Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
River water fraction and source of water rich in nitrates in Káraný wells
AbstractThe water supply system Káraný (WSSK), supplied by water from Quaternary fluvial aquifer and induced recharge from the Jizera River, has been affected by increase of nitrate content in recent years. Infiltration tests demonstrated low infiltration rate at soil surface of agricultural land and therefore Horton surface flow is generated after heavy rains and during watering periods. Horton surface flow is disappearing into open cracks. This concentrated recharge may be responsible for fast transport of water and nitrates via vadose zone. The fraction of water from Jizera River in individual wells of WSSK is calculated using calcium, sulphate and hydrogen carbonate concentrations. For Sojovice, Skorkov and Benátky part of WSSK the water from Jizera River accounts for ~ 70-80%, ~ 30-40% and ~ 45-55% respectively. The remaining part of water is either derived from Quaternary fluvial aquifer (high nitrates) and/or water from Cretaceous Jizera Formation Aquifer (nitrates <40 mg/l).