A framework for karst ecohydrology   总被引：7，自引：0，他引：7  

Ognjen Bonacci  Tanja Pipan  David C. Culver 《Environmental Geology》2009,56(5):891-900

Ecohydrology can be defined as the science of integrating hydrological and biological processes over varied spatial and temporal scales. There exists in karst a strong and direct interaction between the circulation and storage of groundwater and surface water. These fluxes in turn affect the spatial distribution of organisms in these habitats. Because of the fact that the appearance, storage and circulation of water in karstified areas is significantly different from other more homogenous and isotropic terrains, karst ecohydrology should develop original methods and approaches. At the same time, traditional approaches are also very useful. Large karst underground geomorphological patterns occur in many sizes and varieties, ranging from a few meters long or deep to very large, the deepest being deeper than 1 km and longer than hundreds of kilometres. In this article, special attention is paid to ecohydrological functions of karst underground features (caves, pits, conduits, etc.), which play a crucial dual role in (1) hydrology and hydrogeology of water circulation and storage and (2) ecology of many rare and endangered species. Differences in morphology, hydrology, hydrogeology and climate have resulted in a range of different environments, which provide the opportunity for the coexistence of different species. The role of the epikarst and vadose zones, as well as caves in ecohydrological processes, is discussed. The importance of the flood factor in karst ecology is analysed. The aim of this article is to move forward the discussion among different disciplines to promote and develop a conceptual framework for karst ecohydrology.  相似文献   

Comparison of tree transpiration under wet and dry canopy conditions in a Costa Rican premontane tropical forest          下载免费PDF全文

Luiza Maria Teophilo Aparecido  Gretchen R. Miller  Anthony T. Cahill  Georgianne W. Moore 《水文研究》2016,30(26):5000-5011

Spatial and temporal variation in wet canopy conditions following precipitation events can influence processes such as transpiration and photosynthesis, which can be further enhanced as upper canopy leaves dry more rapidly than the understory following each event. As part of a larger study aimed at improving land surface modelling of evapotranspiration processes in wet tropical forests, we compared transpiration among trees with exposed and shaded crowns under both wet and dry canopy conditions in central Costa Rica, which has an average 4200 mm annual rainfall. Transpiration was estimated for 5 months using 43 sap flux sensors in eight dominant, ten midstory and eight suppressed trees in a mature forest stand surrounding a 40‐m tower equipped with micrometeorological sensors. Dominant trees were 13% of the plot's trees and contributed around 76% to total transpiration at this site, whereas midstory and suppressed trees contributed 18 and 5%, respectively. After accounting for vapour pressure deficit and solar radiation, leaf wetness was a significant driver of sap flux, reducing it by as much as 28%. Under dry conditions, sap flux rates (J_s) of dominant trees were similar to midstory trees and were almost double that of suppressed trees. On wet days, all trees had similarly low J_s. As expected, semi‐dry conditions (dry upper canopy) led to higher J_s in dominant trees than midstory, which had wetter leaves, but semi‐dry conditions only reduced total stand transpiration slightly and did not change the relative proportion of transpiration from dominant and midstory. Therefore, models that better capture forest stand wet–dry canopy dynamics and individual tree water use strategies are needed to improve accuracy of predictions of water recycling over tropical forests. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A review of the ecohydrology discipline: Progress,challenges, and future directions in China     

XIA Jun  ZHANG Yongyong  MU Xingmin  ZUO Qiting  ZHOU Yujian  ZHAO Guangju 《地理学报(英文版)》2021,31(8):1085-1101

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 pro-posed according to international scientific frontiers and national ecological civilization con-struction 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,par-ticularly with the social sciences.Furthermore,the future research interests in China include:combining multi-source information,constructing comprehensive monitoring systems,study-ing spatiotemporal patterns of key ecohydrological variables and their variation characteris-tics,developing integrated models of ecological,hydrological,and economic processes,es-timating 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 eco-systems,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.  相似文献   

Insights into plant water uptake from xylem‐water isotope measurements in two tropical catchments with contrasting moisture conditions          下载免费PDF全文

