Introduction

Question 1

Meteorological drought

Answer 1

 Primary cause is lack of precipitation over a large area and for an extensive period of time

 Depending on climate:
humid → > 1-2 month no rainfall,
semiarid → > 1 season no rainfall,
arid → > 2 years no rainfall

Question 2

Hydrological drought

Answer 2

 The water deficit propagates through the hydrological cycle and may cause a hydrological drought with depletion of groundwater and streamflow deficiency → low streamflow period

 Low flow of a river falls below a certain threshold QS, which can be defined depending on type and intensity of water use, ecological conditions or specific statistical criteria.