Summary:

In the paper are presented groundwater level changes in house wells located within upper Nysa Klodzka catchment for period 1971-2005. Low groundwater flow periods are designated by application of two methods: first one - on the basis of soil drought hazard index kn and second one - low flow and very low flow designated by truncation levels: probability of water level p = 50% (very low flow), probability p = 90% (low flow). Obtained results enable to designate low flow periods in analysed term and make possible to compare both methods. In method using of soil drought hazard index, more restricted criteria are used, so this methods is fit to designation low groundwater flow in multiannual periods. Following method may be applicated to define beginning and end of low groundwater flow periods within the year.