| Spotlight Damming structures and flood


protection on Sudeten rivers The Sudetenland is a watershed between the Oder, Elbe and Danube Rivers basins and is characterised by a very dense river network. Nysa Luzycka, Bobr with Kwisa, Kaczawa, Bystrzyca and Nysa Klodzka are the principal rivers in the area. The enormous historic flood in the area was the one in 1897, both on the current Polish side and on the Czech side (the area of the Jizera Mountains). That flood was also crucial for creating a system of flood protection structures. A few days in July 1897 permanently changed the approach to flood protection and led to the construction of many reservoirs, which were also built for purposes other than flooding, including power generation. The flood at the end of July 1897 incentivised German engineers and technicians to take measures to prevent disaster in the future. Work was undertaken to develop the rivers and streams in the Sudetenland, which at the time belonged to Prussia. An ambitious plan was drawn to construct hydraulic structures such as dams and reservoirs to help harness the power of flood waters. The project included the construction of debris dams, gradually regulating streams, and constructing various water reservoirs (multi-purpose and for flood control) and dry reservoirs. Work had already begun in 1901. At the beginning of the 20th century, work was undertaken on the Klodzko Basin, the Jeleniogorska Basin and the Bobr Valley protection systems to avoid further disasters. Regulation of the tributaries of the Bobr originating in the Karkonosze was carried out with retaining walls along the banks, thresholds and debris dams. A dry reservoir, Stronie Slaskie on the Morawka River, was opened in 1907 and Miedzygorze on the Wilczka River, in the Klodzko Basin, in 1909. At the Karkonosze foothills, three dry reservoirs were built: on the Lomnica River in Myslakowice, on the Kamienna River in Jelenia Gora-Sobieszow and the Wrzosowka River with the Podgorna River in Jelenia Gora-Cieplice. The last one was built between 1904 and 1905. Dams and hydroelectric power stations at Lesna (1905) and Zlotniki (1919) on the Kwisa and Pilchowice (1912) on the Bobr were built later. Undoubtedly the largest of the completed projects was the Pilchowice Dam. Professor Otto Intze from Aachen was the leading designer of this dam, and even Kaiser Wilhelm came to participate in its opening. This is why it is worth taking a closer look at these structures. The location of the dams is shown in Figure 1.


Dry reservoirs The main purpose of constructing a dry reservoir is


a downstream area flood protection. The principal role of a dry flood protection reservoir is to intercept significant volumes of a flood wave in the reservoir’s bowl (limited by the dam) and to allow continuous outflow of water in a safe quantity to areas located at the downstream side of the reservoir. As a result of the flood protection programs launched after the flood of 1897, many hydraulic investments were made on an unprecedented scale. The outbreak of the First World War only slowed down their rapid implementation. Most of the structures, especially dry flood control reservoirs, were built on the rivers of Kotlina Klodzka and Kotlina Jeleniogorska. Some of them are worth discussing.


Miedzygorze. The Miedzygorze reservoir on the Wilczka stream was put into operation in 1909 (Figure 1). The valley was dammed by a stone dam (Figure 7), 110m long and 29m high, enclosing a catchment area of 25km2


. The parameters of the


dam discharge facilities are as follows: two bottom discharges 8.8m3


and surface overflow 37.5m3


capacity of the reservoir is 0.83 million m3 below the dam were estimated at 80-100m3


/sec, middle discharge 15m3 /sec. The maximum . Flows /sec


/sec,


during the 1997 floods, which far exceeded the total discharge of the designed discharge elements. The structure, despite extensive damage, did not fail. Stronie Slaskie. The dry flood control reservoir is located in the municipality of Stronie Slaskie on the Morawka (Figure 1) stream and has a maximum capacity of 1.38 million m3


. The reservoir was


built between 1906 and 1910 and was initially permanently filled with water. A 500m long earth dam closes a catchment area of 53.46km2


. It has


a bottom and middle discharge and a surface overflow (Figure 8). Cieplice. The dry reservoir, closing a catchment area of 94 million m3


Below: Figure 10. Dam in Lesna (photo: Wojciech Redowicz)


, is located on the Wrzosowka


stream in Jelenia Gora, in the Cieplice district (Figure 1). The structure consists of an earth dam with a length of 2925m and a maximum head level of 8.4m, a bottom discharge, a middle discharge and an overflow. The maximum capacity of the reservoir is 4.93 million m3


.


Myslakowice. The Myslakowice dry reservoir is located on the Lomnica stream in the Mysłakowice commune (Figure 1) and closes a catchment area of 49.6km2


. A dam, upper and lower discharges, www.waterpowermagazine.com | July 2023 | 13


Above: Figure 9. The Myslakowice Dam in 1913 [https://polska- org.pl/3333378,foto. html?idEntity=5834987]


Top: Figure 8. The dam in Stronie Slaskie [https:// polska-org.pl/892375,foto. html?idEntity=5170049]


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53