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Water pollution induced by rainfed and irrigated agriculture in Medirerranean environment, at basin scale
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Authors
Advisor(s)
Abstract(s)
The pollution of the superficial and subsuperficial water occurred from the agricultural areas, can
assume a great importance in the context of all sources of water pollution. In fact, the intensification of
the agricultural activity, in particular the irrigated agriculture increases the use of the agrochemical
products, and the problems in the soil and water bodies. When the climatic conditions are favorable, or
the irrigation systems are not well operated, this is an economic problem from the farmers and an
environmental problem from the society. The study area is a small basin (190 ha), located in centre of
Portugal, near the Natural Park of International Tagus. It is well drained, and the agricultural activity is
developed in two different seasons; the winter season where the farmers produce especially winter
cereals, and the irrigation season where they produce typical crops in this region (corn, sorghum,
tobacco), and recently bioenergetics crops like soybean.
This study is focused in the water pollutants, nitrates and ammonium, sediments and total dissolved
solids. Their dynamic in the basin, more or less dependent of the runoff, is different between pollutants
and between both seasons. So, the nitrates load depends, all time, of the availability in the soil and the
runoff volume, due to its solubility. The ammonium shows a different dynamic; when it is present in
large amount in the soil, their load depends of the sediments load and the extremes peak flow, with
high power to carry outside the basin. The total daily load of sediments not shows a direct relation with
de runoff volume, except when it has a sufficient energy to detach and carry out, as in the extremes
events. Therefore, the total daily load accumulated curve of this pollutant along the time, develops by
levels related with each extreme event. Another aspect important to accentuate is the clear
dependence of the amount of sediments to the conditions in the watershed, for similar intensity
storms. For total dissolved solids, this study allows to conclude a very clear relation between the runoff
volume and the load of this pollutant, in both seasons. In the other hand, this study not allows to
conclude if the loss of this pollutant is higher in the winter or irrigation season.
Description
Keywords
Non point source Water pollution Rainfed agriculture Irrigated agriculture Watershed
Pedagogical Context
Citation
DUARTE, A.C. (2010) - Water pollution induced by rainfed and irrigated agriculture in medirerranean environment, at basin scale. In BALWOIS-2010 Water Observation and Information System for Decision Support, Ohrid (Republic of Macedonia, 2010 - Proceedings.