Ground water nitrate pollution in Tadla (Morocco)

[u'In Morocco, diffuse ground water pollution by nitrates in irrigated areas has caused an increase in the risk of water quality deterioration. This has generated a health risk in rural areas, since most of the rural population get their drinking water supply from the aquifer. The present study was carried out in the Tadla region. The plain of Tadla is situated in the centre of Morocco, in the Oum Erbia river basin. It covers a surface area of 3600 km . The Oum Erbia river (160 km long) divides this plain into two large irrigated areas (Beni Amir in the east (3300 ha) and Beni Moussa in the south (6900 ha)), with different hydrological characteristics. The irrigation water comes from the Oum Erbia river, the Bin El Ouidane dam and from two important waters tables: Beni Amir (190 Mm ) and Beni Moussa (250 Mm ). The objectives of this study were to quantify the degree of ground water contamination by nitrates and to identify the potential causes of this pollution.', u'The monitoring of nitrate concentrations in ground water was carried out during the period of August 1996 to April 1998, in 100 wells in the region of study. The physical environment and agricultural practices were determined either by field measurements, laboratory analyses or by investigations with farmers at 40 selected sites. The results are presented by thematic maps using a geographical information system.', u'The level of ground water nitrate pollution is becoming a serious problem. The point pollution is localized around or downstream of urban built up areas such as Fquih Ben Saleh, Beni Mellal, Souk Sebt and Oulad Ayad. This pollution, caused by household wastes, is likely aggravated by waste dumping from the sugar refineries (SUBM, SUTA and SUNAT) as well as by waste water reuse in agriculture. Other zones with nitrate concentrations more than 50 mg NO -/L were observed in wells situated downstream from Beni Amir and east of Beni Moussa. West Beni Moussa was generally not as polluted as east Beni Moussa, but an increase in ground water ...