LANDSCAPE AND SOILS FEATURES THAT BEAR ON THE LAND MANAGEMENT OF LAKE,

Raquel Romeo Carmen Castañeda Estación Experimental de Aula Dei, CSIC, Melchor Maestro Instituto Pirenaico de Ecología, CSIC, Zaragoza MªTeresa García-González Instituto de Ciencias Agrarias, CSIC, Madrid

Abstract

The social value of wetlands has evolved to the point that they are widely recognized as irreplaceable ecosystems. Gallocanta Lake, Aragón (NE Spain), is the largest and best-preserved saline lake in Western Europe. Its high ecological value is reflected in its inclusion in the Ramsar Convention and the Natura 2000 Network. Since 1971, the Spanish Government has taken several actions to safeguard the environment of this site. The current management plan (Plan de Ordenación de Recursos Naturales, PORN) limits the use of and activities that are permitted in the lake and it surroundings, and it encourages the protection and restoration measures for the conservation of habitats. However, a precise delineation of the saline wetlands in agricultural environments is hampered by a lack of soil and vegetation maps, sources of information are crucial for wetland management, and by a lack of cooperation from the landowners. The aim of this study was to develop a baseline map for environmental studies that bear on the management and protection of the wetland. The combination of geomorphological data derived from photointerpretation and geological data in a geographical information system helped to identify homogeneous landscape units and their relationships to current land use. Keywords: Conservation; GIS; Landscape; Photointerpretation; Wetland.

1. Introduction

1.1. Gallocanta Lake: Wetland of international importance Gallocanta Lake is the largest and best-preserved saline lake in Western Europe. It has a high ecological value due to the singular hydric regime. Alternating wet (flooding) and dry (drought) periods have led to the development of biological communities in which the species are adapted to drought events. In 1971, the Spanish Government began actions to protect Gallocanta Lake. In 1972, during a period when the water level of the lake was high and large numbers of waterfowl were present, the Spanish Government declared the lake a Controlled Hunting Area, which was intended to regulate waterfowl hunting (1% of the waterfowl that flocked to the lake were harvested (Leranoz and González, 2009). In the late 1970s, a plan to drain the lake was thwarted by the efforts of ecological activists and the support of Félix Rodríguez de la Fuente, a well-respected conservationist. In 1985, the lake was declared a National Refuge for Hunting (6720 ha) and, in 1987, was declared a Special Protection Area for Birds (SPAs). The latter designation met the Directive for the Conservation of wild birds in the European Community (79/409/EEC). In 2001, the boundaries of the protected area were extended [―and its size increased‖] to 17,510 ha. In 1994, the lake was included in the international Ramsar Convention along with (BOE Nº 135 of 06/07/94); specifically, as waterfowl habitats. The Ramsar Convention takes into account ecological, botanical, zoological, limnological, and hydrogeological factors (Leranoz and González, 2009) for the conservation and prudent use of wetlands and their resources.

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The government management plan for the lake, PORN (Plan de Ordenación de Recursos Naturales) was definitively approved in 2006 (19,303 ha), 11 years after the plan had started (BOA n° 45 of 19/04/1995). PORN protects plants and birds, but abiotic aspects such as landforms, processes, and soils are not included. In 2007 (Law 11/2006 of November 30, BOE No. 23 26/01/2007), a 1924-ha area that included the lake and the vegetation fringes were declared a ―Reserva Natural Dirigida‖, and 4553 ha were declared a Peripheral Protection Area. Landscape and geomorphological features are the natural attributes that are to be preserved in the Reserva.

