 This study examined the effects of climate, soil type, and groundwater systems on hydrological droughts. It found that droughts are more common in wetter climates such as A-, C- and D- areas, and that groundwater systems can significantly affect the frequency and severity of droughts. Additionally, it was determined that quicker groundwater systems lead to more frequent and severe droughts compared to slower ones. This article was authored by H. A. J. VanLanen, N. Wonders, L. M. Talaksen, and others.