Assessing optical earth observation systems for mapping and monitoring temporary ponds in arid areas     

Valrie Soti  Annelise Tran  Jean-Stphane Bailly  Christian Puech  Danny Lo Seen  Agnes Bgu 《International Journal of Applied Earth Observation and Geoinformation》2009,11(5):344-351

Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands were tested on a study site in Northern Senegal. Three main results are presented, validated with field data and intended to highlight different spectral, spatial and temporal characteristics of the methods: (1) Among several water indices tested, two Middle Infrared-based indices (MNDWI—Modified Normalized Difference Water Index and NDWI₁—Normalized Difference Water Index) are found to be most efficient; (2) an objective method is given prescribing the necessary sensor spatial resolution in terms of minimal detected pond area; and (3) the potential of multi-temporal MODIS imagery for tracking the filling phases of small ponds is illustrated. These results should assist in epidemiological studies of vector-borne diseases that develop around these ponds, but also more generally for land and water management and preservation of threatened ecosystems in arid areas.  相似文献   

我国沙尘暴特征及其与干旱关系的研究进展   总被引：6，自引：1，他引：5  

李耀辉  张书余 《地球科学进展》2007,22(11):1169-1176

阐述了我国沙尘暴空间分布、时间演变的最新事实特征,综述了我国沙尘暴与干旱关系研究方面有代表性的新成果,在此基础上探讨了沙尘暴灾害的形成及其与干旱相互作用的物理机制。  相似文献   

Regional geologic environs and natural resources of Badia Sector, Jordan     

A. S. Al-Homoud  R. J. Allison  D. L. Higgitt  K. White  B. F. Sunna 《Environmental Geology》1998,36(1-2):18-26

 This paper summarizes the information on the geology and natural resources of the Jordan Badia Research and Development Programme. The research focused on the issue of the environment in arid lands as an aid to provide practical options for sustainable development. This paper presents results of field studies in the following areas related to the sustainable development of the Safawi area in the northern Jordan Badia; geomorphology, including landform, soil, lands, processes and hazards, geology and physical resources and surface water hydrology. Tertiary-Quaternary continental basalt flows and tuffs cover approximately 11 000 km², the majority of the Safawi area. In addition to extensive basalt lava flows, the programme area includes a variety of geological outcrops and potential sources of economic products that include the following: Tuff/Scoria, Zeolite/Olivine, Porcellanite, potential sources of aggregate/construction materials, ornamental stone, building stone, basalt for manufacturing of rock wool, and materials suitable for producing lightweight aggregate. The whole of the eastern Badia exhibits major fault systems, many of which were identified from Landsat TM images. The system of wadis which drains the Badia is extensive, with the general flow from the north to the south and south-west. A noticeable geomorphic surficial deposit occuring throughout much of the Badia is fine-grained, water-lain sediments that vary in size and character. The local designation for the fine sediment deposits is Qaa. An MSS scene for the area under consideration has been studied. Twelve major geomorphic subdivisions or zones can be identified. Individual land system units have been identified by traversing the programme area. Key sites have been visited based on Landsat TM image interpretation. To a large extent, key areas were subdivided after their initial identification on the Landsat scene and corroboration in the field. The surface drainage of the Badia region can be broadly divided into wadi systems, areas of distinct channelized flow, and Qaa, predominantly fine-grained sedimentary basins of low relief. Spatial variability in infiltration rates across the wadi-Qaa system were determined from field experiments. Infiltration rates were found to be medium-high in the wadi channels but decrease rapidly for the Qaa materials. Apparently runoff from wadi side slopes will be high, and water storage occurs along the wadi channels while ponding occurs in the Qaa areas. Received: 13 March 1997 · Accepted: 13 January 1998  相似文献   

Environmental isotopic study on the recharge and residence time of groundwater in the Heihe River Basin, northwestern China   总被引：9，自引：2，他引：7  

Zongyu Chen  Zhenlong Nie  Guanghui Zhang  Li Wan  Jianmei Shen 《Hydrogeology Journal》2006,14(8):1635-1651

