Effects of climate change and land-use changes on spatiotemporal distributions of blue water and green water in Ningxia, Northwest China

Water resources are a crucial factor that determines the health of ecosystems and socio-economic development;however,they are under threat due to climate change and human activities.The quantitative assessment of water resources using the concept of blue water and green water can improve regional water resources management.In this study,spatiotemporal distributions of blue water and green water were simulated and analyzed under scenarios of climate change and land-use changes using the Soil and Water Assessment Tool(SWAT)in Ningxia Hui Autonomous Region,Northwest China,between 2009 and 2014.Green water,a leading component of water resources,accounted for more than 69.00%of the total water resources in Ningxia.Blue water and green water showed a single peak trend on the monthly and annual scales during the study period.On the spatial scale,the southern region of Ningxia showed higher blue water and green water resources than the northern region.The spatiotemporal distribution features of blue water,green water,and green water flow had strong correlations with precipitation.Furthermore,the simulation identified the climate change in Ningxia to be more influential on blue water and green water than land-use changes.This study provides a specific scientific foundation to manage water resources in Ningxia when encountered with climate change together with human activities.

Hollow and substrate-supported Prussian blue,its analogs,and their derivatives for green water splitting

To meet the current energy needs of society,the highly efficient and continuous production of clean energy is required.One of the key issues facing the green hydrogen evolution is the construction of efficient,low-cost electrocatalysts.Prussian blue(PB),Prussian blue analogs(PBAs),and their derivatives have tunable metal centers and have attracted significant interest as novel photo-and electrochemical catalysts.In this review,recent research progress into PB/PBA-based hollow structures,substrate-supported nanostructures,and their derivatives for green water splitting is discussed and summarized.First,several remarkable examples of nanostructured PB/PBAs supported on substrates(copper foil,carbon cloth,and nickel foam)and hollow structures(such as single-shelled hollow boxes,open hollow cages,and intricate hollow structures(multi-shell and yolk-shell))are discussed in detail,including their synthesis and formation mechanisms.Subsequently,the applications of PB/PBA derivatives((hydr)oxides,phosphides,chalcogenides,and carbides)for water splitting are discussed.Finally,the limitations in this research area and the most urgent challenges are summarized.We hope that this review will stimulate more researchers to develop technologies based on these intricate PB/PBA structures and their derivatives for highly efficient,green water splitting.

Numerical Investigation of Green Water Loading on Flexible Structures Using Three-Step CFD-BEM-FEM Approach

In this paper, the effect of green water impact on a flexible structure is studied based on three-step computational fluid dynamics(CFD)–boundary element method(BEM)–finite element method(FEM) approach. The impact due to shipping of water on the deck of the vessel is computed using commercial CFD software and used as an external force in coupled BEM-FEM solver. Other hydrodynamic forces such as radiation, diffraction, and Froude-Krylov forces acting on the structure are evaluated using 3 D time domain panel method. To capture the structural responses such as bending moment and shear force, 1 D finite element method is developed. Moreover, a direct integration scheme based on the Newmark–Beta method is employed to get the structural velocity,displacement, etc., at each time step. To check the effect of the green water impact on the structure, a rectangular barge without forward speed is taken for the analysis. The influence is studied in terms of bending moment, shear force, etc. Results show that the effect of green water impact on the bow region can be severe in extreme seas and lead to various structural damages. Similarly,it is also verified that vessel motion affects green water loading significantly and therefore one must consider its effect while designing a vessel.

Risk assessment of agricultural green water security in Northeast China under climate change

