How the storm event of April 2, 2013 affected the shallow lakes in the Pampas?

BAHNMÜLLER, A.; CALISSANO, A.; GILABERT, A.; NIEVA, N.; ARENA, M.; VITALE, A. J.; BOHN, V. Y.; PICCOLO, M.C.

Bahia Blanca

Workshop; Global Lake Ecological Observatory Network 15 (GLEON 15); 2013

Instituto Argentino de Oceanografia

An extreme weather event occurred from March 30 to April 2, 2013 on the Pampa region, Argentina. The storm was characterized by severe precipitation rates and a large spatial variability. The intensity of the rain generated several problems in the area: flooding, death of people (many others suffer injuries) and significant economic losses. The precipitation of April 2, 2013, with 392.2 mm is the highest values measured in the Astronomic Observatory of La Plata University. The meteorological situation associated with the event of heavy rainfall over the Buenos Aires Province was dominated by the presence of a low pressure center at middle levels of the troposphere. The phenomenon persisted for more than 36 h. The purpose of the study was to analyze the change of the water parameters at four shallow lakes due to the passage of the storm. The studied lakes are: La Helvecia (33° 25´ 28.30? S - 62° 53´ 55.26? W), La Barrancosa (37° 05? 53.34? S - 58° 11? 49.58? W), La Salada (39° 27? 43.78? S - 62° 41? 55.82? W) and Grande de Otamendi (34° 13? 58.33? S - 58° 52? 21,51? W). Limnological high frequency parameters were acquired from buoys deployed on each lake. The synoptic weather conditions were obtained from the National Argentine Meteorological Service. Water level, temperature, salinity and suspended sediment, caused by the strong winds, were the main physical parameters affected by the storm. In the lakes, the event originated an average decrease of water temperature of 2 °C generated by the rapid decrease in air temperature. The surface salinity decrease because of the intense rain and the daily water level raised 10 cm in few hours in almost all the lakes. Although the four lakes are separated by thousands of km (e.g., 1200 km between La Helvecia and La Salada) the response of the shallow lakes to the passage of the storm was similar. However, the economical and property damage occurred in the communities of each lake were different. Not all the studied lakes presented management plans to prevent damages from extreme weather events. The main result of this analysis is to highlight that the management in lakes is critical to avoid serious inconvenient to the communities living on their coasts.