Projected Spatiotemporal Dynamics of Drought under Global Warming in Central Asia

Drought, one of the most common natural disasters that have the greatest impact on human social life, has been extremely challenging to accurately assess and predict. With global warming, it has become more important to make accurate drought predictions and assessments. In this study, based on climate model data provided by the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), we used the Palmer Drought Severity Index (PDSI) to analyze and project drought characteristics and their trends under two global warming scenarios—1.5 °C and 2.0 °C—in Central Asia. The results showed a marked decline in the PDSI in Central Asia under the influence of global warming, indicating that the drought situation in Central Asia would further worsen under both warming scenarios. Under the 1.5 °C warming scenario, the PDSI in Central Asia decreased first and then increased, and the change time was around 2080, while the PDSI values showed a continuous decline after 2025 in the 2.0 °C warming scenario. Under the two warming scenarios, the spatial characteristics of dry and wet areas in Central Asia are projected to change significantly in the future. In the 1.5 °C warming scenario, the frequency of drought and the proportion of arid areas in Central Asia were significantly higher than those under the 2.0 °C warming scenario. Using the Thornthwaite (TH) formula to calculate the PDSI produced an overestimation of drought, and the Penman–Monteith (PM) formula is therefore recommended to calculate the index

Genesis and mobilization of fluoride in groundwater of India: Statistical evaluation, health impacts, and potential remedies

Groundwater contamination by fluoride (F¯ >1.5 mg/L) is pervasive and typically confined to arid and semi-arid regions. Therefore, several parts of India are contaminated with F¯. However, genesis, sources, and mobilization of F¯ in groundwater are unclear or so far evaluated based often on studies conducted at a local scale. To understand the severity of F¯ contamination at the national scale and to devise remedial strategies, we performed a statistical evaluation between F¯ and its influencing factors, including geology, hydro-meteorology, and potential hydro-chemical parameters based on a large dataset (n = ∼2000) published in the last two decades throughout India. Results revealed that (a) alkalinity plays a pivotal role in the mobilization of F¯ into groundwater from the sediments/rocks, (b) high F¯ in groundwater is more pronounced in the arid and semi-arid areas of alluvial plains than hard rock regions, and (c) positive correlation of elevated F¯ with SiO2 and K+ indicates the dominance of geogenic sources linked to the weathering of fluorine bearing silicates. Investigations show that one-third of the Indian drinking water wells are contaminated with F¯, thereby risking the health of over millions of people through the drinking water pathway. Findings from this study have addressed the most possible sources, pathways, and regional prevalence of F¯ contamination in the groundwater of India, and suggested the suitable remedial measures based on prevailing surface and sub-surface conditions. Lastly, this review also addresses challenges and propose future research directions to tackle high F¯ groundwater and ensure safe drinking water supply in India

Analysis of Factors Influencing Carbon Emissions in the Energy Base, Xinjiang Autonomous Region, China

Analyzing the driving factors of regional carbon emissions is important for achieving emissions reduction. Based on the Kaya identity and Logarithmic Mean Divisia Index method, we analyzed the effect of population, economic development, energy intensity, renewable energy penetration, and coefficient on carbon emissions during 1990–2016. Afterwards, we analyzed the contribution rate of sectors’ energy intensity effect and sectors’ economic structure effect to the entire energy intensity. The results showed that the influencing factors have different effects on carbon emissions under different stages. During 1990–2000, economic development and population were the main factors contributing to the increase in carbon emissions, and energy intensity was an important factor to curb the carbon emissions increase. The energy intensity of industry and the economic structure of agriculture were the main factors to promote the decline of entire energy intensity. During 2001–2010, economic growth and emission coefficient were the main drivers to escalate the carbon emissions, and energy intensity was the key factor to offset the carbon emissions growth. The economic structure of transportation, and the energy intensity of industry and service were the main factors contributing to the decline of the entire energy intensity. During 2011–2016, economic growth and energy intensity were the main drivers of enhancing carbon emissions, while the coefficient was the key factor in curbing the growth of carbon emissions. The industry’s economic structure and transportation’s energy intensity were the main factors to promote the decline of the entire energy intensity. Finally, the suggestions of emissions reductions are put forward from the aspects of improving energy efficiency, optimizing energy structure and adjusting industrial structure etc. View Full-Tex

