Guadiana River Basin Research Articles

First record of intraspecific cleaning behavior by the threatened Leuciscidae Squalius alburnoides (Steindachner, 1866) at the Guadiana River basin (Portugal).

Squalius alburnoides (Steindachner, 1866) is an endemic threatened species from the Iberian Peninsula. Here, we report the first observations of intraspecific cleaning behavior in isolated summer pools in the Guadiana River Basin (Portugal). We found that focal S. alburnoides solicited cleaning by adopting an immobile tail-stand position known as "posing," which immediately signaled a response to a few conspecifics that approached and inspect them. Our study expands the list of cleanerfish species in freshwaters, giving emphasis to the importance of mutual positive behavior within an endangered species, particularly when facing seasonal disturbance.

Missing Rainfall Daily Data: A Comparison Among Gap-Filling Approaches

AbstractMissing data is a frequent problem in meteorological and hydrological temporal observation data sets. Finding effective solutions to this problem is essential because complete time series are required to conduct reliable analyses. This study used daily rainfall data from 60 rain gauges spatially distributed within Portugal's Guadiana River basin over a 30-year reference period (1976–2005). Gap-filling approaches using kriging-based interpolation methods (i.e. ordinary kriging and simple cokriging) are presented and compared to a deterministic approach proposed by the Food and Agriculture Organization (FAO method). The suggested procedure consists of fitting monthly semi-variogram models using the average daily rainfall from all available meteorological stations for each month in a reference period. This approach makes it possible to use only 12 monthly semi-variograms instead of one for each day of the gap period. Ordinary kriging and simple cokriging are used to estimate the missing daily precipitation using the semi-variograms of the month of interest. The cokriging method is applied considering the elevation data as the secondary variable. One year of data were removed from some stations to assess the efficacy of the proposed approaches, and the missing precipitation data were estimated using the three procedures. The methods were validated through a cross-validation process and compared using different performance metrics. The results showed that the geostatistical methods outperformed the FAO method in daily estimation. In the investigated study area, cokriging did not significantly improve the estimates compared to ordinary kriging, which was deemed the best interpolation method for a large majority of the rainfall stations.

Integrating stakeholders' inputs to co-design climate resilience adaptation measures in Mediterranean areas with conflicts between wetland conservation and intensive agriculture

Designing sustainable management strategies in groundwater-dependent socio-economic systems in areas with scarce water resources and protected wetlands is a challenging issue. The high vulnerability of these systems to droughts will be exacerbated even further under future climate change (CC) and socio-economic scenarios. A novel integrated bottom-up/top-down approach is used to identify “climate resilient pathways”, from which to co-design adaptation strategies to reduce the impact of potential future CC and socio-economic scenarios. The approach followed two steps (1) the generation of local CC and socio-economic scenarios by downscaling global/regional climate models and (2) the identification and assessment of potential adaptation strategies through an iterative bottom-up/top-down approach. Top-down assessments of the impact of CC have been undertaken by propagating local scenarios within a chain of mathematical models based on expert criteria/assumptions. This allowed us to analyse of the physical vulnerability of the system under different potential CC and socio-economic scenarios by simulating them with a sequential modelling of rainfall–recharge, agriculture, and hydrological processes through a distributed groundwater finite difference model. These model results were discussed with the stakeholders at a first workshop, which aimed to identify potential adaptation strategies. The influence of the adaptation strategies on the future hydrological status was assessed by simulating them through the chain of models. These results were the inputs into the discussions at a second workshop, which aimed to validate and/or improve the results of the first workshop. The methodology was applied in the Upper Guadiana River Basin, where there is a long-standing conflict between wetland conservation and groundwater overexploitation for intensive agriculture. The future horizon 2016–2045 is analysed with the scenarios compatible with the emission scenario RCP4.5. The research has allowed us to conclude that groundwater pumping reduction would be the most robust and effective measure to reduce the impact of CC in the area.

