Carrying Capacity and Coupling Coordination of Water and Land Resources Systems in Arid and Semi-arid Areas: A Case Study of Yulin City, China

Quantitatively assessing the carrying capacity of water and land resources systems in arid and semi-arid areas is crucial for achieving the 2030 Sustainable Development Goals.In this work,taking Yulin City in China as a case study and employing the Criteria Importance Through Intercriteria Correlation(CRITIC)method,a modified model of coupling degree was developed to evaluate the car-rying capacity of water and land resources systems endowment and utilization,as well as their coupling coordination degree from 2013 to 2020.Our findings indicate that the water and land resources of Yulin are diminishing due to declines in agriculture,higher industrial water use,and wetland shrinkage.However,reallocating domestic water for ecological sustainability and reducing sloping farmland can mitigate this trend of decline.Temporally,as the coupling coordination between water and land resources system endowment in Yulin continuously improved,the coupling coordination between water and land resources system utilization first decreased and then in-creased with 2016 as the turning point.Spatially,the carrying capacity of water and land resources systems,the coupling coordination degree between water and land resources system endowment,and the coupling coordination degree between water and land resources system utilization in Yulin exhibited the same pattern of being higher in the six northern counties than in the six southern counties.Improving the water resources endowment is vital for the highly efficient use of water and land resources.

Relationships Between River Water Quality and Landscape Factors in Haihe River Basin, China: Implications for Environmental Management

River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.

Degradation problems of the land/water ecotones in China and their ecological impact to water systems

Degradation of land/water ecotones in China is a serious problem and it is often neglected by people. The types of ecotone degradation are described and analyzed. The degradation of land/water ecotones enhanced the water quality reduction, bank erosion, desasters such as landslide, flood and drought, biodiversity reduction, lost of fertilized lands, decrease of the resource value of water scenic beauty and many others. The paper analyzes how these problems are related with each other.

Transdisciplinary research for supporting the integration of ecosystem services into land and water management in the Tarim River Basin,Xinjiang,China

There is a growing need for both science and practice domains to collaboratively and systematically seek knowledge-based strategies for sustainable development. In recent years, transdisciplinary research has emerged as a new approach that enables joint problem solving among scientists and stakeholders in various fields. In this paper, we aim to introduce transdisciplinary research for supporting the integration of the concept of eco- system services into land and water management in the Tarim River Basin, Xinjiang, Northwest China. While a large number of ecosystem service studies have helped to raise the awareness for the value of nature in China, a number of challenges remain, including an improved understanding of the relationships between ecosystem structure, functions and services, and the interaction of the various ecosystem services. A meaningful valuation of ecosystem services also requires the consideration of their strong spatial heterogeneity. In addition, ways to introduce the con- cept of ecosystem services into decision-making in China need to be explored. Thus, successful integration of the concept of ecosystem services into actual land and water management requires a broad knowledge base that only a number of scientific disciplines and stakeholders can provide jointly, via a transdisciplinary research process. We regard transdisciplinary research as a recursive process to support adaptive management that includes joint knowledge generation and integration among scientists and stakeholders. System, target, and transformation knowledge are generated and integrated during the process of （1） problem （re）definition, （2） problem analysis and strategy development, and （3） evaluation of the impact of the derived strategy. Methods to support transdisciplinary research comprise participatory modelling （actor-based modelling and Bayesian Networks modelling） and partici- patory scenario development. Actor-based modelling is a semi-quantitative method that is based on the analysis of problem perspectives of individual stakeholders as depicted in perception graphs. With Bayesian Networks, com- plex problem fields are modelled probabilistically in a simplified manner, using both quantitative data and qualitative expert judgments. These participatory methods serve to integrate diverse scientific and stakeholder knowledge and to support the generation of actually implementable management strategies for sustainable development. For the purpose of integrating ecosystem services in land and water management in the Tarim River Basin through trans- disciplinary research, collaboration among scientists and institutional stakeholders from different sectors including water, agriculture, forestry, and nature conservation is required. The challenge is to adapt methods of transdisci- plinary research to socio-cultural conditions in China, particularly regarding ways of communication and deci- sion-making.

