Runoff Response to Climate Warming and Forest Disturbance in a Mid-Mountain Basin

A headwater basin in the Sumava Mountains (Czech Republic), the upper Vydra basin, has undergone forest disturbance as a result of repeated windstorms, a bark beetle outbreak, and forest management. This study analyzed the long-term (1961–2010) hydro-climatic changes by using a combination of statistical analyses, including Mann-Kendall tests, CUSUM analysis, Buishand’s and Petitt’s homogeneity tests, and Kriging. Although the runoff balance over the study period experienced no apparent changes due to climate warming and forest disturbance, significant changes were detected in the share of direct runoff and baseflow, intra-annual variability of the runoff regime, seasonal runoff patterns, and the distribution of peak and low flow events. The seasonal runoff substantially shifted from summers (decreased from 40% to 28%) to springs (increased by 10%). The occurrence of peak flow events has doubled since the 1980s, with a seasonal shift from late spring towards the early spring, while the occurrence of low-flow days decreased by two-thirds. By 1990, these changes were followed by a seasonal shift in runoff from autumn to mid-winter. The changes in hydrological regime in the mid-mountain basin indicate the sensitivity of its hydrological system and the complexity of its feedback with the changing environment. OPEN ACCESS