Preliminary Study of the Impact of Guadalhorce River Mouth Channeling (Málaga, Spain) on Groundwater and Related Wetlands (original) (raw)
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Catena, 2020
The Guadalhorce River mouth (Málaga, Southern Spain) was channelized between 1997 and 2003 to reduce flooding potential in adjacent densely populated sections of Málaga. The channel was bifurcated near the Mediterranean Sea, surrounding an isolated wetland complex composed of eight different ponds. Groundwaterlevel and wetland-stage data, combined with water-chemistry data from wells and wetlands, collected since 1977, have documented the hydrological and ecological responses to channelization. The results show that channelization has extended the tidal influence inland from the Mediterranean Sea through the Guadalhorce River and the subjacent coastal aquifers, producing a change in groundwater hydrodynamics. The isolation of the wetlands resulting from channelization has provoked a significant salinization of both surface water and groundwater, the extent of which varies among wetlands. These decadal-scale changes in water chemistry have promoted the appearance or increase of halophilic vegetation and have caused a shift from diving birds to predominantly shorebirds in some wetlands. Documentation of these unexpected ecosystem responses is a necessary first step for land managers who need to consider groundwater and surface water as a single resource, particularly in groundwater-dependent ecosystems along the densely populated and ecologically sensitive Mediterranean coastal areas.
Groundwater-Surface Water Interactions in “La Charca de Suárez” Wetlands, Spain
Water, 2020
La Charca de Suárez (LCS) is a Protected Nature Reserve encompassing 4 lagoons located 300 m from the Mediterranean coast in southern Spain. LCS is a highly anthropized area, and its conservation is closely linked to the human use of water resources in its surroundings and within the reserve. Different methodologies were applied to determine the hydrodynamics of the lagoons and their connection to the Motril-Salobreña aquifer. Fieldwork was carried out to estimate the water balance of the lagoon complex, the groundwater flow directions, the lagoons-aquifer exchange flow and the hydrochemical characteristics of the water. The study focussed on the changes that take place during dry-wet periods that were detected in a 7-month period when measurements were collected. The lagoons were connected to the aquifer with a flow-through functioning under normal conditions. However, the predominant inlet to the system was the anthropic supply of surface water which fed one of the lagoons and pro...
Environmental Geology, 2007
The analysis and interpretation of physical and limnological parameters combined with hydrochemical (major ions and stable isotopes) analyses enabled us to evaluate the hydrogeological functioning and the hydrogeochemical evolution of groundwater in two adjacent lakes related to a karstic aquifer (Archidona, southern Spain). Lake water, groundwater and the outflow from a spring, were monitored periodically from 1998 to 1999 and sporadically from 2000 to 2006. The evolution of groundwater chemistry from recharge (dolines) to discharge areas (spring) showed an increment of 20% in magnesium and 15% in sulphate, and such higher increments were recorded for the water from the lakes, suggesting the existence of different hydrogeological paths. A simple water budget model, together with morphological interpretation, suggests that groundwater discharge into the lakes is of relative importance to the input into these systems. Finally, we believe that the development of a new typology for hydro-morphological elements, by means of several hydrological factors and the assessment of pressures and impacts will be useful for the correct management of these lakes and other semi-arid aquatic ecosystems.
2014
The Campo de Dalías (Almería, southeastern Spain) was the backdrop for the development of intensive agricultural activity during the 1970s. Due to the poor natural soil development, the agriculturalists opted for a system that involved quarrying silt and clay deposits that could be used as soil in the greenhouses. In parallel, poor water quality in the upper aquifer caused the gradual abandonment of boreholes and a generalised rise in piezometric levels. These factors have favoured the formation of a series of artificial wetlands in the abandoned clay pits (Onayar, Cabriles and Balsa del Sapo (''Toad Pond'') being the most significant). In Balsa del Sapo, the water column rose 3.5 m between October 2007 and February 2011. There has been a continuous fall in the electrical conductivity of the surface water, which has gone from 14,500 lS cm-1 in 2004 to 4,100 lS cm-1 in 2013. The most recent concentrations are close to those found in the groundwater. The same situation is detected for Cl, SO 4 and Na ion concentrations in the surface and groundwater. These data show the groundwater-surface water interaction in the Balsa del Sapo. Nevertheless, the sharp rise in surface water level has created a flood hazard (due to the shallow topography of the area), both for people living in the vicinity and their property. This is an endorheic zone where a number of ramblas (gullies) draining the southern face of the Sierra de Gádor mountains converge. The Campo de Dalías is a spectacular example of the changes that can occur in a semiarid agricultural area as a result of intensive groundwater abstraction. These changes are directly related to the management of water resources, the most recent consequence of which is the increased risk of flooding. Hence, there is a need to consider the management of these water resources to achieve a more sustainable use, which is compatible with the environmental protection of the wetland and which will give some guarantee of flood protection for people and property.
