Seawater intrusion and crop response to salinity in coastal Lebanon

Research conducted between 1999 and 2004 to assess pressure on coastal zone focused on three main objectives: first, the evaluation of seawater intrusion in southern coastal wells, second, the soil salinization in greenhouses irrigated by well waters, and third the management of saline water in two soil textures. Groundwater contamination was assessed by regular sampling of six wells for 30 months. The salinity of water fluctuated around 3 dS m[-1] and the Simpson index [Cl/HCO[3]] indicated levels of moderate to injurious contaminations. The Na/Cl ratios remained < 1, suggesting a seawater intrusion rather than an anthropogenic origin. In all sites, greenhouse growers had to rely on other water sources [e.g. rainwater, domestic] to supply the crop needs. In some cases, the crop had to be interrupted as salinity decreased yields. Improving the management of water and nutrients was studied in a tomato/Jew's-mallow sequence. Three levels of water salinity [1, 2.5 and 5 dS m[-1]] were tested in sandy and clay soils. Under sound management of fertilizers input and a leaching fraction, the salinity had no obvious negative effect on tomato in the clay soil. The Jew's mallow had a role in the removal of residual salts.

Monitoring of groundwater salination by seawater intrusion on the Lebanese coast

In order to monitor the effects of the seawater intrusion on the groundwater quality, the coastal region from Choueifat to Rmeyle located south Mount - Lebanon had been chosen to be studied. Six wells have been selected. Water samples have been collected for a period of three years from 1999 to 2002, at the rate of one sample a month. A complete physico-chemical analysis has been done in order to measure the increase in salinity as well as the variation in piezometric level. The results obtained from the study showed that the regions of Choueifat, Jiye and Rmeyle are subject to seawater intrusion. This intrusion is directly and simultaneously related to the pumping period and intensity but poorly related to the amount of rainfall. It also depends on the geologic nature of the study area. Furthermore, the actual intrusion in the study zone aggravates the existing salinity problems. Indeed the salinity rates of well water ranged between 0.7 dS/m and 5.5 dS/m [the majority being above 2 dS/m] resulting in salinity rates not tolerable for crops, thus threatening their growth and production