Introduction to water resources impacts modelling Erika Coppola, ICTP, Trieste

Impact modelling: Vulnerability and adaptation with respect to water resources Hydrologic implications of climate change for water resources Focus of the school Uncertainty in a Climate Change scenario

Defining V&A assessment –Often V&A is analysis, not assessment –Why? Because the focus is on biophysical impacts, e.g., hydrologic response, crop yields, forests, etc. However, assessment is an integrating process requiring the interface of physical and social science and public policy

Examples of Adaptation – Water Supply Construction/modification of physical infrastructure –Canal linings –Closed conduits instead of open channels –Integrating separate reservoirs into a single system –Reservoirs/mydroplants/delivery systems –Raising dam wall height –Increasing canal size –Removing sediment from reservoirs for more storage –Interbasin water transfers

Examples of Adaptation – Water Supply (continued) Adaptive management of existing water supply systems –Change operating rules –Use conjunctive surface/groundwater supply –Physically integrate reservoir operation system –Coordinate supply/demand

Examples of Adaptation – Water Supply (continued) Policy, conservation, efficiency, and technology –Domestic Municipal and in-home re-use Leak repair Rainwater collection for nonpotable uses Low flow appliances Dual supply systems (potable and nonpotable) –Agricultural Irrigation timing and efficiency Lining of canals, closed conduits Drainage re-use, use of wastewater effluent High value/low water use crops Drip, micro-spray, low-energy, precision application irrigation systems Salt-tolerant crops that can use drain water

Examples of Adaptation – Water Supply (continued) Policy, conservation, efficiency, and technology (continued) –Industrial Water re-use and recycling Closed cycle and/or air cooling More efficient hydropower turbines Cooling ponds, wet towers and dry towers –Energy (hydropower) Reservoir re-operation Cogeneration (beneficial use of waste heat) Additional reservoirs and hydropower stations Low head run of the river hydropower Market/price-driven transfers to other activities Using water price to shift water use between sectors

Tools in Water Resource V&A Studies Hydrologic models (physical processes) –Simulate river basin hydrologic processes –Examples – water balance, rainfall-runoff, lake simulation, stream water quality models Water resource models (physical and management) –Simulate current and future supply/demand of system –Operating rules and policies –Environmental impacts –Hydroelectric production –Decision support systems (DSS) for policy interaction Economic models

Snow Accumulation Precipitation Sublimation Snowmelt Runoff Evaporation Recharg e Infiltration Evapotranspiration Surface Runoff Groundwater flow Discharge Mountain Front Recharge Surface Runoff Discharge Studying the Hydrologic Cycle at Various Scales Globally: 86% of Evap. and 78% of Precip. occur over the oceans

Distribution of Freshwater

Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

Two Primary Water Resources/Hydrology Challenges: Hydrologic Hazards ( Floods and Droughts) Water Supply Requirements ( Quantity and Quality)

“General” and Widespread Floods Bangladesh floods in 2004 August 19, 1993 August 14, 1993 Mississippi River Missouri River Illinois River MISSISSIPPI Floods 1993 Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

Drought most visible in falling reservoir levels Lake Powell, Colorado River, USA Normal Years Recent Southwest Drought 2004 Source: J. Kane SRP 2004

Climate Change and Hydrologic Implications Precipitation amount –Global average increase –Marked regional differences Precipitation frequency and intensity –Less frequent, more intense (Giorgi et al., 2011;Trenberth et al., 2003) Evaporation and transpiration –Increase total evaporation

Climate Change and Hydrologic Implications (continued) Changes in runoff –Despite global precipitation increases, areas of substantial runoff decrease Coastal zones –Saltwater intrusion into coastal aquifers –Severe storm-surge flooding Water quality –Lower flows could lead to higher contaminant concentrations –Higher flows could lead to greater leaching and sediment transport

Water Resources from a Services Perspective Not just an evaluation of rainfall-runoff or streamflow But an evaluation of the potential impacts of global warming on the goods and services provided by freshwater systems

The Big Question? The Link Between Climate and Hydrology

Global Warming And Hydrologic Cycle Connection Heating Temperature Evaporation Water Holding Capacity Atmospheric Moisture Temperature o F Saturated Vapor Pressure t t+20 Green House Effect Rain Intensity Drought Flood Drought Created by: Gi-Hyeon Park

The Recent Drought in Historical Context: Reconstruction of Proxy records: - Analysis of Tree Rings and Stable Isotopes How Extreme Can it Get ?????

