El agua en la llanura pampeana: 2005 Quirós desde los humedales primigenios hasta su transformación para las actividades agropecuarias Rolando Quirós, Hugo T. von Bernard y María B. Boveri Area de Sistemas de Producción Acuática Facultad de Agronomía, Universidad de Buenos Aires Conference presented to V SEMINARIO INTERNACIONAL CYTED-XVII: "Un enfoque integrado para la gestión sustentable del agua. Experiencias en zonas húmedas". CETA, FVET, UBA, 6-8 de abril 2005, Buenos Aires, Argentina.
the Pampas 1. Rolling 2. Central 3. Central 4. Southern 5. Mesopotamian 6. Flooding from Viglizzo et al., 2001
the pampean wetlands 1. Rolling 2. Central 3. Central 4. Southern 5. Mesopotamian 6. Flooding from Viglizzo et al., 2001
factors that determine the main characteristics of the pampean wetlands geomorphology of the plains climate climate variability long-term variability short-term variability seasonal variability
geomorphology of the plains (1) UPLAND HIGH MIDSLOPE LOW MIDSLOPE LOWLAND SHALLOW LAKES TEMPORARY STREAMS STREAMS RIVERS CANALS 0.1 to 0.5 % 0.5 to 3 % or more 1 to 0.5 % less than 0.5 % extremely low slope geomorphological unit modified from Fuschini Mejia, 1994
geomorphology of the plains (2) Compound longitudinal dunes (pleistocene) Simple longitudinal dunes (holocene) Megaparabolic dunes (holocene) from Malagnino, 1988
geomorphology of the plains (3) 0.03 landscape slopes (m/km)
long-term climate variability of the plains (1) 1600 1400 1200 1000 800 600 Precipitación (mm) 400 200 0 1918/19 1928/29 1938/39 1948/49 1958/59 1968/69 1978/79 1988/89 1998/99 Campaña Anual Obs Ciclo Promedio from Pérez et al., 2003
long-term climate variability of the plains (2) 1500 Precipitaciones anuales (mm) 1300 1100 900 700 500? 300 1874/75 1894/95 1914/15 1934/35 1954/55 1974/75 1994/95 2014/15 2034/35 Campañas Pp Calculada Pp Observada from Sierra et al., unpublished
short-term climate variability in the plains Salado river discharge Q (m3/sec) 200 180 160 140 120 100 80 60 40 20 0
noviembre 2001
los lagos someros (lagunas): componente central del humedal pampeano
satellital imagens from Instituto de Clima y Agua, INTA
octubre 1997 Descarga Río Salado 200 180 160 140 Q (m3/seg) 120 100 80 60 40 20 0
marzo 1998 Descarga Río Salado 200 180 160 140 Q (m3/seg) 120 100 80 60 40 20 0
febrero 1999 Descarga Río Salado 200 180 160 140 Q (m3/seg) 120 100 80 60 40 20 0
noviembre 2001 Descarga Río Salado 200 180 160 140 Q (m3/seg) 120 100 80 60 40 20 0
ciclo sequía inundación característico del humedal pampeano inundación en la sequía y sequía en la inundación conductividad eléctrica (ms/cm, 25 o C) 10 sequía 8 6 sequía 4 inundación 2 0 sequía sequía inundación inundación verano invierno verano invierno verano invierno 1999 2000 2001 100 90 80 70 60 50 40 30 20 10 0 descarga río Salado (m3/seg) seasonal variability in very shallow lake salinity is included Rosso and Rennella, unpublished data
lake morphology (1) 0 porcentaje de la superficie 0 25 50 75 100-1 Z (m) -2 porcentaje de la superficie 0 25 50 75 100 0-3 -1 Z (m) -2-3 0 porcentaje de la superficie 0 25 50 75 100-1 Z (m) -2-3 un 70% de la superficie de una laguna pampeana tiene profundidades mayores a la profundidad media
lake morphology (2) 0 desarrollo de la profundidad (%) -20-40 -60-80 -100 0 20 40 60 80 100 desarrollo del volumen (%) un 75-80 % del volumen de una laguna pampeana se encuentra por encima de su profundidad media
lake morphology (3) 6 5 4 Z media (m) 3 2 1 0 0 1 2 3 4 5 6 7 8 9 Zmaxima (m) profundidad media = 0.7 profundidad máxima forma de cubeta: semi elipsoide de revolución
primordial grasslands an hypothetical landscape for primordial pampean wetlands
current grasslands (1) fotos: INTA
current grasslands (2) fotos: INTA
current grasslands (3) from Guerschman et al., 2001
environmental efforts on the pampean wetlands dredging, canalization and damming of water bodies changes in land use patterns increased land erosion agriculture (pastures, implanted pastures, annual crops, extensive livestock growing, animal feed-lots) unregulated urbanization with deficient or without sewage treatment works unregulated land-fill usually with toxic substances
