STUDIES ON FOREST WATER CYCLING

Principal ideas, research approaches and installations in both Liangshui and Maoershan Ecological Stations were diseussed. Significance of comparability and synchronous detennination in research methods were stressed. Comparison analysis was done on the results gained from diferent methods. Adaptive mechanisms of Mongolian oak (Quercus mongolica) to drought and unproductive sites wer expounded through hydrological cycling studies. Surface runoff and flood peak were decreased and the developing processes of flood peak were postponed or delayed because of the presence of huge forest canopy and forest floor. However, the conclusions of forest influences on total runoff,especially in spring and in the dry season t are significant to agricultul practices in notheast China and turned out contrary for satershed sizes or different approaches, which should be studied further.

Summer Atmospheric Water Cycle under the Transition Influence of the Westerly and Summer Monsoon over the Yarlung Zangbo River Basin in the Southern Tibetan Plateau

This study compares the summer atmospheric water cycle,including moisture sources and consumption,in the upstream,midstream,and downstream regions of the Yarlung Zangbo River Basin in the southern Tibetan Plateau.The evolutions of moisture properties under the influence of the westerly and summer southerly monsoon are examined using 5-yr multi-source measurements and ERA5 reanalysis data.Note that moisture consumption in this study is associated with clouds,precipitation,and diabatic heating.Compared to the midstream and downstream regions,the upstream region has less moisture,clouds,and precipitation,where the moisture is brought by the westerly.In early August,the vertical wet advection over this region becomes enhanced and generates more high clouds and precipitation.The midstream region has moisture carried by the westerly in June and by the southerly monsoon from July to August.The higher vertical wet advection maximum here forms more high clouds,with a precipitation peak in early July.The downstream region is mainly affected by the southerly-driven wet advection.The rich moisture and strong vertical wet advection here produce the most clouds and precipitation among the three regions,with a precipitation peak in late June.The height of the maximum moisture condensation is different between the midstream region(325 hPa)and the other two regions(375 hPa),due to the higher upward motion maximum in the midstream region.The diabatic heating structures show that stratiform clouds dominate the upstream region,stratiform clouds and deep convection co-exist in the midstream region,and deep convection systems characterize the downstream region.

Changes in Water Use Efficiency Caused by Climate Change,CO_(2) Fertilization,and Land Use Changes on the Tibetan Plateau

Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.

Optimal Dynamic Voltage Restorer Using Water Cycle Optimization Algorithm

This paper proposes a low complexity control scheme for voltage control of a dynamic voltage restorer(DVR)in a three-phase system.The control scheme employs the fractional order,proportional-integral-derivative(FOPID)controller to improve on the DVR performance in order to enhance the power quality in terms of the response time,steady-state error and total harmonic distortion(THD).The result obtained was compared with fractional order,proportionalintegral(FOPI),proportional-integral-derivative(PID)and proportional-integral(PI)controllers in order to show the effectiveness of the proposed DVR control scheme.A water cycle optimization algorithm(WCA)was utilized to find the optimal set for all the controller gains.They were used to solve four power quality issues;balanced voltage sag,balanced voltage swell,unbalanced voltage sag,and unbalanced voltage swell.It showed that one set of controller gain obtained from the WCA could solve all the power quality issues while the others in the literature needed an individual set of optimal gain for each power quality problem.To prove the concept,the proposed DVR algorithm was simulated in the MATLAB/Simulink software and the results revealed that the four optimal controllers can compensate for all the power quality problems.A comparative analysis of the results in various aspects of their dynamic response and%THD was discussed and analyzed.It was found that PID controller yields the most rapid performance in terms of average response time while FOPID controller yields the best performance in term of average%steady-state error.FOPI controller was found to provide the lowest THD percentage in the average%THD.FOPID did not differ much in average response from the PID and average%THD from FOPI;however,FOPID provided the most outstanding average steady-state error.According to the CBMA curve,the dynamic responses of all controllers fall in the acceptable power quality area.The total harmonic distortion(THD)of the compensated load voltage from all the controllers were within the 8%limit in accordance to the IEEE std.519-2014.

