Modern database management 11 pdf

Most of this article was written in 2009, with subsequent updates on certain aspects, most recently modern database management 11 pdf 2013. A key problem of water resources management in Egypt is the imbalance between increasing water demand and limited supply.

In order to ensure future water availability coordination with the nine upstream Nile riparian countries is essential. In the 1990s the government launched three mega-projects to increase irrigation on “new lands”. These projects all require substantial amounts of water that can only be mobilized through better irrigation efficiency on already irrigated “old lands” as well as the reuse of drainage water and treated wastewater. 1902 and barrages on the Nile in the 19th and early 20th century. The Old Aswan Dam partially stored the waters of the Nile to allow the growing of multiple crops per year in the Nile Delta, while the barrages raised the water level of the Nile so that water could be diverted into large irrigation channels running in parallel to the river.

The dam brought major benefits such as increased water availability for Egyptian agriculture leading to higher income and employment, hydropower production, flood control, improved navigation, and the creation of fisheries in Lake Nasser. But it also had environmental and social impacts including resettlement, loss of fertile silt that now accumulates in the reservoir behind the dam, waterlogging combined with an increase in soil salinity, and increased coastal erosion. Unrelated to the construction of the Aswan High Dam, water quality deteriorated through drainage return flows and discharges of untreated municipal and industrial wastewater. Beginning in the 1980s wastewater treatment improved and water quality in the Nile gradually improved again. Until 1992 the government decided which crops farmers had to grow, which allowed the authorities to deliver specific volumes of water to each canal based on the water needs of the crops. In 1992 a major change occurred when cropping patterns were liberalized and farmers were free to grow what they wanted.