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1.
Tunisia presents many favorable conditions for the outbreak of water erosion because of its climatic and physical characteristics. This phenomenon represents a serious threat to the natural resources of soil and water. The aim of the present study is to identify the most vulnerable areas in order to help managers implement an effective management program. Thematic layers and parameters were integrated in the InVEST (Integrated Valuation of Environmental Services and Trade-offs) SDR (Sediment Delivery Ratio). Soil loss and sediment yield were calculated by the model and compared to observed data. The Rmel river basin was divided into 17 sub-watersheds using the dam axis as the main outlet. Results reveal that approximately 60% of the basin presents soil loss more than 5 ton/ha/year. Soil erosion map demonstrates that soil erosion risk increases with increased slope gradient, especially in agricultural lands. Sub-catchment prioritizations have been fixed based on soil erosion risk. Results show that sub-catchment 16 presents the highest soil loss with a value of 65 ton/ha/year. Sub-catchment presenting high soil erosion risk needs to give a high priority in conservation planning.  相似文献   

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We examined patterns of habitat function (plant species richness), productivity (plant aboveground biomass and total C), and nutrient stocks (N and P in aboveground plant biomass and soil) in tidal marshes of the Satilla, Altamaha, and Ogeechee Estuaries in Georgia, USA. We worked at two sites within each salinity zone (fresh, brackish, and saline) in each estuary, sampling a transect from the creekbank to the marsh platform. In total, 110 plant species were found. Site-scale and plot-scale species richness decreased from fresh to saline sites. Standing crop biomass and total carbon stocks were greatest at brackish sites, followed by freshwater then saline sites. Nitrogen stocks in plants and soil decreased across sites as salinity increased, while phosphorus stocks did not differ between fresh and brackish sites but were lowest at salty sites. These results generally support past speculation about ecosystem change across the estuarine gradient, emphasizing that ecosystem function in tidal wetlands changes sharply across the relatively short horizontal distance of the estuary. Changes in plant distribution patterns driven by global changes such as sea level rise, changing climates, or fresh water withdrawal are likely to have strong impacts on a variety of wetland functions and services.  相似文献   

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Jaggar watershed is a constituent of the Gambhir river basin, in eastern Rajasthan and covers an area of 352.82 km2, representing arid climate. The drainage network is dendritic to sub-dendritic pattern however parallel to sub-parallel has also developed locally. The Jaggar watershed has been divided into fourteen sub-watersheds, designated as SW1 to SW14, for prioritization purpose. The prioritization of the sub-watersheds has been done on the basis of morphometric analysis and land use/land cover categories. Various morphometric parameters (linear and shape) have been determined for each sub-watershed and assigned rank on the basis of value/relationship with erodibility so as to arrive at a compound value for final ranking of the sub-watersheds. Land use/land cover mapping has been carried out using IRS LISS III data of 1998. Based on morphometric and land use/land cover analysis and their ranks, the subwatersheds have been classified into four categories as very high, high, medium and low in terms of priority for conservation and management of natural resources. The prioritization results based on morphometry reveal that only SW7 and SW10 fall under very high priority, whereas SW6, SW11 and SW13 fall under very high priority on the basis of land use/land cover analysis. However on the integration of morphometry and land use/land cover only SW14 show common priority whereas rest have little or no correlation.  相似文献   

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This paper aims to assess the risk of natural and anthropogenic hazards for cultural heritage in Cyprus by integrating multi-temporal GIS and earth observation analysis, in the area of Paphos District. The work presented here attends to re-evaluate previous results from earth observations and GIS analysis and go a step forward targeting more reliable outcomes for cultural heritage management. The scope of the paper was to develop a more accurate methodology for risk assessment against natural and anthropogenic hazards (e.g., soil erosion; urban expansion), based on homogeneous clustering of the monuments under consideration. The accomplished assessment approach, being lopsided and generic, cannot be applied across the board and undistractedly for cultural heritage management of all types of monuments of the district. Instead, the proposed clustering of monuments based on a variety of parameters is taking into consideration characteristics of their immediate environment, resulting rational local-based outcomes more useful for monuments and sites safeguarding and for prevention measurements. For each one of the five clusters of monuments located in the Paphos District, an analytical hierarchy process (AHP) method was followed in order to address the individual and unique characteristics of the monuments and sites within the same cluster area. Subsequently, the weight factors from these clusters were interpolated to the whole district, prior to the application of the overall AHP risk assessment. Ultimately, the results were compared with the overall AHP method applied for the entire Paphos District, indicating that the proposed methodology can be more accurate and realistic for the different groups of the monuments.  相似文献   

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Aerial photographs and GIS analysis were used to map the distribution of tidal marsh vegetation along the salinity gradients of the estuaries of the Altamaha and Satilla Rivers in coastal Georgia. Vegetation maps were constructed from 1993 U.S. Geological Survey Digital Orthophoto Quarter Quads, 1∶77,000-scale color infrared photographs taken in 1974 and 1∶24,000-scale black and white photographs taken in 1953, Changes between years were identified using a GIS overlay analysis. Four vegetation classifications were identified and groundtruthed with field surveys: salt marsh (areas containing primarilySpartina alterniflora), brackish marsh (Spartina cynosuroides andS. alterniflora), Juncus (Juncus roemerianus), and fresh marsh (Zizania aquatica, Zizaniopsis miliacae, and others). There was no evidence for an upstream shift in marsh vegetation along the longitudinal axis of either estuary over the time frame of this analysis, which implies there has not been a long-term increase in salinity. Although the inland extent of each marsh zone was further upstream in the Satilla than the Altamaha, they corresponded to similar average high tide salinities in each estuary: areas classified as salt marsh occurred from the mouth up to where average high tide salinity in the water was approximately 15 psu;Juncus ranged from 21 to 1 psu; brackish marsh ranged from 15 to 1 psu; and fresh marsh was upstream of 1 psu. Approximately 63% of the 6,786 ha of tidal marsh vegetation mapped in the Altamaha and 75% of the 10,220 ha mapped in the Satilla remained the same in all 3 yr.Juncus was the dominant classification in the intermediate regions of both estuaries, and shifts between areas classified asJuncus and either brackish or salt marsh constituted the primary vegetation change between 1953 and 1993 (87% of the changes observed in the Altamaha and 95% of those in the Satilla). This analysis suggests that the broad distribution of tidal marsh vegetation along these two estuaries is driven by salinity, but that at the local scale these are dynamic systems with a larger number of factors affecting the frequently changing borders of vegetation patches.  相似文献   

