Archive

  • Select all
    |
    Special Issue: Ecohydrology
  • Special Issue: Ecohydrology
    XIA Jun, ZHANG Yongyong, MU Xingmin, ZUO Qiting, ZHOU Yujian, ZHAO Guangju
    Download PDF ( ) HTML ( )   Knowledge map   Save

    In recent decades, the ecohydrology discipline was developed to provide theoretical and technical foundations for the protection and restoration of complex ecological systems (e.g., mountains, rivers, forests, farmlands, and lakes), and to further ecological civilization construction and green development in China. In this study, the progress and challenges of the ecohydrology discipline are elaborated, and the future development directions are proposed according to international scientific frontiers and national ecological civilization construction demands. Overall, the main discipline directions are to develop new ecohydrological monitoring methods, to comprehensively understand ecohydrological mechanisms and their basic theories, to promote integration of multi-scale and multi-variable models by considering both terrestrial and aquatic ecosystems, and to encourage multidisciplinary integration, particularly with the social sciences. Furthermore, the future research interests in China include: combining multi-source information, constructing comprehensive monitoring systems, studying spatiotemporal patterns of key ecohydrological variables and their variation characteristics, developing integrated models of ecological, hydrological, and economic processes, estimating their uncertainty; and conducting interdisciplinary studies that include the natural and social sciences. The application prospects in China are further explored for a variety of ecosystems, including forests, grasslands, rivers, lakes, wetlands, farmlands, and cities. This study will provide a reference to support the development of the ecohydrology discipline in China, and will provide a solid theoretical and technical foundation for the implementation of national ecological civilization construction.

  • Special Issue: Ecohydrology
    ZHANG Yuhang, YE Aizhong, YOU Jinjun, JING Xiangyang
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Dual factors of climate and human on the hydrological process are reflected not only in changes in the spatiotemporal distribution of water resource amounts but also in the various characteristics of river flow regimes. Isolating and quantifying their contributions to these hydrological alterations helps us to comprehensively understand the response mechanism and patterns of hydrological process to the two kinds of factors. Here we develop a general framework using hydrological model and 33 indicators to describe hydrological process and quantify the impact from climate and human. And we select the Upper Minjiang River (UMR) as a case to explore its feasibility. The results indicate that our approach successfully recognizes the characteristics of river flow regimes in different scenarios and quantitatively separates the climate and human contributions to multi-dimensional hydrological alterations. Among these indicators, 26 of 33 indicators decrease over the past half-century (1961-2012) in the UMR, with change rates ranging from 1.3% to 33.2%, and the human impacts are the dominant factor affecting hydrological processes, with an average relative contribution rate of 58.6%. Climate change causes an increase in most indicators, with an average relative contribution rate of 41.4%. Specifically, changes in precipitation and reservoir operation may play a considerable role in inducing these alterations. The findings in this study help us better understand the response mechanism of hydrological process under changing environment and is conducive to climate change adaptation, water resource planning and ecological construction.

  • Special Issue: Ecohydrology
    GUO Mengyao, SHE Dunxian, ZHANG Liping, LI Lingcheng, YANG Zong-Liang, HONG Si
    Download PDF ( ) HTML ( )   Knowledge map   Save

    This study uses two forms of the Palmer Drought Severity Index (PDSI), namely the PDSI_TH (potential evapotranspiration estimated-by the Thornthwaite equation) and the PDSI_PM (potential evapotranspiration estimated by the FAO Penman-Monteith equation), to characterize the meteorological drought trends during 1960-2016 in the Loess Plateau (LP) and its four subregions. By designing a series of numerical experiments, we mainly investigated various climatic factors' contributions to the drought trends at annual, summer, and autumn time scales. Overall, the drying trend in the PDSI_TH is much larger than that in the PDSI_PM. The former is more sensitive to air temperature than precipitation, while the latter is the most sensitive to precipitation among all meteorological factors. Increasing temperature results in a decreasing trend (drying) in the PDSI_TH, which is further aggravated by decreasing precipitation, jointly leading to a relatively severe drying trend. For the PDSI_PM that considers more comprehensive climatic factors, the drying trend is partly counteracted by the declining wind speed and solar radiation. Therefore, the PDSI_PM ultimately shows a much smaller drying trend in the past decades.

  • Special Issue: Ecohydrology
    WANG Qin, WANG Shuwen, HU Qingfang, WANG Yintang, LIU Yong, LI Lingjie
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Climate change and human activity can cause remarkable hydrological variation. Traits of hydrological series such as runoff before and after the change points could be significantly different, so the calculation of instream ecological water requirements (EWRs) is confronted with more challenges. Taking the Xitiaoxi River (XTXR) in the upper reach of the Taihu Lake Basin as an example, this paper investigates the calculation of EWRs using the range of variability approach (RVA) under changing environment. The change point diagnosis of the natural and observed runoff series are conducted for XTXR. Then, differences in the hydrological alternation indicators and instream EWRs processes obtained from various daily runoff series are compared. It was found that the natural and observed annual runoff series in XTXR from 1957 to 2018 both show significant variations, and the change points are in 2007 and 1999 respectively. If runoff data before the change points or all runoff data are used, the instream EWRs obtained from natural runoff are significantly lower than those obtained from the observed runoff. At the monthly time step, EWRs differences within a year mainly occurred from May to August. Also, calculation results of the instream EWRs are strongly related to the selected period of runoff series. The EWRs obtained using runoff series after the change points have rather acute fluctuation within a year. Therefore, when the RVA method is used under changing environment, the instream EWRs should be prudently determined by comparing different calculation results on the basis of river runoff restoration and variability analysis. To a certain extent, this paper enriches our understanding about the hydrological method for EWRs estimation, and proposes new ideas for future research on EWRs.

