User:AloofBidoof/Lake Balaton

Limnology
Lake Balaton is the largest freshwater lake within Hungary, with a 0.3% of Hungary's national reserve. It is around 17-19,000 years old. The majority of water is supplied from precipitation, stream flow, and underground water sources. A significant source of water loss stems from water evaporation. Balaton's surface area is around 596 km^O2, with a length of 78km. Its depth averages around 3.25 - 3.40 m, with a volume of approximately 2.2 km^3. The area of the watershed is 5675 km^2. Originally there were five small lakes in the surrounding area that broke down due to erosion and tectonic movement, resulting in the formation of Lake Balaton. There is remaining evidence of this from the northern shore where the Tihany Peninsula projects from.

Lake Balaton is supplied with 45% of its water supply from the Zala river. This results in the Zala river heavily affecting Lake Balaton's water quality as it also receives 35 - 40% of its nutrients from the rivers mouth. The river also drains half of the lakes catchment area. The sluice gates of Siófok provide the lake with an outflow located in the easter end, with the water being replaced about every two years. In the 20th century, the Kis-Balaton Water protection System (KBWPS) wetland was created in order to act as a filter and improve Lake Balaton's water quality. The KBWPS has managed to successfully reduced the blooming of Cyanobacteria in the lake compared to the quantity that blooms within the protection system.

During the mid 1970s to the mid 1990s, Lake Balaton experienced severe eutrophication as a result of phosphorus loading from anthropogenic activity. The western part of the lake has been found to be the most polluted part of the lake, with the water quality deteriorated and containing relatively high amounts of pollutants. This is due to an influx of nutrients (Nitrogen and Phosphorus) and chemicals from near agricultural actives and the Zala River which carries about half of those pollutants. Major work has been done in the past in order to improve Lake Balaton's health. By 1996, studies have found that a reduction in the external and internal phosphorus loadings, as well as the removal of benthivorous cyprinids has significantly improved the water quality within the hypertrophic western part of the lake. The rapid improvement is attributed to enhanced internal phosphorus loading done after the reduction in external nutrient load.

In 2019, a study conducted an investigation into 71 large lakes around the world in order to ascertain the long-term trends of near-surface phytoplankton blooms during summertime. The lakes were chosen based on their conditions during the summer, were greater than 40 square miles, had different settings, and that had various levels of human impact. The study was conducted using high-resolution Landsat 5 satellite imagery that had been collected for the past three decades between 1984 - 2012 by NASA, during the months of June to October or December to April depending on the location and when summer occurs. Due to phytoplankton's high concentration of chlorophyll, they reflect near-infrared light as well as absorb blue and green light producing strong infrared signals within infrared imagery. It was found that 48 out of 71 (68%) of those lakes had increased in bloom intensity. Only 6 out of the 71 (8%) lakes studied had a decrease in bloom intensity, including Lake Balaton. The researchers found four trends that phytoplankton blooms typically followed: 1) Blooms decrease, 2) Blooms increase, 3) Blooms decrease then increase, 4) No significant trend with most of the deterioration occur during the later years of the study. According to the researchers, Lake Balaton's gradual improvement is likely due to the local government's efforts in better water management, as well as Lake Balaton having little to no warming over time.