Jaivime Evaristo  Jeffrey J. McDonnell  Martha A. Scholl  L. Adrian Bruijnzeel  Kwok P. Chun 《水文研究》2016,30(18):3210-3227

Water transpired by trees has long been assumed to be sourced from the same subsurface water stocks that contribute to groundwater recharge and streamflow. However, recent investigations using dual water stable isotopes have shown an apparent ecohydrological separation between tree‐transpired water and stream water. Here we present evidence for such ecohydrological separation in two tropical environments in Puerto Rico where precipitation seasonality is relatively low and where precipitation is positively correlated with primary productivity. We determined the stable isotope signature of xylem water of 30 mahogany (Swietenia spp.) trees sampled during two periods with contrasting moisture status. Our results suggest that the separation between transpiration water and groundwater recharge/streamflow water might be related less to the temporal phasing of hydrologic inputs and primary productivity, and more to the fundamental processes that drive evaporative isotopic enrichment of residual soil water within the soil matrix. The lack of an evaporative signature of both groundwater and streams in the study area suggests that these water balance components have a water source that is transported quickly to deeper subsurface storage compared to waters that trees use. A Bayesian mixing model used to partition source water proportions of xylem water showed that groundwater contribution was greater for valley‐bottom, riparian trees than for ridge‐top trees. Groundwater contribution was also greater at the xeric site than at the mesic–hydric site. These model results (1) underline the utility of a simple linear mixing model, implemented in a Bayesian inference framework, in quantifying source water contributions at sites with contrasting physiographic characteristics, and (2) highlight the informed judgement that should be made in interpreting mixing model results, of import particularly in surveying groundwater use patterns by vegetation from regional to global scales. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Water use strategies of two co‐occurring tree species in a semi‐arid karst environment          下载免费PDF全文

Brooke A. Swaffer  Kate L. Holland  Tanya M. Doody  Chris Li  John Hutson 《水文研究》2014,28(4):2003-2017

The flow of precipitation from the surface through to groundwater in karst systems is a complex process involving storage in the unsaturated zone and diffuse and preferential recharge pathways. The processes associated with this behaviour are not well understood, despite the prevalence of karst aquifers being used as freshwater supplies. As a result, uncertainty regarding the ecohydrological processes in this geological setting remains large. In response to the need to better understand the impact of woody vegetation on groundwater recharge, annual evapotranspiration (ET) rates and tree water sources were measured for two years above a shallow, fresh karst aquifer. Water use strategies of the co‐occurring Eucalyptus diversifolia subsp. diversifolia Bonpl. and Allocasuarina verticillata (Lam.) L. Johnson were investigated using a monthly water balance approach, in conjunction with measurement of the stable isotopes of water, leaf water potentials and soil matric potentials. The results suggest that it is unlikely groundwater resources are required to sustain tree transpiration, despite its shallow proximity to the soil surface, and that similarities exist between ET losses and the estimated long‐term average rainfall for this area. Irrespective of stand and morphological differences, E. diversifolia and A. verticillata ET rates showed remarkable convergence, demonstrating the ability of these co‐occurring species to maximise their use of the available precipitation, which avoids the requirement to differentiate between these species when estimating ET at a landscape scale. We conclude that the water holding capacity of porous geological substrates, such as those associated with karst systems, will play an important role in equilibrating annual rainfall variability and should be considered when assessing ecohydrological links associated with karst systems. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Modelling climate‐change impacts on stream temperature of Formosan landlocked salmon habitat     

