Is self-regulation a myth? Case study on Spanish groundwater user associations and the role of higher-level authorities   总被引：2，自引：0，他引：2  

E. Lopez-Gunn  Luis Martinez Cortina 《Hydrogeology Journal》2006,14(3):361-379

Self-regulation of groundwater users offers tremendous potential for effective groundwater management. The attributes of higher-level authorities that are more likely to facilitate the beneficial management of groundwater in economic, social and environmental terms are discussed. For this purpose, eight groundwater user associations in Spain have been compared. Factors that support institutional change were analyzed, namely: salience, common understanding, trust and reciprocity, autonomy, prior organizational experience and local leadership. These factors are complemented by features that strengthen actions by higher-level authorities that oversee self-regulation by water users (clear boundaries, legitimate recognition of appropriators, facilitating roles, trust in cross-scale linkages, clear division of responsibilities, institutional culture and co-management model choices). Self-regulation includes the creation of reflexive organizations that are capable of learning, provided first, the administration itself is modernized to meet the challenges of self-regulation, and second, that ‘regulatory capture’ is avoided by external organizations, ensuring that the regulator and the regulated are not so close in their relationship as to be detrimental to effectiveness.

E. Lopez-GunnEmail:

  相似文献   

Scales of heterogeneity of water quality in rivers: Insights from high resolution maps based on integrated geospatial, sensor and ROV technologies     

Andrew F. Casper  Barnali DixonEric T. Steimle  Mike L. HallRobyn N. Conmy 《Applied geography (Sevenoaks, England)》2012,32(2):455-464

While the spatial heterogeneity of many aquatic ecosystems is acknowledged, rivers are often mistakenly described as homogenous and well-mixed. The collection and visualization of attributes like water quality is key to our perception and management of these ecosystems. The assumption of homogeneity can lead to the conclusion that data collection from discrete, discontinuous points in space or time provide a comprehensive estimate of condition. To counter this perception, we combined high-density data collection with spatial interpolation techniques to created two-dimensional maps of water quality. Maps of four riverine transitions and habitats - wetland to urban, river to reservoir, river to estuary and a groundwater intrusion - were constructed from the continuous data. The examples provided show that the most basic water quality parameters - temperature, conductivity, salinity, turbidity, and chlorophyll florescence - are heterogeneous at spatial scales smaller than those captured by common point sampling statistical strategies. The 2-dimensional, interpolation-based maps of the Hillsborough River (Tampa, FL) show significant influences of a variety of geographic features including tributary confluences, submarine groundwater inflow, and riparian interfaces. We conclude that many sampling strategies do not account for the type of patchy heterogeneity observed. The integration of existing in-situ sensors, inexpensive autonomous sampling platforms, and geospatial mapping techniques provides high resolution visualization that can adds a more comprehensive geographic perspective needed for environmental monitoring and assessment programs.  相似文献   

三江源区径流演变及其对气候变化的响应(英文)   总被引：2，自引：2，他引：0  

张永勇  张士锋  翟晓燕  夏军 《地理学报(英文版)》2012,22(5):781-794

Runoff at the three time scales(non-flooding season,flooding season and annual period) was simulated and tested from 1958 to 2005 at Tangnaihai(Yellow River Source Region:YeSR),Zhimenda(Yangtze River Source Region:YaSR) and Changdu(Lancang River Source Region:LcSR) by hydrological modeling,trend detection and comparative analysis.Also,future runoff variations from 2010 to 2039 at the three outlets were analyzed in A1B and B1 scenarios of CSIRO and NCAR climate model and the impact of climate change was tested.The results showed that the annual and non-flooding season runoff decreased significantly in YeSR,which decreased the water discharge to the midstream and downstream of the Yellow River,and intensified the water shortage in the Yellow River Basin,but the other two regions were not statistically significant in the last 48 years.Compared with the runoff in baseline(1990s),the runoff in YeSR would decrease in the following 30 years(2010-2039),especially in the non-flooding season.Thus the water shortage in the midstream and downstream of the Yellow River Basin would be serious continuously.The runoff in YaSR would increase,especially in the flooding season,thus the flood control situation would be severe.The runoff in LcSR would also be greater than the current runoff,and the annual and flooding season runoff would not change significantly,while the runoff variation in the non-flooding season is uncertain.It would increase significantly in the B1 scenario of CSIRO model but decrease significantly in B1 scenario of NCAR model.Furthermore,the most sensitive region to climate change is YaSR,followed by YeSR and LcSR.  相似文献   