Hydrobiologia, 2009
In natural systems, the chemistry of floodplain waters is a function of the source of the water, which is influenced by geomorphic features of riparian wetlands. However, anthropogenic disturbances may alter both geomorphic features and the natural balance of water mixing in the floodplain. The aim of this study was to classify riparian wetlands and characterize their water characteristics in one reach of the Middle Ebro River to assess the hydrochemical functioning of the system. In order to accomplish that goal, water samples were collected at 40 sampling sites during low-water conditions and two floods of different magnitude. Moreover, geomorphic characteristics of riparian wetlands were also analyzed to interpret the results at broader spatio-temporal scales. Three group of wetlands were identified using multivariate ordination: (1) major and secondary channels highly connected to the river by surface water, containing weakly ionized water with high nitrate levels during floods; (2) secondary channels and artificial ponds located in riparian forests near the river, most of which were affected by river seepage during the examined events. This type of sites had high major ions concentrations and elevated spatial variability with respect to nutrient concentrations during floods; (3) Siltated oxbow lakes, whose hydrogeochemical features seemed to be unaffected by factors related to river fluctuations. Total dissolved solids, major ion (sulfate, chloride, sodium, calcium, magnesium, and potassium) and nutrient (nitrate, ammonium and organic nitrogen, and phosphate) depended upon the relationships between surface and subsurface water flows. Seasonal changes and geomorphic characterization indicated that a strong functional dependence of floodplain wetlands close to the main river channel is established, whereas most of the floodplain area remains disconnected from river dynamics. Moreover, the effect of nitrate-enriched agricultural runoff seems to affect water quality and hydrochemical gradients of the system. Based on our results, we propose different types of actions for the management of the Ebro River flow to ensure a more natural ecological functioning of its floodplains.
Estuarine, Coastal and Shelf Science, 2011
Keywords: deltaic environments coastal wetlands groundwater recharge irrigation semi-arid climate Almeria province a b s t r a c t During recent historical times the Adra river delta, a detrital coastal aquifer of nearly 32 km 2 located in a semi-arid, mountainous area of SE Spain, has undergone different changes caused by human activity. Within this context, both the river dynamics in the plain and the geomorphology of the coastline have at various times resulted in the formation of small lagoons. At present only two small (<0.5 km 2 ) lagoons exist, at the eastern edge of the aquifer, which, although closely surrounded by commercial marketgarden greenhouses, are protected under international agreements. During the last 30 years of the twentieth century traditional agricultural irrigation techniques have undergone significant changes to improve their efficiency. Surface-water resources in the Adra river basin are regulated via the Beninar reservoir. In addition, the use of groundwater is increasing progressively. Both these factors affect the recharge of the coastal aquifer. To monitor these changes measurements of electrical conductivity and water level fluctuations have been recorded in these lagoons for the last 35 years (1975e2010). A comparison of the hydrochemical characteristics of the water in the lagoons and of the surrounding groundwater from 2003 to 2010 shows marked differences induced by the different hydrological dynamics in each lagoon, as well as by the hydrogeological impact of changes in land use in the delta. The increase in water demand is a consequence of the extension of irrigated areas from the fluvio-deltaic plain to its slopes, originally occupied by unirrigated crops. A reduction in irrigation return-flow is linked to the use of new irrigation techniques. These modifications affect both the recharge regime of the aquifer and its water quality. Moreover, extreme precipitation events, which are characteristic of Mediterranean semi-arid environments, can affect the lagoons' hydrological dynamics to a considerable extent. One such example is the unusually rainy period from January to March 2010 (>600 mm). This event, along with other effects, has dramatically lowered the salinity of the water in both lagoons. This case study reveals the extreme vulnerability of deltaic environments and also how lagoons can reflect anthropogenic changes over the whole river basin.
