Christoph Jan KUELLS "Ecohydrological principles in economic models of water resources in drylands and desert restoration"
Ecohydrological Principles inEconomic Models of WaterResources in DrylandsC. KuellsUniversity of Freiburg, Chair Environmental HydrologyWG 2 EU COST Action ES1104, Desert Restoration Hub
Scope and ObjectiveSimplify and cooperateSimplify desert hydrologyfor other disciplines4 key principlesConclusions and outlook 11.04.2013 2
4 Key PrinciplesEcohydrology of drylands 1. Time scales of system response Response of dryland ecohydrology is slow 2. Scaling nested hierarchical systems Different from agronomy, meteorology 3. Feedbacks and non-linear response Action changes systems 4. Balancing cycles of water and solutes Sufficiency, sustainability, efficiency, resilienc e
1.1 Hydrological Systems and TimeResidence time and response times are linked CFC sampling CFC water Henry’s law CFC air
1.2 Groundwater Residence Times10 to > 50 years for an active system up to 105 y
1.3 Ecohydrological Response Land use change and impact on recharge Reduction of recharge Increase in recharge 1 (Smitt et al., 2002) 1 (Daves et al., 2001) 0.9 0.9 0.8 35 years 0.8 15 yearsDegree of Impact 0.7 0.7 15 years 35 years MRT 0.6 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 0 10 20 30 40 50 0 10 20 30 40 50 Years since impact MRT=Mean Residence Time
2.2 Topology of Ecohydrological SystemsBlue produces, orange consumes recharge
2.3 Scale EffectsComplex scaling of unoff and recharge in drylands
3.1 FeedbacksEcohydrological processes have strong feedbacks Water and solute balance of an alluvial aquifer Pumping (P) changes transpiration (T), recharge (T), storage (S), lateral in- and outflow (L) and vertikal seepage (V). Benito et al., 2008: Comparing flood recharge dynamics in two ephemeral rivers in southern Africa: Implications for Integrated Water Resource Management. Water Research (subm.)
3.2 Feedbacks in Ecohydro-SystemsResults of coupled modeling, Namaqualand Less salt more recharge Thresholds less plants loss dy u=unexploited e=evaporation t=transpiration d=depletion
4. Ecohydrological System CyclesWater and solutes in supply system of WindhoekLehmann (2011) Water Supply of Windhoek.
ConclusionsWhat does this mean for economic modeling?• Check on time scales and residence times• Scale and topology is important• Systems change and system response changes• Water and solute cycles need to be watched and balanced (SSER objective functions)These properties of ecohydrological systems indrylands are not only constraints to observe …They represent the key to ecohydrological systemmanagement and desert restoration