External parasites: how anchor worms affect Iberian endemic fish

Lernaea cyprinacea, commonly known as anchor worm, is a cosmopolitan invasive copepod that parasitizes a wide variety of freshwater fish, including several native and endemic species of the Iberian Peninsula (Sánchez-Hernández 2017), like the Squalius alburnoides from the Guadiana River basin depicted in the photograph, with 3 different individuals attached. Anchor worm was introduced to Iberia from Asia in the 1970s (Simon Vicente et al. 1973). While males are free-living, adult females attach their anchors – a modification of the head – to the fish host, usually in the fins, gills or mouth. Infestation by this external parasite is easily recognised by the wounds, ulcers and inflammatory processes that it induces in the fish skin and muscle (Hossain et al. 2018, see photograph). It may also induce anaemia, malformations, reduced growth and increased susceptibility to secondary infections (Sánchez-Hernández 2017). Small fish are specially affected in their swimming ability, respiration and health condition due to infections and mechanical compression of internal organs, both resulting from the ulcerous skin lesions developed at anchoring sites (Guagliardo & Tanzola 2016). Since infestation prevalence are hypothesised to be positively correlated with higher water temperatures (Marcogliese 2001), outbreaks are expected to increase in intermittent southern Iberian rivers under a global climate change scenario (Macedo-Veiga et al. 2019), which will likely contribute to the aggravation of the conservation status of the already imperilled native fish species. Although broader studies are needed, reported prevalences are higher in native Iberian fish than in sympatric alien species (Macedo-Veiga et al. 2019)

Ecological role of the Eurasian otter, Lutra lutra (Mustelidae, Carnivora) as a seed dispersal species for riparian vegetation in Iberian fresh waters

Endozoochory is a mutualistic interaction between plants and animals. Such a relationship has rarely been examined in the Eurasian otter Lutra lutra. This study aimed to assess the use and electivity of fruit by this carnivore, along with the viability of ingested seeds. Otter spraints and fruit were collected from the River Bullaque (Guadiana River basin, central Spain) in June and September 2018-2019. A high occurrence of fruit (> 40%) was found in spraints during September. Otters ingested fruit in June from only one plant species: Iberian bushweed Flueggea tinctoria (Phyllanthaceae); whereas seeds ingested in September belonged to four plant species: apple mint Mentha suaveolens (Lamiaceae), common hawthorn Crataegus monogyna, dog rose Rosa canina and elmleaf blackberry Rubus ulmifolius (three Rosaceae species). According to the environmental availability, otters displayed avoidance for mint and rose, neutral selection for hawthorn and preference for blackberry. Germination was unsuccessful for mint seeds, whereas germination was the highest for blackberry (37%; 49% for blackbird Turdus merula, a well-known frugivorous species). Otters appear to display an ecological role as seed dispersers for riparian vegetation in Iberian fresh waters. These findings provide insights into this endozoochorous co-evolution between plants and Carnivora.

The Acheulean of the Upper Guadiana River Basin (Central Spain). Morphostratigraphic Context and Chronology

In the upper basin of the Guadiana River, especially in the sectors drained by its right-bank tributaries, the Bullaque and Becea rivers, important concentrations of Acheulean and Mousterian industries can be found in a superficial position. These industries have provided series containing tens of thousands of pieces. Deposits in stratigraphic position have also been identified, related to the fluvial terraces of the Guadiana and Jabalón rivers and some tributaries. Within the sector studied, in the province of Ciudad Real, the position of these deposits is related to alluvial fans developed on the slopes of the immediate reliefs. These fans, mainly composed of Lower and Middle Ordovician quartzite gravel, were eroded in their distal positions by the Bullaque and Becea rivers, forming very low terraces on which large concentrations of Acheulean and Mousterian lithic industry can be found. El Sotillo, the only known stratigraphic site in the area, was excavated in 2017–2019 and consists of several levels with Mousterian and Acheulean industry. We present the technological characteristics of the main Acheulean assemblage recognised at this site, for which numerical dates have been obtained placing its chronology in the second half of the Middle Pleistocene. The location of these sites, in surficial position and El Sotillo, allows us to recognise a territorial space with specific geographic characteristics and a very significant human impact.

