Predicting Unmet Irrigation Demands due to Climate Change An integrated Approach in WEAP

Transcription

1 Predicting Unmet Irrigation Demands due to Climate Change An integrated Approach in WEAP Marc Haering Emad Al-Karablieh, Amer Salman University of Jordan G-Wadi International Session 5: Risks Assessment and Management strategies 25th of November, 2009, Jordan

2 Contents 1. Introduction: Climate Change and IWRM Risk Assessment: Modeling Approaches 2. The Study Area: Water Resources and Allocation Climate Conditions and Projections 3. WEAP Application: Problem Definition Current Accounts Building Scenarios 5. WEAP Results: Changing Water Availability in Supply Schemes Unmet Irrigation Demands 6. Conclusions & Recommendations Page 2

3 Introduction Climate Change and IWRM? Climate Change adds additional uncertainty to management practices IWRM enhances the potential for adaptation to Climate Change Resources availability CC CC Socioeconomic context Demand patterns 1. Introduction Page 3

4 Risk Assessment: Modeling Approaches Direct vs. Indirect Impacts In irrigated agriculture, the impact of precipitation changes is of indirect nature, expressed through limited irrigation water availability and supply. Micro Scale vs. Macro Scale Process-level crop simulations are accurate rather on a micro scale. In case of regionalization: heterogeneity (spatial) and variability (temporal) lead to inaccurate assertions. Segregated vs. Integrated Approach In addition to physiological effects, socioeconomic interactions have to be taken into consideration. 1. Introduction Page 4

5 Study Area: Lower Jordan River Basin 80% of Jordan s water resources, population and its activities lay within the basin. Vast expansion of agriculture has led to a commitment of resources. Hydrological and climatic regimes are marginal for agriculture. High population density within the basin, rapid population growth, increasing demand of water. Study area is sensitive to Climate Change 2. The Study Area Page 5

6 Climate Change in the LJRB already noticeable since 1970s future projections: negative precipitation trends and increasing temperatures CC Projections ( ) relative to baseline ( ): Variable Range of Values 1. Temperature 0,9 o C to 1,27 o C 2. Precipitation -18% to 0% 3. Runoff change -20% to 0% 4. Groundwater Recharge Change -50% to 0% Sources: World Bank 2008, GLOWA 2008, IPCC 2007, MoE The Study Area Page 6

7 The Lower Jordan River Basin Catchment: 6,800km 2 (Semi-natural system boundaries) Population: 4,7 Mio Water Balance: Precipitation: 300mm/a Runoff: 75mm/a Evaporation: 225mm/a Land Cover: 19,7% 52,5% 12,4% Irrigated Areas: Highlands 33,000ha (Source: Groundwater) Jordan Valley 30,000ha (Source: Surface Water) 2. The Study Area Page 7

8 WEAP Application Schematic View 3. WEAP Application Page 8

9 WEAP Applicational Steps Problem Definition Current Accounts Building Scenarios Evaluating Scenarios How and to what degree will the LJRB and its supply/demand system be affected by future climate change? Include: All sources of supply (to all sectors) All demand sides (all sectors) Existing and planned inter-basin water transfers 3. WEAP Application Page 9

10 Temporal Scale Yearly Time Steps Advantages: Simplified water balance Changes in storage (reservoirs) negligible Aquifer discharge modeled as direct runoff fraction Disadvantages: Seasonal variations and fluctuations not modeled Assertions on weather extremes not possible 4. Methodology Page 10

11 Building Scenarios ( ) Basic Scenarios: Population growth, domestic & agricultural water use efficiency Adapted from Glowa JR, Phase II Entered as Step functions Climate Change Scenarios: Catchment precipitation, groundwater recharge, irrigation water use rate Incremental steps, derived from GCM s, hydrological models Entered through linear interpolation Page 11

12 WEAP Scenarios ( ) Best Case Worst Case Basic Scenarios Incremental Climate Change Scenarios 4. Methodology Page 12

13 Changing Water Availability: Zarka River Total Runoff Volume is increasing for all scenarios Change in relative contribution of inflow raises quality concerns

14 Changing Water Availability: KAC Reduced Inflow is partly offset by return flows 30 MCM reserved for the South KAC can be used as buffering

15 Unmet Irrigation Demands: Highlands Unmet demands most pronounced for the - Zarka Basin, indicating the high competition for water with growing urban demands. 5. Results Page 15

16 Unmet Irrigation Demands: Jordan Valley Unmet demands in the Jordan Valley are merely pronounced for the Northern Jordan Valley, that is supplied with freshwater. 5. Results Page 16

17 Conclusions The study presents a first attempt to model the entire LJRB in WEAP. Limitations: yearly time steps on the temporal scale, seminatural basin boundaries on the spatial scale. Groundwater surface water interaction not sufficiently modeled. Quantitative results have to be considered with reservations. Success: Water balance of supply and demand, as well as competition and interaction between sectors with different priorities are modeled comprehensively. Regional and integrative scopes of the study are well represented. Results show a high vulnerability of irrigated agriculture for the highlands and a moderate vulnerability for the North of Jordan Valley, where freshwater is the source of supply. 5. Results Page 17

18 Thank you for attention Dipl. Hydr. Marc Haering M.Sc Institute for Technology and Resources Management in the Tropics and Subtropics (ITT)