Role of human impacts on drastic changes of inflow to lake Balaton – potential hydrological and economic consequences – comprehensive hydrological study of lake Balaton watershed – role of human impacts on drastic changes of inflow

Lake Balaton is an important natural and economic asset of Hungary. In the past, similarly to other large lakes, it provided habitat for wild life as well as livelihood and drinking water for the people living in its neighbourhood. In the second part of the last century, water related tourism developed a great deal and Lake Balaton became an important economic factor of the national economy. A necessary condition to maintain or develop the tourism industry in the Lake Balaton Resort Area it is enough to have good quality water in Lake Balaton and a pleasant and rich natural environment in the region. The extended drought period from 2000 to 2004 underlined the vulnerability of the water resources of Lake Balaton to changing hydro-meteorological conditions. It is well known that the water balance of the lake was changing to the worse in the last 3 decades. In this study, human activities affecting the water balance of the lake were investigated. It was found that annually 210 to 230 lake mm of water was deterred from the lake due to human impacts such as the construction/restoration of the Balaton Minor Water Protection System, reservoirs and fish ponds constructed in the watershed, disturbance of the main karstic reservoir by bauxite mining, direct water use from the lake, changes in the land use pattern in the watershed, and already manifested impacts of climate change through decreasing discharges of the tributaries of Lake Balaton. Based on the findings of the study, recommendations were made such as launching a complex water resource preservation program for the whole watershed including rain water management and utilization, land use planning giving priority to water resource management, elimination of illegal water withdrawal, banning the construction of further shallow reservoirs and fish ponds and the improvement of the hydro-meteorological monitoring system