Basketry as an ecosystem service of wetlands: traditional crafts in central Spain

Ecosystem services from wetlands include products such as food, water, fibers, timber, medicinal plants, and genetic resources for agriculture. One of the most abundant supplies is the raw material for basketry. In this study we aim to document the role of wetland plants as resources for basketry and broom-making in the Guadiana river basin and to analyze the local traditional knowledge of the species used in the area. We describe different types of baskets and other artifacts, and document basketry techniques. We found 30 species belonging to 12 families, 18 of them occurring in wetlands, four in irrigated fields, and seven in the adjacent dry territories. Twenty species are used in the manufacture of brooms. Twenty two types of basketry artifacts are described with their uses. The area shows a relevant cultural heritage, not merely as it was in the past, but also adapted to the new cultural and social contexts. The degradation and loss of wetlands in central Spain threatens these ecosystems and their associated cultural heritage. We suggest the declaration of this intangible human heritage as the “Culture of the Mediterranean Wetlands” before it disappears.

The catastrophic floods in the Guadiana River basin since 1500 CE

The task of retrieving information about past flood events is very important to reconstruct flood series data. In this work, a wide range of different sources including newspapers, technical reports, and books was consulted in order to recover information about catastrophic flood events in Badajoz (Spain). A set of 37 catastrophic floods of the Guadiana River that occurred in Badajoz in the winter months (DJFM - December, January, February, and March) have been recovered since 1500 CE. This strong seasonality constrain is due to the important influence of the large-scale circulation patterns in winter affecting the climate of the Iberian Peninsula. Moreover, it is found that there is a clear difference between a higher number of floods in the 19th and 20th centuries and a substantial lower value of floods in the 16th–18th centuries. Finally, we evaluated the long-term evolution and inter-annual variability of the precipitation and the main large-scale atmospheric circulation patterns that govern climate variability in Iberia (NAO and EA modes) for the period 1851–1985. This analysis suggests that most extreme floods observed in this period (26 events) correspond to consecutive months with higher than usual precipitation, driven in part by unusual values of both the NAO and the EA modes of variability.

Numerical reconstruction of historical extreme floods: The Guadiana event of 1876

In recent decades, the development of numerical tools has facilitated the ability to reproduce extreme flood events, which allows a far better understanding of their features, contributing to mitigate their negative effects in similar future scenarios. This paper analyzes the flood event that occurred in December 1876 in Badajoz (Spain-Guadiana basin), one of the most catastrophic flood events recorded in Europe, using a three-stage methodology. First, an estimation of the precipitation recorded in the Guadiana river basin during the days prior to the event was carried out starting from the precipitation data recorded in two precipitation stations located in the western part of the basin; second, Guadiana river flow in Badajoz was obtained by means of the HEC-HMS code using the precipitation estimated in the first stage. Third, the flood registered on December 1876 in Badajoz was reproduced using the numerical code Iber+. The peak flow obtained was equal to: 12,774 ± 1,360 m3s−1. This value improves the accuracy of estimated shown in previous works which, most of them, are lower limits of this value. Numerical results of the flood event in Badajoz and in areas surrounding the city show a good agreement with water marks and some descriptions of the event found in the literature. Results obtained in this work demonstrate the ability of the methodology to reproduce historical extreme flood events even when the availability of input data is relatively scarce.

Comparing performance indicators to characterize the water supply to the demands of the Guadiana River basin (Spain)

ABSTRACT Water indicators and indices are useful tools to assess river basin performance, that is, to measure whether the basin operates satisfactorily under a wide range of possible future demands and hydrological conditions. Spanish regulations assess the performance of water demands by using reliability indicators (RIs), established by law in 2008. This article raises the possibility of updating RIs by comparing them with sustainability indicators (SIs). SIs are widely used for the assessment of river basin performance and several policy scenarios. We applied a water allocation model to the Guadiana River basin in Spain to compare indicators under three scenarios. The study was framed within the science of socio-hydrology, combining the physical environment of a water system with its influence on social aspects. SIs gave better results than RIs when comparing future scenarios. We also propose the introduction of a vulnerability indicator into Spanish regulations.