Sept 1951 Elephant Butte, NM Jan 2003 Middle Rio Grande Basin, NM AD Grissino-Mayer, Baisan, Morino, & Swetnam, 2001 Late 16 th cent Megadrought Great Drought Highly variable Reconstructed PDSI PastPresentFuture Recent US Southwest Drought in Historical Context

Two Primary Water Resources/Hydrology Challenges: Hydrologic Hazards ( Floods and Droughts) Water Supply Requirements ( Quantity and Quality)

Projected Regions of Water Stress Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

Distribution of Fresh Water Use % 17.1% 49.5% % 6.0% 87.0% % 22.0% 59.4% % 17.0% 23.0% % 13.1% 41.7% % 3.0% 93.0% Agriculture Industry Domestic Fresh Water Use ( 10 9 Cubic Meters) Water Source Water Use USAChinaIndia RussiaJapanBrazil 92% 6% 2% 70.3 Iran Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

-10% 0% 10% 20% 30% 40% 50% 60% 70% 80% Asia Europe Middle East & North Africa Sub-Saharan Africa North America Central America & Caribbean South America Oceania World Projected Population Increase % -4% 52% 71% 17% 36% 33% 30% 29% Projected Population Growth Distribution 1995 world population 5.7 Billion 2025 Projection 8.3 Billion Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

Our projections of future water use have been flawed Cubic Kilometers per Year Actual Global Water Withdrawals Projections SOURCE: Dr. Peter H. Gleick, Pacific Institute for Studies in Development

Rapid Change in Global Demographics Source: United Nations, 1996

Population Without Access to Improved Water Supply: 2000 Total: 1,100 million SOURCE: Dr. Peter H. Gleick, Pacific Institute for Studies in Development

The school focus

Hydrology Model Critical questions –How does rainfall on a catchment translate into flow in a river? –What pathways does water follow as it moves through a catchment? –How does movement along these pathways impact the magnitude, timing, duration, and frequency of river flows?

Planning Model Critical questions –How should water be allocated to various uses in time of shortage? –How can these operations be constrained to protect the services provided by the river? –How should infrastructure in the system (e.g., dams, diversion works) be operated to achieve maximum benefit? –How will allocation, operations, and operating constraints change if new management strategies are introduced into the system?

Data Requirements Prescribed supply (riverflow given as fixed time series) –Time series data of riverflows (headflows) cfs –River network (connectivity) Alternative supply via physical hydrology (watersheds generate riverflow) –Watershed attributes Area, land cover... –Climate Precipitation, temperature, windspeed, and relative humidity

Data Requirements (continued) Water demand data –Municipal and industrial demand Aggregated by sector (manufacturing, tourism, etc.) Disaggregated by population (e.g., use/capita, use/socioeconomic group) –Agricultural demands Aggregated by area (# hectares, annual water-use/hectare) Disaggregated by crop water requirements –Ecosystem demands (in-stream flow requirements)

Calibration and Validation Model evaluation criteria –Flows along mainstream and tributaries –Reservoir storage and release –Water diversions from other basins –Agricultural water demand and delivery –Municipal and industrial water demands and deliveries –Groundwater storage trends and levels

Final Aim of our exercise

Uncertainty in climate change impact assessment in water resources Global climate models (GCMs) use different but plausible parameterisations to represent the climate system. Sometimes due to sub-grid scale processes (<250km) or limited understanding.

Uncertainty in climate change impact assessment Therefore climate projections differ by institution: 2°C2°C

Multiple ensembles for various prescribed temperature changes 9 model runs Simon Gosling, Walker Institute for Climate System Research, University of Reading Global Average Annual Runoff

The ensemble mean But what degree of uncertainty is there? Global Average Annual Runoff Change from Present (%)

Uncertainty in simulations Number of models in agreement of an increase in runoff

Catchment-scale Seasonal Runoff The LiardThe Okavango The Yangtze

Seasonal Runoff Agreement of increased snow- melt induced runoff Agreement of dry- season becoming drier Less certainty regarding wet-season changes Large uncertainty throughout the year

What can we do to decrease the uncertanty Further downscaling: Regional climate modelling Bias correction techniques ENSEMBLE approach: Dynamical downscaling Statistical downscaling VALUE European COST project

Ensuring Water in a Changing World International Water Cycle Research Initiatives Addressing These Issues: - WCRP (GEWEX, CLIVAR, CLiC) - UNESCO Initiatives (PUB, HELP) - And Many National Programs Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

P E QsQs  S s  S g QgQg IgIg Coupled Ocean-Atmosphere Models Mesoscale Models SVATs Hydrologic/Routing Models Water Resources Applications GEWEX CLIVAR Hydrologic Services Water resources management agencies GEWEX Role in Climate Research CLiC Monsoon Processes Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

MODEL PARAMETER ESTIMATION DATA If the “World” of Watershed Hydrology Was Perfect! Requirements and State of Hydrologic Forecasting Source: Soroosh Sorooshian Center for Hydrometeorology and Remote Sensing University of California Irvine

Thanks!