Rainwater Harvesting for Agricultural Irrigation: An Analysis of Global Research

Within a context of scarce water resources for agriculture, rainwater harvesting constitutes a promising alternative that has been studied by different disciplines in recent years. This article analyses the dynamics of global research on rainwater harvesting for agricultural irrigation over the last two decades. To do this, qualitative systematic analysis and quantitative bibliometric analysis have been carried out. The results reveal that this line of research is becoming increasingly important within research on irrigation. Environmental sciences and agricultural and biological sciences are the most relevant subject areas. Agricultural Water Management, Physics and Chemistry of the Earth, and Irrigation and Drainage are the journals that have published the most articles on the subject. India, China, the United States (USA), South Africa, and the Netherlands are the countries that lead this line of research. Although significant progress has been made in this subject area, it is necessary to increase the number of studies on the capacity of rainwater harvesting systems to cover irrigation needs in different farming contexts, the factors that determine their adoption by farmers, the economic and financial feasibility of their implementation, and their contribution to mitigating global climate change

Ozone production in four major cities of China: sensitivity to ozone precursors and heterogeneous processes

Abstract. Despite a large volume of research over a number of years, our understandings of the key precursors that control tropospheric ozone production and the impacts of heterogeneous processes remain incomplete. In this study, we analyze measurements of ozone and its precursors made at rural/suburban sites downwind of four large Chinese cities – Beijing, Shanghai, Guangzhou and Lanzhou. At each site the same measurement techniques were utilized and a photochemical box model based on the Master Chemical Mechanism (v3.2) was applied, to minimize uncertainties in comparison of the results due to differences in methodology. All four cities suffered from severe ozone pollution. At the rural site of Beijing, export of the well-processed urban plumes contributed to the extremely high ozone levels (up to an hourly value of 286 ppbv), while the pollution observed at the suburban sites of Shanghai, Guangzhou and Lanzhou was characterized by intense in-situ ozone production. The major anthropogenic hydrocarbons were alkenes and aromatics in Beijing and Shanghai, aromatics in Guangzhou, and alkenes in Lanzhou. The ozone production was found to be in a VOCs-limited regime in both Shanghai and Guangzhou, and a mixed regime in Lanzhou. In Shanghai, the ozone formation was most sensitive to aromatics and alkenes, while in Guangzhou aromatics were the predominant ozone precursors. In Lanzhou, either controlling NOx or reducing emissions of olefins from the petrochemical industry would mitigate the local ozone production. The potential impacts of several heterogeneous processes on the ozone formation were assessed. The hydrolysis of dinitrogen pentoxide (N2O5), uptake of the hydroperoxyl radical (HO2) on particles, and surface reactions of NO2 forming nitrous acid (HONO) present considerable sources of uncertainty in the current studies of ozone chemistry. Further efforts are urgently required to better understand these processes and refine atmospheric models

Migration, Risk and Livelihoods: A Chinese Case

China has turned from a ‘low risk’ to a ‘high risk’ society since the start of the market reforms in the late 1970s. Market, while bringing diverse livelihood opportunities to rural people, has simultaneously distributed risks, and the exposure and vulnerability to them unequally among different social groups. This paper attempts to apply the risk concept to the study of one of the most socially disadvantaged groups in China, namely rural-urban migrants, through analysing the narratives of members of a migratory family of the Hui Muslim national minority from the Qinghai-Tibet Plateau, who run a business in the northern city of Tianjin. Drawing on ethnographic fieldwork, the research adopts an actor-oriented perspective combined with qualitative longitudinal research methodology (or ‘extended case method’) to delineate a livelihood trajectory of this family, and explore the relationships between livelihood, risk, social networks, agency and public policy interventions

Migration, risk and livelihoods: A Chinese case

China has turned from a 'low risk' to a 'high risk' society since the start of the market reforms in the late 1970s. Market, while bringing diverse livelihood opportunities to rural people, has simultaneously distributed risks, and the exposure and vulnerability to them unequally among different social groups. This paper attempts to apply the risk concept to the study of one of the most socially disadvantaged groups in China, namely rural-urban migrants, through analysing the narratives of members of a migratory family of the Hui Muslim national minority from the Qinghai-Tibet Plateau, who run a business in the northern city of Tianjin. Drawing on ethnographic fieldwork, the research adopts an actor-oriented perspective combined with qualitative longitudinal research methodology (or 'extended case method') to delineate a livelihood trajectory of this family, and explore the relationships between livelihood, risk, social networks, agency and public policy interventions. --rural-urban migration,risk,contingency,uncertainty,livelihood,social networks,agency,social security,translocality,longitudinal research,narrative,extended case method,China

