Hydrologic and Soil Science in KOILIARIS RIVER WATERSHED

A Mediterranean Critical Zone Observatory

The Koiliaris River watershed is a Critical Zone Observatory that represents severely degraded soils due to heavy agricultural impact such as grazing, over many centuries. It represents Mediterranean soils under imminent threat of desertification (soil carbon loss) due to climate change that is predicted by the UN IPCC for the region over the next century. The Koiliaris River watershed is situated 25 km east from the city of Chania, Crete, Greece. The total watershed area is 130 km2 and the main supply of water originates in the White Mountains. At high elevations (altitude 2014 m), the maximum slope is 43% while at the lower elevations the slope measures 1-2%. Land use includes cropland and pasture (35%), olive and orange groves (32.1%), shrub and brush (32.3%) and mixed forest (0.6%). The geology of the Basin consists of 71.8% Plattenkalk which is comprised mainly by dolomites, marbles, limestone and re-crystallized limestone with cherts; 9.5% calcaric marls in Neogene formations; 6.1% marls in Neogene formations; 6.1% schists and 6.4% quaternary alluvial deposits.

Intensive hydrologic and geochemical monitoring has been conducted since 2004 while the site has historical data since the ‘60s. In addition, a telemetric high-frequency hydrologic and water quality monitoring station has been deployed to obtain data for the characterization of the hydrologic and biogeochemical processes with varying process response-times. The main type of soil degradation in the basin is water erosion, which is due to the clearing of forests and natural vegetation for cropping and livestock grazing. De-vegetation and inappropriate cultivation practices induces soil organic matter losses making soils susceptible to erosion and desertification with global consequences for food security, climate change, biodiversity, water quality, and agricultural economy.