The recharge and origin of groundwater and its residence time were studied using environmental isotopic measurements in samples from the Heihe River Basin, China. δ¹⁸O and δD values of both river water and groundwater were within the same ranges as those found in the alluvial fan zone, and lay slightly above the local meteoric water line (δD=6.87δ¹⁸O+3.54). This finding indicated that mountain rivers substantially and rapidly contribute to the water resources in the southern and northern sub-basins. δ¹⁸O and δD values of groundwater in the unconfined aquifers of these sub-basins were close to each other. There was evidence of enrichment of heavy isotopes in groundwater due to evaporation. The most pronounced increase in the δ¹⁸O value occurred in agricultural areas, reflecting the admixture of irrigation return flow. Tritium results in groundwater samples from the unconfined aquifers gave evidence for ongoing recharge, with mean residence times of: less than 36 years in the alluvial fan zone; about 12–16 years in agricultural areas; and about 26 years in the Ejina oasis. In contrast, groundwater in the confined aquifers had ¹⁴C ages between 0 and 10 ka BP.  相似文献   

Arbuscular mycorrhizal associations in Solanum centrale (bush tomato), a perennial sub-shrub from the arid zone of Australia     

A.L. Dennett  L.W. Burgess 《Journal of Arid Environments》2011,75(8):688-694

Arbuscular mycorrhizal (AM) fungi convey well documented benefits to plant growth in domesticated species. We investigated AM in Solanum centrale, a desert shrub of central Australia and traditional food for Indigenous Australians. AM were observed in roots of S. centrale from wild and cultivated stands of different ages and management regimes. Greenhouse seedlings grown in sterilised sand were provided with no or minor additions of phosphorus, with or without AM fungi. Inoculated seedlings not fertilised with phosphorus exhibited moderate AM formation. Added phosphorus resulted in an absence of AM. Inoculation did not significantly affect dry weight, root length and plant height of seedlings fertilised with phosphorus but significantly increased the size of unfertilised seedlings. Inoculation significantly increased root phosphorus content, decreased root to shoot ratio and decreased root biomass at all phosphorus additions, despite the absence of observable AM. Thus it appears AM fungi in the root zone influenced certain plant characteristics, regardless of phosphorus nutrition. Overall, S. centrale benefited from the presence of AM through increased phosphorus uptake, but only when the seedlings were growing in soil with extremely low available phosphorus. The response was immediate in our experimental system and is likely to be important in the wild.  相似文献   

Flow transmission along an arid zone anastomosing river,cooper creek,australia     

A. David Knighton  Gerald C. Nanson 《水文研究》1994,8(2):137-154

Cooper Creek is characterized by an exceptionally wide floodplain and a complex system of anastomosing channels which together can accommodate a large range of highly variable flows. In consequence flood frequency curves are unusually steep. With minimal tributary contribution over the two study lengths — Currareva-Nappa Merrie (> 400 km) and Nappa Merrie-Innamincka (32 km) — downstream output is largely controlled by upstream input, so that similar flow regimes and hydrograph forms can be maintained despite transmission losses and the variable activation of channels. Input-output relationships defined in terms of total flow volume and peak discharge suggest that, above a threshold flow of about 25% duration, transmission losses exceed 75% on average over the Currareva-Nappa Merrie length. The large difference in absorption between primary channels on the one hand and subsidiary channels and the floodplain surface on the other means that transmission losses vary non-linearly with stage. They are relatively low when flow is confined to the primary channels, but increase at higher stages as lesser channels and the floodplain are activated. Early levels do not recur until flows of < 0.5% duration are attained when output/input ratios increase rapidly with discharge. The influences of seasonality and background flow on output discharge are small relative to that of input discharge. Despite the long river distance, peak flows at Currareva and Nappa Merrie are well correlated. However, over the shorter Nappa Merrie-Innamincka length with its more confined system of channels, correlations are better and transmission losses less. They vary from 60% just above the threshold discharge to <10% at flows below 20% duration. Over this length outflow hydrographs can be effectively estimated by the three parameter Muskingum procedure, at least on an event by event basis, but further application must await additional records to understand fully how the parameters vary in an environment where streamflow is transmitted through a highly variable system of channels.  相似文献   

Distribution of Macroinvertebrate assemblages along a saline wetland in harsh environmental conditions from Central-West Argentina     

Erica E. Scheibler  Néstor F. Ciocco 《Limnologica》2011,41(1):37-47

The goal was to examine how macroinvertebrate taxonomic richness and density respond to spatial-temporal changes and to the influence of water physicochemical characteristics along the Bañado Carilauquen (BC). Benthic samplings were conducted seasonally and environmental parameters were recorded in five reaches of the BC. Cluster analysis was applied to compare taxonomic richness among sites. Community structure and spatial-temporal variation were explored using logarithmic regression. CCA was applied to explore the relationship between species and environmental variables. A total of 36 taxa were identified, predominantly insects. A growing gradient of conductivity and hardness was registered between headwaters (HD; relatively soft waters) and outlet (OL; very hard and saline waters). Total density of taxa showed significant differences among sampling sites and climate seasons. A decline in richness and density was observed from HD to OL. The spatial conductivity gradient is the major factor modulating macroinvertebrate distribution along this saline arid wetland. With the exception of the headwaters, hard, eutrophic, polysaprobic and contaminated waters such of those of the BC represent critical conditions for the development of macroinvertebrate assemblages.  相似文献   