1.2. Geological and pedological studies

Geological surveys in the 19th C. indicated that the maximum size of Gallocanta Lake was 1800 ha (Pérez and Roc, 1999), and 4 m-deep. Hernández-Pacheco and Aranegui (1926) described some of the landforms and their use, e.g., the cultivation of the alluvial fans at the base of the Santa Cruz Range and the terrace that extended from Gallocanta to . Dantín Cereceda (1941) provided a study of the geomorphology and geology of the lake, and Villena (1971, 1976) and Calvo et al. (1978) produced the first detailed maps of the area. The geological report of Aranzadi (1980) identified in the Quaternary sediments of the lake evidence of the environmental impact of humans. The study included a continuous geological map ~1:20,000 scale and the descriptions of the cores (4-16 m) taken from the lake and the soils on the periphery. More recently, geomorphological studies noted the karstic origin of the lake (Gracia and Gutiérrez, 1999) within a regional geological framework. Pérez and Roc (1999) studied the lake sediments based on 13 cores (12-52 cm) that were dug in the northwestern portion of the lake and other cores, of ~2.3 m, taken from the center of the lake. Information in the cores provided a basis for a map of the sedimentary facies in the lake bottom and its surroundings (Pérez et al., 2002). The development of the lake during the Holocene has been reconstructed using the mineralogical and isotopic data from the core samples taken from a depth of up to 2.8 m (Luzón et al., 2007a, 2009). Luzón et al. (2007b) described the presence of edaphic processes that were related to the presence of hydromorphic soils. Sediment data collected in those studies have not been used to assess the current functionality of the lake and its delimitation, which is information that is needed for land management. The management of the water resources around the lake is based on the findings from hydrogeological studies, which were conducted to assess the effects that the extraction of groundwater around the lake produced in the lake water level in recent decades (García-Vera et al., 2009). The presence of water is the most important feature of the lake, and water conservation in the area is critical for biodiversity, the management of which focuses on migratory bird populations (Leranoz and González, 2009). The lake undergoes cyclical and seasonal changes in the amount of water it holds, independently of human actions (Comín, 1991). Currently, the use of water for irrigated agriculture is limited for conservation purposes. Soils are the foundation for habitats and have been exposed to the hydric changes that occurred in the lake. Analyses of the soils would provide insights into the potential effects of current land uses around the lake and would be a benefit to agriculture and conservation. Soil composition and salinity strongly influence the distribution of the vegetation and, therefore, soil studies are essential in designing a plan for the recovery of natural vegetation on the fringes of the lake.

1.3. Features of the lake

Gallocanta Lake (1+100 m a.s.l.) is a saline lake in Aragón, Spain (Figure 1), that is fed by surface runoff and by groundwater from several aquifers. It lies within the center of a 54,300-ha endorheic basin (CHE, 2003). The Triassic substrate composition, mainly, evaporites and marls, dictates the salinity (NaCl) of the surface water. In exceptionally wet years, the surface water has covered as much as 14 km2 and reached a depth of as much as 2.45 m (CHE, 2003). Following periods of prolonged drought, the lake dries up. The climate in the area is Mediterranean and semi-arid, and typical of mid-latitude steppes. Mean annual rainfall is 488 mm (range = 210 mm-650 mm). The mean annual temperature is 10.7 ºC, and the mean temperature during long, cold winters is < 5 °C. Daily maximum temperatures can exceed 40 °C. The

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main wind direction is NW and can reach 100 km h-1 (Pérez and Roc, 1999). Typically, the dry period lasts for two months each year (Figure 2, Pérez et al. 2009).

1.4. Geological and geomorphological features

The lake is in the central sector of the Iberian Range and is the local base level of the sporadic or intermittent streams that drain into it. To the north, Gallocanta Lake is bounded by the Paleozoic Santa Cruz Range and, to the south and southwest, by Mesozoic carbonate materials of the Lower Jurassic and the Upper Cretaceous strata. The lake is of karstic origin (Gracia et al., 1999) and has reached the Upper Triassic impermeable clay and gypsum layers (Keuper). It occupies the bottom of a karstic depression (or polje) that covers ~550 km2 and contains >20 smaller lakes. Pérez and Roc (1999) identified the large extent of Pliocene and Holocene coarse detrital deposits that border the lake. From those deposits, Aranzadi (1980) drew the extent of the glacis, mudflats, alluvium, and colluvium. The most recent geological map of the lake basin was created by the Ebro Basin Authority (CHE, 2003), but it does not include the Quaternary materials, although the official report recognized the complexity of these recent materials and their importance to the current land use. The alluvium and the valley bottom deposits terminate in alluvial fans at the edge of the lake, where they form shoreline bars. Three levels of terraces at 6-10 m, 4-5 m, and 2 m above the lake testify to the retraction of the lake (CHE, 2003). Prevailing NW winds cause lacustrine dynamics, especially waves and currents that rise to the SE, reworking the sediments, and creating spits. The general geomorphological features that are associated with the processes of the lake and its surroundings are summarized in next sections.

