Climate change and Hydrological impact modeling: achievements and challenges

2. Lecture at • 气候变化与水资源模拟: 进展与挑战 Chongyu Xu 许崇育 University of Oslo 许崇育 挪威奥斯陆大学 Climate change and Hydrological impact modeling: achievements and challenges Chong-yu Xu Chongyu Xu http://folk.uio.no/chongyux/ Dept of Geosciences, University of Oslo

3. Where can you find me?

4. If you have the following problems Too little water – drought Too much water – flood Pollution Erosion

5. Issues in catchment management • Water resources management • Water supply, hydropower • Irrigation and drainage • Social, economic, environmental • Flood management • Flood forecasting, risk analysis, damage analyses • Planning of protective and controlling structures (dams, dikes, gates) • Optimization of the reservoir system (maximize the profit) • Dam break scenarios • Water quality management • Waste water purification & outlets • Reservoirs • Toxic and harmful releases • Eutrophication • Watershed erosion management • Agricultural & forestry practices • Ecosystem conservation • Sediment management • Reservoirs, • Morphological changes • Dredging • Land use management • Urban development, • Agriculture & forestry practices • Re-settlement • Infrastructure planning • Social, cultural, and economic interests

6. Catchment managementhydrologic view • Catchment management is to find best solution and balance between: • Water available (quantity, quality) • Water demand (quantity, quality) • Water transportation/delivety/use efficiency • Others • Water logging and salinization, flooding, etc. • erosion and sediment load, etc. • Sustainable management means that the solution we made and the balance we achieved have no negative effect to our next generations.

7. Components of catchment management systems Climate system: Precipitation, temperature, etc Climate model Hydrological model Hydrologic system: Watershed, streams, etc Water availability Hydraulic constructions: dam, reservoirs, etc Regulatory requirements Reservoirs: Water control Water control Water supply & allocation Water management Model Natural system requirements Human requirements

8. Application of hydrologic models MANAGEMENT RESEARCH & TEACHING DESIGN OPERATION Dams & reservoirs design water yield capacity, failure Floods frequency mapping Urbanization storm drains flood plains channel alterations Irrigation & drainage water yield diversions Flow forecasting Reservoir control Urban storm drain control Water resources assessment Land-use change Climate change Point nonpoint Pollution Groundwater recharge University training Industrial training Research

9. Background • Climate will change (or has been changing) due to greenhouse effect, • Availability and variability of regional water resources will be affected, • GCMs have been used as the only available tool for modeling future climate evolution, • There are gaps between GCMs ability and hydrology need.

10. What a GCM looks like?

11. Inputs and outputs of climate models • Inputs: Main forcings or boundary conditions: • Solar radiation • Atmospheric composition (gases, H2O, CO2, O3, and aerosols) • Surface characteristics (albedo, roughness,…) • Outputs: climatologic and hydrologic variables: • Temperature, pressure, wind, • Humidity, cloudness, precipitation, • Runoff, evapotranspiration, soil moisture Accuracy declines

12. What a hydrological model looks like? Lumped model Semi-distributed

13. What a hydrological model looks like?

14. Spatial mismatch between GCM and hydrological models Chongyu Xu http://folk.uio.no/chongyux/ Dept of Geosciences, University of Oslo

15. Gaps between GCM ability and hydrological demand Better Simulated Less-well Simulated Not-well Simulated New models Ability Gaps Working Variable mismatch Wind speed Temperature Air pressure Precipitation Cloudiness Humidity Runoff Soil moisture Evaporation Macro-scale hydrological models Vertical Scale mismatch 500 hPa 800 hPa Earth Surface Statistical downscaling Spatial Scales mismatch Global 300*300 Km Regional 50*50 Km Local 0-50 Km Dynamic & statistical downscaling Temporal Scales mismatch Mean annual Mean monthly Daily or shorter Bucket – SVAT GCMs ability increases Hydrological importance increases

16. GCM Downscaling Regional Climate scenario RCM Dynamic downscaling RCM Dynamic downscaling Emission scenarios GCM Delta change RCM Dynamic downscaling Delta change Statistical downscaling Delta change Hypothetic Hydrological modeling under changing climate Hydrologic modeling Routing MLHM Water resources scenarios LWBM CHM CHM Chongyu Xu http://folk.uio.no/chongyux/ Dept of Geosciences, University of Oslo

17. Landuse Change Assessment of climate change impact on water resources management

18. My work in modeling • Development and application of hydrological models • Global and continental scales water balance modeling • Catchment scale water balance modeling • Hillslope and local scales physically based storm-runoff modeling

19. Example results of Global water balance model Global Mean annual runoff Average annual runoff in China. Average annual runoff in Northern Europe.

20. Example results of catchment modeling – subtropical catchments Modeled actual evapotranspiration Subtropical monsoon catchments in Southern China Modeled soil moisture

21. Example results of storm floods modelling • Model structure: • Fully distributed • DEM and GIS supported • Physically-based differential equations: • Overland flow - St. Venant equations • Channel routing - kinematic wave and • Manning’s equation • Groundwater flow - continuity equation and • Darcy’s law

22. Thank you! http://folk.uio.no/chongyux/ Dept of Geosciences, University of Oslo Chongyu Xu http://folk.uio.no/chongyux/

23. 许崇育教授简历 奥斯陆大学 • 许崇育, 博士, 教授. 挪威奥斯陆大学地球科学系 • 主要从事的研究领域: • 不同气候区域和不同时空尺度的水文模型的建立和应用 • 水文模型参数估计和不确定性检验方法的研究 • 流域蒸发能力和区域实际蒸发计算方法的研究 • 气候变化及其对水资源与水环境的影响的研究 • 获奖, 荣誉及兼职: • 世界气象组织杰出青年科学家奖 • 中科院海外评审专家 • 南京大学城市与资源系兼职教授 • 武汉大学水文与水资源系兼职教授 • 中科院海外杰出人才 • 中国科学院北京地理资源所兼职教授 • 国际水文科学杂志编委 • 个人网页: http://folk.uio.no/chongyux/