New evidence for the links between the local water cycle and the underground wet sand layer of a mega-dune in the Badain Jaran Desert, China

Scientists and the local government have great concerns about the climate change and water resources in the Badain Jaran Desert of western China. A field study for the local water cycle of a lake-desert system was conducted near the Noertu Lake in the Badain Jaran Desert from 21 June to 26 August 2008. An underground wet sand layer was observed at a depth of 20–50 cm through analysis of datasets collected during the field experiment. Measurements unveiled that the near surface air humidity increased in the nighttime. The sensible and latent heat fluxes were equivalent at a site about 50 m away from the Noertu Lake during the daytime, with mean values of 134.4 and 105.9 W/m2 respectively. The sensible heat flux was dominant at a site about 500 m away from the Noertu Lake, with a mean of 187.7 W/m2, and a mean latent heat flux of only 26.7 W/m2. There were no apparent differences for the land surface energy budget at the two sites during the night time. The latent heat flux was always negative with a mean value of –12.7 W/m2, and the sensible heat flux was either positive or negative with a mean value of 5.10 W/m2. A portion of the local precipitation was evaporated into the air and the top-layer of sand dried quickly after every rainfall event, while another portion seeped deep and was trapped by the underground wet sand layer, and supplied water for surface psammophyte growth. With an increase of air humidity and the occurrence of negative latent heat flux or water vapor condensation around the Noertu Lake during the nighttime, we postulated that the vapor was transported and condensed at the lakeward sand surface, and provided supplemental underground sand pore water. There were links between the local water cycle, underground wet sand layer, psammophyte growth and landscape evolution of the mega-dunes surrounding the lakes in the Badain Jaran Desert of western China.

Research progress of socio-economic water cycle in China

China has made great progress in the study of socio-economic water cycle. She has completed national water resources appraisement and medium to long-term water supply planning. She has been engaging in study on water-deficient regions in North China and Northwest China for about half a century. For solving water shortage problem in northern China, she has put forward the famous South-to-North Water Transferring Projects, which has been set as one of the four biggest national projects in the Tenth Five-Year-Plan period although there are still debates. For promoting water use efficiency, China has been reforming her water management system, including water right system and water price system. There has already been a case of water right purchase. China has also done a lot of research on the interaction between human activity, water and ecosystem. For meeting the need of sustainability and coordinating water resources development and environmental protection, the study of ecological water requirement became very hot in recent years. There are three focuses of socio-economic water cycle study now in China: water transfer projects from the south to the north, water resources management and ecological water requirement.

Effect of apple production base on regional water cycle in Weibei upland of the Loess Plateau

Weibei upland, located in southern part of the Loess Plateau, is a commercial apple production base in China. The enlargement of apple-planting area has a great impact on the regional water cycle. The effects of different land use on hydrological parameters are compared and studied in this paper. The main results are as follows (1) The initial and steady infiltration rates in apple orchard are higher than those in other land use types such as grassland, idle land and farmland. Their initial rates of infiltration are 0.823 cm/min, 0.215 cm/min, 0.534 cm/min and 0.586 cm/min in apple orchard, grassland, idle land and farmland respectively. Their steady infiltration rates are 0.45 cm/min, 0.038 cm/min, 0.191 cm/min and 0.155 cm/min respectively. (2) There is no runoff generated in plot of apple orchard in all 8 storm events in observed natural rainfalls, while runoff is generated in winter wheat plot, corn plot and alfalfa plot with runoff coefficients of 2.39%, 1.58% and 0.31% respectively. (3) The transpiration of apple trees is strong and thus soil moisture is gradually depleted. The average soil water contents in 3–9 m soil profile in Changwu plots with apple trees of 14 and 32 years in age are 11.77% and 11.59% and in Luochuan plots with those of 15 and 28 years in age are 11.7% and 11.59% respectively, which are nearly 9.0% of wilting moisture of Changwu soil and 8.6% of wilting moisture of Luochuan soil. The pathway of rainfall percolating to groundwater is hindered by dry soil profile.