Structural patterns of city-level CO2 emissions in Northwest China

In Northwest China, quantifying city-level CO2 emissions is fundamental to CO2 alleviation but encounters difficulties in data availability and quality. Further, structuring city-level emissions could be conductive to CO2 reduction. This study applies a practical methodology to 16 northwestern Chinese cities to grasp their historical trajectories of CO2 emissions. Then, structuring CO2 emissions is explored in terms of industrial structure, energy mix and urban-rural disparities for 8 northwestern Chinese cities. Results show that: (1) for 16 cities (2010–2015), capital and industrial cities generated most emissions. Meanwhile, CO2 emissions were mostly incompatible with CO2 intensity, but consistent with CO2 per capita; (2) for 8 cities (2006–2015), energy producing sectors, heavy manufacturing sectors, and coal remained major drivers of emissions. Then, the interconnection between industrial structure and energy mix exerted temporally varying impacts on emissions from energy producing sectors and heavy manufacturing sectors. Besides, urban gas consumption and rural coal use continued affecting most of household consumption emissions and household consumption emissions per capita. Moreover, the interplay between emissions and population was changed when emissions by energy type were decomposed among urban and rural households; and (3) uncertainty results averagely fall in the range of −39% to 6%. Finally, implications for CO2 reduction and future work are proposed

Criterions, Prediction and Prevention of Loess Liquefaction

Although loess liquefaction is not very common during earthquakes in Northwest of China, it is disastrous if it happens. Both study and valid evidence from Haiyuan 8.5 Earthquake in 1920 and Tajikistan 5.9 Earthquake in 1989 have proved that loess liquefaction could be very disastrous under certain conditions. In this paper, the criterions of loess liquefaction are discussed to show that unlike typical liquefaction of sand, loess which falls into the category of both silt clay and clayey silt has unique characteristics during liquefaction test. To predict liquefaction of loess, a simple method based on laboratory test and field evidences using GIS is proposed. The prediction results and corresponding measure have been adopted in Seismic Design Code for Buildings in Lanzhou Urban Area. Finally, recent approach of treatment of loess with chemicals methods is developed, which may have some application implication as an simple and feasible treatment method against liquefaction of loess

Urban Development with the Constraint of Water Resources: A Case Study of Gansu Section of Western Longhai-Lanxin Economic Zone

Water is the essential resource for urban development of Gansu section of West Longhai-Lanxin economic zone, which is not only the “Golden Development Line” of Gansu province but also the significant component of the new Silk Road within China. Based on more than 2000 data points reflecting various meaningful aspects of urban systems and water resource systems, and using a quantitative measurement model and ArcGIS, this study aimed at discussing the temporal-spatial variations of water resources constraint on urbanization in the Gansu section. From 1989 to 2007, the water resources constraint intensities (WRCIs) of Gansu section and its nine cities have been generally decreasing, albeit with much fluctuation, and the decrease has been more rapid since 2000, with Lanzhou and Jinchang as the most representative cities. From the perspective of water resource constraint on urbanization, the research on urbanization process of Gansu section is not only necessary for the shaping of an independent theoretical system on relationship between water resource and urbanization, but also has very crucial practical significance for promoting construction of resource-saving and environment-friendly cities in Gansu section, arid and semi-arid areas as well as for promoting harmonious regional development

The relationships between PM2.5 and meteorological factors in China: Seasonal and regional variations

The interactions between PM2.5 and meteorological factors play a crucial role in air pollution analysis. However, previous studies that have researched the relationships between PM2.5 concentration and meteorological conditions have been mainly confined to a certain city or district, and the correlation over the whole of China remains unclear. Whether or not spatial and seasonal variations exit deserves further research. In this study, the relationships between PM2.5 concentration and meteorological factors were investigated in 74 major cities in China for a continuous period of 22 months from February 2013 to November 2014, at season, year, city, and regional scales, and the spatial and seasonal variations were analyzed. The meteorological factors were relative humidity (RH), temperature (TEM), wind speed (WS), and surface pressure (PS). We found that spatial and seasonal variations of their relationships with PM2.5 do exist. Spatially, RH is positively correlated with PM2.5 concentration in North China and Urumqi, but the relationship turns to negative in other areas of China. WS is negatively correlated with PM2.5 everywhere expect for Hainan Island. PS has a strong positive relationship with PM2.5 concentration in Northeast China and Mid-south China, and in other areas the correlation is weak. Seasonally, the positive correlation between PM2.5 concentration and RH is stronger in winter and spring. TEM has a negative relationship with PM2.5 in autumn and the opposite in winter. PS is more positively correlated with PM2.5 in autumn than in other seasons. Our study investigated the relationships between PM2.5 and meteorological factors in terms of spatial and seasonal variations, and the conclusions about the relationships between PM2.5 and meteorological factors are more comprehensive and precise than before.Comment: 3 tables, 13 figure