Decomposition and Decoupling Analysis of Carbon Emissions in Xinjiang Energy Base, China

China faces a difficult choice of maintaining socioeconomic development and carbon emissions mitigation. Analyzing the decoupling relationship between economic development and carbon emissions and its driving factors from a regional perspective is the key for the Chinese government to achieve the 2030 emission reduction target. This study adopted the logarithmic mean Divisia index (LMDI) method and Tapio index, decomposed the driving forces of the decoupling, and measured the sector’s decoupling states from carbon emissions in Xinjiang province, China. The results found that: (1) Xinjiang’s carbon emissions increased from 93.34 Mt in 2000 to 468.12 Mt in 2017. Energy-intensive industries were the key body of carbon emissions in Xinjiang. (2) The economic activity effect played the decisive factor to carbon emissions increase, which account for 93.58%, 81.51%, and 58.62% in Xinjiang during 2000–2005, 2005–2010, and 2010–2017, respectively. The energy intensity effect proved the dominant influence for carbon emissions mitigation, which accounted for −22.39% of carbon emissions increase during 2000–2010. (3) Weak decoupling (WD), expansive coupling (EC), expansive negative decoupling (END) and strong negative decoupling (SND) were identified in Xinjiang during 2001 to 2017. Gross domestic product (GDP) per capita elasticity has a major inhibitory effect on the carbon emissions decoupling. Energy intensity elasticity played a major driver to the decoupling in Xinjiang. Most industries have not reached the decoupling state in Xinjiang. Fuel processing, power generation, chemicals, non-ferrous, iron and steel industries mainly shown states of END and EC. On this basis, it is suggested that local governments should adjust the industrial structure, optimize energy consumption structure, and promote energy conservation and emission reduction to tap the potential of carbon emissions mitigation in key sectors

Virtual water flows, water footprint and water savings from the trade of crop and livestock products of Germany

Comprehensive assessment of the virtual water trade of Germany with the world is performed and the national water footprint through the trade of crop and livestock products from 1991 to 2016 is assessed. Virtual water flows based on 328 products with more than 200 countries indicate Germany as a net virtual water importer. Average virtual water import was 100.5 Bm3/y, virtual water export was 60.2 Bm3/y and net virtual water import was 40.3 Bm3/y. Trade patterns of virtual water transfer differ for the various commodity types. Trade between Germany and the world implies a global water loss of 5.9 Bm3/y. This study portrays that trade between countries is not only related to the economics but interlinked with the agricultural water use and management practices of the respective nations. Sustainable management of the resources will require a collective consideration of the agricultural, water and economic sectors while developing strategies

Cross comparison of five popular groundwater pollution vulnerability index approaches

Identification of a suitable overlay and index method to map vulnerable zones for pollution in weathered rock aquifers was carried out in this study. DRASTIC and four models derived from it, namely Pesticide DRASTIC, modified DRASTIC, modified Pesticide DRASTIC and Susceptibility Index (SI) were compared by applying them to a weathered rock aquifer in southern India. The results were validated with the measured geochemical data. This study also introduces the use of temporal variation in the groundwater level and nitrate concentration in groundwater as input and for validation respectively to obtain more reliable and meaningful results. Sensitivity analysis of the vulnerability index maps highlight the importance of one parameter over another for a given hydrogeological setting, which will help to plan the field investigations based on the most or the least influential parameter. It is recommended to use modified Pesticide DRASTIC for weathered rock regions with irrigation practises and shallow aquifers (<20 m bgl). The crucial input due to land use should not be neglected and to be considered in any hydrogeological setting. It is better to estimate the specific vulnerability wherever possible rather than the intrinsic vulnerability as overlay and index methods are more suited for this purpose. It is also necessary to consider the maximum and minimum values of input parameters measured during a normal year in the models used for decision making

Identifying priority watersheds to mitigate flood and drought impacts by novel conjunctive water use management

