Sustainability of small reservoirs and large scale water availability under current conditions and climate change

Semi-arid river basins often rely on reservoirs for water supply. Small reservoirs may impact on large-scale water availability both by enhancing availability in a distributed sense and by subtracting water for large downstream user communities, e.g. served by large reservoirs. Both of these impacts of small reservoirs are subject to climate change. Using a case-study on North-East Brazil, this paper shows that climate change impacts on water availability may be severe, and impacts on distributed water availability from small reservoirs may exceed impacts on centralised water availability from large reservoirs. Next, the paper shows that the effect of small reservoirs on water availability from large reservoirs may be significant, and increase both in relative and absolute sense under unfavourable climate change

Proton Availability at the Air/Water Interface

The acidity of the water surface sensed by a colliding gas is determined in experiments in which the protonation of gaseous trimethylamine (TMA) on aqueous microjets is monitored by online electrospray mass spectrometry as a function of the pH of the bulk liquid (pH_(BLK)). TMAH^+ signal intensities describe a titration curve whose equivalence point at pH_(BLK) 3.8 is dramatically smaller than the acidity constant of trimethylammonium in bulk solution, pK_A(TMAH^+) = 9.8. Notably, the degree of TMA protonation above pH_(BLK) 4 is enhanced hundred-fold by submillimolar LiCl or NaCl and weakly inhibited at larger concentrations. Protonation enhancements are associated with the onset of significant direct kinetic solvent hydrogen isotope effects. Since TMA(g) can be protonated by H_2O itself only upon extensive solvent participation, we infer that H3O^+ emerges at the surface of neat water below pH_(BLK) 4

Land and Water Carrying Capacity in Tourism Area of Nusa Penida, Bali

Environmental resources are very important in supporting tourism activities. As a developing tourism area Nusa Penida needs sufficient land and water resources. Increasing population of residents and tourists triggers new activities that affect the patterns of land use and available water, which in turn has a negative impact on the availability of land and water. The carrying capacity of the environment is disrupted due to the utilization of environmental resources that exceed its capacity. This study aims to calculate the availability, needs and status of the carrying capacity of land and water in the Nusa Penida Tourism Area. The methodology of this study is to calculate the availability of land and water, calculate land and water needs for residents and tourists and calculate the carrying capacity of land and water. This study predicts the availability of land and water, land and water needs and the carrying capacity of land and water in the Nusa Penida Tourism Area until 2023. From the results of data analysis shows that the availability of land in Nusa Penida amounted to 5,350 hectares. Projected land needs until the year 2028 of 24,640 hectares, the carrying capacity of the land in Nusa Penida deficit. The results of the calculation of land requirements based on the ecological footprint amounted to 17,724.283 hectares, while the availability of land in Nusa Penida was 5,350 hectares. This shows that the carrying capacity of the land in Nusa Penida has a deficit of 12,374,283 hectares. Availability of water based on rainfall and springs in Nusa Penida is 95,443,402.56 m3 /year. The results of data analysis show that in 2028 water needs for residents and tourists are estimated at 83,398,400 m3 /year. Projection of the carrying capacity of water in Nusa Penida based on rainfall surplus of 901,002.56 m3 /year. Projection of the carrying capacity of water in Nusa Penida based 10% utilization of springs Penida and Guyangan in 2028 surplus of 2,433,865,856.44 m3 /year Projection of the carrying capacity of water in Nusa Penida based on rainfall + 10% utilization of springs Penida and Guyangan in 2023 surplus of 2,529,309,259 m3 /year. Projection of the carrying capacity of water in Nusa Penida based on rainfall + all springs water potencyin Nusa Penida in 2028 surplus of 34,958,390,240 m3 /yea