1.5. Land use

Aranzadi (1980) distinguished among the different land uses based on three geological domains and their landforms: silicic, carbonatic, and mixed domain. The silicic domain, which has a very steep slope, is unsuitable for agriculture with the exception of the shale, which usually favored the developing of depressed areas. These depressions have gentle slopes and weathered, fine-grained residues that are suitable for the development of soils. Carbonate and mixed domains are most suited to agriculture because of their gentle topography and the presence of clays. The cereal is common in the carbonate and mixed glacis. A forth domain is the saline mudflats, which are unsuitable for crops because of the proximity of the water table, soil salinity, and waterlogging; however, despite their poor yield, some mudflats are cultivated, which limits the potential growth of the natural vegetation. Figure 1. Gallocanta Lake, the Natural Reserve (green line), and the Peripheral area (red line) in , Spain. Provinces and municipalities are indicated

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Figure 2. Mean monthly rainfall and temperature for the Gallocanta Lake in Weather Station (1961-1990), Spain, modified from Pérez et al. (2009)

In the area rainfed winter cereals are the main source of income. About 80% of the Natural Reserve is devoted to the raising of cereal, barley, rye, and wheat. In the PORN, given its importance for the conservation of steppe birds, the area covered by cereals is an environmental unit. About 400 ha are irrigated with groundwater south (Bello and municipalities) and west () of the lake. The municipalities own a large proportion of the lake area and some portions are the property of private landowners. The boundaries between some properties cannot be identified in the cadastral plans because they are illegible. Several conflicts over land use have prevented an official delimitation of the public hydric domain. The area is a resource for leisure and outdoor activities, and many perceive agriculture as posing a threat of degradation. The conflict between agricultural development and environmental conservation has hindered the implementation of Common Agricultural Policy measures.

2. Objectives

The aim of this study was to create a base map of Gallocanta Lake for use in environmental studies that focus on the management and protection of the wetland and its surroundings. We used geomorphological photointerpretation that will allow delineating homogeneous landscape units that are associated with specific soils and their current use as wildlife habitat or for agriculture. Identification of the morphological, sedimentary and edaphic conditions will increase understanding about the natural dynamics of Gallocanta Lake and the wetland‘s sensitivity to changes in land use. The specific objectives were as follows: - To identify areas that are representative of the dynamics of the lake and its surroundings. - To synthesize the findings of previous studies and maps. - To produce a map of land features that is applicable to the study of the environment based on the information in existing maps. - To integrate landscape and soil features into the interpretation of current land use.

3. Methods

3.1. The study area

The lake exhibits morphological asymmetry along the NW-SE axis (Figure 3) that is the result of lithologic and topographic differences between the two sides of the lake, which lead to differences in sedimentary environments and water inputs. Therefore, two sampling areas were chosen, one on the northern margin (NM) and the other on the southern margin (SM) of the lake (Figure 3). In both margins, fluvial and lacustrine processes converge. The NM covered 600 ha at the foot slope of the Santa Cruz Range and, on average, was 1500 m wide. In the NM, the elevation ranged between 925 m at the edge of the lake to 1025 m at the foot of the slope. The NM extended from the intermittent stream Prado Ancho Arroyo,

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which discharges into the Lagunazo Grande, to the Cañizar Spring near Los Lagunazos.The SM extended between the villages of Las Cuerlas and Bello, and the A-2506 road, was crossed by the Pozuelos Rambla intermittent stream, and its elevation ranged from 925 to 1010 m. Figure 3. The sampling areas (rectangles) on the north (NM) and south (SM) margins of Gallocanta Lake, Aragon, Spain. The SIG Oleícola orthophotograph (1997) at the background

3. 2. Materials and methods

The cartographic data used in this study included historical and current aerial photographs, and topographical and geological maps (Table 1). Stereoscopic photointerpretation using a mirror stereoscope was used and the resulting geoforms were transposed over the orthophotographs. The historical aerial photographs were georeferenced and managed using the geographic information system ArcGIS®.

Table 1. Cartographic documents used for photointerpretation. Format: P, paper; VD, vectordigital; RD, raster digital.

