Future changes in precipitation and water availability over the Tibetan Plateau projected by CMIP6 models constrained by climate sensitivity

Precipitation projections over the Tibetan Plateau(TP)show diversity among existing studies,partly due to model uncertainty.How to develop a reliable projection remains inconclusive.Here,based on the IPCC AR6–assessed likely range of equilibrium climate sensitivity(ECS)and the climatological precipitation performance,the authors constrain the CMIP6(phase 6 of the Coupled Model Intercomparison Project)model projection of summer precipitation and water availability over the TP.The best estimates of precipitation changes are 0.24,0.25,and 0.45 mm d^(−1)(5.9%,6.1%,and 11.2%)under the Shared Socioeconomic Pathway(SSP)scenarios of SSP1–2.6,SSP2–4.5,and SSP5–8.5 from 2050–2099 relative to 1965–2014,respectively.The corresponding constrained projections of water availability measured by precipitation minus evaporation(P–E)are 0.10,0.09,and 0.22 mm d^(−1)(5.7%,4.9%,and 13.2%),respectively.The increase of precipitation and P–E projected by the high-ECS models,whose ECS values are higher than the upper limit of the likely range,are about 1.7 times larger than those estimated by constrained projections.Spatially,there is a larger increase in precipitation and P–E over the eastern TP,while the western part shows a relatively weak difference in precipitation and a drier trend in P–E.The wetter TP projected by the high-ECS models resulted from both an approximately 1.2–1.4 times stronger hydrological sensitivity and additional warming of 0.6℃–1.2℃ under all three scenarios during 2050–2099.This study emphasizes that selecting climate models with climate sensitivity within the likely range is crucial to reducing the uncertainty in the projection of TP precipitation and water availability changes.

煤层气井井喷机理分析

山西省某矿在地面施工煤层气井正常钻进至峰峰组进发生了井喷,开始钻孔喷出物为气水混合物,慢慢水量减少,后来喷出物以煤层气为主。为了寻找煤层气井发生井喷的原因,保证煤矿安全生产。在井喷区域进行了补充勘探和地面物探,并收集了以往地质资料。分析表明:煤层气井发生井喷的水源为太原组灰岩水和峰峰组灰岩水的混合水,通道为裂隙断层带和岩溶陷落柱,动力为地应力、水压和气压的共同作用。

Effects of Different Water Stresses on Eco-physiological Characteristics of Hippophae rhamnoides Seedlings

In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.

1-D Controlled source electromagnetic forward modeling for marine gas hydrates studies

We discuss the feasibility of using controlled-source electromagnetic （CSEM） in the frequency domain for prospecting marine gas hydrates. Based on the Ocean Drilling Program （ODP） Leg 164 log data, we have established several 1-D resistivity models which have different gas hydrate concentrations. Meanwhile, we analyzed the electromagnetic response of marine gas hydrates in the frequency domain based on these models. We also studied the relationship between electrical field magnitude or phase and parameters such as receiver-transmitter distance and frequency. Our numerical modeling results provide us with a quantitative reference for exploration and resource evaluation of marine gas hydrates.

Water, CO_2 and Energy Exchange at Vegetation-air Interface

[Objective] The aim was to analyze water and heat fluxes, CO2 fluxes and energy balance in wheat ecosystem in Luancheng County of Hebei Province. [Method] Based on data of water and heat flux, and CO2 fluxes, routine meteorological and biomass data in Luancheng in 2008, water and heat fluxes, CO2 fluxes and energy balance in wheat ecosystem were explored. [Result] The results showed that latent and sensible heat and CO2 fluxes were of obvious daily and seasonal changes; latent and sensible heat fluxes shaped an inverted U in daily change, and CO2 fluxes were of a U-shape; daily flux peak differed significantly. Furthermore, the change of latent heat, sensible heat and CO2 fluxes were closely related to environ- mental factors. Detailedly, the three were sensitive to light intensity and net radiation, and correlation coefficients were 0.92, 0.66, 0.65 and 0.90, 0.69, 0.74, respectively. Besides, the fluxes, sensitive to temperature, proved better in sunny day, especially for latent flux which is more sensitive to water in soils after precipitation. In addition, closure degree of energy balance in wheat fields was 0.91 and non-closure, caused by measurement error and neglection of heat storage, was observed, too. What＇s more. closure degree differed in months and time periods within a day. [Conclusion] The research concluded water and heat fluxes, CO2 fluxes, transport mechanisms and concerning factors, providing scientific reference for revealing mechanism of evapo- ration and heat dissipation of canopy, relationship between photosynthesis and water use efficiencyand energy distribution mechanism.

