Political history of High Aswan Dam (HAD) construction In June 1956 the Soviet Union offered President of Egypt Nasser $1.12 billion at 2% interest for the HAD construction. On 19 July the US State Department announced that American financial assistance for the HAD was not feasible in present circumstances. On 26 July 1956 with wide Egyptian acclaim Nasser announced the nationalization of the Suez Canal as well as fair compensation for the former owners. Nasser planned on the revenues generated by the canal helping to fund construction of the HAD. When the Suez War broke out, the United Kingdom, France & Israel seized the canal & the Sinai, but pressure from the US and Soviet Union at the United Nations forced them to withdraw. In 1958 the Soviet Union provided funding for the HAD project. The Soviet Union provided technicians & heavy machinery. The HAD was designed by Hydroproject Institute (Moscow), 25,000 Egyptian engineers & workers took part in the HAD construction. HAD construction and reservoir filling (1960–1976)1960: Start of construction on 9 January 19601964: First dam construction stage completed, reservoir started filling1970: The HAD, as-Sad al-'Aali, completed on 21 July 19701976: Reservoir reached its maximum capacity2011: Construction of pumping plant (downstream of HAD) & irrigation canal to Nubia

Photo1. Egyptian President Nasser & Soviet Photo2. Nasser observing the Nile closure (14.05.1964)leader Khrushchev at the ceremony of the Nile diversion during HAD construction (14.05.1964) The HAD main innovation features The HAD (together with the Hoover Dam, USA) was awarded by the Britannica Encyclopedia as the most prominent dams of the first half of the XX century. The HAD is 111 m high rockfill dam (curved in plan, Photos 3, 4) with wide central clay core, its length is 3830m, width 980m at the base & 40m at the crest, the HAD body contains of 43,000,000 cubic m of rockfill, clay & sands. The unprecedented 40m wide crest & 16m freeboard (Fig.1) were adopted for a case of possible attack of Israel bombers. Fortunately, during the 6-days Israel-Egypt War (May 1967) it wasn’t happened.

Photo 3. View on HAD from the upper level of the left bank

Photo 4. The HAD panorama (downstream view)

Fig. 1. High Aswan Dam (H=111 m, Egypt) - rockfill dam with clay core, blanket & 200 m deep injection grout curtain

1 – pavement over crushed stone; 2 – 3 filter layers (crushed stone d=40-150 mm, 5-35 mm & less than 5 mm); 3 – quarry rock fines; 4 – 100 & 70 m deep drainage wells; 5 – dune (fine) sand; 6 – compacted dune sand; 7 – rockfill with size less than 150 mm, sluiced with dune sand; 8 – depression curve; 9 – crushed stone d=40-150 mm; 10 – rockfill dumped & compacted by water jet; 11 – middle sized sand; 12 – compacted dune sand; 13 - compacted middle sized sand; 14 – 200 m deep injection grout curtain; 15 – grout & control galleries; 16 – clay core; 17 – crushed stone; 18 – clay blanket; 19 – crushed stone d=40-150 mm; 20 – various sized sand; 21 – pebbles & boulders with sand; 22 – interlayering loams, sandy clays, sands & sandstones; 23 – igneous rock

As the HAD was to be constructed in the existent 35 m deep reservoir of the old Aswan dam the effective solution was adopted in the project - to locate the HAD foundation above the old Aswan reservoir level by dumping in reservoir rock fragments in the upstream & downstream coffer-dams (from self-unloading barges) during excavation of 85 m deep tail-race canal on the right bank. After the Nile closure the sluicing of dune sand into the pores of rockfill of both coffer-dams was made, followed by the hydraulic filling of dune sand in the central part of HAD foundation, including the wide clay core (Fig 1). The deep (down to 40 m) effective dynamic compaction of the dune sand zone was achieved by two special large installations mounted on large barges, each equipped with 4 steel submersible vertical pipes with inner vibrators. In the 250 deep channel section of the HAD the heterogeneous permeable foundation (consists of sands, gravels & pebbles) the principal anti-seepage system of 200 m deep injection grout curtain was performed (the deepest & largest in the world). The injection grout curtain of telescopic form (with hydraulic gradient 2-4 across the curtain) consists of 15 rows of grout bore holes with 3 m spacing. 9 various grout mixtures (from bentonite cement to polymer, sodium silicate) were prepared in the grout factory, pumped in pipes to the core site & two grout & control galleries & injected down in grout boreholes by Soletanche technique (France). The deepest central row of grout bore hole was injected from the third central grout & control gallery (Fig. 1). The post-grouted permeability of each soil strata of grout curtain was 100-500 times less than before grouting. Taking in account that before the HAD grout curtain there was only one precedent (1959) of 100 m deep grout curtain in the homogeneous alluvial foundation of Serre Ponson rockfill dam (France), during the HAD design the second additional anti-seepage system was provided for a case of grout curtain inefficiency. This system consists of the upstream clay blanket of rugged form connected with the upstream toe of the clay core and two rows of 100 & 70 m deep drainage wells on the crest of the downstream coffer-dam. The International Expert Board, headed by Karl Terzaghi (father of Soil Mechanics) during its meeting in 1962 with Soviet design engineers, headed by Chief Design Engineer Nikolai Malyshev & Egypt high-ranked officials, approved Soviet project as more safe & effective comparing with previous project by A.Gibbs (UK).