The supporting capability of Water and land resources for sustainable increase of yield in North China Plain

The potential of yield increase in the North China Plain is about 30 billion kg by ameliorating the low yield and medium low yield farmlands and 4 billion kg by reclaiming unused land. Water shortage will be the main limitation to the further increase of grain crop yield. The amount of water shortage is 8 200 million m3 at present, and will be 17 720 million m3 in 2 000. Yield increase can not be realized by using more water in the future. Other factors such as decrease of the area of cultivated land and the grain crop growing area, deterioration of environment and destruction of resources will also affect the development of grain production. Some suggestions have been proposed in the paper for attaining sustainable increase of yield in the plain.

Study on the Balance of Agricultural Water and Land Resources on Ningxia Plain

The article puts forward the process and means of regional water and land balance research, and then from two scenarios which are the balances under natural regulation and human intervention, calculated and analysed the balance between water and land on Ningxia Plain. For the balance under natural regulation named farmland water balance, using farmland water resource balance equation, the research estimated the monthly farmland water balance of 8 major crops for all of the 12 counties on Ningxia Plain in the period of 1960-2001; for the balance under human intervention, the research estimated land-use water balance equation of the counties in 2000, and calculated the balance between land use and water resources including irrigating water of all the 12 counties on Ningxia Plain. Results showed that①precipitation can not meet the water demand of the crops for growth and development on Ningxia Plain, and water shortage is the primary character of farmland water balance under natural regulation,②the diversity of water and land balance of different counties is distinctly influenced by the crop structure, water quantity for irrigation and irrigation level.③Irrigation water could meet the crop water demand on Ningxia Plain in 2000, but there was not much space to expand irrigating cultivated land.

Roles of Science and Technology in Soil and Water Conservation in the New Era

Firstly,current situation and main problems of science and technology development of soil and water conservation were analyzed,and then roles of science and technology in soil and water conservation were studied. At last,exploration ways of roles of science and technology in soil and water conservation were proposed.

Spatial Distribution of Water Quality Indexes and Their Response to Land Use Patterns in the Gaotan River Basin

The relationship between water quality and land use is of significance for the protection of the water environment. Here we take the Gaotan River Basin in Liangping District as the research object, and comprehensively use the spatial analysis with geographical information system(GIS), Pearson correlation analysis, and redundancy analysis(RDA) to study the ecological response of four water quality indexes of chemical oxygen demand(COD), biochemical oxygen demand in the 5 th day(BOD5), ammonia nitrogen(NH3-N), and total phosphorus(TP) on land use patterns on a sub-basin scale. The results show that land use patterns of the Gaotan River Basin have an important impact on water quality: wooded land can improve the water environment of the river; dry land, land for urban and rural housing and public facilities, and land for mining and industrial use are the main sources of COD, BOD5, and NH3-N; garden plot, land for building communications, and water areas have a weak impact on pollutants, indicating that agricultural non-point source pollution and domestics pollution in rural areas are the major cause of the deterioration of the water quality of the Gaotan River. The research results are of guiding significance to the treatment of water environment of the Gaotan River Basin.

