Lower fertility rates or religion beliefs
The river had been called <span>"river of sorrows" due to its constant flooding during its earlier civilizations. </span>
Because the climate can change and get hotter? idk
The more people that are migrating to urban areas (urbanization) needs more crops for the citizens which causes more people to grow crops and without crop rotating or methods to prevent soil degradation. More likely answer is that more industry grows in the urbanized areas and they have poor management of the soil which causes soil degradation<span />
An occluded front is usually associated with severe thunderstorms or a drizzle.