David Regüés

Estela Nadal-Romero

Jose Ángel Llorente

José Arnáez

Makki Khorchani

Manuel López-Vicente

Noemí Lana-Renault

Nuria Pascual

Paz Errea

Purificación Ruiz-Flaño

Rafael Ojanguren

Repositorio de Universidad de La Rioja

Geophysical Research AbstractsVol. 20, EGU2018-6660, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Changes in catchment hydrological connectivity under different postfarmland abandonment scenariosNoemí Lana-Renault (1), Manuel López-Vicente (2), Estela Nadal-Romero (3), Rafael Ojanguren (1), Jose ÁngelLlorente (1), Paz Errea (4), David Regüés (4), Purificación Ruiz-Flaño (1), Makki Khorchani (4), José Arnáez (1),and Nuria Pascual (1)(1) University of La Rioja, DCH, Physical Geography, Logroño, Spain (noemi-solange.lana-renault@unirioja.es), (2)Departamento de Suelo y Agua, Estación Experimental de Aula Dei, EEAD-CSIC, Zaragoza, Spain, (3) Departamento deGeografía, Instituto Universitario de Ciencias Ambientales (IUCA), Universidad de Zaragoza, Zaragoza, Spain, (4) InstitutoPirenaico de Ecología, CSIC, Zaragoza, SpainFarmland abandonment has been one of the major changes in many Mediterranean mountainous areas throughoutthe 20th century. Large areas of former agricultural land have undergone natural revegetation. In other cases,extensive afforestation programs have been conducted to reduce land degradation following farmland aban-donment. On terraced landscapes, the lack of maintenance may cause failures in the terrace risers, resulting innew sediment sources on the hillslopes. The heterogeneity of landscapes present in mountainous regions of theMediterranean increases the uncertainty in forecasting changes in water resources and soil conservation afterfarmland abandonment. This study describes the evolution of land use in three small headwater catchmentsin northern Spain, representing different farmland abandonment scenarios (natural revegetation, afforestationand terraced fields), and examines its implications on catchment hydrological connectivity. It also analyses thehydrological responses of the three abandoned scenarios to similar rainfall events, and compares them to that ofnatural forested areas. Vegetation tended to increase in the three catchments, but there were important differencesin the characteristics of the current land cover. Arnás, the catchment left to a process of natural revegetation,contained a mosaic of shrubs (64%) and forest (27%) at different stages of succession, largely conditioned bythe topography and soil properties. The Araguás_afforestation sub-catchment was extensively afforested in the1960s, with 75% of its surface currently covered by forest, most of it planted artificially. In the Munilla catchment,occupied by terraced fields, vegetation recovery was partly restrained by the introduction of cattle and 80% ofthe total area was covered by sparse shrubs. Land abandonment resulted in a general reduction in computedhydrological connectivity (Borselli’s index – updated version) in the three studied catchments, except in localizedareas close to the main channel, new forest roads and trails, and upstream of terrace wall collapses, all areasof increased hydrological connectivity. The decrease in hydrological connectivity was much lower in Munilla,characterized by an absence of dense vegetation and still dominated by a terraced topography. The hydrologicalresponses of these catchments differed significantly, showing the influence of not only vegetation cover but ofthe properties of soil remaining after previous agricultural activities. In this study, the parametrization of thehydrological index (IC) was greatly determined by the land cover and extension of the stream layer. Our resultssuggest, however, that soils characteristics play an essential role in the hydrological behavior of the studiedenvironments. Thus, alternative methods for evaluating hydrological connectivity are required, which shouldinclude soil properties (e.g. permeability) or the assessments of IC for different targets (e.g., ephemeral gullies,sinks or springs).This study was received financial support from Project ESPAS (CGL2015-65569-R), funded by the Span-ish Ministry of Economy and Competitiveness and FEDER.

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Changes in catchement hydrological connectivity under different post farmland abandonment scenarios

Changes in catchement hydrological connectivity under different post farmland abandonment scenarios

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