Northeast China is an important base for grain production,dominated by rain-fed agriculture that relies on green water.However,in the context of global climate change,rising regional temperatures,changing precipitation patterns,and increasing drought frequency pose threats and challenges to agricultural green water security.This study provides a detailed assessment of the spatiotemporal characteristics and development trends of green water security risks in the Northeast region under the base period(2001-2020)and the future(2031-2090)climate change scenarios(SSP245 and SSP585)using the green water scarcity(GWS)index based on raster-scale crop spatial distribution data,Delta downscaling bias-corrected ERA5 data,and CMIP6 multimodal data.During the base period,the green water risk-free zone for dry crops is mainly distributed in the center and east of the Northeast region(72.4% of the total area),the low-risk zone is primarily located in the center(14.0%),and the medium-risk(8.3%)and high-risk(5.3%)zones are mostly in the west.Under SSP245 and SSP585 future climate change scenarios,the green water security risk shows an overall expansion from the west to the center and east,with the low-risk zone increasing to 21.6% and 23.8%,the medium-risk zone increasing to 16.0% and 17.9%,and the high-risk zone increasing to 6.9% and 6.8%,respectively.Considering dry crops with GWS greater than 0.1 as in need of irrigation,the irrigated area increases from 27.6%(base period)to 44.5%(SSP245)and 48.6%(SSP585),with corresponding increases in irrigation water requirement(IWR)of 4.64 and 5.92 billion m~3,respectively,which further exacerbates conflicts between supply and demand of agricultural water resources.In response to agricultural green water security risks,coping strategies such as evapotranspiration(ET)-based water resource management for dry crops and deficit irrigation are proposed.The results of this study can provide scientific basis and decision support for the development of Northeast irrigated agriculture and the construction planning of the national water network.

Numerical Investigation of Heave and Pitch Motion Effects on Green Water Loading for a Floating Body

In this paper,the influence of heave and pitch motions on green water impact on the deck is numerically investigated.The vessel motions are determined using a potential theory based method and provided as input to finite volume based CFD computations of green water phenomenon.A dynamic mesh approach is adopted to determine instantaneous body positioning in the fluid domain.Detailed validation studies with published experimental results for 2D and 3D fixed vessel cases are initially performed to validate the present numerical approach before studying the moving vessel problem.The results show that inclusion of heave and pitch motion changes the disturbed wave field near the bow which influences the free surface as well as the impact loading due to green water.The effect of wave steepness on green water impact is also investigated and it is seen that the present numerical method is capable of capturing green water load.It is observed that the effects of vessel motions on green water load are not negligible and one should consider this effect too.The incorporation of vessel motions in the vertical plane affects the green water loading on the deck.

Microcystin Accumulation in Nile Tilapia, <i>Oreochromis niloticus</i>and Giant Freshwater Prawns, <i>Macrobrachium rosenbergii</i>in Green Water System Cultivation

Phytoplankton including blue-green algal or cyanobacterial blooms frequently occurred in aquaculture ponds. Some cyanobacteria produced cyanotoxins that may accumulate in the food web and eventually in the aquaculture products. In this study, accumulatation of microcystins in Nile tilapia (Oreochromis niloticus) and giant freshwater prawn (Macrobrachium rosenbergii) cultured in green water system was investigated.Nile tilapia was cultured in green water system and fish food;green water system with Microcystis aeruginosa Kützingand fish food and green water system with M. aeruginosa. Giant freshwater prawn was cultured: in green water systems with and without toxic M. aeruginosa. Microcystins of 8.32±0.76 and9.35±1.45μg·kg—1 d.w. were detected in fish cultured in green water system with M. aeruginosa and fish food and in green water system with M. aeruginosa, respectively. Microcystins of 14.42±1.63 μg·kg—1 was found in prawn samples. It implied that aquaculture products were likely to be contaminated with microcystins. This finding is useful for aquaculture in terms of food safety.

Green Roof Performance for Stormwater Management in Equatorial Urban Areas Using Storm Water Management Model (SWMM)

Many Low Impact Developments (LIDs) have recently been developed as a sustainable integrated strategy for managing the quantity and quality of stormwater and surrounding amenities. Previous research showed that green roof is one of the most promising LIDs for slowing down rainwater, controlling rainwater volume, and enhancing rainwater quality by filtering and leaching contaminants from the substrate. However, there is no guideline for green roof design in Malaysia. Hence, Investigating the viability of using green roofs to manage stormwater and address flash flood hazards is urgently necessary. This study used the Storm Water Management Model (SWMM) to evaluate the effectiveness of green roof in managing stormwater and improving rainwater quality. The selected study area is the multistory car park (MSCP) rooftop at Swinburne University of Technology Sarawak Campus. Nine green roof models with different configurations were created. Results revealed that the optimum design of a green roof is 100 mm of berm height, 150 mm of soil thickness, and 50 mm of drainage mat thickness. With the ability to reduce runoff generation by 26.73%, reduce TSS by 89.75%, TP by 93.07%, TN by 93.16%, and improved BOD by 81.33%. However, pH values dropped as low as 5.933 and became more acidic due to the substrates in green roof. These findings demonstrated that green roofs improve water quality, able to temporarily store excess rainfall and it is very promising and sustainable tool in managing stormwater.