干旱区典型绿洲热场分布规律研究——以渭干河-库车河三角洲绿洲为例     

张兆永  海米提·依米提 《辽宁气象》2011,(2):32-38

利用Landsat7ETM＋遥感资料热红外波段定量反演晴空状态下夏季干旱区典型绿洲地表真实温度,运用影像叠加分析、直方图比对、缓冲区分析和空间自相关分析及剖面线分析等方法,分析其热场分布规律。结果表明：绿洲热场分布具有显著正空间自相关特性,Moran’s值为0．5489,Z值为48．44,同时呈现出显著的局部空间集聚现象;就局部而言,在相同热力环境下,由于盐碱地与裸地热容量不同,盐碱地温度低于周边裸地温度,盐碱地平均温度比周边300、900m和1500m缓冲区裸地的平均气温分别低0．59、0．44℃和0．26℃;然而盐碱地大多分布在裸地的高温区中心,且温度变化幅度小,在裸地低温区周围分布较少,所以就整体而言,裸地平均气温低于盐碱地温度,热场分布规律依次为水体温度21．65、耕地温度27．86、林草地温度35．59、城镇温度40．06℃、裸地温度42．07℃。水体、城镇、盐碱地、裸地的温度波动较小,热力景观单一,热场分布均匀,而耕地和林草地的温度梯度大,热力景观复杂多样,热场分布极不均匀,局部热场存在突变现象。绿洲荒漠交错带的面积较大,可以降低荒漠对绿洲的热力侵蚀,对保护绿洲有重要作用。  相似文献   

干旱区典型绿洲热场分布规律研究——以渭干河-库车河三角洲绿洲为例          下载免费PDF全文

张兆永  海米提·依米提 《气象与环境学报》2011,27(2):32-38

利用Landsat 7 ETM+遥感资料热红外波段定量反演晴空状态下夏季干旱区典型绿洲地表真实温度,运用影像叠加分析、直方图比对、缓冲区分析和空间自相关分析及剖面线分析等方法,分析其热场分布规律.结果表明:绿洲热场分布具有显著正空间自相关特性,Moran's值为0.5489,z值为48.44,同时呈现出显著的局部空间集...  相似文献   

Oasis dynamics change and its influence on landscape pattern on Jinta oasis in arid China from 1963a to 2010a: Integration of multi-source satellite images     

《International Journal of Applied Earth Observation and Geoinformation》2014

As one of the vital research highlights of global land use and cover change, oasis change and its interaction with landscape pattern have been regarded as an important content of regional environmental change research in arid areas. Jinta oasis, a typical agricultural oasis characterized by its dramatic exploitation and use of water and land resources in Hexi corridor, northwest arid region in China, was selected as a case to study the spatiotemporal oasis change and its effects on oasis landscape pattern. Based on integration of Keyhole satellite photographs, KATE-200 photographs, Landsat MSS, TM and ETM+ images, we evaluated and analyzed the status, trend and spatial pattern change of Jinta oasis and the characteristics of landscape pattern change by a set of mathematical models and combined this information with landscape metrics and community surveys. During the period of 1963a–2010a, Jinta oasis expanded gradually with an area increase of 219.15 km², and the conversion between oasis and desert was frequent with a state of “imbalance–balance–extreme imbalance conditions”. Moreover, most of the changes took place in the ecotone between oasis and desert and the interior of oasis due to the reclamation of abandoned land, such as Yangjingziwan and Xiba townships. Furthermore, the area, size and spatial distribution of oasis were influenced by human activities and resulted in fundamental changes of oasis landscape pattern. The fractal characteristics, dispersion degree and fragmentation of Jinta oasis decreased and the oasis landscape tended to be simple and uniform. Oasis change trajectories and its landscape pattern were mainly influenced by water resource utilization, policies (especially land policies), demographic factors, technological advancements, as well as regional economic development. We found that time series analysis of multi-source remote sensing images and the application of an oasis change model provided a useful approach to monitor oasis change over a long-term period in arid area. It is recommended that the government and farmers should pay more attention to the fragility of the natural system and the government should enhance the leading role of environmental considerations in the development process of oasis change, particularly with respect to the utilization of the limited water and land resources in arid China.  相似文献