Scale, or resolution Documents Date Format and precision 491 Calamocha 1ª ed. 50000 2006 P 490 Odón 1ª ed. 50000 2006 P Spanish National Topographic Map 491-I Bello 2ª ed. 25000 2006 P / VD 490-II Las Cuerlas 2ª ed. 25000 2002 P / VD

Spanish Geological Map, MAGNA Sheet 491 50000 1983 P / VD series 2nd, 1st ed. Sheet 490 50000 1983 P / VD Aerial photograph stereoscopic USAF-B Flight 33000 1956-57 P pairs Interministerial Flight 18000 1976-1980 P SIG Oleícola 1 m / pixel 1997 RD Orthorectified aerial photograph PNOA* 0.5 m / pixel 2006 RD 20 m / pixel SIG Oleícola 4 m approx. 1997/98 RD Digital Elevation Model precision ASTERDEM 30 m / pixel 2000 RD Topographic map of Aragón Sheets 490, 491, 464, 465 5000 2000 VD 09/1999 Satellite images Landsat 5TM scene 200/32 30 m / pixel RD 01/2000 Hydrographic network 50000 1995/2000 VD Administrative boundaries and Hydrogeological map 25000 2003 VD hydrological data PORN** delimitation 25000 2005 VD

*PNOA: Plan Nacional de Ortofotografía Aérea; **PORN: Plan de Ordenación de Recursos Naturales.

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The historical USAF-B photographs (Table 1) and the 1997 and 2006 orthophotographs were used in the selection of the NM and SM sampling areas. The Interministerial photographs (Table 1) were used to create the landforms. In addition, we used the digital terrain models and the contour lines to validate the land features resulting from photointerpretation, which were assessed in the field using a Global Positioned System. Soil samples were collected using a hand auger at specific sites. Soil salinity was measured using the electrical conductivity of a saturated paste extract (Soil Salinity), the calcium carbonate equivalent (CCE) was calculated using the official method of MAPA (1994), gypsum content was measured using thermogravimetry ( et al., 2006), and texture was assessed by laser diffraction. The mineralogy of ground soil samples ( 2 mm) and their clay fraction ( 2 m) was quantified using X-ray diffraction (Philips X'Pert diffractometer with Cu-K radiation monochrome with graphite.

4. Results and discussion

4.1. Geology of Gallocanta Lake

The geological sheets 490 and 491 of the Spanish Geological Map differ in their descriptions of the surface units and formations (Table 2). Most of the surface formations in the NM and the SM are of lacustrine origin, except (1) the alluvial fans at the base of the Lower Pleistocene materials and (2) the alluvial plain at the base of the Holocene materials, both of which are within the NM. The Lower Pleistocene materials included (1) fluvial-lacustrine terraces (42 / L4i and 39 / L5i), formed from silts and clays interbedded with layers of quartzite and limestone gravels and, locally, extremely cemented, and (2) alluvial fans (43 / F7i) formed from gravels and non-cemented silts and clays. The Middle Pleistocene materials included the fluvial-lacustrine terraces (47 / L3m and 40 / L4m), formed from silts and clays interbedded with layers of quartzite and limestone gravels and, locally, extremely cemented. Table 2. Terms used in sheets 491 and 490 of the Spanish Geological Map MAGNA E = 1:50000 series (1983) Map memory: Surface Formations Legend for sheet Legend for sheet Geomorphological Sedimentary Cartographic 491 490 legend environment unit H491 and H490 H491 H490 H491 H490 51. Silts and gravels 47. Silts and gravels with Endorheic areas Endorheic depressions L h with organic matter organic matter 1

Accumulation deposit 50. Quartzite gravels 48. Quartzite gravels and Fluvial-lacustrine in relation to endorheic L h and silts silts terraces 2 areas Holocene 54. Alluvial gravels Valley bottom, alluvial * Flat-bottomed valleys F h * and silts plains* 1

47. Quartzite 40. Quartzite conglomerates and conglomerates and muds. L m L m ne ne muds. Locally Accumulation deposit 3 4 Locally cemented Fluvial-lacustrine Medium Pleistoce in relation with cemented terraces endorheic areas 42. Fine sands and 39. Loose conglomerates L4i L5C gravels. and micro-conglomerates 43. Loose conglomerates Lower Lower * Colluvium fans Alluvial fans * F7i * Pleistocene and breccia with silt- clay matrix. Fans.

* Not indicated.

