and Tamarix along gradients of flow alteration in western North American rivers. , 2010, Ecological applications : a publication of the Ecological Society of America.

[19]  M. R. Vidal-Abarca.  Los ríos de las cuencas áridas y semiáridas: una perspectiva ecológica comparativa y de síntesis , 1990 .

[20]  Jennifer G O Wilhelm,et al.  Habitat Assessment of Non-Wadeable Rivers in Michigan , 2005, Environmental management.

[21]  M. Zamorano,et al.  Implementation of the European Water Framework Directive: Integration of hydrological and regional planning at the Segura River Basin, southeast Spain , 2011 .

[22]  S. Vicente‐Serrano,et al.  The impact of droughts and water management on various hydrological systems in the headwaters of the Tagus River (central Spain) , 2010 .

[23]  R. Naiman,et al.  The challenge of providing environmental flow rules to sustain river ecosystems. , 2006, Ecological applications : a publication of the Ecological Society of America.

[24]  Andrea Buffagni,et al.  Occurrence and variability of River Habitat Survey features across Europe and the consequences for data collection and evaluation , 2006, Hydrobiologia.

[25]  W. J. Matthews,et al.  Biotic and Abiotic Controls in River and Stream Communities , 1988, Journal of the North American Benthological Society.

[26]  R. Scott,et al.  ECOHYDROLOGICAL IMPLICATIONS OF WOODY PLANT ENCROACHMENT , 2005 .

[27]  P. Weisberg,et al.  Does river regulation increase the dominance of invasive woody species in riparian landscapes , 2010 .

[28]  D. Cooper,et al.  Processesof Tamarix invasion and floodplain development along the lower Green River, Utah. , 2006, Ecological applications : a publication of the Ecological Society of America.

[29]  Francisco Martínez-Capel,et al.  Six decades of changes in the riparian corridor of a Mediterranean river: a synthetic analysis based on historical data sources , 2013 .

[30]  W. Graf.  Downstream hydrologic and geomorphic effects of large dams on American rivers , 2006 .

[31]  S. Vicente‐Serrano,et al.  Recent trends in Iberian streamflows (1945-2005) , 2012 .

[32]  Keith F. Walker,et al.  A perspective on dryland river ecosystems , 1995 .

[33]  E. Tabacchi,et al.  LANDSCAPE STRUCTURE AND DIVERSITY IN RIPARIAN PLANT COMMUNITIES: A LONGITUDINAL COMPARATIVE STUDY , 1996 .

[34]  Susana Nieto,et al.  Trends of precipitation over the Iberian Peninsula and the North Atlantic Oscillation under climate change conditions , 2010 .

[35]  F. H. Dawson,et al.  Quality assessment using River Habitat Survey data , 1998 .

[36]  N. LeRoy Poff,et al.  The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards , 2007 .

[37]  S. Siegel,et al.  Nonparametric Statistics for the Behavioral Sciences , 2022, The SAGE Encyclopedia of Research Design.

[38]  Maurice J. Duncan,et al.  Flow variability in New Zealand rivers and its relationship to in‐stream habitat and biota , 1990 .

[39]  Raymond N. Gorley,et al.  PERMANOVA+ for PRIMER. Guide to software and statistical methods , 2008 .

[40]  F. H. Dawson,et al.  Using river habitat survey for environmental assessment and catchment planning in the U.K. , 2000, Hydrobiologia.

[41]  Mark D. Dixon,et al.  Riparian vegetation along the middle Snake River, Idaho: zonation, geographical trends, and historical changes , 1999 .

[42]  J. Olden,et al.  Homogenization of regional river dynamics by dams and global biodiversity implications , 2007, Proceedings of the National Academy of Sciences.

[43]  Geoffrey E. Petts,et al.  Long-term Consequences of Upstream Impoundment , 1980, Environmental Conservation.

[44]  Nigel Holmes,et al.  Benchmarking habitat quality: observations using River Habitat Survey on near‐natural streams and rivers in northern and western Europe , 2010 .

[45]  Andrea Buffagni,et al.  Characterising Hydromorphological Features of Selected Italian Rivers: A Comparative Application of Environmental Indices , 2004 .

[46]  T. Hollenhorst,et al.  Use of GIS and remotely sensed data for a priori identification of reference areas for Great Lakes coastal ecosystems , 2005 .

[47]  J. Olden,et al.  Redundancy and the choice of hydrologic indices for characterizing streamflow regimes , 2003 .

[48]  R. Batalla,et al.  Reservoir-induced hydrological changes in the Ebro River basin (NE Spain) , 2004 .

