Most are facing increasing problems of alternating seasons of water shortages and severe flooding. Many of the sources of these problems, such as groundwater depletion, covering of aquifers with urban landscapes and filling in low-lying areas with the built environment, are found in the immediate area of these cities. But other problems arise distant from the city, including deforestation of uplands resulting from urban demand and international markets for wood, deforestation is a major source of both water scarcities in dry seasons and flooding in wet seasons.