The Water-Energy-Land (WEL) nexus and the analysis of Land issues Karl Harmsen Sr Fellow, ZEF, University of Bonn Consultant, DIE, Bonn European Report on Development (ERD) 2012 Consultation on Governance of Natural Resources with a focus on Land NH Hotel, Maastricht, 18-19 May 2011
1. WEL nexus: definition
NEXUS 1. a connection energy or link 2. a connected group or series land water
2. WEL nexus: = Water = Energy = Land
2.1. Water • Hydrological cycle • Land/water – atmosphere interactions • Water quality • Soil water balance and water-use efficiencies • Soil & water conservation • Water harvesting & small reservoirs
West African Science Service Center on Climate and Adapted Land Use < 1% liquid water
Function of Temperature Evapo- Precipitation Transpiration Surface vegetation Water Recharge Soil Storage Groundwater Recharge [Harmsen, 2007]
2.2. Energy • Global energy balance - land use/land cover (albedo) - greenhouse gases, - aerosols, dust, bush fires, wind erosion - evapo-transpiration • Use of fossil and renewable energy • Production of sources of renewable energy
78% 55%
Energy balance The difference between the total incoming and total outgoing energy in the climate system. If this balance is positive, warming occurs; if it is negative, cooling occurs. Averaged over the globe and over long time periods, this balance must be zero. Because the climate system derives virtually all its energy from the Sun, zero balance implies that, globally, the amount of incoming solar radiation on average must be equal to the sum of the outgoing reflected solar radiation and the outgoing thermal infrared radiation emitted by the climate system. A perturbation of this global radiation balance, be it anthropogenic or natural, is called radiative forcing.
Global average radiative forcing (RF) in 2005 (best estimates and 5 to 95% uncertainty ranges) with respect to 1750 for CO2, CH4, N2O and other important agents and mechanisms, together with the typical geographical extent (spatial scale) of the forcing and the assessed level of scientific understanding (LOSU). Source: IPCC, 2007.
Comparison of observed changes in surface temperature with results simulated by climate models using either natural or both natural and anthropogenic forcings. Decadal averages of observations are shown for the period 1906-2005 (black line) plotted against the centre of the decade and relative to the corresponding average for the 1901-1950. Lines are dashed where spatial coverage is less than 50%. Blue shaded bands show the 5 to 95% range for 19 simulations from five climate models using only the natural forcings due to solar activity and volcanoes. Red shaded bands show the 5 to 95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings (IPCC, 2007)
Relative changes in precipitation (in percent) for the period 2090-2099, relative to 1980-1999. Values are multi-model averages based on the SRES A1B scenario for December to February (left) and June to August (right). White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change (IPCC, 2007)
AFRICA December to February
AFRICA June to August
interactions and links: 1. Land & water (the surface of the Earth) play a role in the energy balance [climate change] 2. Interventions at the surface of the Earth may use energy, both renewable and fossil (e.g., solar energy for photosynthesis cq crop growth, fossil fuel for transport and machinery) 3. Interventions at the surface of the Earth may generate sources of renewable energy (e.g., food and feed, fuelwood, organic waste, oil crops)
2.3. Land Land productivity & degradation • loss of vegetation • water & wind erosion • deterioration of the physical, chemical & biological soil quality • soil & water conservation • carbon and nitrogen cycles
Degraded soils. Soil degradation is a key global environmen- tal indicator. Very degraded soils are found especially in semi-arid areas (Sub-Saharan Africa, Chile), areas with high population pressure (China, Mexico, India) and regions undergoing deforestation (Indonesia). Degraded soils reduce the possibilities for agriculture, increasing the expansion of drylands/deserts and hightening the risk for erosion. This map presents the state of global soil degradation, from the GLASOD study in 1997 (UNEP-GRID Arendal website)
Deforestation in Cote d’Ivoire (source: UNEP-GRID)
Carbon cycle: • Emission of CO 2 and/or CH 4 • Mineralization-immobilization (sequestration) of carbon = source of energy for biota = important for soil quality = availability of trace elements to plants
Nitrogen cycle: • Mineralization- immobilization • Nitrate reduction • Emission of NOx
3. Land Use Systems
Reference: LADA, 2008. Mapping land use systems at global and regional scales for land degradation assessment analysis. Nachtergaele, F., and Petri, M. LADA Technical Report no. 8, version 1.1. The Land Use Database of the World was developed a part of the project Land Degradation Assessment in Drylands (LADA), a 4-year project funded by the Global Environment Facility (GEF). The project is implemented by the United Nations Environment Programme (UNEP) and executed by the Food and Agriculture Organization of the United Nations (FAO).
Farming systems in West Africa:1, irrigated; 2, tree crop; 7, root crop; 8, cereal-root crop mixed; 11, agro-pastoral millet/sorghum; 12, pastoral; 13, sparse (arid); 14, coastal artisanal fishing (From FAO).
environment system
Conservation of mass (k): Influx – Efflux = Accum/Deplet – Source/Sink If source/sink = 0 Influx - Efflux = Accum/Deplet Thus, if Influx = Efflux Accum/Deplet = 0 That is, there is no accumulation or depletion of mass (k) System is sustainable if Influx = Efflux Or if Accum or Deplet are ‘sustainable’
Solar H 2 O CO 2 O 2 energy Photosynthesis - Respiration Leaching Natural Forest
Solar H 2 O CO 2 O 2 energy Biomass: Fertilizer Photosynthesis - CHONSP + minerals Respiration minerals Leaching Field crops
environment mass energy I agric output agric inputs labour machinery rural credit knowledge livestock system pests diseases
4. Scales in space and time
processes space time upscaling & downscaling
>1000 km - global 100-1000 km - regional 10-100 km - meso 1-10 km - local < 1 km - plot Spatial scales
T = 5 years
T = 10 years
5. Derive criteria for integrated NRM
CONTEXT Effective natural resource management (NRM) for inclusive and sustainable growth in the context of increased scarcity and climate change: What roles for the public and private sectors? KEY WORDS • integrated NRM • sustainable development • increasing scarcity of resources • climate change
Criteria for NRM for sustainable development against the background of increasing scarcity of the resources and climate change Energy balance: 1. decrease the emission of greenhouse gases (e.g., CO2) and reduce activities that negatively affect the energy balance (increase in ∆H) such as wind erosion (dust), burning of vegetation (aerosols, CO2), land degradation (loss of vegetation, decrease in productivity, soil color=albedo)
Criteria (continued) 2. Fossil energy: decrease the use of fossil energy or replace by renewable energy 3. Develop new sources or technologies of renewable energy, promote their use and increase the efficiency of these products. Water: 4. Decrease negative human interference with the water cycle 5. Limit the use of fossil groundwater and develop alternatives.
Criteria (continued) 6. Increase the efficiency of the use of sweet water for agricultural, industrial and domestic purposes. In agriculture, increase water use efficiency by plants and animals, and decrease losses from the land (evapo-transpiration, leaching, surface runoff) and from water distribution (irrigation) systems . 7. Protect the quality of surface and groundwater.
Criteria (continued) Land: 8. Make efficient use of the resource (scarcity!) and decrease degradation of the resource, e.g., loss of vegetation and biodiversity, water and wind erosion, loss of soil organic matter, deterioration of physical and chemical soil properties, etc. 9. Optimize land management with regard to the water cycle (including quality!) 10 Reduce the emission of greenhouse gases (C- cycle, N-cycle, S-Cycle), aerosols, dust (fires)
6. Optimize the functioning of the system in terms of WEL and derive management strategies
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