Spatiotemporal characteristics and water budget of water cycle elements in different seasons in northeast China

In this paper, we study the spatiotemporal characteristics of precipitable water, precipitation, evaporation, and watervapor flux divergence in different seasons over northeast China and the water balance of that area. The data used in this paper is provided by the European Center for Medium-Range Weather Forecasts （ECMWF）. The results show that the spatial distributions of precipitable water, precipitation, and evaporation feature that the values of elements above in the southeastern area are larger than those in the northwestern area; in summer, much precipitation and evaporation occur in the Changbai Mountain region as a strong moisture convergence region; in spring and autumn, moisture divergence dominates the northeast of China; in winter, the moisture divergence and convergence are weak in this area. From 1979 to 2010, the total precipitation of summer and autumn in northeast China decreased significantly; especially from 1999 to 2010, the summer precipitation always demonstrated negative anomaly. Additionally, other elements in different seasons changed in a truly imperceptible way. In spring, the evaporation exceeded the precipitation in northeast China; in summer, the precipitation was more prominent; in autumn and winter, precipitation played a more dominating role than the evaporation in the northern part of northeast China, while the evaporation exceeded the precipitation in the southern part. The Interim ECMWF Re-Analysis （ERA-Interim） data have properly described the water balance of different seasons in northeast China. Based on ERA-Interim data, the moisture sinks computed through moisture convergence and moisture local variation are quite consistent with those computed through precipitation and evaporation, which proves that ERA- Interim data can be used in the research of water balance in northeast China. On a seasonal scale, the moisture convergence has a greater influence than the local moisture variation on a moisture sink, and the latter is variable slightly, generally as a constant. Likewise, in different seasons, the total precipitation has a much greater influence than the evaporation on the moisture sink.

New progress of research on water cycle in atmosphere in China

New progresses are introduced briefly about the water cycle study on atmosphere of China made in recent years. The introduction includes eight aspects as follows: 1) precipitation characteristics, 2) stability of climatic system, 3) precipitation sensitive region, 4) regional evaporation and evapotranspiration, 5) water surface evaporation, 6) vegetation transpiration, 7) cloud physics, and 8) vapor source.

Climatic Features of Cloud Water Distribution and Cycle over China

Analyses of cloud water path （CWP） data over China available from the International Satellite Cloud Climatology Project （ISCCP） are performed for the period 1984-2004. Combined with GPCP precipitation data, cloud water cycle index （CWCI） is also calculated. The climatic distributions of CWP are found to be dependent on large-scale circulation, topographical features, water vapor transport and similar distribution features which are found in CWCI except in the Sichuan Basin. Influenced by the Asia monsoon, CWP over China exhibits very large seasonal variations in different regions. The seasonal cycles of CWCI in different regions are consistent and the largest CWCI occurs in July. The long-term trends of CWP and CWCI are investigated, too. Increasing trends of CWP are found during the period with the largest increase found in winter. The decreasing trends of CWCI dominate most regions of China. The differences in long-term trends between CWP and CWCI suggest that CWP only can influence the variation of CWCI to a certain extent and that other factors need to be involved in cloud water cycle researches. This phenomenon reveals the complexity of the hydrological cycle related to cloud water.

Evolutionary trend of water cycle in Beichuan River Basin of China under the influence of vegetation restoration

The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India.It also aims to define depth to granitoid and structural elements which traverse the selected area.Magnetic data(n=84)measured,processed and interpreted as qualitative and quantitatively.The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies.The magnetic values ranged from-137 nT to 2345 nT with a mean of 465 nT.Reduction to equator shows significant shifting of causative bodies in the southern and northern directions.Analytical signal map shows exact boundary of granitic bodies.Cosine directional filter has brought out structural element trending NE-SW direction.Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines.Sudden decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence.Magnetic breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore well.Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,respectively.Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from<10 m to>90 m.Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.

