Given ever rising levels of local water stress (see Prologue, Section lii), combined with the fact that there are 286 international rivers and 592 transboundary aquifers shared by 153 countries (UN, 2018a), it could be expected that water-related conflicts have been increasing and/or are likely to increase in the future. However, current evidence does not fully support this hypothesis. Conflicts are often difficult to attribute to a single reason, however, water is often one among several contributing factors. They can also be categorized based on the use, impact, or effect that water had within the conflict.