丹江口水库向白洋淀补水生态调度方案研究   总被引：2，自引：0，他引：2  

张丽丽  殷峻暹  张双虎  蒋云钟 《湿地科学》2012,10(1):32-39

白洋淀是华北平原最大的淡水湖泊。近年来,入淀水量和降水量持续减少导致淀水位持续下降。尽管国家实施了多次的生态补水调度,但由于缺乏长效补水机制,白洋淀生态环境恶化趋势仍没有得到有效控制。南水北调中线一期工程的建设,使利用丹江口水库向白洋淀补充生态环境用水成为可能。本文通过研究丹江口水库不同运行调度方案,探讨了利用水文和气象预测、预报信息来指导水库生态调度的可行性。在分析生态预报调度方式内涵的基础上,结合丹江口水库相机补充白洋淀生态用水实例来说明该方法的实用性和可行性。研究表明,基于预报信息的生态优化调度方案,可使白洋淀多年平均补水量增加48%以上。  相似文献   

Investigation of water signatures at gully-exposed sites on Mars by hyperspectral image analysis     

Chaojun Fan  Dirk Schulze-Makuch 《Planetary and Space Science》2009,57(1):93-104

High-resolution images from the Mars Obiter Camera (MOC) onboard the Mars Global Surveyor (MGS) show a variety of gully features on sloped surfaces of Mars. The mechanism of gully formation is still under debate, although a majority of studies tend to favor a mechanism related to liquid water flow based on geomorphology and fluid mechanics considerations. In this study, we examined four known gully sites using Visible and Infrared Mineralogical Mapping Spectrometer (OMEGA) imagery. In particular, we analyzed the absorption depths of the water-associated absorption bands and concluded that there are stronger water signatures at the gully-exposed sites than in the surrounding areas. This implies that the water signatures, most likely representing water ice, isolated water molecules, and/or hydroxyl molecules incorporated into minerals, are still present in the shallow unconsolidated soils. This study provides additional evidence that water was likely involved in the formation of the gully features and is still locally active on the Martian surface in the present time.  相似文献   

Water and related chemistry in the solar system. A guaranteed time key programme for Herschel     

P. Hartogh  E. Lellouch  M. Banaszkiewicz  E.A. Bergin  N. Biver  M.I. Blecka  D. Bockelée-Morvan  J. Cernicharo  G. Davis  P. Encrenaz  A. González  T. de Graauw  D. Hutsemékers  E. Jehin  M. Kidger  A. de Lange  D.C. Lis  J. Manfroid  R. Moreno  G. Orton  M. Rengel  M. Sánchez-Portal  S. Sidher  B. Swinyard  N. Thomas  B. Vandenbussche  C. Waelkens 《Planetary and Space Science》2009,57(13):1596-1606

“Water and related chemistry in the Solar System” is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and the comets. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System species, will be measured for the first time in a Jupiter-family comet. A comparison with existing and new measurements of D/H in Oort-cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of proto-planetary ices, will be obtained. The D/H and other isotopic ratios, diagnostic of Mars’ atmosphere evolution, will be accurately measured in H₂O and CO. The role of water vapor in Mars’ atmospheric chemistry will be studied by monitoring vertical profiles of H₂O and HDO and by searching for several other species (and CO and H₂O isotopes). A detailed study of the source of water in the upper atmosphere of the Giant Planets and Titan will be performed. By monitoring the water abundance, vertical profile, and input fluxes in the various objects, and when possible with the help of mapping observations, we will discriminate between the possible sources of water in the outer planets (interplanetary dust particles, cometary impacts, and local sources). In addition to these inter-connected objectives, serendipitous searches will enhance our knowledge of the composition of planetary and cometary atmospheres.  相似文献   

A Flume Experiment on the Adjustment of the Mean and Turbulent Statistics to a Transition from Short to Tall Sparse Canopies     

