Two decades of runoff measurements (1974 to 1993) at the pegelstation Vernagtbach/Oetztal Alps
This report summarizes the runoff data collected at the "Pegelstation Vernagtbach" in the Oetztal Alps, Tyrol. The drainage basin controlled by the Station Covers 11.44 km2, of which 81 % is glacierized by Vernagtferner and hasan altitudinal ränge from 2635 m a.s.l. to 3635 m a.s.l., with 3115 m a.s.l. as the mean altitude. Runoff records, which start in 1974, are given as monthly, daily and hourly mean values. In addition, the mean diurnal Variation is presented for each month. The records show the typical features of the glacier runoff regime, with high discharge during fair weather periods in summer, and low discharge during bad weather and throughout the winter and spring; thus, on average, about 90 % of annual runoff is recorded between June and September. The climatic pattern of the two decades and the resulting mass balances of Vernagtferner tend towards increasing runoff amounts, in particular since the middle of the 1980s. 1991 was the year with highest runoff (0.806 nr/s yearly average), August 1992 delivered the highest monthly mean (4.048 m/s), on July 19,1987 an average daily runoff of 6.123 m3/s was recorded, and 10.68 m3/s was the highest hourly average on August 22, 1993. The rise in absolute amounts was accompanied by increasing diurnal variations, which, on average, were less than 1 m3/s in August 1974, but almost 5 m / s in the same month of 1992.