Redistribution Of Water Resources Research Articles

Complex Hydrological Regimes, and Processes, In the Negev Arid Area, Israel

Spatial relationships, or connectivity, represent a basic concern in our understanding of geomorphic processes, and their effects on the degree of connectivity along hillslopes, at the interface hillslopes-channels, and along streams, will affect the spatial redistribution of water resources, sediment movement, sediment deposition and consequently the operation of biological fluxes. High values of connectivity are indicative of an efficient system; while a low connectivity would encourage infiltration losses, sediment deposition, and spatial redistribution of water resources. Many factors may affect the degree of connectivity, and the importance of a given factor may vary in a wide range of local conditions. Climatologist use aridity indices to express the relationships between climatic and environmental variables. This approach leads to the idea that average annual rainfall, up to 300 mm, controls water availability for plants, soil properties, runoff generation and soil erosion [1, 2, 3, 4]. This approach may be valid for soil covered areas, and annual crops, very sensitive to rainfall. Its validity is questionable in drier areas where most of the surface is rocky, and the limited soil patches are saline.

Temporal variation of groundwater hydrochemistry and water stable isotopes under long-term mining disturbance in a coal mine, northwest China

Groundwater plays a key role in water supplies in arid/semi-arid regions. Long-term coal mining can change the groundwater flow systems and chemistry, and may consequently lead to re-distribution of water resources and pose the threat to safety of mining. Therefore, identifying the hydrological changes over time due to long-term mining is of great significance for preventing and controlling such negative effects. In this study, the temporal changes of groundwater hydrochemistry influenced by coal mining were systematically evaluated in the Ningtiaota coal mine, based on the hydrochemical, isotopic and groundwater level data from 2012 to 2019. The results show that the content of the major ions (e.g., Ca2+, Mg2+) of groundwater in overburden aquifers (Zhiluo formation (J2z) and Yanan formation (J2y)) in the southwest area decreased to the lowest in June 2018 during the whole study period. The hydrochemical type evolved from HCO3–Ca·Mg type in 2012 to HCO3–Na type in June 2018, then it changed to HCO3–Ca·Mg type again after that. Meanwhile, the water stable isotopes (δ2H, δ18O) in J2z and J2y groundwater show obviously consistent depletion in June 2018 (e.g., boreholes J17 and SK16). The changes of hydrochemical and stable isotopic characteristics in J2z and J2y groundwater in June 2018 were probably caused by the increasing recharge from overlying water bodies (includes Quaternary groundwater and surface water). The development of Water Flowing Fractured Zone provides favorable condition for overlying water infiltration into J2z and J2y aquifers due to long-term mining of underlying coal seam. Furthermore, the heavier rainfall enhanced recharge from overlying water to J2z and J2y groundwater, which could dilute the original hydrochemical composition and lead to isotopic depletion. This study revealed the temporal variation of groundwater hydrochemical and isotopic components and their indication to groundwater recharge under the influence of long-term mining, which could have a signification for the sustainable management of water resources and the safety of mining in coal mine areas.

Spatiotemporal Variation of Snow Cover and Its Response to Climate Change in the Source Region of the Yangtze River, China

In the context of global warming, snow cover changes have an extremely important impact on the hydrological cycle and the redistribution of water resources in arid and semi-arid regions. In this paper, based on the daily cloud-free snow area remote sensing product data in the source region of Yangtze River (SRYR) from 2000 to 2019, the snow phenology variables such as the snow cover day (SCD), snow onset date (SOD), snow end date (SED), and snow duration day (SDD) were extracted separately for each hydrological year, and the vertical distribution of snow cover area (SCA) in the SRYR was analyzed by combining with the digital elevation model (DEM). In addition, we also combined climate factors and land cover types to further explore the spatiotemporal variation characteristics of snow phenology in response to different influencing factors, in order to reveal the spatiotemporal variation patterns of snow cover in the SRYR. The results showed that: (1) The SCA in the SRYR has a more obvious vertical distribution, with the maximum SCA reaching 61.58% at high elevation, while at low elevation, the SCA is mostly below 20%. The distribution of SCD in the study area showed a significant exponential correlation with DEM (R2 = 0.87). (2) The area of SOD in the SRYR showed an advanced trend of about 63.37%, while the area of SED showed a delayed trend of about 69.59%, and the area which showed significant trends is 4.29% and 4.36%, respectively. Therefore, the trends of both SOD and SED showed insignificant changes. (3) Temperature change is the main factor affecting the change of snow cover in the SRYR. Among them, 90.9% of the regions showed a significant positive correlation between temperature and SCD, while precipitation showed a significant negative correlation with SCD in about 75.3% of the total area of SRYR. Under the stable snow area (SCD > 60), the land cover type is glacial or permanent snow about 1.5 × 103 km2, which covers almost the entire glacial or permanent snow of the SRYR.

