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

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

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

4. less than 1,000 Water Scarcity In 1996 Water Scarcity Index (WSI) (m^3/year/person) number of countries Total: 153 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. chaotic:25Safe: 50 Water Scarcity 4

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

6. 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, 6million people blind Infections related to defective Sanitation 700 million infected Sanitation Caused Problems 6

7. 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 50Bm3→almost 0 the salinity increased 10→ 30(g/l) the amount of fish catch decreased 40,000 ton/y→0 Ecosystem Crisis 7

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