Water quantity-quality combined evaluation method for rivers＇ water requirements of the instream environment in dualistic water cycle： A case study of Liaohe River Basin

In this article the meaning of the quantity and quality of environmental flows of river in dualistic water cycle is discussed, and compared with the meaning of unitary water cycle. Based on the analysis of the relationship between environmental flows of river requirements, the efficiency of water resource usage, the consumption coefficient, and the concentration of waste water elimination, the water quantity and water quality calculation method of the environmental flows of river requirements in dualistic water cycle is developed, and the criteria for environmental flows of river requirements are established, and therefore the water quantity-quality combined evaluation of natural river flows requirements are realized Taking the Liaohe River as a model, the environmental flows of river requirements for Xiliao River, Dongliao River, mainstream Liaohe River, Huntai River and northeast rivers along the coasts of the Yellow and Bohai seas in unitary water cycle are calculated, each taking up 39.3%, 63.0%, 43.9%, 43.3% and 43.5% of runoff respectively. Evaluated according to Tennant recommended flow, the results show that： except Xiliao River is ＂median＂, the rest are all upon ＂good＂, the Dongliao River is even ＂very good＂. The corresponding results in dualistic water cycle are that, the proportion of natural flows for each river is 57.5%, 74.1%, 60.8%, 60.3% and 60.4%; while the combined evaluation results show that： considering ＂quantity＂, except Xiliao River, the rest rivers can all achieve the ＂quantity＂ criteria of the en- vironmental flows of river requirements, but if considering the aspect of ＂quality＂, only Dongliao River can reach the ＂quality＂ standard. By water quantity-quality combined evaluation method, only Dongliao River can achieve the criteria. So the water quality is the main factor that determines whether the environmental flows can meet the river ecosystem demands.

Research on Ecological Water Cycle and Purification in Rural Landscape——Take Zhangjia Village Ecological Wastewater Treatment Project in Henan Province as an Example

Rural landscape is not only a natural landscape,but also a cultural landscape.The improvement of rural environment in Lushi County is carried out under the background of“Building Beautiful Villages”.Through the plan of environmental improvement,the appearance of villages in rural areas will be significantly improved,and the gap between urban and rural areas will be shortened.This research addresses the problems of scarce water resources,imperfect rainwater collection facilities,and increased environmental pollution in rural areas,and explores a flexible,effective,and integrated landscape ecological water treatment system that integrates with natural ecosystems.The practice has shown that the flexible combination of different technical measures according to local conditions and the construction of ecological water self-circulation and self-purification systems can reduce maintenance costs and achieve sustainable landscape.The virtuous cycle of the revetment’s micro-ecology greatly improves the environmental carrying capacity of the landscape.Reasonable water management system is more flexible in dealing with unexpected problems.The thesis proposes landscape design strategies for water circulation and water purification in rural areas,and applies them to actual design cases.It attempts to introduce a combined treatment system to achieve a more diverse landscape concept and further explore the healthy and sustainable development of rural water environment.

Incorporation of a Dynamic Root Distribution into CLM4.5： Evaluation of Carbon and Water Fluxes over the Amazon