Assessment of Geological Security and Integrated Assessment Geo-environmental Suitability in Worst-hit Areas in Wenchuan Quake

The Wenchuan earthquake in 2008 and geo-hazards triggered by the earthquake caused large injuries and deaths as well as destructive damage for infrastructures like construction, traffic and electricity. It is urgent to select relatively secure areas for townships and cities constructed in high mountainous regions with high magnitude earthquakes. This paper presents the basic thoughts, evaluation indices and evaluation methods of geological security evaluation, water and land resources security demonstration and integrated assessments of geo-environmental suitability for reconstruction in alp and ravine with high magnitude earthquakes, which are applied in the worst-hit areas （12 counties）. The integrated assessment shows that： （1） located in the Longmenshan fault zone, the evaluated area is of poor regional crust stability, in which the unstable and second unstable areas account for 79% of the total; （2） the geo-hazards susceptibility is high in the evaluation area. The spots of geo-hazards triggered by earthquake are mainly distributed along the active fault zone with higher distribution in the moderate and high mountains area, in which the areas of high and moderate susceptibility zoning accounts for 40.1% of the total; （3） geological security is poor in the evaluated area, in which the area of the unsuitable construction occupies 73.1%, whereas in the suitable construction area, the areas of geological security, second security and insecurity zoning account for 8.3 %, 9.3% and 9.3 % of the evaluated area respectively; （4） geo-environmentai suitability is poor in the evaluated area, in which the areas of suitability and basic suitability zoning account for 3.5% and 7.3% of the whole evaluation area.

Analysis of ecological effects of comprehensive treatment in the Tarim River Basin using remote sensing data

Based on multi-type,multi-temporal remote sensing data,we have monitored recent changes in cultivated land use and vegetation,in sandy areas and salinized desertification in the Green Corridor zone of the main channel of the Tarim River Basin.The results of our investigation show that the ecological environment in the Green Corridor of the main channel of the Tarim River Basin has conspicuously improved from 2002 to 2004.These improvements show up largely in such aspects as an increase in the rate of vegetation cover,a reduction in desertification land areas and a weakening in the intensity of sandy and the salinized land.On the other hand,the cultivated area in the Tarim River Basin significantly increased from 2002 to 2004.The rate of growth in cultivated areas during this period was significantly higher than that from 1999 to 2002.The increase in the use of irrigation resulting from the substantial increase in cultivated areas has a long-term potential restraining effect on the restoration of ecological functions of the Tarim River.

THE FEATURE AND EVALUATION OF ECOTONE IN CHINA

Based on explicating the definition of ecotone, this paper discussed emphatically the distribution and features of joint zone between land and water, transition zone between mountains and plains, and intersection zone between agricultural and animal husbandry regions. The geographic environment of the three ecotones were evaluated, their developing tendency predicted and the corresponding measures to be taken in the 21st century pointed out.

Effectiveness of empirical orthogonal function used in decorrelation of GRACE time-variable gravity field

Empirical orthogonal function （EOF） was used to process the spherical harmonic coefficient （SHC） of 115 Gravity Recovery and Climate Experiment （GRACE） RL05 monthly gravity field models from March 2003 to February 2013 released by CSR （Center for Space Research）. We analyzed the effectiveness of EOF in decorrelation of gravity field. Results show that only a small Gaussian smoothing radius was needed by EOF to significantly weaken the north -south stripes compared with the empirical moving-window filtering algorithm. The comparative experiments with a Global Land Data Assimilation System （GLDAS） hydrological model also show that EOF did not much affect the real geophysical signals, and that the removed signals were nearly uncorrelated with the real geophysical signals. As the Gravity Recovery and Climate Experiment （GRACE） missions continue, EOF can be used to significantly remove the correlated errors from monthly gravity fields and reserve rich effective signals.

Land subsidence monitoring by D-InSAR technique

Nowadays, the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) tech- nique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values, but the analysis of subsidence process and mechanism are insufficient. In order to resolve these problems, 6 scenes of ERS1/2 images captured during 1995 and 2000 in a certain place of Jiangsu province were selected to obtain the subsidence and velocities in three time segments by ''two-pass'' D- InSAR method. Then the relationships among distributions of pumping wells, exploitation quantity of groundwater, and confined water levels were studied and the subsidence mechanism was systematically analyzed. The results show that using D-InSAR technique to monitor the deformation of large area can obtain high accuracies, the disadvantages of classical observation methods can be remedied and there is a linear relationship among the velocities of land subsidence, the water level and the exploitation quantity.

