On significance and history of irrigation schemes construction on the example of Zemo Samgori irrigation scheme
Agrarian irrigation is the ancient field of agriculture in Georgia and represents its integral part. Scientific researches prove that alignment of irrigation canals was on a high level in early Bronze Age that is confirmed by numerous traces of ancient canals. It’s known that according to the natural-climate conditions, East Georgia, where the major part of irrigation canals is concentrated is characterized by the lack of atmospheric rainfall and unequal annual distribution. Humidity deficit for crops in vegetation period differs within the range of 400-500 mm (4-5 m3/ha) equaling to 4-5 times irrigation. The same can be said about several regions of West Georgia, with comparatively less intensity. It’s proved scientifically that strict droughts are observed in East Georgia once per every 4-5 year. Droughts on reinfed areas cause full destruction of annual crops, physiological degradation of fruit gardens and vineyards, while during humidity deficit agricultural crop yield decreases by 30-40%. Numerous tests have proved that in case of two times irrigation, crop yield increases by 30% in average, while every next irrigation increases crop yield by additional 18-20%. Irrigation has a positive impact not only in drought but comparatively less rainfall periods as well. Keeping optimal volume of humidity for the plant is actually impossible however regulation between its lower and upper limits (40-80%) can be reached by irrigation. Lands adjacent to Tbilisi, served by Zemo Samgori irrigation scheme used to be irrigated in past. In 60s of 19th century the scheme for irrigation of Samgori and Karaiazi valleys was developed, however the problem of Samgori Valley irrigation was finally solved in 20th century. Development of the irrigation-hydro power project for Samgori massif lands started in 1925 and completed in 1931. Construction works started in 1941, though were halted due to the start of the World War II. The construction works were renewed in 1947, after approval of the first stage works of the technical design, considering construction of Paldo headworks, upper main canal and Tbilisi reservoir. Construction of Zemo Samgori irrigation scheme represented general public construction indeed.
In the shortest period, considering that time poor technical equipment and provision, 15 mln. M3 land was excavated, concrete works with total volume of 415 000 m3 were undertaken. On the canal trench, aligned on heavy relief, numerous complex hydraulic structures were arranged, including: 10 tunnels with total length of 8439, 2 galleries with total length of 309m, 5 inverted siphons with total length of 1762 m, 3 aqueducts with total length of 177 m, 3 chutes with total length of 1551 m. Finally, open ceremony of 40 km long main canal took place on November 4, 1951 enabling to irrigate 14 200 ha of agricultural land area. Besides filling of Tbilisi reservoir started too. Technical maintenance of Zemo Samgori irrigation scheme started in 1954, while construction of the whole scheme completed in 1964, after launching operation of Sioni Reservoir.
In the shortest period, considering that time poor technical equipment and provision, 15 mln. M3 land was excavated, concrete works with total volume of 415 000 m3 were undertaken. On the canal trench, aligned on heavy relief, numerous complex hydraulic structures were arranged, including: 10 tunnels with total length of 8439, 2 galleries with total length of 309m, 5 inverted siphons with total length of 1762 m, 3 aqueducts with total length of 177 m, 3 chutes with total length of 1551 m. Finally, open ceremony of 40 km long main canal took place on November 4, 1951 enabling to irrigate 14 200 ha of agricultural land area. Besides filling of Tbilisi reservoir started too. Technical maintenance of Zemo Samgori irrigation scheme started in 1954, while construction of the whole scheme completed in 1964, after launching operation of Sioni Reservoir.