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The Holocene sediments included (1) river-lacustrine terraces (50 and 48 / L2h) formed from silts and clays with layers of quartzite and limestone gravels; locally, extremely cemented, (2) endorheic bottoms

(51 and 47 / L1h) filled with clay and silt, with organic matter and loosely cemented gravels or, locally, extremely cemented, and (3) alluvial plains (54 / F1h) formed from siliceous and or non-cemented carbonate gravels The alluvial fans and flat-bottomed valleys of the NM extended from the footslope of the Santa Cruz Range to the lake sediments. The contact between the alluvial and valley sediments and the lake bottom sediments is discordant. In the SM, three cartographic units were fluvial-lacustrine terraces L4i / L5C, L3m / L4m, and L2h). The geology of first two terraces are from the Lower and Middle Pleistocene, and the third is of Holocene origin. The fluvial-lacustrine terraces have discordant contact with the sediments of the endorheic bottom (Figure 4). Figure 4. A simplified scheme of the geological units in the study area in Aragon, Spain, derived from the MAGNA sheets 490 and 491

4.2. Landforms of the Gallocanta Lake

Figure 5 shows the landforms of the north and south margins of Gallocanta Lake. Using the cartographical standards of IGME (2004) and geomorphological maps used in soil studies (Artieda, 1996), we identified in the margins of Gallocanta Lake three broad categories of landforms (sensu Evans, 2011): structural, erosion, and accumulation (Figure 5). The five accumulation forms were alluvial fan, alluvial valley, terrace, playa, and the ―gray soil band‖. The first three terms were defined in the MAGNA maps; the terms playa and the ―gray soil band‖ were identified in the interpretation of the orthophotographs (Table 1) and Landsat images (see section 4.3, below). The structural forms identified were as follows: cliff, escarpment, hoya, mesa, residual hill, and terrace edge or crest. Hoyas are depressions or alveoli in glacis and terraces that are not connected to a fluvial network (González Bernáldez 1992), and they were present on both sides of the lake. At Gallocanta Lake, most of the hoyas are circular or subcircular and accumulate moisture, although some are elongated and appear to have their major axis perpendicular to the lake shoreline. Usually, hoyas can be

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recognized by their natural vegetation, soil color, and differences from the greenness of the crops. Residual hills (found at the NM site, only) are polygenic forms that vary little in elevation, are elliptical in planform and, typically, are parallel to the shoreline (Martín et al., 2004). In the NM, the length of their major axis ranged from 40 m to 100 m. Mesas (found at the NM site, only) are flat reliefs that have diverse morphologies (Abad et al., 2005) and, at Gallocanta Lake, the length of the major axis did not exceed 350 m. At Gallocanta Lake, several types of breaklines were identified. A net escarpment, the most common landform in the NM, is an abrupt change in the slope although, with a small vertical increase. Net escarpments occurred within and between the alluvial valley and alluvial fans, and on the lacustrine terraces. The escarpments were either perpendicular or parallel to the shoreline of the lake. In the SM, breaklines were uncommon because of the smooth relief of this margin, and the shoreline was not as rectilinear as it was in the NM. Where breaklines were attenuated, there were degraded escarpments, which were more common in the SM than they were in the NM. In the NM, a 2.6-km-long escarpment separated the terrace from the alluvial fans and the alluvial valley. Along most of its length, that escarpment sloped downward in both sides, probably, accentuated by plowing. Given the continuity and distinct features of that escarpment, we defined it as a terrace edge or crest. The terrace edges in the SM have been reshaped considerably, principally, by plowing. Cliff (sensu Gracia (1993)) were defined by the vertical jump (1-1.5 m) between the terrace and the playa, which were present in the NM. That continuous, well-defined cliff is a distinct feature of the northern margin of the lake. Shorelines and watercourses were the erosion forms identified at Gallocanta Lake. The shoreline of the NM was continuous and sharp. Others have defined it as a ―sand bar‖ (Aranzadi, 1980) or a ―zone with Salicornia and algae‖ (Pérez and Roc, 1999; Luzón et al., 2007a). In the study area, the playas extend from the shoreline to the cliff and, typically, they host halophytes, algal mats, and efflorescences along the fringes of the lake. Most of the watercourses were intermittent streams such as arroyos and ramblas. In planform, they all had abrupt disruptions in their natural course, possibly, because of agricultural activities. In the NM, the final [section of the Povaya Spring Arroyo was straight (then, anthropic) and the Cerrada Alta Arroyo had a stepped course that almost parallels the escapement. In the SM, the Pozuelos Rambla discharges water into the lake after extended periods of rain or when water levels rise, only (San Román et al., 2007). Figure 5. Landforms of the northern and southern margins of Gallocanta Lake, Aragon, Spain

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4.3. Landforms, the landscape and land use on the northern and southern margins of Gallocanta Lake