Stable Isotopes in Precipitation in Xilin River Basin,Northern China and Their Implications

Under the increasing pressure of water shortage and steppe degradation, information on the hydrological cycle in steppe region in Inner Mongolia, China is urgently needed. An intensive investigation of the temporal varia-tions of δD and δ^18O in precipitation was conducted in 2007-2008 in the Xilin River Basin, Inner Mongolia in the northern China. The 6D and δ^18O values for 54 precipitation samples range from ＋1.1%o to -34.7%0 and -3.0%0 to -269%0, respectively. This wide range indicates that stable isotopes in precipitation are primarily controlled by differ-ent condensation mechanisms as a function of air temperature and varying sources of vapor. The relationship between δD and δ^18O defined a well constrained line given by δD = 7.896180 ＋ 9.5, which is nearly identical to the Meteoric Water Line in the northern China. The temperature effect is clearly displayed in this area. The results of backward tra-jectory of each precipitation day show that the vapor of the precipitation in cold season （October to March） mainly originates from the west while the moisture source is more complicated in warm season （April to September）. A light precipitation amount effect existes at the precipitation event scale in this area. The vapor source of precipitation with higher d-excesses are mainly from the west wind or neighboring inland area and precipitation with lower d-excesses from a monsoon source from the southeastern China.

Experimental Investigation of a Vertical Tubular Desalination Unit Using Humidification-Dehumidification Process

A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.

Oasis System and Its Reasonable Development in Sangong River Watershed in North of the Tianshan Mountains,Xinjiang,China

Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.

矿业项目价值评估及敏感性分析

为了更好地实现我国的"走出去"战略目标,本文从矿业项目经济评价和敏感性分析方面着手,以折现现金流法(DCF)为基础,实例设计矿业项目经济评价模型,立体展现企业如何评估矿业项目当前价值,并且具体分析各参数的变化如何对项目产生影响及其敏感性,以解决矿企降低投资风险,提高国际竞争力的问题。作者在实际与国外矿企交流、谈判和合作过程中,发现他们会变换项目评价所涉及的参数,这些微小的变换却能造成结果的迥然不同,也是我国矿企与国际接轨的关键。因此,熟练掌握与运用价值评估模型是我们所欠缺的,培养和壮大结构合理的高水平人才队伍是实现我国"走出去"战略目标所应解决的重要环节。

Impacts of climate change on agricultural water resources and adaptation on the North China Plain

Climate change is having a considerable impact on the availability of water resources for agricultural production on the North China Plain （NCP）, where the shortage of water is currently disturbing the stability and sustainability of agricultural production with respect to the drying tendency since the 1950s. However, although potential evapotranspiration （ET） has shown a decreasing trend under climate change, actual ET has slightly increased with an acceleration in hydrological cycling. Global climate model （GCM） ensemble projections predict that by the 2050s, the increased crop water demand and intensified ET resulting from global warming will reduce water resources surplus （Precipitation-ET） about 4%-24% and increase significantly the irrigation water demand in crop growth periods. This study assesses possible mitigation and adaptation measures for enabling agricultural sustainability. It is revealed that reducing the sowing area of winter wheat （3.0%-15.9%） in water-limited basins, together with improvement in crop water-use efficiency would effectively mitigate water shortages and intensify the resilience of agricultural systems to climate change.

Impacts of Climate Change on Water Resources in Diyala River Basin, Iraq

Diyala River is the third largest tributary of the Tigris River running 445 km length and draining an area of 32,600 km2. The river is the major source of water supply for Diyala City for municipal, domestic, agriculture and other purposes. Diyala River Basin currently is suffering from water scarcity and contamination problems. Up-to-date studies have shown that blue and green waters of a basin have been demonstrating increasing variability contributing to more severe droughts and floods seemingly due to climate change. To obtain better understanding of the impacts of climate change on water resources in Diyala River Basin in near 2046-2064 and distant future 2080~2100, SWAT （soil and water assessment tool） was used. The model is first examined for its capability of capturing the basin characteristics, and then, projections from six GCMs （general circulation models） are incorporated to assess the impacts of climate change on water resources under three emission scenarios： A2, AIB and B1. The results showed deteriorating water resources regime into the future.

Vulnerability assessment of water resources to climate change in Chinese cities

Climate change is an inevitable trend,which challenges security of water resources in China,especially in cities.Assessing vulnerability of water resource to climate change in cities has important role for policy makers. The paper constructs a vulnerability function,including exposure,sensitivity and adaptive capacity,according to the vulnerability concept proposed by IPCC,establishes an assessment indicators system of water resources to climate change in cities,and analyzes vulnerability features of Chinese cites based on 655 cities＇data in 2006.The vulnerability assessment results show that there are distinctive differences among all the cities,between east,central and west cities,between ordinary,big and mega cities,while there is no statistical significant difference between north and south cities.Based on the research,the paper suggests that strategic emphasis should focus on the central cities and ordinary cities

Steam Reforming of Natural Gas： A Value Addition to Natural Gas Utilization in Nigeria

