Among the numerous renewable energy resources, the main advantage of water energy is that it utilizes the current of the streams and rivers regardless of the given time of the day or season. The main purpose of this study was to create a low capacity, floating hydropower plant that is suitable for shallow and even narrow water bodies. The device was designed to create electric energy while floating on the water’s surface; therefore, it can be used not only in natural streams but also in drainage channels and wastewater treatment plants. The prototype was tested under real circumstances to identify the impacts of various settings on the energy efficiency. Measurements were conducted in Veszprém, Hungary on the Brook Séd. The average depth of the riverbed was 36 cm. Based on the field measurements, optimal efficiency was achieved by using six paddles. On the other hand, much lower efficiency was achieved when low (two or three) or high numbers (12 or 15) of paddles were used. A design framework was elaborated that can facilitate the construction of a floating water wheel for any watercourse. The sensitivity analysis of the sizing variables used in the estimation of performance is supported by network analysis techniques.

Increased population growth and changing environmental conditions have focused attention on sustainability of karst spring flow. In Hungary, the quality of karst springs is acceptable for drinking water supply; the only treatment it needs is the disinfection. Aggtelek is one of the best-studied karst regions; a hydrologic monitoring network was built and operated at the Jósvafo Research Station for about 50 years. The long-term data for the 15 major karst springs, rainfall, and temperature was available for analyses. This paper presents a methodology to estimate karst spring recharge, which can then be adapted to predict karst spring flow in lessstudied areas.