Ching‐Pin Tung  Tsung‐Yu Lee  Yi‐Chen Yang 《水文研究》2006,20(7):1629-1649

A physics‐based model is provided for predicting the impact of climate change on stream temperature and, in turn, on Formosan landlocked salmon (Oncorhynchus masou formosanus) habitat. Because upstream watersheds on Taiwan Island are surrounded with high and steep mountains, the influence of mountain shading on solar radiation and longwave radiation is taken into account by using a digital elevation model. Projections using CGCM2 and HADCM3 models and CCCM and GISS models provided information on future climatic conditions. The results indicate that annual average stream temperatures may rise by 0·5 °C (HADCM3 short term) to 2·9 °C (CGCM2 long term) due to climate change. The simulation results also indicate that the average suitable habitat for the Formosan landlocked salmon may decline by 333 m (HADCM3 short term) to 1633 m (CGCM2 long term) and 166 m (HADCM3 short term) to 1833 m (CGCM2 long term) depending on which thermal criterion (17 °C and 18 °C respectively) is applied. The results of this study draw attention to the tasks of Formosan landlocked salmon conservation agencies, not only with regard to restoration plans of the local environment, but also to the mitigation strategies to global climate change that are necessary and require further research. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Isotope hydrology and water sources in a heavily urbanized stream     

Christian Marx  Dörthe Tetzlaff  Reinhard Hinkelmann  Chris Soulsby 《水文研究》2021,35(10):e14377

Complex networks of both natural and engineered flow paths control the hydrology of streams in major cities through spatio-temporal variations in connection and disconnection of diverse water sources. We used spatially extensive and temporally intensive sampling of water stable isotopes to disentangle the hydrological sources of the heavily urbanized Panke catchment (~220 km²) in the north of Berlin, Germany. The isotopic data enabled us to partition stream water sources across the catchment using a Bayesian mixing analysis. The upper part of the catchment streamflow is dominated by groundwater (~75%) from gravel aquifers. In dry summer periods, streamflow becomes intermittent in the upper catchment, possibly as a result of local groundwater abstractions. Storm drainage dominates the responses to precipitation events. Although such events can dramatically change the isotopic composition of the upper stream network, storm drainage only accounts for 10%–15% of annual streamflow. Moving downstream, subtle changes in sources and isotope signatures occur as catchment characteristics vary and the stream is affected by different tributaries. However, effluents from a wastewater treatment plant (WWTP), serving 700,000 people, dominate stream flow in the lower catchment (~90% of annual runoff) where urbanization effects are more dramatic. The associated increase in sealed surfaces downstream also reduces the relative contribution of groundwater to streamflow. The volume and isotopic composition of storm runoff is again dominated by urban drainage, though in the lower catchment, still only about 10% of annual runoff comes from storm drains. The study shows the potential of stable water isotopes as inexpensive tracers in urban catchments that can provide a more integrated understanding of the complex hydrology of major cities. This offers an important evidence base for guiding the plans to develop and re-develop urban catchments to protect, restore, and enhance their ecological and amenity value.  相似文献   

Developing environmental standards for abstractions from UK rivers to implement the EU Water Framework Directive / Développement de standards environnementaux sur les prélèvements d'eau en rivière au Royaume Uni pour la mise en œuvre de la directive cadre sur l'eau de l'Union Européenne     

《水文科学杂志》2013,58(6):1105-1120

Abstract

Under the European Union Water Framework Directive, Member States must put in place a river basin planning framework to determine what measures are necessary to maintain and improve the ecological status for all surface water bodies. The governmental organisations legally responsible for implementing the Directive in the UK have recognised that an appropriate river flow regime is fundamental to maintain a healthy river and, as a result, they need to regulate abstractions and effluent discharges and ensure sufficient water is released from impoundments. This paper reports on the process of producing environmental standards that define the maximum abstraction allowable from UK rivers, to leave sufficient flow to maintain a healthy river ecosystem. As there are currently insufficient data available to determine the relationships between river flow and ecological status empirically, expert knowledge was captured through a series of workshops at which leading UK freshwater scientists defined maximum levels of river flow regime alteration that would achieve ecological objectives for different river water body types. For the least ecologically sensitive rivers, maximum abstractions in the range 15–35% of the natural flow were proposed, depending on the flow magnitude and time of year. For the most sensitive rivers, the maximum abstraction proposed was in the range 7.5–25%. The knowledge was used by the responsible UK authorities to develop environmental standards. The authorities subsequently used the environmental standards to determine regulatory standards that could be implemented within practical constraints and current licensing policies.  相似文献