Petrochemicals play a vital role in the economy of any nation. The products of the industry are the building blocks in many industries as they deepen the forward and backward linkages of the petroleum sector with the rest of the economy. The industry uses a variety of hydrocarbon feedstock such as different cuts of naphtha from refinery and natural gas. One of the problems facing the industry is lack of reliable feedstock supplies. Nigeria has the potential to be a major petrochemicals producer. With proven gas reserves currently estimated at 187 tcf, not much has been accomplished with respect to the effective exploitation and utilization of this resource as most of the nation＇s natural gas production has been flared, liquefied for export or re-injected to enhance greater crude oil recovery. It has become imperative to further find ways to exploit and utilize the nation＇s natural gas reserves and translate it to the improvement of the nation＇s economy. Steam reforming of natural gas is one of the avenues for conversion of natural gas to petrochemicals. This paper, however, reviews various ways of utilizing natural gas, examines the process details of steam reforming of natural gas as a route to optimized natural gas utilization and industrialization in Nigeria. Syngas （synthesis gas） is a versatile feedstock for most petrochemicals and chemical intermediates. Thus utilizing natural gas in this way would strengthen the petrochemical industry making it possible for the country to change from raw materials to value-added products supplier, boost the economy and solve the ＂hydra-headed＂ problem of unemployment in Nigeria with its multiplier employment effect.

On the Law Right of the Gas Water of Water Resources

With the development of science and technology, the researches and application of water resources including the gas water have been constantly developed. Through an analysis on the flaws of the water right theory, and by executing reconstruction and renewal of the theory and system of water right in modem society, the water right position of the gas water will be established, leading to the maturity of the whole law effectiveness and substantial results of water right.

Key Issues on Cryospheric Changes,Trends and Their Impacts

On the basis of analyzing the importance of cryospheric researches in China and current status of cryospheric sciences in the world, this paper addresses key issues and main contents of present cryospheric sciences in China. The key issues currently addressed are： i） mechanisms of different types of glaciers in response to climate change and the scale-conversion in water resources assessments; ii） modeling of water and heat exchanges between frozen soil and vegetation; iii） parameterization of physical processes in cryosphere as well as coupling with climate models. To gain full clarification of these key issues, works of the following three aspects should be highlighted, i.e., cryospheric processes and responses to climate change, influences of cryospheric changes, and adaptation strategies for cryospheric changes.

The Role of Hydropower in Climate Change Mitigation and Adaptation： A Review

Hydropower is a clean,renewable,and environmentally friendly source of energy.It produces 3930(TW·h)·a–1,and yields 16% of the world's generated electricity and about 78% of renewable electricity generation(in 2015).Hydropower and climate change show a double relationship.On the one hand,as an important renewable energy resource,hydropower contributes significantly to the avoidance of greenhouse gas(GHG) emissions and to the mitigation of global warming.On the other hand,climate change is likely to alter river discharge,impacting water availability and hydropower generation.Hydropower contributes significantly to the reduction of GHG emissions and to energy supply security.Compared with conventional coal power plants,hydropower prevents the emission of about 3 GT CO2 per year,which represents about 9% of global annual CO2 emissions.Hydropower projects may also have an enabling role beyond the electricity sector,as a financing instrument for multipurpose reservoirs and as an adaptive measure regarding the impacts of climate change on water resources,because regulated basins with large reservoir capacities are more resilient to water resource changes,less vulnerable to climate change,and act as a storage buffer against climate change.At the global level,the overall impact of climate change on existing hydropower generation may be expected to be small,or even slightly positive.However,there is the possibility of substantial variations across regions and even within countries.In conclusion,the general verdict on hydropower is that it is a cheap and mature technology that contributes significantly to climate change mitigation,and could play an important role in the climate change adaptation of water resource availability.However,careful attention is necessary to mitigate the substantial environmental and social costs.Roughly more than a terawatt of capacity could be added in upcoming decades.

Climate Change and its Impact on Water Resources in the Huai River Basin

Rainfall and air temperature data from six meteorological stations above the Bengbu Sluice and hydrological and water resources evaluation data from the Bengbu Hydrological Station in the Huai River Basin from 1961 to 2008 are used to analyze the impact of changes in climatic factors on the amount of water resources in the Basin. There was a general trend of rise in its average annual air temperature, with the highest increase of 0.289℃/10a recorded at Bengbu in Anhui Province. Rising rainfall was mainly observed in the western part of the study area, while rainfall actually declined in the eastern part, i.e. the middle reaches of the Huai River. The Average rainfall in the study area was in a vaguely declining trend. In other words, the rainfall in the Basin is still much affected by natural fluctuations. On the whole, there was a trend of gradual decrease in the quantity of the Basin＇s water resources for the period under study. Water resources quantity is found to fall with decreasing rainfall and rising air temperature. Regression analysis is used to establish a mathematical model between water resources quantity and climatic factors （i.e. air temperature and rainfall） in order to explore the impact of climate change on water resources in the Basin. Moreover, various scenarios are set to quantitatively analyze the response of water resources to climate change. Sensitivity analysis shows that changes in rainfall have a much bigger impact on its water resources quantity than changes in its air temperature.