Desertification Reversion in Relation to Land Use Change and Climate in Naiman County, Inner-Mongolia, China

Analyses of desertified land and land use change in Naiman County of Inner-Mongolia showed that there was a fluctuated in-crease of rain-fed cropland in the period from 1951 to 1960, then decreased until the middle of the 1990＇s, then increased again, while irrigated cropland consistently increased. The woodland and build-up land consistently increased while grassland area de-creased. The area of water body increased from 1975 to 1995 and then decreased while river beach decreased. Wetland change fluctuated with a maximum of 303.53km2 in 1995 and a minimum of 62.08 km2 in 2002. Invasion of cropland into river beach does not only change land coverage on the beach, but also the hydrological process of the river systems and deeply influence wa-ter availability. The correlation between cropland and underground water table is negative and significant. Increase of irrigated cropland is the primary cause of water availability reduction. Water table reduction is negatively correlated to cropland. The total desertified land has decreased since 1975. A rapid increase occurred before 1959, but it is difficult to assess the change of deserti-fication due to lack of data from 1959 to 1975. Changes of different types of desertified lands were different. There is no signifi-cant correlation between land use and different types of desertified land, but there is a significant negative correlation between woodland and total desertified land. The correlation between grassland and total desertified land is positive and significant. There is a significant correlation between different land cover and key factors such as water body and annual precipitation, river beach and runoff, area of shifting dune and annual precipitation, and cropland and underground water table. Desertification reversion in Naiman County is fragile and will be even much more fragile due to population growth, rapid land use and climate change. This will lead to continued invasion of irrigated cropland into more fragile ecosystems and reduction of water availability.

Evaluating land subsidence by field survey and D-In SAR technique in Damaneh City, Iran

Based on the data from piezometers, well logs, geophysical surveys and the interferometric synthetic aperture radar（In SAR） technique, this study investigates the main causes of land subsidence in Damaneh City, Iran. The size, openings and direction of fissures were measured by micrometer and compass. The locations of fissures and wall cracks were determined by GPS. The geoelectrical data were used to determine the composition, thickness, depth and shape of lower parts of the aquifer. Groundwater fluctuations were evaluated by available piezometers. The In SAR technique was used to measure land deformation from space and to map the dense changes of surface displacements. The results indicate that the main cause of ground subsidence is the decline of groundwater heads and changes in composition and thickness of compressible lacustrine sediments. The subsidence map obtained from the radar data of ASAR sensor of ENVISAT satellite shows that the subsidence zone is mainly in northern city that is underlain by very thick fine sediments. The subsidence rates from March to December 2005 and from July 2011 to January 2012 are 6.7 and 7.0 cm/a, respectively. The results also show good correlations among the formation of earth features, decline in groundwater head and thickness of fine-grained sediments. We recommend that the groundwater withdrawal for agricultural and industrial sectors should be restricted and urban expansion in the northern part of the city should be constrained.

High-resolution remote sensing mapping of global land water

Land water, one of the important components of land cover, is the indispensable and important basic information for climate change studies, ecological environment assessment, macro-control analysis, etc. This article describes the overall study on land water in the program of global land cover remote sensing mapping. Through collection and processing of Landsat TM/ETM+, China's HJ-1 satellite image, etc., the program achieves an effective overlay of global multi-spectral image of 30 m resolution for two base years, namely, 2000 and 2010, with the image rectification accuracy meeting the requirements of 1:200000 mapping and the error in registration of images for the two periods being controlled within 1 pixel. The indexes were designed and selected reasonably based on spectral features and geometric shapes of water on the scale of 30 m resolution, the water information was extracted in an elaborate way by combining a simple and easy operation through pixel-based classification method with a comprehensive utilization of various rules and knowledge through the object-oriented classification method, and finally the classification results were further optimized and improved by the human-computer interaction, thus realizing high-resolution remote sensing mapping of global water. The completed global land water data results, including Global Land 30-water 2000 and Global Land 30-water 2010, are the classification results featuring the highest resolution on a global scale, and the overall accuracy of self-assessment is 96%. These data are the important basic data for developing relevant studies, such as analyzing spatial distribution pattern of global land water, revealing regional difference, studying space-time fluctuation law, and diagnosing health of ecological environment.

