HUMAN IMPACT ON WATER CYCLE NGO People and Water, SK ENKI, CZ Třeboň, 16th June 2009

FRESHWATER STOCKS ON EARTH

NEOLITIC REVOLUTION Ca years ago Pictures: M. Gojda, Krajinná archeologie, Západočeská univerzita

The Slavonic countries stretch from the Mediterranean Sea through to the Northern Seas... The Slavs build most of their own castles...on meadows rich in water and bushes... They till the soil very intensively... Famines caused by long-term drought don't exist in [their] lands... If it rains only a little, they do not have poor results, because these lands are damp... /Ibrahim Ibn Jacqub at-Turtushi, About the Western Slavs, middle of the 10th century/

Deforestation J. A. Foley et al. - Green surprise? How terrestrial ecosystems could affect earth’s climate, Front Ecol Environ 2003;

BIOTIC PUMP

CURRENT RATE OF DEFORESTATION km2/year i.e. 1.3 % annual decrease of remaining 30% wood on Earth /According to FAO/

DEFORESTATION & AGRICULTURE Deforestation / some forms of farming cause: increase of runoff (and erosion) lower infiltration (groundwater recharge) lower evaporation (change of regional climate) decrease of organic matter content in soil (decrease of ability to hold water)

Whoever improves the soil, cultivates land lying waste and drains swamps, is making conquest from barbarism. /Frederick II, King of Prussia in / DRAINING SWAMPS

In civilised countries, the rule should be that rivers and streams are canals... [The river should be] directed into single bed with gentle curves... where it is practicable, a straight line... /Johann Gottfried Tulla, The Principles of Future Work on the Rhine, 1809/ ALTERATION OF RIVERS

natural meanders removed adjacent swamps drained shortening length increases slope acceleration of runoff deepening of the riverbed lowering/draining groundwater table lowering land's ability to retain water ALTERATION OF RIVERS

URBAN REVOLUTION – SEWERS, CANALIZATION

PAVEMENT IMPACT infiltration decreases (groundwater recharge decreases) evaporation decreases (air humidity decreases) runoff increases (through sewage to rivers and sea) Free surface Paved surface

IMPERVIOUS SURFACES AND RUNOFF

RUNOFF FROM URBAN AND FOREST ENVIRONMENTS

Decrease of runoff is overlooked flood prevention measure

SOIL SEALING IN CITIES impervious surfaces cover 5% of the EU about 20 billion m3 of rainwater sluiced from municipalities of Europe annually

Precipitation (mm/ year) Volume of water circulating Runoff (indicator of soil sealing) Europe km336 % Slovakia km334 % Prešov, SK (City center) mil. m372 % Plot of land 6300,5 mil. m337 % Residential house m376 % WATER BALANCE OF THE INVESTIGATED TERRITORY

LAND USE TRANSITION J.A. Foley et al. - Global Consequences of Land Use, Science, 2005

EXTENT OF HUMAN LAND USE J. A. Foley et al. - Green surprise? How terrestrial ecosystems could affect earth’s climate, Front Ecol Environ 2003;

SOIL SEALING DESTROYS SMALL WATER CYCLE(S) ON LAND

EARTH – WATER BUDGET Oceans Atmosphere Land Evaporation km³/year Precipitation km³/year Runoff km³/year Precipitation km³/year Evaporation km³/year There is more water in „small“ water cycles than in „large“ water cycle!!!

(PARTIAL) CONCLUSION Human activities have a significant impact on the water cycle

THANK YOU FOR YOUR ATTENTION!