Drought and Ecological Flows in the Lower Guadiana River Basin (Southwest Iberian Peninsula)

Drought temporal characterization is a fundamental instrument in water resource management and planning of basins with dry-summer Mediterranean climate and with a significant seasonal and interannual variability of precipitation regime. This is the case for the Lower Guadiana Basin, where the river is the border between Spain and Portugal (Algarve-Baixo Alentejo-Andalucía Euroregion). For this transboundary basin, a description and evaluation of hydrological drought events was made using the Standardized Precipitation Index (SPI) with monthly precipitation time series of Spanish and Portuguese climatic stations in the study area. The results showed the occurrence of global cycles of about 25–30 years with predominance of moderate and severe drought events. It was observed that the current requirements of ecological flows in strategic water bodies were not satisfied in some months of October to April of years characterized by severe drought events occurring in the period from 1946 to 2015. Therefore, the characterization of the ecological status of the temporary streams that were predominant in this basin should be a priority in the next hydrologic plans in order to identify the relationships between actual flow regimes and habitat attributes, thereby improving environmental flows assessments, which will enable integrated water resource management.

Temporal and Spatial Variations of Secchi Depth and Diffuse Attenuation Coefficient from Sentinel-2 MSI over a Large Reservoir

The Alqueva reservoir (South of Portugal) in the Guadiana river basin constitutes the most important water resource in southern Portugal for domestic and agricultural consumption. We present a methodology developed to characterize spatial and temporal variations of Secchi depth and diffuse attenuation coefficient (both related to dissolved/suspended particles and to water transparency), using high spatial resolution satellite images from Sentinel-2 Multi-Spectral Instrument (MSI). Empirical relations between satellite retrievals of surface reflectances and in situ measurements of water parameters were defined and applied to the entire reservoir for spatial and temporal analysis in the period July 2017–June 2019, useful in the identification of microalgae blooms and rapid variations in water characteristics, which allowed us to differentiate five zones. Water estimates with lower transparency and higher attenuation of radiation were found in the northern area of Alqueva reservoir during the months characterized by higher water temperatures, with Secchi depth monthly averages near 1.0 m and diffuse attenuation coefficient near or above 1.5 m-1. Satellite retrievals of water with greater transparency in the reservoir were obtained in the southern area in months with low water temperature and atmospheric stability, presenting some monthly Secchi depth averages above 3 m, and diffuse attenuation coefficient below 0.8 m-1. January 2018 presented great transparency of water with a Secchi depth of 7.5 m for pixels representing the 95th percentile and diffuse attenuation coefficient of 0.36 m for pixels representing the 5th percentile in the Southern region.

La Monarquía Hispánica y el control de los recursos hídricos: hacia la desecación de Las Tablas de Daimiel de 1751

El control de los recursos hídricos fue un objetivo fundamental para la Monarquía Hispánica en La Mancha durante la Edad Moderna. La desecación en 1751 de la superficie encharcada que forma el actual Parque Nacional de Las Tablas de Daimiel, promovida por Fernando VI, es un buen ejemplo de dicho control. Este artículo analiza los principales factores que confluyeron en aquella decisión que supuso la primera gran obra hidráulica de la monarquía borbónica en la cuenca del Guadiana. Para ello se ha estudiado, principalmente, la evolución de los molinos harineros del entorno de Las Tablas de Daimiel durante la Edad Moderna, los conflictos ocasionados por el control del caudal y la climatología de la zona durante la época estudiada. La presión de los molineros sobre el río y el aumento de la aridez provocaron una creciente conflictividad que la monarquía intentó resolver con la desecación. Sin embargo, el principal objetivo fue satisfacer los intereses recaudatorios de la monarquía y los de una serie de ganaderos de la zona vinculados al rey.