Spatial and temporal variation and driving factors of wetland in the Amu Darya River Delta, Central Asia

The Aral Sea in Central Asia has shrunk by 90% since 1960. The resulting desertification and salt and dust storms have diminished biodiversity in the Amu Darya River Delta, triggering the Aral Sea Crisis. Timely monitoring of trends and spatial patterns in deltaic wetlands is beneficial for biodiversity conservation and ecological restoration. Existing studies have mainly focused on the response of vegetation and microbial communities to ecological changes while ignoring the indicative role of wetlands-associated changes. This study analyzed the spatial and temporal patterns of long time series wetland changes extracted from remote sensing imagery through cover frequency maps and landscape indices. The hydrological data, land use/land cover change maps, and statistical data were combined to explore the driving factors of wetland change over the past 40 years. The results showed that the wetland area increased by 2242.96 km2 (90.72%) from 1977 to 2019. The wetland area increased at 268.01 km2/a from the 1970s to the early 1990s, with a fluctuating change since 1994. Wetlands are mainly distributed in the transition zone between the delta and the Aral Sea, accounting for approximately 81.61% of the total wetland area. The proportion of wetlands on the east and west sides significantly expanded along the canal system, increasing from 0.13% in 1977 to 9.74% in 2019. The degree of fragmentation of the wetland landscape in the entire delta increased by 1.7 times. With decreasing runoff into the delta, the expansion of cultivated land and the construction of reservoirs and irrigation canals changed the spatio-temporal distribution of water resources. In contrast, agricultural irrigation has raised the groundwater level. Human activities, such as the expansion of cultivated land and the construction of reservoirs and irrigation canals, are the main reasons for the spatio-temporal changes in wetland distribution, and exacerbated the decrease in water flow into the Aral Sea and its shrinkage. The restoration of wetlands is not a proof of ecological improvement, it resulted from the redistribution of water resources in the delta. The increase in wetland area represents an apparent ecological contrast with the drying up of the Aral Sea, and the phenomenon is not conducive to the ecological restoration of the delta.

Evaluating grain virtual water flow in China: Patterns and drivers from a socio-hydrology perspective

To ensure regional grain security, the grain is transferred from grain surplus provinces to grain deficient provinces in China, then water embedded in grain (virtual water) flows accordingly, which promotes the spatial redistribution of water resources. To explore the influencing factors of virtual water flow, this study first obtained the inter-provincial virtual water flow pattern, and then constructed a virtual water flow trade gravity model based on socio-hydrology theory and estimated the model with multiple regression methods. And the impulse response function was used to analyze the response trajectory of virtual water flow under the shock of other endogenous variable fluctuation. The results show that from 1997 to 2014, the quantity of inter-provincial grain virtual water flow increased from 73 billion m3to 124.64 billion m3. The positive driving effect of the population and per capita GDP in virtual water inflow areas is significant, and the negative suppression effect of the grain output per unit in inflow-areas and the population in outflow-areas is significant. Heilongjiang is the province with the largest outflow of virtual water, and the outflow is more sensitive to the shock of local per capita water resources fluctuation. Guangdong is the province with the largest inflow, and the inflow is more sensitive to the local per capita GDP fluctuation. Chinese Mainland’s grain virtual water flow pattern and trend will continue to exist in the future. In addition to the endowment of water resources, social and economic factors also need to be considered during the process of water resources management.