Spatio-temporal analysis of urbanization and land and water resources efficiency of oasis cities in Tarim River Basin

This paper examines the spatial pattern of land and water resources as well as urbanization and their interactions in the Tarim River Basin, Xinjiang, China. In order to do so, we extract the data associated with efficiency of land and water resources and urbanization for the years of 1995, 2000, 2005 and 2008. Specifically the paper investigates the extent to which agglomeration of population and economic activities varies geographically and inter- plays with spatial pattern of resources efficiency through computation of Global Moran＇s I index, Getis-Ord Gi＊ index and a coordinated development model. The method used provides clear evidence that urbanization, land and water resources efficiency have shown uneven spatial pattern due to oasis distribution, climate, and initial phase of urban development. Some conclusions can be drawn as follows. （1） Agglomeration and dispersion of urbanization are not consistent with those of land and water resources efficiency. （2） Evolution of the hot and cold spots of urbanization, and land and water resources efficiency, in different trajecto- ries, indicate that there are no significant interactions between them. （3） The evidence that numbers of hot and cold spots of the three factors present varying structures reveals the dominance of unequal urban development in the study area. （4） Significant differences are also found between sub-river basins in terms of the three factors, which is a reflection of the complex physical geography of the area. （5） The degree of coordinated development of cities in the Tarim River Basin is generally low in part as a reflection of difference in spatial patterns of the three factors. It is also shown that the pattern of the degree of coordinated development is relatively stable compared with evolution of hot and cold spots of the three factors.

Preliminary analysis of spatiotemporal pattern of global land surface water

Land surface water(LSW) is one of the most important resources for human survival and development, and it is also a main component of global water recycling. A full understanding of the spatial distribution of land surface water and a continuous measuring of its dynamics can support to diagnose the global ecosystem and environment. Based on the Global Land 30-water 2000 and Global Land 30-water 2010 products, this research analyzed the spatial distribution pattern and temporal fluctuation of land surface water under scale-levels of global, latitude and longitude, continents, and climate zones. The Global Land 30-water products were corrected the temporal inconsistency of original remotely sensed data using MODIS time-series data, and then calculated the indices such as water area, water ration and coefficient of spatial variation for further analysis. Results show that total water area of land surface is about 3.68 million km2(2010), and occupies 2.73% of land area. The spatial distribution of land surface water is extremely uneven and is gathered mainly in mid- to high-latitude area of the Northern Hemisphere and tropic area. The comparison of water ratio between 2000 and 2010 indicates the overall fluctuation is small but spatially differentiated. The Global Land 30-water products and the statistics provided the fundamental information for analyzing the spatial distribution pattern and temporal fluctuation of land surface water and diagnosing the global ecosystem and environment.

Experimental Study of the Imbalance of Water Budget over the Loess Plateau of China

The imbalance of land-surface water budget was discovered in past studies, but there have been few further investigations on the relevant causes. To probe into the problem, annual variations of precipitation and land-surface evapotranspiration were analyzed by using the historical observation data from a compre- hensive land-surface observation base of LOPEX （Loess Plateau Experiment）. A remarkable imbalance in the land-surface water budget was found, and the total annual imbalance reached 20.6%. Then, the impact factors related to additional water budget components and observational methods were studied. The total annual imbalance could be reduced to 3.8% by using a combination of compensated land-surface water bud- get components and the surface evapotranspiration values obtained from the large-scale weighing lysimeter rather than from the eddy correlation method.