  • Regular Articles
  • Regular Articles
    LI Yuheng, WU Wenhao, WANG Yongsheng
    Download PDF ( ) HTML ( )   Knowledge map   Save

    There is less than a decade left to accomplish the goal of ending global poverty by 2030. This paper investigates global poverty dynamics and finds a shift in the world's poverty gravity center from South Asia to Africa in the period 1990-2015. Sub-Saharan Africa has become the main battlefield for poverty reduction in the world. Global poverty reduction has been accompanied by political instability and local conflicts, economic marginalization, rural decline, and natural hazards as well as climate change which are jointly impacting the least developed areas and making the world's poverty reduction vulnerable to external shocks. The “STAR” scheme, including maintaining political stability, promoting targeted poverty alleviation, implementing regular assessments of poverty reduction initiatives, and revitalizing rural and poverty-stricken areas, is proposed with specific measures to enhance the resilience capacity of poverty alleviation in the world.

  • Regular Articles
    NIU Fangqu, JIANG Yanpeng
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Since the implementation of the economic reform and opening up policy in 1978, China has miraculously created long-term high-speed economic growth, but has also had to face the problem of excessive consumption of resources as well as an intensification of environmental pollution. As a result, China is now facing a slowdown in development. China must maintain a certain speed of development to realize its goal of being a powerful nation, and becoming a developed country by 2050. To this end, China is facing a transformation of its economic development. There is a need to agree on an expected economic growth rate, along with the corresponding development modes or means of regulation in the medium- and long-term periods. This study developed a systematic-dynamic model to simulate the coupling relationship between economic growth, development modes, and the environmental supply system, and explored the possible options for future economic growth as well as the resource use and environmental protection requirements (the main factors). The results showed that to achieve the development goal of becoming a developed country by 2050, while maintaining a good ecological environment, the suitable growth rate for China's economy is 3.8%-6.3%. Within this range, a growth rate of 3.8%-4.4% was found to be relatively safe, while a growth rate of 4.4%-6.3% required further technical progress. This study provides an early warning in regard to China's environmental and development status. The study was a response to the “Future Earth” framework document and, in terms of development speed, it developed a theoretical system for the determination of resource and environmental carrying capacity (RECC).

  • Regular Articles
    Ilan STAVI, Eli ZAADY, Alexander GUSAROV, Hezi YIZHAQ
    Download PDF ( ) HTML ( )   Knowledge map   Save

    A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev. The most impacted shrub species is the Noaea mucronata (Forssk.) Asch. and Schweinf. In a four-year study, we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces, suggesting that the dead shrub patches encompass improved micro-habitats. However, unexpectedly, the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces. At the same time, soil quality in the dead shrub patches was higher than that in the inter-patch spaces. Therefore, it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water, supporting increased herbaceous productivity. For explaining the discrepancy between herbaceous vegetation and soil-water, we formulated a conceptual framework, which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem. We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died. The dead shrub patches encompass a unique form of ecosystem engineering. The study high- lights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.

  • REN Yisheng, LU Lin, YU Hu, ZHU Daocai
    Download PDF ( ) HTML ( )   Knowledge map   Save

    China's policy on ecological compensation (eco-compensation) in watershed ecosystems is of economic, social and environmental significance for China's ecological governance and protection of natural areas. It involves balancing the interests of regional stakeholders, coordinating the development of regional environments and establishing effective cooperation models, making it a classic topic for geographical research. This study introduces the concept of institutional “stickiness” to the theory of politics of scale to analyze the features and mechanisms of the game behavior of government entities in the process of implementing watershed eco-compensation in the Xin'an River Basin. Our results show the following: government entities at various levels, including the central, provincial and municipal governments, experienced the three stages of game strategy of competition, cooperation and “coopetition”; building a government community of shared interests can promote watershed eco-compensation, and “appropriate intervention” by the central government is key to achieving inter-provincial watershed eco-compensation; there was clear institutional stickiness during the transition from a “vertical” model of watershed eco-compensation to a “vertical-horizontal” model, with government entities using policy innovations and social participation to limit and reduce stickiness so as to reshape the watershed eco-compensation system; scalar jumping is the core mechanism that promoted eco-compensation in the study basin, and government entities shaped the discourse on watershed eco-compensation by redistributing powers and capital and creating informal constraints, which promoted the transformation of eco-compensation from a “strong state-weak society” structural model, to a “strong state-strong society” model in the Xin'an River Basin. These results can provide theoretical support for the construction of inter-regional watershed eco-compensation mechanisms, provide a scientific basis for the rational evaluation and guidance of watershed eco-compensation practices, and promote the coordinated and sustainable socioeconomic development of watersheds.

  • Review Article
  • Review Article
    WANG Xue, LI Xiubin
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Understanding the manifestations and underlying drivers of agricultural land use change in China is of great importance for both domestic and global food security. However, little is known about the holistic pattern of agricultural land use change across China, especially from the perspective of intensity since the evidence has been gathered mainly through case studies at local levels. This study conducts a systemic review of agricultural land use change and its underlying drivers in China by aggregating 169 relevant case studies from 123 publications. The cases related to intensification and disintensification, which are the two types of agricultural land use change, are generally equal, accounting for 50% of the total number of cases. Intensification and disintensification can be further divided into the same three categories: expansion/contraction of agricultural land, changes in agricultural land use activities and changes in land management intensity. Demographic, economic, technological, and institutional drivers, together with location factors, are frequently noted as significant underlying drivers, while sociocultural drivers and farm(er) characteristics are less frequently recognized. Finally, three major land use change trajectories are summarized mainly concerning rising labor costs and the concomitant increase in off-farm employment, the ecological improvement policy, and advances in agricultural technology.