Climate change, glacier retreat, and water availability in the Caucasus region

The paper discusses the observed and projected warming in the Caucasus region and its implications for glacier melt, water availability and potential hazards. A strong positive trend in summer air temperatures of 0.05 degrees C year(-1) is observed in the high-altitude areas (above 2000 m) providing for a strong glacier melt. A widespread glacier retreat has also been reported between 1985 and 2000, with an average rate of 8 m year(-1). A warming of 5-7 degrees C is projected for the Sum mer months in the 2071-2100 period under the A2 emission group of scenarios, Suggesting that enhanced glacier melt and a changing water balance can be expected.

Effects of restricted water availability and increased temperature on the grain filling, drying and quality of winter wheat

Experiments in controlled environments examined the effects of the timing and severity of drought, and increased temperature, on grain development of Hereward winter wheat. Environmental effects on grain specific weight, protein content, Hagberg Falling Number, SDS-sedimentation volume, and sulphur content were also studied. Drought and increased temperature applied before the end of grain filling shortened the grain filling period and reduced grain yield, mean grain weight and specific weight. Grain filling was most severely affected by drought between days 1-14 after anthesis. Protein content was increased by stresses before the end of grain growth, because nitrogen harvest index was less severely affected than was dry matter harvest index. Hagberg Falling Number was increased to the greatest extent by stresses applied 15-28 days after anthesis. Treatment effects on grain sulphur content were similar to those on protein content, such that N:S ratio was not significantly affected by drought nor temperature stresses. The effects of restricted water on grain yield and quality were linearly related to soil moisture between 44 and about 73% field capacity (FC) from days 15-28. Drought stress (but not temperature stress) before the end of grain filling decreased SDS-sedimentation volume relative to drought applied later. (C) 2003 Elsevier Science Ltd. All rights reserved.

Effects of restricted water availability and increased temperature on the grain filling, drying and quality of winter wheat

Experiments in controlled environments examined the effects of the timing and severity of drought, and increased temperature, on grain development of Hereward winter wheat. Environmental effects on grain specific weight, protein content, Hagberg Falling Number, SDS-sedimentation volume, and sulphur content were also studied. Drought and increased temperature applied before the end of grain filling shortened the grain filling period and reduced grain yield, mean grain weight and specific weight. Grain filling was most severely affected by drought between days 1-14 after anthesis. Protein content was increased by stresses before the end of grain growth, because nitrogen harvest index was less severely affected than was dry matter harvest index. Hagberg Falling Number was increased to the greatest extent by stresses applied 15-28 days after anthesis. Treatment effects on grain sulphur content were similar to those on protein content, such that N:S ratio was not significantly affected by drought nor temperature stresses. The effects of restricted water on grain yield and quality were linearly related to soil moisture between 44 and about 73% field capacity (FC) from days 15-28. Drought stress (but not temperature stress) before the end of grain filling decreased SDS-sedimentation volume relative to drought applied later. (C) 2003 Elsevier Science Ltd. All rights reserved.

A sensitivity study for water availability in the Northern Caucasus based on climate projections

A strong climatic warming is currently observed in the Caucasus mountains, which has profound impact on runoff generation in the glaciated Glavny (Main) Range and on water availability in the whole region. To assess future changes in the hydrological cycle, the output of a general circulation model was downscaled statistically. For the 21st century, a further warming by 4–7 °C and a slight precipitation increase is predicted. Measured and simulated meteorological variables were used as input into a runoff model to transfer climate signals into a hydrological response under both present and future climate forcings. Runoff scenarios for the mid and the end of the 21st century were generated for different steps of deglaciation. The results show a satisfactory model performance for periods with observed runoff. Future water availability strongly depends on the velocity of glacier retreat. In a first phase, a surplus of water will increase flood risk in hot years and after continuing glacier reduction, annual runoff will again approximate current values. However, the seasonal distribution of streamflow will change towards runoff increase in spring and lower flows in summer.