Ensuring the purity of water resources in the Don River basin

Uncontrolled levels of persistent organic pollutants (POPs), which are prohibited for use under the POPs Convention, are the environmental concerns and, when applied on a large scale, will disrupt entire ecosystems. The identification of their impact on the purity of water resources is relevant and affects the planning of water supply for the population and the economy, the justification of water management measures and the redistribution of water resources within the basin. The aim of the research was to identify the content of hazardous pesticides in the surface waters of water bodies of the river basin Don. The data on the concentrations of α-, γ-hexochlorocyclohexane (HCCH), dichlorodiphenyl trichloroethane (DDT), dichlorodiphenyl dichloroethane (DDE), trifluralin, parathion methyl, karbofos, and fosalon were analyzed in surface waters and bottom sediments. It is noted that organochlorine pesticides (OCPs) are found in most places (up to ’100%) and in the number of samples in the bottom sediments of the surface waters of the Don River. It is significant that in the water of water bodies of the Don basin, including in the Don River, the detection frequency of the most active γ-HCCH is detected more often than α-HCCH. In the context of the projected increase in fresh water consumption in the Don River Basin, measures are being discussed to protect water resources from pollution.

Landscapes of sandy areas along a rainfall gradient (90-450 mm, average annual rainfall) in the south-eastern Mediterranean area, Israel

Dryland areas are regarded as highly sensitive to climatic changes. A positive relationship between average annual rainfall, and environmental factors (water availability, species diversity, etc.), is often assumed for areas with an average annual rainfall of 100-300 mm. However, the global climatological models fail to address an important issue. The above assumption disregards the fact that a climate change in some dry-land areas is not limited to climatic factors. It is often accompanied by a pronounced variability in surface properties, such as the deposition of loess in a wet climatic phase, and of sand during a dry climatic phase. Needless to say, the spatial variability of the new surface properties may have variable effects on water resources and related environmental variables. In addition, the climatic models, based on average annual rainfall, disregard the rainfall characteristics at the rain-shower level, which greatly influence the degree to which rainwater will percolate, or will be transformed into runoff, thereby significantly affecting the spatial redistribution of water resources. In other words, a climate change in dryland areas would be expected to have differential hydrological effects in a sandy area, a rocky area, or in a loess covered area. Differential spatial hydrological effects would be also expected within each of the areas listed above. The present manuscript deals with the complex relationships between average annual rainfall, and environmental variables in sandy areas, at three research sites, along a rainfall gradient of 90-450 mm, in the south eastern Mediterranean area, Israel. Data obtained clearly show that average annual rainfall is not a good indicator of water resources, and ecosystem structure, in each of the sites; and the controlling factors vary from one site to another.

SPATIOTEMPORAL STRUCTURE OF THE AVERAGE ANNUAL RIVER RUNOFF IN BELARUS

Modern maps of the average long-term annual distribution of the modules and coefficients of variation of the river runoff in Belarus for the period 1953-2017 are constructed. The analysis of the developed maps allows concluding that there was some insignificant redistribution of water resources in the territory of Belarus. The obtained patterns of spatial runoff distribution correlate well with the general patterns of runoff formation in Eastern Europe. The updated runoff distribution data can be transformed into modern global hydrological maps.     &nbsp

Effective economic growth under conditions of regional water management dependence

