Lorz et al. study of the Distrito Federal (DF) region of Brazil has found that past change in water availability has been largely due to Land use/cover change (LUCC) more so than climate change, although climate also has an effect. DF covers 5,790km2 and has a “Cerrado biome” with a savanna landscape, and dry seasons from the end of March through September. Agriculture has expanded since the 1970s. Agriculture requires high volumes of extra extractions surface and ground water, resulting in decrease of base flow discharge levels by 40–70% from the 70s. While Agriculture also affects water quality, urban development has released the most pollution into watersheds. Water demands in DF are near their maximum capacities, and populations will likely grow along with urbanization and a resulting increase in lifestyles that demand more resources. DF, with 83% urban population is in need of an assessment for a future water plan that will limit water supply pollution, and with the recent increase in agriculture, a water system will need to obtain more water. –Darien Martin
Lorz, C. et al. 2011. Challenges of an integrated water resource management for the
distrito federal, western central brazil: climate, land-use and water resources. Environmental Earth Science. Special issue.
Past data was used along with new studies done by Lorz et al. for land cover/use change, climate change, and water cycling from groundwater, to surface, to resources. Lago Paranoá was evaluated as a case study of the effects of urban pollution. Twenty-one organic compounds were tracked in the lake’s water at various sites.
Fifty eight percent of the natural land was lost from 1954–1998, and additional land continues to be converted to agricultural and urban uses. Although no-tillage is practiced in DF, 90% of the agriculture is giant mechanized operations, which can contribute large amounts of fertilizer pollution into waterways, and use large amounts of water. From 2002-2007, agriculture land area increased 47%. Urban areas grew, mostly along roads, from 0.1% to 10.6% in 1954–2001.
Climate Change was studied in terms of changes in precipitation. From data in the past from 1961–1990 and other periods projected up to 2099, dry seasons are predicted to be longer, and wet seasons, predicted to generate more rain at once. This would result in a small decrease in annual precipitation.
Groundwater and stream water supplies will be affected. Groundwater effects, in the future, will depend on the type of storage infrastructure. More porous, shallow aquifer systems have a larger danger of becoming polluted than deeper ones. Deeper aquifers. There has been a decrease in base flow discharge of streams, likely due to increased evapotranspiration of cultivated crops, increased water extraction for crops, increased water extraction for urban areas, and increased evaporation, from hard surfaces, in housing areas.
Water quality has not reached levels that are higher than regulated levels yet, but quality degradations are on the rise from sediments and organic compounds in waterways. Oxygen depletion from added organic compounds with ammonium increase near urban areas and Waste Water Treatment Effluent.
Lago Paranoá ‘s pollution levels have improved since its detrimental occurrence of eutrophication, which occurred in the 1970’s. Now, in DF, a new step has been installed in wastewater treatment, in order to remove phosphorus, but the lake is still in danger from pollution. An increased urban population has ingested and or purchased more pharmaceuticals that end up in the water. Organic compound pollutions that don’t exceed standards now, but an increase in phosphorus concentrations is predicted. Pharmaceutical concentrations are lower than in European lakes, probably partially as a result of warm water temperatures and lots of UV radiation, which helps to degrade pharmaceutical chemicals.
It is suggested that there should be increased support for programs that continue to monitor pesticides, pharmaceuticals, sediment, and other urban pollutants in DF. In addition plans are encouraged to reclaim ruined sites, prevent erosion, and manage sediment. New technologies and green efforts will help to maintain water resources in a growing and urbanizing, Distrito Federal.