On Gallocanta Lake, the shoreline forms are particularly important because they indicate an area highly influenced by the surface and groundwater water fluctuations, and in which lacustrine natural vegetation and agriculture coincide. Although agricultural land consolidation has not been accomplished, the agricultural area has undergone many changes in the last decades. Field observations and aerial photographs confirmed those changes, most of which involve the boundaries of the agricultural plots and new roads. Currently, agricultural activities have obscured field boundaries, old roads, and some hoyas; however, these features are evident in the soil colors in recent orthophotographs. Agriculture has created a homogeneous undulated landscape, except for the narrow plots (recent and abandoned) which were arranged in palisade along the shoreline. As with other saline wetlands in Aragón (Conesa et al., 2011), the interface between Gallocanta Lake and the crops is important from the perspective of habitat conservation. By overlapping the orthophotographs and the Landsat images from different dates, the GIS aided in the delineation of the playas and the shorelines. The Landsat images (Díaz de Arcaya et al., 2004) indicated variation in the moisture conditions of the lake and they provide a temporal perspective that complements the detailed orthophotographs. Satellite images taken in recent decades demonstrate that the surface water fluctuated between wet (Figure 6a) and dry (Figure 6b) seasons, which is reflected in the presence of multiple parallel shorelines, particularly, in the SM. The parallel shorelines indicate the location of the edge of the lake at different times. The gentle slope of the southern margin of the lake means that a significant increase in the water surface can cause the flooding of agricultural plots that, otherwise, are cultivated in dry years. Currently, the landward relict shorelines are covered by crops (Figure 6a) and differ from the lakeward shorelines, which are flooded, intermittently (Figure 6a, b). Figure 6. The shorelines (yellow) of the NM and SM of Gallocanta Lake, Aragon, Spain, superimposed on Landsat images (RGB 457) taken in a wet (02/09/1992) and a dry (12/01/2000) season

The relict shorelines delineate the grey soil band (Figures 5 and 7a), which has considerable lateral continuity and reflects a specific soil composition caused by persistent flooding and a vegetation cover that differs from present-day conditions. The soil, a fundamental component of the landscape, bears witness to the fluctuations of the lake and changes in land use. The soils of the interface between the wetland and crops have to be characterized to understand (1) past and current hydric conditions in the area surrounding the lake, (2) the appropriate limits on its use, and (3) the growing conditions needed for natural vegetation. Soil samples from 12 cores (up to 175 cm deep) taken along transects that were

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perpendicular to the shore on the northern (174 m) and southern (469 m) margins of the lake revealed a gradient in the composition of the soils. Figure 7. Grey soil (a) and vegetation (Salicornia) (b) on the northern margin of Gallocanta Lake, Aragon, Spain, in October 2010

The vegetation in the SM included prairies of Salicornia (Figure 7b), Puccinellia, and Limonium near the shore, and prairies of Juncus and Gramineae in the direction of the crops. In the NM, the most saline fringe of vegetation included Aeluropus litoralis, Suaeda splendens, Suaeda spicata, Salicornia herbacea, Sphenopus divaricatus, and Limonium costae. Other plants such as Elymus cf. Pungens, Dactylis glomerata, Medicagosativa, Tragopogon dubius, and Crepis pulcra were present in uncultivated plots. Soil salinity (ECe) was highest on the southern margin of the lake. ECe ranged from 1.2 to 87.0 dS m-1 in the SM, and from 7.3 to 61.2 dS m-1 in the NM. Soil salinity increased towards the lake and the upper soil horizons were not always the most saline. The soils in the agricultural plots were not saline. The components of the soils of the two margins of the lake differed (Table 3), particularly, the higher proportion of carbonates (CCE) in the northern margin despite the siliceous composition of the substrate (Aranzadi, 1980). About a third of the samples had a clay loam texture, and the proportion of fine textures was higher in the soils of the NM than in the soils of the SM (Table 3). The mineralogical composition of samples from the SM indicated the predominance of quartz in the ≤ 2 mm fraction (31-79%), and, to a lesser extent, calcite (18-39%) and dolomite (3-28%). In the NM, quartz (3-40%) and calcite (11%) were less abundant, but dolomite content increased (49-80%). Gypsum was also identified (17%). Smectite contents from 11% to 15% were found in the clay fraction (≤ 2 µm) of high saline samples collected near the lake on both margins. Illite was the major component (up to 73%) of that fraction and dolomite (3-9%) and quartz (8-15%) were found on both margins. Calcite was present in small proportion in the SM (4%) and the NM (traces). Table 3. Sampling details from the 2009 field season and average soils composition in the NM and SM of Gallocanta Lake, Aragon, Spain. ECe = electrical conductivity in saturated paste, OM = organic matter, CCE = calcium carbonate equivalent, and USDA = US Department of Agriculture Lake Augher Transect ECe OM CCE Gypsum USDA texture margin depth (cm) length (m) (dS m-1) (%) (%) (%)