Alqueva dam in the Guadiana River Basin—Past and future of illusive water abundance

AbstractThe historical need for water storage in the Guadiana Basin led to the construction of a large scale dam, creating a reservoir with capacity of 4,000 million m3 and maximum flooded area of 25,000 ha. The Alqueva Dam is a large multi‐purpose project (irrigation, hydro‐electricity production, domestic supply, recreation) that answers to the old expectations of water storage in the dry region of Alentejo, Portugal. The long “stop‐start” decision process was dominated by political objectives, and both local communities and major political forces envisaged Alqueva as a “magic” solution for development of the Alentejo. This Project had a general national consensus, although many environmental NGOs were clearly against it. The final decision of the European Union to fund the Project, due to the regional development perspective, was the decisive step to resume the project. This paper discusses the “social perception of scarcity” and the paradox of how this addition of a large volume of water storage in the Guadiana basin led to a dramatic cultural change in regional landscape and livelihoods, creating new opportunities for foreign stakeholders, and users, but at the same time did not necessarily increase access to water for most of the local communities and small scale farms.

Determination of denudation rates by the measurement of meteoric 10Be in Guadiana river sediment samples (Spain) by low-energy AMS

The concentration of meteoric 10Be in estuarine sediment samples has been measured by Spanish Accelerator for Radionuclides Analysis (SARA) at CNA and subsequently used to assess the denudation rate in Guadiana river basin together with the sediment budget method, on both sides of the frontier between Spain and Portugal. The two methods yielded coincident results. The estimation by the 10Be method gave the denudation rate of (0.76 ± 0.10) × 10−2 cm/y. After correcting for an approximate 80% attenuation of the sediment discharge into the ocean, caused by the river dams, the sediment budget method yielded the rate of (0.77 ± 0.17) × 10−2 cm/y.

Dietary traits of invasive bleak Alburnus alburnus (Actinopterygii, Cyprinidae) between contrasting habitats in Iberian fresh waters

The bleak Alburnus alburnus (L., 1758) is a limnophilic fish native to most of Europe. This cyprinid species is a successful invader in the Iberian Peninsula, where it threatens the highly endemic fish fauna. However, studies on bleak autoecology are scarce in this region, with few data on foraging strategies. The aim of this work was to compare the dietary traits of bleak populations between contrasting habitats in Iberian fresh waters. For this purpose, bleak were seasonally collected from the small River Gevora and the Sierra Brava Reservoir (Guadiana River Basin, southwestern Spain). As percentages of occurrence and ingested mass, plant material and planktonic Crustacea were the most important food categories in the river and the reservoir, respectively. The intake of pelagic prey was higher in the reservoir, especially during summer. Benthic prey, plant material and detritus were more consumed in the river, especially benthos and detritus during spring, whereas plant intake decreased during this season. Shannon index, as a measure of trophic diversity, was higher in the reservoir, except for spring. Overall results suggest that this wide trophic plasticity will facilitate the bleak invasion process throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna.

Assessment of Ecological Risk Based on Projected Hydrological Alteration

It is widely accepted that changes in river flows related to Climate Changes (CCs) may result in several impacts on ecosystems. The main goal of this paper is to assess the ecological risk associated with projected/future flow alteration in the Portuguese Guadiana River Basin. Thus, five climate change scenarios were defined based on bias corrected and spatially downscaled climate projections. These projections were used to run a hydrological model (Temez) for the assessment of potential hydrological impacts. Ecologically relevant hydrological indicators were calculated for the baseline hydrological conditions and for each of five hydrological future scenarios (for selected future periods). By way of the evaluation of the potential hydrological changes (based on the comparison between baseline and future metrics), it was possible to assess the likely ecological risk due to flow alteration. This evaluation was performed based on the ecological risk due to flow alteration (ERFA) screening method. This methodology was developed based on the Range of Variability Approach (RVA), a technique used to define ecological limits of hydrologic alteration. The ERFA methodology enables the aggregation of information as colour-coded risk classifications, which allows for the assessment of the locations with higher or lower ecological risk. It was concluded that the selected ecologically-relevant indicators could translate and synthesize the flow alteration resulting from CC. The projected climate change was observed to have the potential to increase the ecological risk of the Guadiana River Basin, a region for which projections indicate increased future mean temperatures and decreased mean precipitation.