Purpose. The purpose of the article is an identifying the impact of regional water management dependence on economic growth in the region.
 Methodology / approach. The subject of the study is theoretical and methodological basics of a new scientific paradigm for regulation the development of the regional socio-economic systems under the conditions of limited water resources. The study used traditional and special research methods, including: historical and logical – to analyze the evolution of regional socio-economic systems under conditions of limited water resources; abstractions and analogies – to reveal the essence of water-efficient regional socio-economic systems in the modern processes of regionalization and globalization; theoretical generalization, analysis and synthesis – to specify the categorical apparatus; statistical analysis to assess the level of needs of regional socio-economic systems in water resources and create an index of regional water management dependence; method of correlation analysis (biserial correlation, using a point biserial Pearson’s correlation coefficient).
 Results. The main idea of the paper is to study the issues of development of regional socio-economic systems under the conditions of limited water resources. Considering this, the paper is aimed at studying the impact of regional water management dependence on economic growth in the region. The tasks for development of regional socio-economic systems on the basis of water efficiency are defined, as well as the concept “water-efficient regional socio-economic system” is defined. The study presents a hypothesis about the need to change the paradigm of regulation of regional development on the basis of water use efficiency and regional water management dependence. In order to trade effectively with the main crops, it is necessary to determine whether there are sufficient water supplies in a given country and its regions. For this purpose, the authors proposes to use own indicator, such as the index of regional water management dependence. Thе characteristic of water management dependence is given, from regions where only up to half of the water supply of the territory is used, and to regions where more than 100 % of the water supply of the territory is used. The research has updated that the expansion of knowledge and understanding of the specifics of the water sector can solve significant problems. It is proved that the economic growth of the Ukrainian economy due to the agricultural sector has its limits and is limited by the water management dependence of the territories, ie the limitation of certain territories of the regions of Ukraine in terms of water resources. The next effective economic growth is possible only through the implementation of water-efficient technologies and intensification of water-efficient activities in the region.
 Originality / scientific novelty. The study for the first time defines the concept of water-efficient regional socio-economic system, so it is a socio-economic system that provides for the restoration of water resources in the region, reducing the water intensity of gross regional product (GRP) and approaching European norms and proposes the classification of regions according to the index of regional water management dependence on the basis of its threshold values. A scientific and methodological approach to assessing the level of needs of regional socio-economic systems in water resources has been improved, based on the application of the index of regional water management dependence, which is proposed to calculate the ratio of total fresh water use in the region to the volume of available river runoff in the region (parts of the water potential). The classification of regional socio-economic systems according to the level of water supply has been improved, which is based on the definition of threshold values of the index of regional water management dependence. The methodological bases for assessing the impact of the spatial economy on regional development under conditions of limited water resources have been improved, which differ in substantiating the dependence of the level of development of regions on the available water potential of the territory.
 Practical value / implications. The results of the study allow a more comprehensive approach to the study of the problem of using water resources in Ukraine in the context of their limitation. The results of the study showed that the economic complex in most regions is water-intensive and unbalanced, as well as does not provide restoration of water resources by environmental parameters and requires the implementation of infrastructure schemes for redistribution of water resources between regions for economic activity. The results are recommended for consideration by local governments and regional administration for the development and implementation of “Regional programs for the development of water management in the region” and for the development of “Strategies for regional development until 2025–2027”.

Optimization of main functions of river basin and redistribution of water resources in the Yellow River

Optimization of main functions of river basin and redistribution of water resources in the Yellow River

Spillover risk analysis of virtual water trade based on multi-regional input-output model -A case study

Massive amounts of water embodied in commodities are transferred via interregional trade which increase the water scarcity risk of exporting region. This study proposed an integrated evaluation framework for sectoral physical water use risks and virtual water flow risks in Northeast China. The initial water use risks for different sectors by provinces were first assessed based on sectoral physical water consumption. Then based on the multi-regional input-output (MRIO) model, a virtual water trade network was established, and simultaneously the virtual scarce water in sectoral export of intermediate goods and final goods were accounted to investigate the virtual water flow risks by sectors. Finally, interprovincial embodied scarce water transfers between Northeast China and the rest of China were mapped, and by grafting the concept of ‘spillover risk’ to the virtual water trade, we analyzed the spillover risk difference of virtual water trade between regions. The results showed that the sectors of Agriculture (Ag) and Other manufacturing (OM) presented the highest risk of water use while Nonmetal mining (NmM) belonged to the potential high-risk sectors of water use for Northeast China. The sectors exported more virtual scarce water in intermediate goods also exported more in the final goods; and the sector of Manufacture of food products and tobacco processing (FP) was the largest contributor to the large exporting virtual scarce water for Liaoning and Jilin while Ag in Heilongjiang province was the largest exporter. The cumulative spillover risk index from rest of China to Liaoning province through virtual water trade is the highest; and the main risk spilt provinces to Northeast China were Xinjiang, Jiangsu, Anhui and Hebei province. The proposed risk framework for water utilization and trade may help promote the redistribution of water resources and explore pathways for sustainable management of water resources.

