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| Titel |
Water quality and agricultural practices: the case study of southern Massaciuccoli reclaimed land (Tuscany, Italy) |
| VerfasserIn |
Chiara Pistocchi, Ilaria Baneschi, Paolo Basile, Silvia Cannavò, Massimo Guidi, Rosalba Risaliti, Rudy Rossetto, Tiziana Sabbatini, Nicola Silvestri, Enrico Bonari |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043146
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| Zusammenfassung |
| Owing to increasing anthropogenic impacts, lagoons and wetlands are being exposed to
environmental degradation. Therefore, the sustainable management of these environmental
resources is a fundamental issue to maintain either the ecosystems and the human
activity.
The Massaciuccoli Lake is a coastal lake of fresh to brackish water surrounded by a
marsh, which drains a total catchment of about 114 km2. Large part of the basin has been
reclaimed since 1930 by means of pumping stations forcing water from the drained areas into
the lake. The system is characterized by:
high complexity of the hydrological setting;
subsidence of the peaty soils in the reclaimed area (2 to 3 m in 70 years), that
left the lake perched;
reclaimed land currently devoted mainly to conventional agriculture (e.g.: maize
monoculture) along with some industrial sites, two sewage treatment plants and
some relevant urban settlements;
social conflicts among different land users because of the impact on water quality
and quantity.
The interaction between such a fragile natural system and human activities leads to an altered
ecological status mainly due to eutrophication and water salinisation.
Hence, the present work aims at identifying and assessing the sources of nutrients
(phosphorous in particular) into the lake, and characterising land use and some
socio-economic aspects focusing on agricultural systems, in order to set up suitable
mitigation measures.
Water quantity and quality in the most intensively cultivated sub-catchment, placed 0.5 to
3 m under m.s.l. were monitored in order to underlain the interaction between water and its
nutrient load. Questionnaires and interviews to farmers were conducted to obtain information
about agricultural practices, farm management, risks and constraints for farming
activities.
The available information about the natural system and land use were collected and
organised in a GIS system: a conceptual model of surface water hydrodinamics was build up
and 14 sampling points were monitored monthly during 2008-2009. The main water physical
and chemical parameters, including nutrients, as well as the principal soil types within the
sub-catchment were analysed.
First results point out:
the reclaimed land presents a dense drainage network hydraulically
interconnected with the shallow aquifer;
surface waters present a high chemical heterogeneity: three main hydrochemical
facies were identified and compared with nutrients contents and soil chemistry;
artificially induced recharge to the reclaimed land aquifer occurs by means of
lake water infiltration. This forces the pumping stations to remove an additional
amount of water in order to allow land cultivation;
the water salinity in the drainage network may increase during summer period.
This could be related both to irrigation using lake water and a further contribution
due to evapotranspiration processes;
agricultural land use changed during the last 15 years, and shifted to less
intensive farming practices. Fertilization levels dropped from 200 and 150 to 100
and 50 kg/ha N and P2O5 respectively, and the irrigated area decreased from
50% to 40% of the total utilised agricultural area;
in the low land peaty area, the higher content of sulphate and phosphate in the
drainage water supports the hypothesis that peat degradation could be a relevant
source of nutrients.
As a result, the impact of fertilizer use on the water quality is limited, while land management
(e.g. water use and land reclamation) constitutes the key issue.
Therefore, local stakeholders participation, farmers above all, should be supported in
future management and planning actions in order to adapt socio-economic needs with the
peculiar biophysical conditions. |
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