Assessing the impact of water availability on growth of neotropical trees

Climate modeling scenarios predict deep changes of the rainfall regime in Amazonia for the next century. The expected increase in dry season length would lead to less water availability for trees. Every month during 3 years, growth measurement was recorded for more than 200 neotropical trees. Tree daily water availability during this period was simulated making use of a soil water balance model. Using a bayesian modeling framework, we analysed (i) the effect of water availability on tree growth and (ii) how functional trait modulated tree responses to drought. For most studied species, tree growth was deeply affected by seasonal water availability. Trees exhibited different water stress sensibilities linked to diffeent functional strategies, from a decrease to a stop in radial stem growth during the drought season. Largest increments were observe at the beginning of the rain season. The remaining part of unexplained variance, may be attributed to ressources competition, indiviual phenology, particular history or genetic. Our results suggest that the intensity of the annual dry season have a large impact on annual tree growth. If rainfall reduction is confirmed in the next decades, tree growth, and hence the whole forest dynamic, will undoubtely be modified. (Résumé d'auteur

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

Ecology of Water Relations in Plants

Water is an important resource for plant growth. Availability of water in the soil determines the niche, distribution and competitive interaction of plants in the environment

Institutional credit and agricultural production nexus

Credit plays an important role in the development of agriculture sector. It capitalizes farmers to adopt new technologies. It helps smooth consumption by providing Working capital and reduces poverty in the process. Both formal and informal lenders are active in rural credit market of Pakistan. There is a need to highlight the relationship between institutional agricultural credit and agricultural production. Time series data for the period of 1973-2009 was used. The study utilized Johansen and Juselius (JJ) cointegration approach and Granger causality test to explore the long-run equilibrium relationship and the possible direction of causality between availability of institutional agricultural credit, labor force availability, cropping intensity, water availability and agricultural production. Result shows the long run relationship among variables. Granger causality test shows the uni-directional causality among institutional agricultural credit and agricultural production and among water availability and agricultural production. The bi-directional causality was found among availability of labor force & cropping intensity and among water availability & cropping intensity.Institutional credit, Agricultural credit, Pakistan

Influence of topography and moisture and nutrient availability on green alder function on the low arctic tundra, NT

The Arctic has warmed by at least 3°C over the past 50 years and this rapid warming is expected to continue. Climate warming is driving the proliferation of shrubs across the tundra biome with implications for energy balance, climate, hydrology, nutrient cycling, and biodiversity. Changes in tundra plant water use attributable to shrub expansion are predicted to increase evapotranspirative water loss which may amplify local warming and reduce run-off. However, little is known about the extent to which shrubs will enhance evapotranspirative water loss in these systems. Direct measures of shrub water use are needed to accurately predict evapotranspiration rates and the associated hydrological and energetic impacts. In addition, it is crucial that we understand the abiotic factors that drive shrub distribution and physiological function to forecast further changes in tundra ecosystem function. Shrubs are expanding in areas that have a higher potential of accumulating moisture, such as drainage channels and hill slopes. Shrub expansion may be limited by variation in water and nutrient availability across topographic gradients. Nevertheless, the associations between shrub function and abiotic limitations remain understudied. To address these knowledge gaps, we measured sap flow, stem water potential, and a range of functional traits of green alder (Alnus viridis) shrubs and quantified water and nutrient availability in shrub patches on the low arctic tundra of the Northwest Territories. Frost table depth was a significant negative driver of sap flow and underlies decreased surface water availability with thaw. This was further supported through significantly lower stem water potential values as the growing season progressed. Shrubs in upslope locations had significantly lower water potentials relative to shrubs in downslope locations, demonstrating topographic variation in shrub water status. Shrubs in channels and at the tops of patch slopes significantly differed in leaf functional traits representing leaf investment, productivity, and water use efficiency. Channel shrubs reflected traits associated with higher resource availability and productivity whereas shrubs at the tops of patches reflected the opposite. This work provides insight into the abiotic drivers of tall shrub water use and productivity, both of which will be essential for predicting ecosystem function

Biofuels and water: an exploration

This paper analyses the different impacts that biofuel production will have on water use and availability