Land use changes in La Plata Basin and impacts in river level

CAMILA PRUDENTE; FEDERICO ARIEL ROBLEDO; SCHRAPFFER ANTHONY; ROMINA RUSCICA; ANNA SÖRENSSON; CAROLINA VERA

Christchurch

Conferencia; International Conference on Southern Hemisphere Meteorology and Oceanography; 2022

American Meteorological Society

The Paraguay Basin extends over an area of 1.095 million km2 including the Pantanal wetland - an important natural reservoir that also acts as a hydrological regulator of the basin - and part of the Gran Chaco, the second largest biome in South America. We analyze the regional changes and impacts of the water level of the Paraguay River during 1951-1980 and 1981-2010. We link those changes with variables that modulate the hydrological cycle: precipitation, evapotranspiration and land use change.Consistent with previous studies, an increase in mean water level of the Paraguay River towards the modern period was observed throughout the entire basin. Moreover, the amount of months with levels above the alert and evacuation level in northeastern Argentina increased notably in 1981-2010. The land use changes that the Paraguay Basin suffered from 1970, occurred mainly to the north and east of the main river, affecting the affluents located in these regions. The same spatial pattern was observed in evapotranspiration that decreased in 1981-2010 with respect to 1951-1980. Considering the absence of significant increase in precipitation over the basin between the two periods, the land use change could have favored the increase in the water level due to increased surface runoff that drains to the main river. Moreover, in the Pantanal region, we found evidence that evapotranspiration processes in the wettest semester (summer and autumn) of 1981-2010 partially modulate the river level.