Hydropowerplant (HPP) main innovation featuresThe HAD main element is a combined type HPP with 12 generators each of 175 MW with total of 2100 MW. Power generation began in 1967. When HPP first reached peak output it produced nearly half of Egypt's entire electricity production (15% by 1998) & allowed most Egyptian villages to use electricity for the first time.

Photo5. D-S view of HPP & tail-race canal (background the monument of Arab-Soviet Friendship (Lotus flower) The HAD has also improved the efficiency & the extension of the Old Aswan HPP (upstream of HAD) by regulating upstream flows. At maximum 11000 cubic m/sec of water can pass through the HPP combined with 12 spillway outlets each equipped with operating radial gate.There are further emergency spillways for an extra 5000 cubic m/sec and the Toshka Canal links the reservoir to the Toshka Depression. The reservoir, named Lake Nasser, is 550 km long and 35 km at its widest with a surface area of 5250 square km. It holds 132 cubic km of water (the second largest reservoir in the world). The HAD significant impact on the Nile river The HAD is a rockfill dam constructed across the Nile River in Aswan, Egypt. HAD construction became a key objective of President Nasser, as the ability to control floods, provide water for irrigation & generate hydroelectricity were seen as pivotal to Egypt's industrialization. The HAD was constructed between 1960 & 1970 and had a significant impact on the economy and culture of Egypt.Before the HAD was built, the Nile river flooded every year during late summer, when water flowed down the valley from its East African drainage basin. These floods brought high water and natural nutrients and minerals that annually enriched the fertile soil along the floodplain and delta; this had made the Nile valley ideal for farming since ancient times. Because floods vary, in high-water years the whole crop might be wiped out, while in low-water years widespread drought and famine occasionally occurred. As Egypt's population grew and conditions changed, both a desire and ability developed to control the floods, and thus both protect and support farmland and the economically important cotton crop. With the reservoir storage provided by the HAD the floods could be lessened and the water stored for later release. Irrigation scheme of the HAD project Due to the absence of appreciable rainfall Egypt's agriculture depends entirely on irrigation. With irrigation two crops per year can be produced, except for sugar cane which has a growing period of almost one year. The HAD releases 55 km3 water per year, of which 46 km3 are diverted into the irrigation canals. In the Nile valley 33600 km2 benefit from these waters producing 1.8 crops per year. The annual crop consumptive use of water is about 38 km3. Hence, the overall irrigation efficiency is very high: 38/46 = 0.82 (82%). The field irrigation efficiencies are much less, but the losses are re-used downstream. This continuous re-use accounts for the high overall efficiency. HAD resulted in protection from floods & droughts, an increase in agricultural production & employment, electricity production & improved navigation that benefits tourism. Conversely, the HAD flooded a large area, causing the relocation of over 100,000 people and submerged archaeological sites, some of which were relocated as well. The HAD is also blamed for coastline erosion, soil salinity & health problems. The cost assessment & HAD benefits remains a controversial issue, however, decades after its completion. According to one estimate, the annual economic benefits of the HAD right after its completion were Egyptian Pound (EPs) 255 million (US$587 million using the 1970 exchange rate of US$2.30 per EP): 140 million EPs agricultural production, 100 million EPs from hydroelectric generation, 10 million EPs from flood protection and 5 million EPs from improved navigation. At the time of its construction, total cost, including unspecified "subsidiary projects" & the extension of electric power lines, amounted to 450 million EPs. Not taking into

