anthropogenic climate change [15]. Future drought trends have
also been projected using a multi-model under multi-scenario
method [21]. Nearly all simulation results suggest that, as a result
of decreased precipitation and/or increased evaporation, future
droughts will become increasingly serious [21,50,14]. Although,
current studies indicates that the future rise in drought and its
impacts is potentially dramatic, these projections should be further
improved based on more in-depth understanding of the contribution
of the natural factors and human activities to drought,
respectively.