Anthony Seraphin  Philippe Guyenne 《Boundary-Layer Meteorology》2008,129(1):47-64

Water-flume experiments are conducted to study the structure of turbulent flow within and above a sparse model canopy consisting of two rigid canopies of different heights. This difference in height specifies a two-dimensional step change from a rough to a rougher surface, as opposed to a smooth-to-rough transition. Despite the fact that the flow is in transition from a rough to a rougher surface, the thickness of the internal boundary layer scales as x ^4/5, consistent with smooth-to-rough boundary layer adjustment studies, where x is the downstream distance from the step change. However, the analogy with smooth-to-rough transitions no longer holds when the flow inside the canopy and near the canopy top is considered. Results show that the step change in surface roughness significantly increases turbulence intensities and shear stress. In particular, there is an adjustment of the mean horizontal velocity and shear stress as the flow passes over the rougher canopy, so that their vertical profiles adjust to give maximum values at the top of this canopy. We also observe that the magnitude and shape of the inflection in the mean horizontal velocity profile is significantly affected by the transition. The horizontal and vertical turbulence spectra compare well with Kolmogorov’s theory, although a small deviation at high frequencies is observed in the horizontal spectrum within the canopy. Here, for relatively low leaf area index, shear is found to be a more effective mechanism for momentum transfer through the canopy structure than vortex shedding.  相似文献   

Ecophysiology of atmospheric moisture in the Namib Desert     

Joh R. Henschel  Mary K. Seely   《Atmospheric Research》2008,87(3-4):362

Although the Namib Desert is classified as hyperarid, with rainfall extremely rare, there are several other sources of atmospheric moisture, namely, humidity, dew and fog, which make it possible for organisms to live there. Methods to use these sources include locating moist micro-climates, drinking from wet surfaces, consuming moist food, collecting water on the body, and absorbing water vapour. In describing these mechanisms from published sources, we highlight the work of Professor Gideon Louw, to whom we dedicate this paper. Louw's pioneering work on water relations and economy, which includes osmoregulation in desert plants and animals such as grass, beetles, and springbok, established a foundation that inspired numerous studies by colleagues and students. Ecophysiology provides many more lessons that have potential to be mimicked and applied in the occult collection of water in arid regions.  相似文献   

Ambient air dry deposition and ionic species analysis by using various deposition collectors in Shalu, central Taiwan   总被引：1，自引：0，他引：1  

Chia-Chun Chu  Guor-Cheng Fang  Jhy-Cherng Chen  I-Cherng Lin 《Atmospheric Research》2008,88(3-4):212-223

This study describes the chemical composition of dry deposition collected at a highway traffic site in central Taiwan during daytime and nighttime periods by using a dry deposition plate (DDP) and water surface sampler (WSS). In addition, the characterization for mass and water-soluble species of total suspended particulate (TSP), both PM_2.5 and PM₁₀, was studied at the study site from August 22 to November 30, 2006. Dry deposition fluxes of ambient air particulates and inorganic species (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻ and SO₄²⁻) were analyzed by Ion Chromatography (DIONEX-100).Results of the particulate dry deposition fluxes and mass concentrations are higher in the water surface sampler with respect to the dry deposition plate used in this study. Statistical results also showed the average dry deposition flux of the ionic species (Na⁺, NH₄⁺, K⁺, Cl⁻, NO₃⁻ and SO₄²⁻) obtained by the DDP and WSS displayed significant differences. Also, the average concentrations of Mg²⁺ and, Ca²⁺ were statistically the same at this study site.  相似文献   

Modelling the Baltic Sea ocean climate on centennial time scale: temperature and sea ice     

Daniel Hansson  Anders Omstedt 《Climate Dynamics》2008,30(7-8):763-778

This study considers the possible use of different kinds of forcing datasets in Baltic Sea ocean climate modelling on centennial time scales, in particular for the past half millennium. We demonstrate that high-quality station data of the past century and gridded multi-proxy reconstructions for the past 500 years can be used with great success but with various levels of detail. We also demonstrate that output data from the state-of-the-art global climate model EcHo-G are not suitable for modelling the Baltic Sea ocean climate. Two climate properties were studied: the annual maximum ice extent (MIB) and the vertically and horizontally integrated annual water temperature. Centennial time scale results indicate that the seventeenth and nineteenth centuries were the coldest centuries, while the 1690s were the coldest decade and 1695 the coldest year in the last 500 years. The results also indicate that the twentieth century was the warmest century with the least MIB of the last 500 years. On a decadal time scale, the 1990s, 1930s and 1730s were the warmest decades and comparable in terms of both water temperature and MIB. The year 1989 had the minimum observed MIB of only 52,000 km², implying that the Baltic Sea has been partly ice covered in all winters of the past half millennium. Even though different climate forcing mechanisms may operate on the climate system today compared to over the last half millennium, this study cannot clearly state that the region is experiencing climate change outside the natural limits of the past 500 years.  相似文献