Water, 2020
Wetlands are environments whose water balance is highly sensitive to climate change and human action. This sensitivity has allowed us to explore the relationships between surface water and groundwater in the long term as their sediments record all these changes and go beyond the instrumental/observational period. The Lagunas Reales, in central Spain, is a semi-arid inland wetland endangered by both climate and human activity. The reconstruction of the hydroclimate and water levels from sedimentary facies, as well as the changes in the position of the surface water and groundwater via the record of their geochemical fingerprint in the sediments, has allowed us to establish a conceptual model for the response of the hydrological system (surface water and groundwater) to climate. Arid periods are characterized by low levels of the deeper saline groundwater and by a greater influence of the surface freshwater. A positive water balance during wet periods allows the discharge of the deepe...
Groundwater dependence of coastal lagoons: The case of La Pletera salt marshes (NE Catalonia)
Journal of Hydrology, 2017
Coastal wetlands are among the most productive ecosystems of the world, playing an important role in coastal defense and wildlife conservation. These ecosystems, however, are usually affected by human activities, which may cause a loss and degradation of their ecological status, a decline of their biodiversity, an alteration of their ecological functioning, and a limitation of their ecosystem services. La Pletera salt marshes (NE Spain) are located in a region mainly dominated by agriculture and tourism activities. Part of these wetlands and lagoons has been affected by an incomplete construction of an urban development and in this moment is the focus of a Life + project, whose aim is to restore this protected area. Several studies have analyzed the role of hydrological regime in nutrients, phytoplankton and zooplankton in this area, however, the role of groundwater was never considered as a relevant factor in the lagoon dynamics, and its influence is still unknown. In this study, the hydrogeological dynamics in La Pletera salt marshes has been analyzed, as a basis to set sustainable management guidelines for this area. In order to determine their dependence on groundwater resources, monthly hydrochemical (with major ions and nutrients) and isotopic (d 18 O H2O and dD) campaigns have been conducted, from November 2014 to October 2015. In particular, groundwater from six wells, surface water from two nearby streams and three permanent lagoons, and sea water was considered in these surveys. Taking into account the meteorological data and the water levels in the lagoons, the General Lake Model has been conducted to determine, not only evaporation and rainfall occurring in the lagoons, but also the total inflows and outflows. In addition, the Gonfiantini isotopic model, together with equilibrium chemical-speciation/mass transfer models, has been used to analyze the evaporation and the physicochemical processes affecting the lagoons. Results show that during the dry season groundwater inputs may account for 15-80% of the water in La Pletera lagoons. Besides, water salinity depends on two main processes: 1) mixing of fresh and sea water occurring within the lagoons or in the aquifer; and 2) evaporation. According to the obtained results, the goal of preserving La Pletera lagoons and their salinity conditions implies maintaining groundwater fluxes towards the ocean, and also the hydraulic connectivity of these lagoons with the aquifer.
The Vega Alta of Segura River (Southeast of Spain): A Wetland of International Importance
Sustainability
The Ramsar Convention is an intergovernmental treaty for the conservation and wise use of wetlands, which establishes nine criteria related to natural values and a cultural one that wetlands must meet to be included in the list of wetlands of international importance. We aim to evaluate if the wetlands of the Vega Alta of the Segura River (southeast of Spain) meet the requirements to fulfil this agreement. Thanks to meticulous fieldwork and a bibliographic review related to the stated objective, we collected information on the existing environmental and cultural values. The results show that this set of wetlands is home to 11 species of threatened vertebrates in Spain, two priority habitats in the European Union, as well as cultural values related to their origin, conservation, and ecological functioning. Likewise, in the area there are archaeological sites, traditional uses of water associated with the cultivation of rice, and religious manifestations. Effective wetland inventories...
Hydrogeology of ponds, pools, and playa-lakes of southern Spain
Wetlands, 2007
I characterized 33 small water bodies from the southern Spain provinces of Seville, Cadiz, and Malaga using hydrochemistry (geochemical analyses), hydrology (water budgets), geological surveys, and local knowledge. Based on hydrogeological criteria (association with permeable materials), water bodies were grouped into three categories: 1) wetlands associated with permeable materials (playa-lakes), 2) wetlands associated with impermeable materials (ponds and pools), and 3) artificial wetlands. The three wetland typologies differed in morpho-structural indices, hydrogeological functioning, water chemistry, flora and fauna, and vulnerability to a range of human impacts, and these attributes need consideration in habitat management and conservation.