NM 30 to 150 174 30.3 0.5 41.2 3.9 Clay-loam SM 115 to 175 469 38.1 0.9 29.0 4.3 Loam and sandy-loam

5. Conclusions A map of the landforms of Gallocanta Lake, Aragon, Spain, has been developed for sampling areas on the northern and southern margins of the lake using procedures that can be applied to the entire wetland. The review of previous geological and geomorphological studies of the lake revealed some discrepancies that were the result of differences in the objectives and scales of the studies.

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In addition to its scientific value, the map includes basic information for land management, both for the protection of the lake and its surroundings and for agriculture and other uses. Combining the relief features identified using historic aerial photographs and the recent orthophotographs is crucial for landforms analysis but complex because it is affected by the diversity and quality of the cartographic documents that are available. The approach used in this study allows for the detection of missing or unidentifiable features in the field; however, those features influence land use. Thus, it is important to know the persistence and functionality of shorelines, hoyas, and wetlands, as well as the traces of escarpments and relief discontinuities that have been removed by agriculture. The identification and description of the relief forms in the area of Gallocanta Lake helps in (1) understanding the natural environment within the context of past and current processes and (2) integrating features from various disciplines. The characterization of soils at the interface between wetlands and crops helps in understanding the functionality of the wetland and can be used to limit land uses. In addition, that characterization is required for the preservation of the natural vegetation.

6. Acknowledgments This research was funded by the Spanish Government through project AGL2009-08931. Data used in the GIS were obtained from SITAR (Sistema de Información Territorial de Aragón), the Ebro Basin Authority (CHE), the Department of Environment of the Government of Aragon, and the Instituto Geográfico Nacional.

7. References Abad, M., Ruiz, F., Cantano, M., Rodríguez-Vidal, J., Pendón, J.G., González-Regalado, M.L., Mantero, E.M., Cáceres, L., & Tosquilla, J. (2005). Análisis de modelados de erosión y depósitos residuales transgresivos en el Sector Central de la Cuenca del Guadalquivir (Tortoniense, SO de España). Geogaceta, 37, 207-210. Aranzadi, J. (1980). Estudios de Impactos Ambientales sobre la Laguna de Gallocanta por la acción del desarrollo agrario. PROYEX, S.A. CEOTMA (MOPU). Madrid, 184 pp. Artieda, O. (1996). Génesis y distribución de suelos en un medio semiárido. Quinto (Zaragoza). Ministerio de Agricultura, pesca y Alimentación. Madrid, 222 pp. Artieda, O., Herrero, J., & Drohan, P.J. (2006). Refinement of the Differential Water Loss Method for Gypsum Determination in Soils. Soil Science Society of America Journal, 70, 1932–1935. Calvo, J., González, J.M., González, J., & Villena, J. (1978). Primeros datos sobre la sedimentación de dolomía de la Laguna de Gallocanta (provincias de Zaragoza y Teruel). Tecniterrae, 21, 1-10. CHE. (2003). Establecimiento de las normas de explotación de la unidad hidrogeológica ―Gallocanta‖ y la delimitación de los perímetros de protección de la laguna. Consultor: EPTISA, Zaragoza. Informe inédito. Comín, F. A., Julià, R., & Comín, P. (1991). Fluctuations, the key aspect for the ecological interpretation of saline lake ecosystems. Oecologia Aquatica, 10, 127-135. Conesa, J.A., Castañeda, C., & Pedrol, J. (2011). Las saladas de Monegros y su entorno. Hábitats y paisaje vegetal. Consejo de Protección de la Naturaleza de Aragón, Zaragoza, 540 pp. ISBN: 978- 84-89862-76-0. En prensa. Dantín, J. (1941). La laguna salada de Gallocanta (Zaragoza). Estudios Geográficos, 3, 269-301. Díaz de Arcaya, N., Castañeda, C., Herrero, J., & Losada, J.A. (2005). Revista de Teledetección, 24, 61- 65. Evans, I.S. (2011). Geomorphometry and landform mapping: What is a landform? Geomorphology (In press), doi: 10.1016/j.geomorph.2010.09.029.