[49]  S. Vicente‐Serrano,et al.  Dam effects on droughts magnitude and duration in a transboundary basin: The Lower River Tagus, Spain and Portugal , 2009 .

[50]  C. Nilsson,et al.  Basic Principles and Ecological Consequences of Changing Water Regimes: Riparian Plant Communities , 2002, Environmental management.

[51]  Daren M. Carlisle,et al.  GAGES: A stream gage database for evaluating natural and altered flow conditions in the conterminous United States , 2010 .

[52]  David P. Braun,et al.  How much water does a river need , 1997 .

[53]  W. C. Johnson,et al.  Forest Overstory Vegetation and Environment on the Missouri River Floodplain in North Dakota , 1976 .

[54]  A. Millán,et al.  The influence of natural flow regimes on macroinvertebrate assemblages in a semiarid Mediterranean basin , 2013 .

[55]  J. Gower.  A General Coefficient of Similarity and Some of Its Properties , 1971 .

[56]  M. Naura,et al.  The development of physical quality objectives for rivers in England and Wales , 2002 .

[57]  J. Ortiz,et al.  Riparian quality and habitat heterogeneity assessment in Cantabrian rivers , 2011 .

[58]  J. Podani.  Extending Gower's general coefficient of similarity to ordinal characters , 1999 .

[59]  P. J. Boon,et al.  Characterization of freshwater pearl mussel (Margaritifera margaritifera) riverine habitat using River Habitat Survey data , 2003 .

[60]  J. Cotton,et al.  The effects of seasonal changes to in-stream vegetation cover on patterns of flow and accumulation of sediment , 2006 .

[61]  M. Molina Arias,et al.  El problema de las comparaciones múltiples , 2014 .

[62]  P. Davies,et al.  Macroinvertebrate assemblages of littoral habitats in the Macquarie and Mersey Rivers, Tasmania : implications for the management of regulated rivers. , 1996 .

[63]  Francisco Lara García,et al.  Índice RQI para la valoración de las riberas fluviales en el contexto de la directiva marco del agua , 2006 .

[64]  A. Arthington,et al.  Basic Principles and Ecological Consequences of Altered Flow Regimes for Aquatic Biodiversity , 2002, Environmental management.

[65]  K. Walker,et al.  Tolerance of riverine plants to flooding and exposure indicated by water regime , 1999 .

[66]  E. Muller,et al.  Hydrologic thresholds for riparian forest conservation in a regulated large Mediterranean river , 2012 .

[67]  K. Sand‐Jensen,et al.  Fine-scale patterns of water velocity within macrophyte patches in streams , 1996 .

[68]  Stéphanie Manel,et al.  Testing large-scale hypotheses using surveys: the effects of land use on the habitats, invertebrates and birds of Himalayan rivers , 2000 .

[69]  Andrea Buffagni,et al.  Preliminary testing of River Habitat Survey features for the aims of the WFD hydro-morphological assessment: an overview from the STAR Project , 2006, Hydrobiologia.

[70]  S. Schneider,et al.  Climate Change 2007 Synthesis report , 2008 .

[71]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[72]  A. Marín,et al.  Natural flow regime, degree of alteration and environmental flows in the Mula stream (Segura River basin, SE Spain) , 2010, Limnetica.

[73]  S. Sabater,et al.  Response of community structure to sustained drought in Mediterranean rivers , 2010 .

[74]  W. Dietrich,et al.  Downstream Ecological Effects of Dams: A geomorphic perspective , 1995 .

[75]  F. Martínez‐Capel,et al.  Hydrological Classification of Natural Flow Regimes to Support Environmental Flow Assessments in Intensively Regulated Mediterranean Rivers, Segura River Basin (Spain) , 2011, Environmental management.

[76]  H. Wolfert,et al.  Geomorphological change and river rehabilitation : case studies on lowland fluvial ystems in the Netherlands , 2001 .

[77]  K. Jorde,et al.  Application of a hierarchical framework for assessing environmental impacts of dam operation: changes in streamflow, bed mobility and recruitment of riparian trees in a western North American river. , 2009, Journal of environmental management.

[78]  F. Magdaleno,et al.  Hydromorphological alteration of a large Mediterranean river: Relative role of high and low flows on the evolution of riparian forests and channel morphology , 2011 .

[79]  Gregor T. Auble,et al.  Downstream effects of dams on channel geometry and bottomland vegetation: Regional patterns in the great plains , 1998, Wetlands.

[80]  Daren M. Carlisle,et al.  Quantifying human disturbance in watersheds: Variable selection and performance of a GIS-based disturbance index for predicting the biological condition of perennial streams , 2010 .