Climate-induced Changes in Spring Maize Water Requirement in Xiliaohe River Watershed

Xiliaohe River watershed plays an important role in regional and national grain security.With the development of society and economy,water consumption that increased dramatically causes water shortages.Crop water requirement can provide quantitative basis for making regional irrigation scheme.In this study,spring maize water requirement is calculated by using PenmanMonteith formula and spring maize coefficient from May to September at 10 meteorological stations in Xiliaohe River watershed from 1951 to 2005.The variation trend of the spring maize water requirement during the whole growing stage,water requirement in every month,and meteorological influencing factors are obtained by using Mann-Kendall method,and the degree of grey incidence between the water requirement and meteorological influencing factors are shown.The results are the spring maize water requirement during the whole growing stages increases at half of the stations in Xiliaohe River watershed,and are remarkably affected by the water requirement in May.The monthly mean,maximum and minimum air temperature form May to September show an increasing trend in Xiliaohe River watershed in recent 55 years.The monthly mean and minimum air temperature increases notably.The relative humidity,precipitation,wind speed and sunshine show a decreasing trend with variety for different months.The monthly maximum air temperature,wind speed,sunshine and monthly mean air temperature have the highest correlation degree with spring maize water requirement from May to September.

Coupled modeling of land hydrology-regional climate including human carbon emission and water exploitation

Carbon emissions and water use are two major kinds of human activities. To reveal whether these two activities can modify the hydrological cycle and climate system in China, we conducted two sets of numerical experiments using regional climate model RegCM4. In the first experiment used to study the climatic responses to human carbon emissions, the model were configured over entire China because the impacts of carbon emissions can be detected across the whole country. Results from the first experiment revealed that near-surface air temperature may significantly increase from 2007 to 2059 at a rate exceeding 0.1 ~C per decade in most areas across the country; southwestern and southeastern China also showed increasing trends in summer precipitation, with rates exceeding 10 mm per decade over the same period. In summer, only northern China showed an increasing trend of evapotranspiration, with increase rates ranging from 1 to 5 mm per decade; in winter, increase rates ranging from 1 to 5 mm per decade were observed in most regions. These effects are believed to be caused by global warming from human carbon emissions. In the second experiment used to study the effects of human water use, the model were configured over a limited region-- Haihe River Basin in the northern China, because compared with the human carbon emissions, the effects of human water use are much more local and regional, and the Haihe River Basin is the most typical region in China that suffers from both intensive human groundwater exploitation and surface water diversion. We incorporated a scheme of human water regulation into RegCM4 and conducted the second experiment. Model outputs showed that the groundwater table severely declined by -10 m in 1971-2000 through human groundwater over- exploitation in the basin; in fact, current conditions are so extreme that even reducing the pumping rate by half cannot eliminate the ground- water depletion cones observed in the area. Other hydrological and climatic elements, such as soil moisture, runoff generation, air humidity, precipitation, wind field, and soil and air temperature, were also significantly affected by anthropogenic water withdrawal and consumption, although these effects could be mitigated by reducing the amount of water drawn for extraction and application.

Climate Change and Future Long-Term Trends of Rainfall at North-East of Iraq

Iraq is facing water shortage problem despite the presence of the Tigris and Euphrates Rivers. In this research, long rainfall trends up to the year 2099 were studied in Sulaimani city northeast Iraq to give an idea about future prospects. The medium high （A2） and medium low B2 scenarios have been used for purpose of this study as they are more likely than others scenarios, that beside the fact that no climate modeling canter has performed GCM （global climate model） simulations for more than a few emissions scenarios （HadCM3 has only these two scenarios） otherwise pattern scaling can be used for generating different scenarios which entail a huge uncertainty. The results indicate that the average annual rainfall shows a significant downward trend for both A2 and B2 scenarios. In addition, winter projects increase/decrease in the daily rainfall statistics of wet days, the spring season show very slight drop and no change for both scenarios. However, both summer and autumn shows a significant reduction in maximum rainfall value especially in 2080s while the other statistics remain nearly the same. The extremes events are to decrease slightly in 2080s with highest decrease associated with A2 scenario. This is due to the fact that rainfall under scenario A2 is more significant than under scenario B2. The return period of a certain rainfall will increase in the future when a present storm of 20 year could occur once every 43 year in the 2080s. An increase in the frequency of extreme rainfall depends on several factors such as the return period, season of the year, the period considered as well as the emission scenario used.