101 "Selected Proceedings from the 15th International Congress On Project Engineering" (Huesca,6-8 July 2011)

García-Vera, M.A., San Román Saldaña, J., Blasco Herguedas, O., & Coloma López, P. (2009). Hidrogeología de la Laguna de Gallocanta e implicaciones ambientales. En M.A. Casterad & C. Castañeda (Eds.), La Laguna de Gallocanta: medio natural, conservación y teledetección. Memorias de la Real Sociedad Española de Historia Natural T VII (Pp. 79-103). González Bernández, F. (1992). Los paisajes del agua. Terminología popular de los humedales. J.M. Reyero editor, Madrid, 216 pp. Gracia, F.J. (1993). Fisiografía de la Laguna de Gallocanta y su cuenca. Xiloca, 11, 177-204. Gracia, F.J., & Gutiérrez, F. (1999). Geomorfología kárstica de las cuencas de Gallocanta y (provincia de Teruel). Instituto de Estudios Turolenses, 87(1), 41-68. Gracia, F.J., Gutiérrez, F., & Gutiérrez, M. (1999). Evolución geomorfológica del polje de Gallocanta (Cordillera Ibérica). Revista de la Sociedad Geológica de España 12 (3-4), 351-368. Hernández-Pacheco, F., & Aranegui, P. (1926). La Laguna de Gallocanta y la geología de sus alrededores. Boletín de la Real Sociedad Española de Historia Natural, XXVI, 419-429. Leránoz, B., & González, J.M. (2009). Hidrogeología de la Laguna de Gallocanta e implicaciones ambientales. En M.A. Casterad y C. Castañeda (Eds.), La Laguna de Gallocanta: medio natural, conservación y teledetección. Memorias de la Real Sociedad Española de Historia Natural Tomo VII (Pp. 7-30). Luzón, A., Mayayo, M.J., & Pérez, A. (2009). Stable isotope characterisation of co-existing carbonates from the Holocene Gallocanta lake (NE Spain): palaeolimnological implications. International Journal of Earth Sciences, 98, 1129-1150. Luzón, A., Pérez, A., Sánchez, J.A., Soria, A.R., & Mayayo, M.J. (2007a). Evolution from a freshwater to saline lake: a climatic or hydrogeological change? The case of Gallocanta Lake (northeast Spain). Hidrogeological Processes, 21, 461-469. Luzón, A., Pérez, A., Mayayo, M.J., Soria, A.R., Sánchez, M.F., & Roc, A.R. (2007ba). Holocene environmental changes in the Gallocanta lacustrine basin, Iberian Range, NE Spain. The Holocene, 17(5), 649-663. MAPA. (1994). Métodos oficiales de análisis. Tomo vol. III. Ministerio de Agricultura, Pesca y Alimentación, Madrid. Martín-Serrano, A., Salazar, A., Nozal, F., & Suárez, A. (2004). Mapa geomorfológico de España. Escala 1:50.000. Guía para su elaboración. Ministerio de Educación y Ciencia. IGME, Madrid, 128 pp. Pérez, A., & Roc A.C. (1999). Los sedimentos de la Laguna de Gallocanta y su comparación con las calizas de en Zaragoza. Consejo de Protección de la Naturaleza de Aragón, Zaragoza, 114 pp. Pérez, A., Luzón, A., Roc, A.C., Soria, A.R., Mayayo, M.J., & Sánchez, J.A. (2002). Sedimentary facies distribucion and genesis of a recent carbonate-rich saline Gallocanta Lake, Iberian Chain, NE Spain. Sedimentary Geology, 148, 185-202. San Román Saldaña, J., García-Vera, M.A., Blasco Herguedas, O., & Coloma López, P. (2007). Hidrogeología de la Laguna de Gallocanta. Xiloca, 35, 65-86. Villena, J. (1971). Estudio geológico de un sector de la Cordillera Ibérica comprendido entre Molina de Aragón y Monreal. Tesis doctoral inédita. Universidad de Granada, 227 pp. Villena, J. (1976). Estudio geológico de un sector de la Cordillera Ibérica comprendido entre Molina de Aragón y Monreal (provincias de Guadalajara y Teruel). Boletín Geológico y Minero, 87(4), 329- 354.

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