n The Climate and the Human Activities n

n The Climate and the Human Activities n Natural Variations of the Water Cycle n Water Crisis in the 21 st Century n The Human Impacts on the Water Cycle: Land Use Changes n Green House Gas Emission and Possible Changes in Extreme Events n n Large Uncertainties n An Intl. Water Cycle Research Initiative 1

Water Problems Floods & Storms Water Scarcity Inadequate Sanitation Threats to Ecosystems 2

Floods Two third of the natural catastrophes worldwide, From 1988 to 1997, is caused by floods & storms. . Deaths: 390, 000 Economic Losses: $700 billion 3

Water Scarcity The water scarcity in one seventh countries is chaotic. One third are classified into the safe zone. A half is now not chaotic and not safe, but very high uncertainty in future. Water Scarcity In 1996 (m^3/year/person) less than 1, 000 Water Scarcity Index (WSI) Safe: 50 number of countries Total: 153 chaotic: 25 4

Water Scarcity In 2025, it is projected that 4 billion people, a half of the world population, will live under a high water stress. 0% No Stress 10% Low Stress 20% Moderate Stress 40% High Stress Water Stress in 2025 80% Very High Stress 5

Sanitation Caused Problems Water-related diseases caused a large number of deaths, more than half of them were children. Fecal-oral infection Diarrhea 1. 5 billion cases for children under 5 3. 3 million deaths Cholera 50, 000 cases, 20, 000 deaths Typhoid Fever 50, 000 cases, 25, 000 deaths Ascariasis 1. 3 billion infected, 59 million clinival cases, 10, 000 deaths Water-washed infections Trachoma 146 million cases, 6 million people blind Infections related to defective Sanitation 700 million infected 6

Ecosystem Crisis Due to the land use change, the regional water cycle was dramatically changed. From 1960 to 1990, the cultivated area increased 200→ 760(Mha) the surface area shrank 68, 000 → 37, 000 (km 2) the river inflow reduced 50 Bm 3→almost 0 the salinity increased 10→ 30(g/l) the amount of fish catch decreased 40, 000 ton/y→ 0 7

Water Problems Floods & Storms Water Scarcity Inadequate Sanitation Threats to Ecosystems Amplified by Water Cycle Variations 8