Deficit irrigation could be considered as one potential option to improve water productivity and obtain some level of assured income under water scarcity and drought conditions in Central Asia. This article investigates water productivity and economic returns to two varieties of potato crop under four different soilmoisture regimes in Uzbekistan. Results suggest that deficit irrigation may not be considered as an option to improve water productivity of potato crop, particularly when the deficit is high. However, deficit irrigation options could be still considered as a viable option to maintain food security and some assured farm income even under extreme drought conditions

Geochemical modelling of the effects of a proposed uranium tailings pond on groundwater quality. Technical article

The impact of a proposed uranium tailings pond on groundwater quality was assessed by geochemical modelling. Groundwater samples were collected from six dug wells in the Nalgonda district, Andhra Pradesh, in southern India, once every 2 months from March 2008 to January 2010, and analysed for calcium, magnesium, sodium, potassium, chloride, sulphate, carbonate, bicarbonate, and uranium. Prediction of groundwater quality was carried out for 100 years using PHREEQC to assess the effects of infiltration of water from the proposed tailings pond. The sensitivity of the model for variations in porosity, hydraulic gradient, hydraulic conductivity, and concentration of uranium in the tailings was evaluated. Geochemical modelling predicts that if the chemical composition of the tailings water is maintained at about the expected mean concentrations, and an appropriate liner is installed with an infiltration rate B1.0 9 10-9 m/s, the concentration of solutes in the groundwater will be increased from present background levels for a down-gradient distance of up to 500 m for the anticipated life of the mine, i.e. 16 years. The concentration of ions in groundwater would exceed background concentrations for up to 100 m at the end of 100 years. This study was used to predict the optimum chemical composition for the tailings and the extent, in terms of time and distance, that the groundwater concentration of various ions would be increased by infiltration of wastes from the tailings pond

Hydrochemical assessment of surface water and groundwater quality along Uyyakondan channel, South India

Groundwater and surface water quality is an important factor that determines its usage for drinking and irrigational use. This study was carried out along a major irrigation water source-Uyyakondan channel in Tiruchirappalli, south India. Fourteen surface water samples along the channel and fifteen groundwater samples close to the surface water sampling locations were collected to determine its suitability for drinking and irrigational purposes. Electrical conductivity, pH and concentrations of calcium, magnesium, sodium, potassium, carbonate, bicarbonate, chloride, sulphate, fluoride and nitrate were determined in the water samples. The chemical composition of the water samples were compared with the drinking water standards of World Health Organisation and Bureau of Indian Standards. Groundwater from this area was suitable for drinking based on magnesium, sulphate, bicarbonate, fluoride and nitrate, while the concentration of calcium, sodium, potassium and chloride exceeded the maximum permissible limits at few locations. Surface water was within the permissible limits for magnesium, potassium, bicarbonate, sulphate, fluoride and nitrate, while calcium, sodium and chloride exceeded the highest desirable limits. Sodium chloride was the dominant groundwater and surface water type. Irrigation water quality was assessed based on magnesium hazard, residual sodium carbonate, sodium percentage, sodium adsorption ratio, permeability index and salinity hazard. Water was suitable for irrigation based on magnesium hazard and residual sodium carbonate. Most water samples were doubtful for irrigation use based on sodium percentage and good for irrigation depending on sodium adsorption ratio. Though 60 % of groundwater and 29 % of surface water samples were suitable for drinking based on water quality index, majority of the water samples were not suitable for irrigation. The water quality in this area needs to be monitored regularly and it is crucial to treat the water before consumption

Environmental assessment of water and soil quality in the Vientiane Plain, Lao PDR

A water and soil quality baseline study was carried out across the ~ 4500 km2 Vientiane Plain in Lao PDR. Eight water quality and nine soil parameters were analysed using field kits at 95 sites in March 2015. Elevated electrical conductivity and chloride were apparent at two sites due to geogenic leaching from the marine rock-salt present in some areas. Groundwater was acidic in most locations. Nitrate and faecal contamination were also observed from nitrogenous fertilizers (diffuse) and from leaky sewage pits (localised) respectively. Soil quality is neither nutrient deficient nor does it pose a threat to plant growth. Where groundwater is used for drinking, removal of bacterial contamination by simple filtration or boiling is sufficient. In the absence of a functional monitoring network in the Vientiane Plain, periodic surveys of this kind should be performed. The results should be made widely available to the relevant government departments and other stakeholders for better management of the land and water resources