The water surfaces' ecosystem services and the opinion of different stakeholders: an approach based on goal programming

The water surfaces have a high environmental value and allow the development of quality traditional products, which may take advantage of the local conditions. Since 1985, the state entities supported and accompanied the construction of a considerable number of dams, all located in the Guadiana river basin, in Algarve, south Portugal. In this context, it is important to understand how the stakeholders involved perceive these water surfaces, namely their role on the provision of environmental goods. This paper proposes a goal programming approach to simulate the preferences and the consensus of the stakeholders involved considering not only the preferences of the majority but also the minority, which often appears undervalued. The results show that the proposed methodology was able to provide new insights about stakeholders' opinions and preferences for a correct management.

Water Resources Impact Assessment Under Climate Change Scenarios in Mediterranean Watersheds

Climate models project a reduction in annual precipitation and an increase in temperature, which may lead to runoff shortages and a consequent water availability reduction, in some Mediterranean regions, such as southern Portugal. The impacts on water availability under different climate change scenarios are assessed using SHETRAN, a physically-based and spatially-distributed hydrological model. SHETRAN is calibrated and validated against daily runoff measurements at outlet and internal sections and against phreatic surfaces using a multi-basin, multi-location and multi-response approach. Nash-Sutcliff efficiency, volume deviation and coefficient of determination ranged, respectively, from 0.58 to 0.76, 0.59 to 0.79 and −9 to 15 %, in the calibration period, and from 0.54 to 0.75, 0.54 to 0.77 and −14 to 12 %, in the validation period. Three GCM and two RCM are used for control (1961–1990) and scenario (2071–2100) periods, under the A2 SRES emission scenario. Observed bias in the climate models’ projected precipitation and temperature are corrected with three bias correction methods. For the scenario period the climate models project a change in precipitation from +1.5 to −65 % and an increase in temperature from +2.7 to +5.9 °C. This trend in climate change projection is reflected in the annual runoff that decreases drastically, between 13 and 90 %, in southern Portugal by the end of the century. The runoff reduction is greater in all watersheds in Autumn and Spring with higher agreement between models and bias correction methods. The runoff decrease seems greater in the Guadiana river basin which is already under significant water stress.

Climate change impacts on irrigated agriculture in the Guadiana river basin (Portugal)

This study evaluates climate change potential impacts on irrigated agriculture in the Guadiana river basin, in the south of Portugal, by running long-term soil water balance simulations using the ISAREG model and taking into consideration the maximum potential yield. The ISAREG simulations were focused in a set of the most locally representative crops to assess the evolution of net and total water requirements, considering a monthly time step for two 30-year future periods, (2011–2040) and (2041–2070). Reference evapotranspiration was estimated using the temperature-based Hargreaves–Samani equation, and the simulations were performed using, as inputs, a combination of five climate change scenarios built using the Ensemble-Delta technique from CMIP3 climate projections datasets to set different alternative climate change bracketing conditions for rainfall and air temperature. Water balance outputs for different climate scenarios were combined with four agricultural scenarios allowing for the estimation of total irrigation requirements.A general increase in crop irrigation requirements was estimated, mainly for those crops as maize, pasture, and orchards that are already big irrigation water consumers. Crops as olive groves and vineyards, well adapted to the Mediterranean conditions, show less sensitivity to climate change. The combined results of crop irrigation requirements for climate change and agricultural scenarios allow for the expectation of sustainability for the agricultural scenarios A and C, essentially defined by the complete use of the irrigation network and systems currently being constructed with the Alqueva project, but not for the ambitious irrigation area expanding scenario B.