Climate-driven change in circulation of nitrogen and irrigation water: Multi-model projections for Central Asia
(English)Manuscript (preprint) (Other academic)
Agricultural intensification in semi-arid regions comes at a cost of relatively high water losses through evapotranspiration and can contribute to releases of nutrients and pesticides that affect downstream water quality. In addition, highly managed river basins may be particularly sensitive to future climate change. However, effects on attenuation and transformation of nutrients are difficult to quantify due to the complexity and variability of relevant processes. We here use the example case of the large (covering 1.3% of the earth’s land surface) and extensively irrigated Aral Sea Drainage Basin (ASDB) in Central Asia, together with 65 GCM projection results and field-data driven nitrogen attenuation modeling, to investigate to which extent projected future climate change (for years 2025, 2050 and 2100) can influence nitrogen cycling and attenuation. Results show that water and nitrogen circulation are sensitive to climate-driven changes in discharge of the principal Amu Darya River in the ASDB. This is likely the case also for other highly managed river basins across the world. Specifically, we show that riverine concentrations of nitrogen may decrease considerably throughout the coming century. This is due to projected climate-related decreases in river flow at the basin outlet, which increases internal nitrogen recirculation ratios, average transport distances, and attenuation.
Climate change, irrigation, nitrogen attenuation, land-use change, GCM, DIN, water quality, river flow
Oceanography, Hydrology, Water Resources
IdentifiersURN: urn:nbn:se:su:diva-93213OAI: oai:DiVA.org:su-93213DiVA: diva2:645536