Positive effect of a canal system and reservoir group on the spatial-temporal redistribution of water resources in a pinnate drainage pattern

The uneven spatial and temporal distribution of water resources in pinnate drainage patterns is a major problem worldwide. As scattered components of water conservancy projects, systems of canals and groups of reservoirs in a basin can redistribute water resources in time and space to solve problems. This redistribution effectively avoids the environmental impact inherent in centralized water conservancy projects. In this study, we focused on a network of 88 reservoirs and 675 km of canals in a basin with a pinnate drainage pattern. The discharge of the trunk stream in the basin was calculated in natural, present and forecasted conditions based on the hydrological frequency curve. Then, the hydrodynamics of the trunk stream were simulated by the HEC-RAS model. Furthermore, we analysed the temporal and spatial distribution of water resources in five zones in the basin by Morlet wavelet analysis to determine the balance between water supply and demand. The results demonstrated that the river catchment in the basin changed periodically over periods of 1 year, 8 years and 18 years, as affected by the reservoir groups. The canal system played a major role in water resource transport in the five zones in the basin. The joint action of the reservoir group and canal system reduced the gap between the supply and demand water balance from 27.11% to 0.89%. This study focused on the influence of decentralized water conservancy projects on the spatial and temporal distribution of water resources and provides ideas for solving the problem of water resource allocation in the studied basin.

IMPROVEMENT OF WATER ALLOCATION EFFICIENCY IN THE AMU-SURKHAN RIVERS BASIN


 
 
 In the article efficiency of water distribution in the territory of Amu-Surkon basin is analysed and based on the results, provided the recommendations. The study is conducted within the project QH-A-QH-2018-409 “Increase efficiency of water resources management in Surkhandarya region: improve interbasin re-distribution of the water resources of Surkhandarya and Sherabaddarya Rivers” funded by Uzbekistan government. The main problems of water management in the Surkhandarya region are: outdated irrigation systems requiring an urgent modernization; large dependence on pump irrigation; low energy efficiency of pumping stations due to use of the old high energy-consuming equipment; irrational distribution and large unproductive technical and operational water losses. Increase of sensitivity to climate change with forecasting of 50% water deficit by 2050 leads to drought and further desertification, including impact on food security. In the article some results are introduced related to improve water allocation by redistribution of water resources between the river basins in the region aimed to reduce of pumped water use for irrigation.
 
 

Climate Variability and Its Impacts on Water Resources in the State of Manipur

The water resources and the hydrologic cycle form an inseparable component of the changing climate. The alteration of the hydrologic cycle due to variation in the climatic component will result in the redistribution of water resources in the course of time. At the same time, the local micro-climate will be affected by the changes in the water regime which will certainly exacerbate climate change to a certain extent. With a growing population and erratic rainfall, the water resources in the state of Manipur are under tremendous pressure to meet the rising demand. Urbanization, large scale deforestation, untimely rainfall and lack of rain water harvesting practices have worsened the water scarcity in the state. Although the global climate change phenomenon cannot be prevented we could try adapting to the current climate variability. Promotion of water conservation and development of rational adaptation practices would go a long way in minimizing the adverse impacts of climate variability on water resources for a sustainable Manipur.

Regional water footprints and interregional virtual water transfers in China

China faces increasingly severe water stress from its limited, unevenly distributed water resources and rapid economic growth. Interregional trade of goods and services within China further leads to a redistribution of water resources through virtual water transfers. Such virtual transfers are subject to constant changes due to the temporal variabilities in driving factors such as production efficiency, consumption patterns and population. Here we use the most recent public data to measure the water footprints of 31 provincial-level regions in China and virtual water transfers among these regions in 2012. We find that virtual water transfer plays a significant role in regional water footprints and greatly changes the allocation of water resources towards regional consumptions. Already water-scarce north China regions benefit from virtual water transfer by outsourcing water-intensive products from other regions. However, the water-scarce Northwest China suffers from virtual water transfer by exporting water-intensive products. We suggest policy makers pay attention to demand-side measures to incentivize parties to improve water efficiency in their production and reduce the consumption of water-intensive goods. Policymaking should consider economic policy and water conservation policy together to alleviate regional water stress through virtual water transfers.