和美乡村视角下的苏南农田“GREEN”水环境治理模式应用研究

随着中国宜居宜业和美乡村建设的不断深入,乡村水环境的治理与保护作为乡村生态文明建设的重要组成部分日益受到社会的重视和关注。在以往大规模灰色基础设施建设的背景下,乡村忽略了对于水生态绿色基础设施的构建,生态格局趋于破碎。农田空间作为农业面源污染的重要源头,结合多学科视角探索农田水环境污染治理新模式具有高度的必要性。立足于苏南地区独特的农田水网体系,紧密结合农业空间生产属性,研究现有农田水环境治理理论方法与实际建设,提炼以“源头绿色—过程净化—末端吸收—生态保育—循环回用”的苏南农田“GREEN”水环境治理模式,探索风景园林学科水治理方法在农田沟渠、河道及湿地等乡村空间的运用路径,并以常州市中天黄金大农场总体规划为例进行实践应用。推动风景园林学科于乡村生产空间的应用模式探索,为未来农业面源污染防治提供参考借鉴。

Slamming and Green Water Loads on Bow-Flare Ship in Regular Head Waves Investigated by Hydroelasticity Theory and Experiment

With the development of ships towards large scale, high speed and light weight, ship hydroelastic responses and slamming strength issues are becoming increasingly important. In this paper, a time-domain nonlinear hydroelasticity theory is developed to predict ship motion and load responses in harsh regular waves.Hydrostatic restoring force, wave excitation force and radiation force are calculated on the instantaneously wetted body surface to consider the nonlinear effects caused by large amplitude motions of ship in steep waves. A twodimensional(2 D) generalized Wagner model and a one-dimensional(1 D) dam-breaking model are used to estimate the impact loads caused by bow flare slamming and green water on deck, respectively;the impact loads are coupled with the hydroelastic equation in time-domain. Moreover, segmented model tests are carried out in a towing tank to investigate the wave and slamming loads acting on the hull sailing in harsh regular head waves and also validate the numerical results.

The Study on Urban Vertical Greening and Balance Water Supply Technology

The paper had analyzed the technology, maintenance and recognition of vertical greening in urban space, and proposed a solution for balance water supply for balconies and streetlights, that is, magnetic auxiliary shallow water level controller, the patent of which had been applied. Magnetic auxiliary shallow water level controller had met water supply of some special parts of urban vertical greening and was sure to accelerate urban vertical greening.

Virtual Water Trade and Food Security for Iraq

Iraq depends on its water resources from the water of the Tigris and Euphrates Rivers and their tributaries. Now, the flow of these rivers is decreasing, and Iraq is experiencing a water shortage problem. The situation is expected to be graver in the future if no action is considered. It is expected that the population will be about 70 million in 2050 and about 90 million in 2070. In such a case, thus, the quantities of water available in the future will not be sufficient to produce most of the requirements of food security, whether that be from agricultural or animal products. To overcome this problem, water management planning should be based on scientific background to overcome the present and expected problems. One of the main factors to be considered should be based on scientific studies of the virtual water footprint of different food crops to provide the largest possible amount of virtual water and avoid the acute shortage of its national water from surface and ground irrigation water (blue water) and rainwater (green water), in addition to working hard to provide the largest possible amount of desalinated water and refined sewage (gray water). In addition, any strategic plan for sustainable development in the country must be comprehensive so that it is not satisfied with improving the situation in the field of food security related to water security, but rather among its other elements is community development that directly affects food security, including setting policies to reduce consumption by reducing the steady increase in population where the population rate is 2.97% now. Collective awareness and guidance programs in all the fields of water and food security are very important to be adopted, so that everyone knows that the issue of food security and what derives from it are an existential issue related to the survival of Iraq as a state and people. In this research, facts are stated so that action is to be considered to minimize the water shortage problem. The new strategic water resources management plan is to be adopted that considers existing and future expected problems.