Carbon stable isotope analysis of cereal remains as a way to reconstruct water availability: preliminary results

Reconstructing past water availability, both as rainfall and irrigation, is important to answer questions about the way society reacts to climate and its changes and the role of irrigation in the development of social complexity. Carbon stable isotope analysis of archaeobotanical remains is a potentially valuable method for reconstructing water availability. To further define the relationship between water availability and plant carbon isotope composition and to set up baseline values for the Southern Levant, grains of experimentally grown barley and sorghum were studied. The cereal crops were grown at three stations under five different irrigation regimes in Jordan. Results indicate that a positive but weak relationship exists between irrigation regime and total water input of barley grains, but no relationship was found for sorghum. The relationship for barley is site-specific and inter-annual variation was present at Deir ‘Alla, but not at Ramtha and Khirbet as-Samra.

Effects of water availability on free amino acids, sugars, and acrylamide-forming potential in potato

Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response.

Contributions of matric and osmotic potentials to the unfrozen water content of frozen soils

Recent reports show that biogeochemical processes continue when the soil is frozen, but are limited by water availability. However, there is little knowledge about the interactive effects of soil and environmental variables on amounts of unfrozen water in frozen soils. The aims of this study were to determine the contributions of matric and osmotic potentials to the unfrozen water content of frozen soil. We determined the effects of matric and osmotic potential on unfrozen water contents of frozen mineral soil fractions (ranging from coarse sand to fine silt) at -7 degrees C, and estimated the contributions of these potentials to liquid water contents in samples from organic surface layers of boreal soils frozen at -4 degrees C. In the mineral soil fractions the unfrozen water contents appeared to be governed solely by the osmotic potential, but in the humus layers of the sampled boreal soils both the osmotic and matric potentials control unfrozen water content, with osmotic potential contributing 20 to 69% of the total water potential. We also determined pore size equivalents, where unfrozen water resides at -4 degrees C, and found a strong correlation between these equivalents and microbial CO2 production. The larger the pores in which the unfrozen water is found the larger the microbial activity that can be sustained. The osmotic potential may therefore be a key determinant of unfrozen water and carbon dynamics in frozen soil. (C) 2008 Elsevier B.V. All rights reserved.

A model-based assessment of the effects of projected climate change on the water resources of Jordan

This paper is concerned with the quantification of the likely effect of anthropogenic climate change on the water resources of Jordan by the end of the twenty-first century. Specifically, a suite of hydrological models are used in conjunction with modelled outcomes from a regional climate model, HadRM3, and a weather generator to determine how future flows in the upper River Jordan and in the Wadi Faynan may change. The results indicate that groundwater will play an important role in the water security of the country as irrigation demands increase. Given future projections of reduced winter rainfall and increased near-surface air temperatures, the already low groundwater recharge will decrease further. Interestingly, the modelled discharge at the Wadi Faynan indicates that extreme flood flows will increase in magnitude, despite a decrease in the mean annual rainfall. Simulations projected no increase in flood magnitude in the upper River Jordan. Discussion focuses on the utility of the modelling framework, the problems of making quantitative forecasts and the implications of reduced water availability in Jordan.

Adapting to climate change impacts on water resources in England - an assessment of draft Water Resources Management Plans

Climate change is expected to produce reductions in water availability in England, potentially necessitating adaptive action by the water industry to maintain supplies. As part of Ofwat's fifth Periodic Review (PR09), water companies recently released their draft Water Resources Management Plans, setting out how each company intends to maintain the balance between the supply and demand for water over the next 25 years, following Environment Agency guidelines. This paper reviews these plans to determine company estimates of the impact of climate change on water supply relative to other resource pressures. The approaches adopted for incorporating the impact in the plans and the proposed management solutions are also identified. Climate change impacts for individual resource zones range from no reductions in deployable output to greater than 50% over the planning period. The estimated national aggregated loss of deployable output under a “core” climate scenario is ~520 Ml/d (3% of deployable output) by 2034/35, the equivalent of the supply of one entire water company (South West Water). Climate change is the largest single driver of change in water supplies over the planning period. Over half of the climate change impact is concentrated in southern England. In extreme cases, climate change uncertainty is of the same magnitude as the change under the core scenario (up to a loss of ~475 Ml/d). 44 of the 68 resource zones with available data are estimated to have a climate change impact. In 35 of these climate change has the greatest impact although in 10 zones sustainability reductions have a greater impact. Of the overall change in downward pressure on the supply-demand balance over the planning period, ~56% is accounted for by increased demand (620 Ml/d) and supply side climate change accounts for ~37% (407 Ml/d). Climate change impacts have a cumulative impact in concert with other changing supply side reducing components increasing the national pressure on the supply-demand balance. Whilst the magnitude of climate change appears to justify its explicit consideration, it is rare that adaptation options are planned solely in response to climate change but as a suite of options to provide a resilient supply to a range of pressures (including significant demand side pressures). Supply-side measures still tend to be considered by water companies to be more reliable than demand-side measures.