account the negative environmental & social impacts of the HAD its costs are thus estimated to have been recovered within only two years. The impacts of the AHD have been overwhelmingly positive. Although the HAD has contributed to some environmental problems, these have proved to be significantly less severe than was generally expected, or currently believed by many people. Periodic floods & droughts have affected Egypt since ancient times. The HAD mitigated the effects of floods, such as in 1964, 1973 & 1988. Navigation along the river has been improved, both upstream and downstream of the HAD. Sailing along the Nile is a favorite tourism activity, which is mainly done during winter when the natural flow of the Nile would have been too low to allow navigation of cruise ships. A new fishing industry has been created around Lake Nasser, though it is struggling due to its distance from any significant markets. The annual production was about 35000 tons in the mid-1990s. Factories for the fishing industry and packaging have been set up near the Lake Nasser. Drought protection, agricultural production & employment The HAD also protected Egypt from the droughts in 1972–1973 & 1983–1987 that devastated East and West Africa. The HAD allowed Egypt to reclaim about 840,000 hectares in the Delta and along the Nile Valley, increasing the country's irrigated area by a third. The increase was brought about both by irrigating what used to be desert & by bringing under cultivation of 385,000 ha that were previously used as flood retention basins. About half a million families were settled on these new lands. In particular the area under rice & sugar cane cultivation increased. In addition about 420,000 hectares, mostly in Upper Egypt, were converted from flood irrigation with only one crop per year to perennial irrigation allowing two or more crops per year. On other previously irrigated land, yields increased because water could be made available at critical low-flow periods. For example, wheat yields in Egypt tripled between 1952 & 1991 & better availability of water contributed to this increase. Most of the 32 km³ of freshwater, or almost 40 percent of the average flow of the Nile that were previously lost to the sea every year could be put to beneficial use. While about 10 km³ of the water saved is lost due to evaporation in Lake Nasser, the amount of water available for irrigation still increased by 22 km³. Loss of sediments Before the HAD construction the Nile deposited sediments of various particle size (dune sand, silt & clay) on fields in Upper Egypt through its annual flood, contributing to soil fertility. However, the nutrient value of the sediment has been overestimated. 88% of the sediment was carried to the sea before HAD construction. The nutrient value added to the land by the sediment was only 6000 tons of potash, 7000 tons of phosphorus pentoxide &17000 tons of nitrogen. These amounts are insignificant compared to what is needed to reach the yields achieved today in Egypt's irrigation. The annual spread of sediment due to the Nile floods occurred along the Nile banks. Areas far from the Nile which never received the Nile floods before are now irrigated. The sediment trapping by HAD has increased coastline erosion (125-175m per year) near the Nile Delta. Sediment deposited in the reservoir is lowering the water storage capacity of Lake Nasser. The reservoir storage capacity is 162 km³, including 31 km³ dead storage at the bottom of the lake below 147 m above sea level, 90 km³ live storage & 41 km³ of storage for high flood waters above 175m above sea level. The annual sediment load of the Nile is about 134 million tons. This means that the dead storage volume would be filled up after 300–500 years if the sediment accumulated at the same rate throughout the area of the Lake Nasser. Obviously sediment accumulates much faster at the upper reaches of the Lake, where sedimentation has already affected the live storage zone. Before the HAD construction the 50,000 km of irrigation & drainage canals in Egypt had to be dredged regularly to remove sediments. After HAD construction aquatic weeds grew much faster in the clearer water, helped by fertilizer residues. The total length of the infested waterways was about 27000 km in the mid-1990s. Mediterranean fishing and brackish water lake fishery declined after the HD was finished because nutrients that flowed down the Nile to the Mediterranean were trapped behind the HAD. For example, the Sardine catch off the Egyptian coast declined from 18000 tons in 1962 to a mere 460 tons in 1968, but then gradually recovered to 8590 tons in 1992. A concern before HAD construction had been the potential scour in river-bed level downstream of HAD as the result of erosion caused by the flow of sediment-free water. Estimates by international experts put the scour between 2-10 m. However, the actual scour has been measured at 0.3-0.7 m, much less than anticipated. Archeological sites 22 monuments & temples, including the Great Abu Simbel temple (Photos 6-7), that were threatened by flooding from Lake Nasser were preserved by moving them to the shores of Lake under the UNESCO Nubia Campaign. Also moved were Philae, Kalabsha & Amada temples. Other monuments were granted to countries that helped with the works (Temples: Debod in Madrid, Taffeh in Leiden & Dendur in New York).

Photo 6. The statue of Ramses the Great at the Abu Simbel Temple is reassembled after having been moved in 1967 to being flooded by Lake Nasser save it from

Photo 7. The Abu Simbel Temple with the rock massif after their transfer on opposite Nile bank on higher elevations