Fast Evaluation of Time-Domain Green Function for Finite Water Depth

For computation of large amplitude motions of ships fastened to a dock, a fast evaluation scheme is implemented for computation of the time-domain Green function for finite water depth. Based on accurate evaluation of the Green function directly, a fast approximation method for the Green function is developed by use of Chebyshev polynomials. Examinations are carried out of the accuracy of the Green function and its derivatives from the scheme. It is shown that when an appropriate number of polynomial terms are used, very accurate approximation can be obtained.

Cocos nucifera L.water as green corrosion inhibitor for acid corrosion of aluminium in HCl solution

The ability of Cocos nucifera L.water（CW） as non-toxic corrosion inhibitor for acid corrosion of aluminium in 0.5 mol/L HCl has been studied using chemical technique.CW shows significant inhibition as corrosion inhibitor,with 93%efficiency at the highest concentration of the inhibitor.The inhibitive action is attributed to the adsorption of the inhibitor molecules on metal surface following Langmuir adsorption isotherm.

Water use, growth and yield of green gram under rainfed upland crop sequences in Gangetic Plains of Indian sub-tropics

A field experiment was conducted to study the effect of different crop sequences on water use, growth and yield of green gram (Vigna radiate (L) Wilezek) during 1992–93 and 1993–94 under rainfed upland condition in Indo-Gangetic plains of West Bengal. Green gram sown in the month of March as pre-rainy (summer) season crop, as and when the winter crops vacated the land, produced highest dry matter of 372 gm-2 which was significantly highest in black gram-yellow sarson sequence. The results of the field experimentation revealed that green gram gave highest grain yield to the extent of 10.80 q/ha when sown after black gram (rainy season) followed by yellow sarson (winter season) while the crop produced 10.63 q/ha under sesame-yellow sarson sequence. Highest water use of 267 mm was achieved in green gram under black gram-yellow sarson sequence and the crop gave water use efficiency of 4.07 kg ha-1mm-1 under black gram-yellow sarson sequences.

Agricultural Water Footprint of Southern Highbush Blueberry Produced Commercially with Drip Irrigation and Sprinkler Frost Protection

A study was conducted from 2010 to 2017 to determine the water footprint for producing blueberries in the Entre Ríos province of Argentina. Three cultivars of southern highbush blueberry (hybrid cross of Vaccinium sp.) were evaluated in the study, including “Star”, “Emerald”, and “Snowchaser”. In each case, the plants were irrigated by drip and protected from frost using overhead sprinklers. Water requirements for irrigation and frost protection varied among the cultivars due to differences in the timing of flowering and fruit development. The annual water footprint for fruit production in each cultivar is expressed in units of cubic meters of water used to produce one ton of fresh fruit and ranged from 212 - 578 m3∙t−1 for “Star”, 296 - 985 m3∙t−1 for “Emerald”, and 536 - 4066 m3∙t−1 for “Snowchaser”. “Snowchaser” flowered earlier than the other cultivars and, therefore, needed more water for frost protection. “Star”, on the other hand, ripened the latest among the cultivars and required little to no water for frost protection. Frost protection required a minimum of 30 m3∙h−1 of water per hectare and in addition to drip irrigation was a major component of the water footprint.

Green roofs for storm water management:a review

The rapid urbanization and industrialization involve an unsustainable use of natural systems,leading to various problems in cities.The urban hydrological system experiences fluctuating amount of surface runoff water when it rains heavily.It has been suggested that green roofs significantly mitigate storm water runoff generation even in tropical climate.Green roofs have become popular due to its proven benefits by mitigating urban heat island effects and protecting biodiversity.The annual rainfall and runoff relationship for green roofs is determined by the depth of the substrate.Water retention capacity mostly depends on substrate's physical conditions such as dry or wetness.Generally 6 mm to 12 mm rainfall is required for dry substrate to initiate runoff whereas response of wet conditions is mostly straight.Besides,there are some other factors affecting runoff dynamics such as type of a green roof and its slope,age of green roof,type of vegetation,soil moisture characteristics,weather.The review indicates that there is not much research in green roofs performance over storm water runoff;hence there is a need for further research.This paper reviews and addresses the role of green roofs in urban storm water management.