Building capacity for co-operative governance as a basis for integrated water resource managing in the Inkomati and Mvoti catchments, South Africa

South Africa's National Water Act and National Water Resource Strategy set out an ambitious vision for Integrated Water Resources Management including a strong focus on the redistribution of water resources towards the poor and on empowering historically disadvantaged communities. To achieve this vision the Department of Water Affairs & Forestry (DWAF) has been pursuing a programme for devolving powers to 19 stakeholder-led catchment management agencies (CMAs) and more locally, transforming irrigation boards into more inclusive water user associations (WUAs), as well as creating new associations. Co-operative governance is a core principle of this programme. As well as being enshrined in South Africa's constitution, this principle is seen as key to enabling CMAs to implement their core functions, which include co-ordinating the activities of water users and water management institutions within their water management area. For WUAs also, the principle of co-operative governance is key to building engagement between White commercial farmers and emerging Black farmers, as well as (in some cases) engaging with a wider set of stakeholder interests including local government and environmental interests. Despite a commitment to the principle of co-operative governance, individual and institutional capacity for facilitating co-operative development processes is in relatively short supply within the South African water sector. This paper describes work-in-progress to build capacity in this area, working with: •� DWAF'snationalInstitutionalGovernanceteam •� TheInkomatiCMA�(ICMA),�thefirstofSouthAfrica'snewcatchmentmanagementagencies •� Two��irrigationboardsandanumberofotherstakeholdersintheMvoticatchment�-�withaviewtothedevelopmentofan� appropriate institutional arrangement (WUA or otherwise) for the co-operative governance of this catchment. This paper focuses on the development of an interactive approach to capacity building in each of these three sites, drawing from a broad portfolio of approaches variously described as social learning, social appraisal, or whole system development. In the Inkomati we have worked primarily with the whole system approach known as Future Search, whereas in the Mvoti we have used the U-process and social appraisal as guiding metaphors and design principles. � Thispaperdescribessomeofourachievements,�challengesandreflectionstodate,�andarguesthattheinteractive� approaches we have been taking are better suited to the implementation of DWAF's institutional reform processes than the more established, top-down approaches, which involve issuing guidance, supported by training programmes. The paper con- cludes with a discussion of the implications for scaling up these types of approaches across the South African water system as a whole, and for the practice of integrated water resource management.

Understanding the role of regional water connectivity in mitigating climate change impacts on surface water supply stress in the United States

Surface water supply for a watershed relies on local water generated from precipitation and water connections with other watersheds. These connections are confined by topography and infrastructure, and respond diversely to stressors such as climate change, population growth, increasing energy and water demands. This study presents an integrative simulation and evaluation framework that incorporates the natural and anthropogenic water connections (i.e., stream flows, inter-basin water transfers, water withdrawals and return flows) among the 2099 8-digit Hydrologic Unit Code (HUC-8) watersheds across the conterminous United States. The framework is then applied to investigate the potential impacts of changes in climate and water use on regional water availability and water stress (the ratio of demand to supply). Our projections suggest that highly water-stressed areas may expand from 14% to 18% and the stressed population would increase from 19% to 24% by 2070–2099. Climate-change mitigation practices (e.g., energy structure reform, technology innovation) could largely offset these trends by reducing demand and enhancing supply. At the watershed scale, the spatially inhomogeneous responses to future changes suggest that regional water connectivity could significantly buffer the potential stress escalations due to the redistribution of water resources and diverse changes in consumptive uses and water supplies in different source areas. However, the detrimental future changes (e.g., depleting river discharges, larger demands of water withdrawal) may aggravate conflicts over water rights among regions and challenge our current water infrastructure system. This study provides new insights into the critical role of regional water connectivity in water supply security, and highlights the increasing need for integrated monitoring and management of water resources at various spatial levels in a changing world.