Roots are responsible for the uptake of water and nutrients by plants and have the plasticity to dynamically respond to different environmental conditions. However, most land surface models currently prescribe rooting profiles as a function only of vegetation type, with no consideration of the surroundings. In this study, a dynamic rooting scheme, which describes root growth as a compromise between water and nitrogen availability, was incorporated into CLM4.5 with carbon-nitrogen （CN） interactions （CLM4.5-CN） to investigate the effects of a dynamic root distribution on eco-hydrological modeling. Two paired numerical simulations were conducted for the Tapajos National Forest km83 （BRSa3） site and the Amazon, one using CLM4.5-CN without the dynamic rooting scheme and the other including the proposed scheme. Simulations for the BRSa3 site showed that inclusion of the dynamic rooting scheme increased the amplitudes and peak values of diurnal gross primary production （GPP） and latent heat flux （LE） for the dry season, and improved the carbon （C） and water cycle modeling by reducing the RMSE of GPP by 0.4 g C m^-2 d^-1, net ecosystem exchange by 1.96 g C m^-2 d^-1, LE by 5.0 W m^-2, and soil moisture by 0.03 m^3 m^-3, at the seasonal scale, compared with eddy flux measurements, while having little impact during the wet season. For the Amazon, regional analysis also revealed that vegetation responses （including GPP and LE） to seasonal drought and the severe drought of 2005 were better captured with the dynamic rooting scheme incorporated.

Xin'anjiang Nested Experimental Watershed(XAJ-NEW)for Understanding Multiscale Water Cycle:Scientific Objectives and Experimental Design

This paper presents the background,scientific objectives,experimental design,and preliminary achievements of the Xin’anjiang nested experimental watershed(XAJ-NEW),implemented in 2017 in eastern China,which has a subtropical humid monsoon climate and a total area of 2674 km2.The scientific objectives of the XAJ-NEW include building a comprehensive,multiscale,and nested hydrometeorological monitoring and experimental program,strengthening the observation of the water cycle,discovering the spatiotemporal scaling effects of hydrological processes,and revealing the mechanisms controlling runoff generation and partitioning in a typical humid,hilly area.After two years of operation,preliminary results indicated scale-dependent variability in key hydrometeorological processes and variables such as precipitation,runoff,groundwater,and soil moisture.The effects of canopy interception and runoff partitioning between the surface and subsurface were also identified.Continuous operation of this program can further reveal the mechanisms controlling runoff generation and partitioning,discover the spatiotemporal scaling effects of hydrological processes,and understand the impacts of climate change on hydrological processes.These findings provide new insights into understanding multi scale hydrological processes and their responses to meteorological forcings,improving model parameterization schemes,and enhancing weather and climate forecast skills.

Impacts of human activities on water cycles in Haihe Basin

This paper studies effects of human activities on water cycle in Haihe basin, focusing on the effects on the key elements of water balance and environmental issues caused by unreasonable water development and utilization. The water cycle system becomes closer than in nature with the river runoff decrease and evapotranspiration increase. River runoff reduction, groundwater over-exploitation, and water pollution have caused a series of environmental problems in the area. The main issues are river dried up, sedimentation and salt accumulation, groundwater depression, land subsidence, sea water intrusion, as well as water pollution. The author believes that the highest level of water development should below 50 percent as a whole. The best way to meet increasing water demands of human activities is to raise efficiency of water resources use. Meanwhile waste water discharge should be reduced through treatment and recycle technology.

Latent dimensions between water use and socio-economic development: A global exploratory statistical analysis

Water use and socio-economic development are interconnected in complex ways.Causalities are not easy to identify but it is evident that a nexus between water use and socio-economic development does exist.Considering the diversity of national situations relating to these interrelated phenomena,its study should be considered from a global perspective.This article critically reviews the literature and information from official sources on the relevance of water use and circular economy in order to create a global picture,linking water with socio-economic development.Data from 195 countries were analyzed statistically.A factor analysis defined five essential latent dimensions on the nexus between water use and socio-economic development:development and basic services,population and resources,economic volume,health and well-being,and population density.Based on the identified factors,countries were classified into six groups:Global South in difficulty,global semi-periphery,advanced economy,Middle East and other Global South developing economy,global weight,and small highly developed economy.The clustering results clarify connections between water use conditions and socioeconomic development.Understanding the variety of national profiles is helpful to reveal the magnitude and urgency of dealing with the nexus between water use and socio-economic development for many countries.