environmental effects in the pampean wetlands changes in natural hydrological patterns changed morphology of water bodies increased inorganic sedimentation increased levels of non-oxidized organic matter and its metabolites nutrient enrichment (mainly P and N) contamination of surface waters and groundwater with toxic substances commonly used in modern agriculture (herbicides, insecticides, and other agro-toxic substances) contamination of surface waters and groundwater (?) with highly toxic substances used in industry huge changes in vegetal and animal biodiversity and abundance for both terrestrial and aquatic ecosystems
legal canals (1) foto: INTA Anguil
legal canals (2) foto: Hugo Dias
illegal canals foto: Municipio Mar Chiquita
Central Pampas 100 80 60 40 20 0 1881 1914 1937 1960 1988 2002 natural pastures cultivated pastures annual crops modified from Viglizzo et al., 2001
Flooding Pampas 100 80 60 40 20 0 1881 1914 1937 1960 1988 2002 natural pastures cultivated pastures annual crops modified from Viglizzo et al., 2001
Total Pampas 100 80 60 40 20 0 1881 1914 1937 1960 1988 2002 natural pastures cultivated pastures annual crops
"natural" land millions of hectares 50 40 30 20 10 0 1881 1914 1937 1960 1988 2002 Central Pampas Flooding Pampas Total Pampas modified from Viglizzo et al., 2001
fertilizers use 1000 900 800 fertilizers use (kg 10-6 /yr) 700 600 500 400 300 200 100 0 1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 year K N P source: FAO
pesticides use 160 140 pesticides (millions kg or l/yr) 120 100 80 60 40 20 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 year herbicides insecticides fungicides other source: SAGPyA
PCB s in water and fish 2.0 18 PCB s in water (ug/l) 1.6 1.2 0.8 0.4 15 12 9 6 3 PCB s in fish liver (ug/kg) 0.0 7 8 9 10 11 12 1 2 3 4 2000-2001 water fish 0 Descarga Río Salado Q (m3/seg) 200 180 160 140 120 100 80 60 40 20 0
lagunas claras y turbias como indicadores de la intensidad de acción antrópica sobre el humedal pampeano "natural" land 50 lagunas claras lagunas turbias millions of hectares 40 30 20 10 0 1881 1914 1937 1960 1988 2002 Central Pampas Flooding Pampas Total Pampas
10 3 Chl (mg/m3) 10 2 10 1 10 0 10 1 10 2 10 3 10 4 TP (mg/m3) 37 lagunas pampeanas, turbias (O) y claras (O)
claras y turbias 3 piscívoros TN:TP 2 claras PCA - 1 1 0-1 MASI -2-3 turbias nutrientes fitoplancton planctívoros -3-2 -1 0 1 2 3 PCA - 2
claras y turbias 3 1 PCA - 1 2 1 0-1 4 1 4 1 1 1 1 4 4 4 1 1 4 2 23 4 4 4 4 1 1 3 3 3 3 3 2 2 2-2 -3-3 -2-1 0 1 2 3 PCA - 2
claras y turbias 10 3 central pampas Chl (mg/m3) 10 2 10 1 flooding pampas 10 0 10 1 10 2 10 3 10 4 TP (mg/m3) central pampas flooding pampas
for pampean terrestrial ecosystems, dramatic changes in weighted biodiversity have been widely documented for vegetal and animal communities, therefore, only some changes in the biota of the aquatic component of the pampean wetlands will be presented here:
lake phytoplankton clear and turbid lakes 10 5 10 4 # cyanobacteria 10 3 10 2 10 1 100 10 0 1 2 clear = 1 turbid = 2 % cyanobacteria 80 60 40 20 0 1 2 clear = 1 turbid = 2
lake fish changes from clear to turbid very shallow pampean lakes
"clear" lakes filter feeding planktivores 0% carp 8% other 24% visual planktivores 35% detritivorous 17% top predator 16% water transparency = 1.50 m
"turbid" lakes filter feeding planktivores 1% carp 3% other 17% visual planktivores 54% detritivorous 20% top predator 5% water transparency = 0.38 m
upper Salado "turbid" lakes filter feeding planktivores 21% other 4% visual planktivores 52% carp 10% detritivorous 10% top predator 3% water transparency = 0.23 m
from primordial wetlands to agricultural land past present natural grasslands natural drainages agriculture, human settlements and highly modified grasslands drainages medium to highly modified clear lakes macrophyte dominated usually with oxic, P unsaturated sediments balanced vegetal and animal communities relatively low levels of organic matter, more oxidative environments nutrient levels according to drainages on highly productive soils turbid lakes phytoplankton dominated hypoxic and anoxic, P saturated sediments simplified vegetal and animal communities high levels of organic matter, reductive environments very high nutrient levels due to agriculture and urbanization extended fish and avian mortalities human health hazards
son preferibles dos años de inundación a un año de sequía Anónimo