The hydrological role of biological topsoil crusts and water repellency in sandy dry-land areas

Dryland areas are regarded as highly sensitive to climatic changes. A positive relationship between rainfall and environmental factors is often assumed for areas with an average annual rainfall of 100–300 mm. This assumption disregards the fact that a climate change in arid areas is not limited to climatic factors. It is often accompanied by a pronounced spatial variability in surface characteristics. The present work deals with the complex relationships among average annual rainfall, surface properties and the spatial redistribution of water resources in sandy areas located in the Northern Negev Desert. Two case studies are considered. The first deals with the hydrological effects of biological topsoil crusts on the water regime, along a rainfall gradient (86–170 mm). This study is based on five monitoring sites. Data obtained show a decrease in water availability with increasing annual rainfall. The findings are attributed to the decisive role played by the non-uniform properties of the topsoil crust along the rainfall gradient. The second case refers to the non-uniform development, and survival, of planted trees. Trees planted on steep dunes are well developed, with a high survival rate, whereas trees planted on low angle dunes are small. This study focused on the role of a water repellent layer on the water regime. Data obtained show a striking difference between steep and low dunes in all aspects studied, namely the degree of water repellency, frequency and magnitude of runoff events, infiltration depth and soil moisture. All variables monitored were found higher on steep than on low dunes. The large trees shed a substantial amount of leaves, whose decay developed a water repellent layer. Runoff generation over the repellent layer enhanced deep water penetration, through the process of subsurface flow. The lack of a water repellent layer over the low dunes prevented runoff generation, with its positive effects.

Spatiotemporal variations of aridity in China during 1961–2015: decomposition and attribution

Changes in global climate intensify the hydrological cycle, directly influence precipitation, evaporation, runoff, and cause the re-distribution of water resources in time and space. The aridity index (AI), defined as the ratio of annual precipitation to annual potential evapotranspiration, is a widely used numerical indicator to quantify the degree of dryness at a given location. This study examined the effects of climate change on AI in China during 1961–2015. The results showed that the nationally averaged AI experienced a notable interdecadal transition in 1993, characterized by increasing AI (wetter) between 1961 and 1993, and decreasing AI (drier) after 1993. Overall, the decreased solar radiation (solar dimming) was the main factor affected the nationally averaged AI during 1961–1993, while the relative humidity dominated the variations of nationally averaged AI during 1993–2015. However, the roles of individual factors on the changes in AI vary in different subregions. Precipitation is one of the important contributing factors for the changes of AI in almost all subregions, except the Mid-Lower Yangtze and Huaihe basins. Solar radiation has been significantly decreased during 1961–1993 in South China, Southwest China, Mid-Lower Yangtze and Huaihe basins, and the Tibetan Plateau. Therefore, it dominated the trends of AI in these subregions. The relative humidity mainly affected the Mid-Lower Yangtze and Huaihe basins, Southwest China, and the Tibetan Plateau during 1993–2015, hence dominated the trends of AI in these subregions. The changes of temperature and wind speed, however, played a relatively weak role in the variations of AI.

Virtual land, water, and carbon flow in the inter-province trade of staple crops in China

In the context of a growing world population and limited resources, trade plays an indispensable role in maintaining a constant food supply, and when commodities exchange occurs, it connects entire ecosystems and societies. In this study we used Chinese inter-province trade in staple crops to investigate the interaction of resource consumption and carbon emission systems. The trade in staple crops was simulated using an optimization model, we found that in the trade pattern the virtual land resources flowed from land-rich to land-poor provinces, but the situation was reversed for the redistribution of water resources. The trade pattern showed that total land resource use increased but water resource use decreased throughout compared with local production of traded commodities, based on the production efficiency of export and import provinces. The total carbon dioxide emissions from staple crops production in the inter-provincial trade was 254 × 108 kg carbon dioxide equivalents (CEs), and the average unit CE emissions was higher for export provinces than importing provinces. We combined the net staple crops trade, resource abundance, and unit CE emissions within provinces to define eight classes describing resource and environment management in specific areas, and to guide improvements in crop production and trade.