Water cycle investigations in Hungarian forest ecosystems

From the biological point of view the value of autotrophy plant association is determined by the carbon fixation and the carbon cycle. Among the plant associations of Hungary, forest has the largest biological carbon fixation and carbon cycle. In general, the annual water cycle is the key factor in the organic material production of the Hungarian forests. The most intensive water con- sumption and organic material production take place from May till July, which period is named main water consumption and respec- tively main growing period, In Hungary the categories of the forest climate are characterized by main tree species and based on the characteristic meteorological data （Jaro and Tatraaljai, 1985）. In Hungary the forest area covered by stand is 1,650,000 hm2. Beech forest climate covers 8% of the forest area, hornbeam-oak forest climate covers 22%, sessile oak-Turkey oak forest climate covers 48% and forest steppe climate covers 22%. Partly in the frame of ICP-Forests, the Department of Ecology in the Forest Research Institute carries out long term, complex ecophysiological investigations on several sample plots （so-called basic plots） throughout the whole country. The organic material production （growth）, the nutrient and water cycle, the measurements of air pollutants and mete- orological parameters, as well as chemical analyses are all part of the investigations. As a comparison the figure of two basic plots （Sopron Pasp0kladfiny） shows the water cycles of a good growing beech stand in beech climate and a wcak pedunculate oak stand in forest steppe climate in the hydrological year of 2001-2002. In the Hungarian forest 60% 70% of the precipitation is used for inter- ception, evaporation, and in the vegetation season, for the transpiration both in beech and forest steppe climate. From other point of view, only 30%-40% of the open air precipitation infiltrates into the soil and can be utilized by the forest.

Strong direct and indirect influences of climate change on water yield confirmed by the Budyko framework

Research findings concerning the main processes influencing water resources differ substantially,and so the topic remains controversial.Recent studies indicate that the changes in water yield,expressed through the n-parameter of Budyko framework,are associated with vegetation coverage changes.Here,we use runoffmeasurements and outputs from 13 dynamic global vegetation models,to investigate the underlying drivers of the n-parameter changes.Unlike previous studies,we instead find that climate change is the primary driver of adjustments on water resources.Changing climatic characteristics,particularly the intensity and seasonality of rainfall,modulates the runoffgeneration process.Indirect effects of climate change occur through altering vegetation properties,which in turn also impact river flow.We also find that in the arid and sparse vegetation regions,water yield is more sensitive to changes in n-parameter.Thus,the Budyko framework provides a reliable parameter-sparse representation of runoffchanges,and reveals that terrestrial water cycle is changing substantially under climate change.This climate forcing requires on-going investigation to generate more refined and reliable projections of future water availability.

Preventing the Deluge: Climate Change, the Four Spheres, Interactions, and Causalities

Climate change means water change, and the impacts of climate change cause not only global sea levels to rise, but also elicit dangerous levels of coastal and mainland flooding. This study relates the effects of climate-change-induced sea level risings to several harmful, and sometimes preventable, factors causing floods. One topic discussed here will be the ocean’s current (more specifically, “The Atlantic Meridional Overturning Current”) as it continues to warm with increasing temperatures. In addition to discussing the effects of the AMOC, it also relates the increasing causes that are contributing to flooding, plus the proliferation of melt from ice sheets, ice caps, and glaciers, which inevitably contributes to the devastating effects of flooding on coastal communities, destroying habitats and contributing to the extinction of both aquatic and land animals, and even impacting human infrastructure and livelihoods. This examination additionally presents the serious implications that climate change and flooding have had on the planet’s freshwater resources and reserves, which are being further destroyed by the added influx of salt water, causing water to then be treated with aquifers, an energy-intensive and highly expensive process. Lastly, this paper provides several suggested possibilities for curbing some of the harmful effects humans have already had on contributing to climate change, as well as the environmental factors that have further caused dangerous levels of flooding.