西南水稻主产区用水现状与绿色高效灌排技术

西南水稻主产区面临季节性干旱、工程性缺水等生产问题,绿色高效灌排技术是该区域实现节水稳产增效的关键举措,对保障国家粮食安全具有重要意义。本文系统梳理了包括云南省、贵州省、四川省、重庆市在内的西南地区水稻生产用水现状和灌排技术现状,阐述了西南水稻主产区绿色高效灌排体系的基本特征、绿色高效灌排的具体技术类型,提出了由稻田精准需水预报、灌区精量配水管理、田间高效用水管理、田间高效排水管理构成的绿色高效灌排技术模式。研究发现,西南水稻主产区水资源丰富但时空分布不均,节水灌溉和排水技术落后且对各地区气候条件、水资源量、地形的适用性有较大差异。建议研发稻田灌排高效协同调控新技术、推广绿色高效灌排技术体系、优化稻田水肥运筹模式、开发稻田智能灌排与信息化管理系统、构建水稻绿色高效灌排技术多维推广体系,据此推动西南水稻主产区节水提质增效与绿色减污降排多赢。

Effects of Long-Term Winter Planted Green Manure on Distribution and Storage of Organic Carbon and Nitrogen in Water-Stable Aggregates of Reddish Paddy Soil Under a Double-Rice Cropping System

In agricultural systems, maintenance of soil organic matter has long been recognized as a strategy to reduce soil degradation. Manure amendments and green manures are management practices that can increase some nutrient contents and improve soil aggregation. We investigated the effects of 28 yr of winter planted green manure on soil aggregate-size distribution and aggregateassociated carbon（C） and nitrogen（N）. The study was a randomized completed block design with three replicates. The treatments included rice-rice-fallow, rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass. The experiment was established in 1982 on a silty light clayey paddy soil derived from Quaternary red clay（classified as Fe-Accumuli-Stagnic Anthrosols） with continuous early and late rice. In 2009, soil samples were collected（0-15 cm depth） from the field treatment plots and separated into water-stable aggregates of different sizes（i.e., 〉5, 2-5, 1-2, 0.5-1, 0.25-0.5 and 〈0.25 mm） by wet sieving. The long-term winter planted green manure significantly increased total C and N, and the formation of the 2-5-mm water-stable aggregate fraction. Compared with rice-rice-rape, rice-rice-Chinese milk vetch and rice-rice-ryegrass, the rice-rice-fallow significantly reduced 2-5-mm water-stable aggregates, with a significant redistribution of aggregates into micro-aggregates. Long-term winter planted green manure obviously improved C/N ratio and macro-aggregate-associated C and N. The highest contribution to soil fertility was from macro-aggregates of 2-5 mm in most cases.

Green Cycle: Sulfate Sorption from Natural Water on Anionic Clay Compound Obtained from Industry Wastewater

In this paper we are describing a green cycle process. The first step was a novel hydrotalcite-like compound (HTLC) synthesized by a co-precipitating method, under standard ambient temperature and pressure, using chemical industry wastewater rich in divalent and trivalent cations, activated by a thermal treatment and finally characterized by scanning electron microscopy (SEM), energy dispersive X-ray fluorescence (EDS) and thermogravimetric analysis (TGA). The second step was a series of batch sorption tests performed with this activated HTLC and untreated underground sulfurous water from the state of Puebla, México. The HTLC calcined at 500°C/3 h exhibited the best sorption ability for ions, demonstrated a decrease of the hardness and sulfate ions to below the regional legal standards for drinking water. Once inactive after being used in water treatment, the sorbed ions were removed by ion exchange in a carbonate-containing solution, resulting in an 80% recycling of the material which upon activation demonstrated a retained capacity for water treatment. This recyclability suggests the exciting possibility of this novel compound as an efficient “green” technology in water treatment processes.

国外绿水经济发展经验研究

进入新发展阶段,人们对水资源的需求由过去单纯的物质和文化需求拓展为美好生活需要的多方面需求。最突出的变化是我国水经济形态发生了深刻变化,诞生一批水经济新业态,笔者认为凡是直接或者间接利用“绿水”来引导资源发挥作用,推动生产力发展的经济形态就是绿水经济。绿水经济在发达国家发展多年,形成了一批具有代表性的经济形态。梳理选取“绿水+高端农业”“绿水+新型工业”“绿水+旅游”“绿水+健康”四个代表性经济形态,剖析各典型经济形态的具体做法,总结提炼主要经验,并提出我国发展绿水经济的政策建议。