Tree species’ tolerance to water stress, salinity and fire

According to climate change predictions, water availability might change dramatically in Europe and adjacent regions. This change will undoubtedly have an adverse effect on existing tree species and affect their ability to cope with a lack or an excess of water, changes in annual precipitation patterns, soil salinity and fire disturbance. The following chapter will describe tree species and proven-ances used in European forestry practice which are the most suitable to deal with water stress, salinity and fire. Each subchapter starts with a brief description of each of the stress factors and discusses the predictions of the likelihood of their occurrence in the near future according to the climate change scenarios. Tree spe-cies and their genotypes able to cope with particular stress factor, together with indication of their use by forest managers are then introduced in greater detail.

Climate change and water in the UK: past changes and future prospects

Climate change is expected to modify rainfall, temperature and catchment hydrological responses across the world, and adapting to these water-related changes is a pressing challenge. This paper reviews the impact of anthropogenic climate change on water in the UK and looks at projections of future change. The natural variability of the UK climate makes change hard to detect; only historical increases in air temperature can be attributed to anthropogenic climate forcing, but over the last 50 years more winter rainfall has been falling in intense events. Future changes in rainfall and evapotranspiration could lead to changed flow regimes and impacts on water quality, aquatic ecosystems and water availability. Summer flows may decrease on average, but floods may become larger and more frequent. River and lake water quality may decline as a result of higher water temperatures, lower river flows and increased algal blooms in summer, and because of higher flows in the winter. In communicating this important work, researchers should pay particular attention to explaining confidence and uncertainty clearly. Much of the relevant research is either global or highly localized: decision-makers would benefit from more studies that address water and climate change at a spatial and temporal scale appropriate for the decisions they make

A tillering inhibition gene influences root-shoot carbon partitioning and pattern of water use to improve wheat productivity in rainfed environments

Genetic modification of shoot and root morphology has potential to improve water and nutrient 19 uptake of wheat crops in rainfed environments. Near-isogenic lines (NILs) varying for a tillering 20 inhibition (tin) gene and representing multiple genetic backgrounds were investigated in contrasting 21 controlled environments for shoot and root growth. Leaf area, shoot and root biomass were similar 22 until tillering whereupon reduced tillering in tin-containing NILs produced reductions of up to 60% in 23 total leaf area and biomass, and increases in total root length of up to 120% and root biomass to 24 145%. Together, root-to-shoot ratio increased two-fold with the tin gene. The influence of tin on shoot 25 and root growth was greatest in the cv. Banks genetic background, particularly in the biculm-selected 26 NIL, and was typically strongest in cooler environments. A separate de-tillering study confirmed 27 greater root-to-shoot ratios with regular tiller removal in non-tin containing genotypes. In validating 28 these observations in a rainfed field study, the tin allele had a negligible effect on seedling growth but 29 was associated with significantly (P<0.05) reduced tiller number (-37%), leaf area index (-26%) and 30 spike number (-35%) to reduce plant biomass (-19%) at anthesis. Root biomass, root-to-shoot ratio at 31 early stem elongation and root depth at maturity were increased in tin-containing NILs. Soil water use 32 was slowed in tin-containing NILs resulting in greater water availability, greater stomatal 33 conductance, cooler canopy temperatures and maintenance of green leaf area during grain-filling. 34 Together these effects contributed to increases in harvest index and grain yield. In both the controlled 35 and field environments, the tin gene was commonly associated with increased root length and biomass 36 but the significant influence of genetic background and environment suggests careful assessment of 37 tin-containing progeny in selection for genotypic increases in root growth.