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Zakynthos, an island of 408 km2 in the Ionian Sea, is completely dependent on its groundwater resources for fulfilling the demands of the water supplies. The use of groundwater resources has become particularly intensive during the last decades because of the intense urbanization, the tourist development and the irrigated land expansion that took place. The main aquifers are developed in limestones (karstic), sandstones of neogene deposits (confined) and alluvial deposits (phreatic). This paper focuses on the assessment of their hydrogeological characteristics and the groundwater quality. For this investigation, groundwater level measurements, drilling data, pumping tests and chemical analyses of groundwater samples were used. The average annual consumption that is abstracted from the aquifer systems, is 4.9 × 106 m3 year−1. The exploitable groundwater reserves were estimated to be 3.3 × 106 m3 year−1. In the last decades, the total abstractions exceed the natural recharge, due to the tourist development; therefore the aquifer systems are not used safely. The results of chemical analyses showed a deterioration of the groundwater quality. According to the analyses the shallow alluvial aquifer and the confined aquifer are polluted by nitrates at concentrations in excess of 25 mg L−1. High sulphate concentrations might be related to the dissolution of gypsum. Seawater intrusion phenomena are recorded in coastal parts of aquifer systems. The increased Cl concentrations in karstic aquifer indicate signs of overexploitation. Strengths, weaknesses, opportunities and threats (SWOT) analysis was applied in order to evaluate the SWOT of the groundwater resources. Moreover, some recommendations are made to assist the rational management that aim at improving the sustainability of the groundwater resources of Zakynthos Island.  相似文献   

8.
Groundwater potential zone mapping has become easier with the inputs from Remote Sensing (RS) & Geographical Information System (GIS) techniques. Various thematic maps like geology, geomorphology, drainage density, slope, landuse/landcover etc can be easily generated through RS & GIS. The present study is aimed at generating groundwater potential map of Koshalya-Jhajhara (K-J) watershed by using integrated approach of RS & GIS. Various thematic layers have been generated and assigned weightages and ranks. These layers have been integrated in GIS software for generating Groundwater Potential Zone (GPZ) map of K-J watershed. The area falls into five categories of groundwater potential zones i.e. very good, good, moderate, poor and very Poor depending on the likelihood of availability of ground water. On the basis of this study it is found that only 5.83 km2 and 4.91 km2 area is under very good and good category of groundwater availability respectively. An area of 24.48 km2 is found under moderate category whereas dominant portion of K-J watershed i.e. 61.83 km2 and 37.87 km2 area falls under poor and very poor category of availability of groundwater respectively.  相似文献   

9.
An integrated approach using hydrogeochemical analysis, remote sensing, GIS, and field data was employed to characterize the groundwater resources in southern Wadi Qena, Egypt. Various thematic maps showing topography, lineaments, wadi deposits, slope, and stream networks were combined through GIS analysis to discriminate groundwater potential zones on the valley floor. The resulting map classifies the area into five groups of groundwater potentiality from very high to very low zones, supported by the groundwater level, well locations, and by the results of previous geophysical studies. Thirty-seven groundwater well data were tested from the Quaternary and Nubian Sandstone aquifers and analyzed for physio-chemical parameters. Results of hydrochemical analysis show that water quality varies widely through the aquifers, and groundwater in the Quaternary aquifer shows the highest salinity values and a predominance of Na and Cl in water chemical facies. Overlay GIS maps of alkalinity (SAR and RSC) and salinity hazards (EC and Cl) of the Quaternary aquifer were prepared. The resulting maps show that samples do not present an alkalinity hazard in most areas but are potentially salinity hazard. Therefore, the water is fit for agricultural use with certain restrictions, but is not suitable for direct human consumption because it is either very hard or too saline.  相似文献   

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With phytolith analysis of an archaeological site (Longshan Culture Period, 4800-4000 B. P.) in Zhumadian City of Henan Province, environmental and cultural information have been obtained. Phytolith assemblages both from the site and from a nearby ancient lake deposit of the same period indicate a warm and wet climate. Since this area is in an environment outside the natural distribution of wild rice, abundant “scooped” bilobate and special glume epidermal phytoliths found in all of the cultural layers and two samples of the lake deposits suggest that rice was cultivated in this region by the local people. © 1994 John Wiley & Sons, Inc.  相似文献   

13.
Tens of thousands of palaeontological and archaeological remains were collected by William Pengelly during 19th century excavations of Kents Cavern, but are now widely dispersed between museums. This has previously precluded spatial analysis. We have now assembled available museum records into a single database, and, using our previously-reconstructed Pengelly excavation map as a base, we have been able to exploit the unique Pengelly location code to set up a GIS mapping system. This allows, for the first time, the analysis of spatial patterns. In addition, the GIS serves to highlight potential problems of recording or curation in the original data. Here we report on the construction of the GIS system and its first use in the analysis of spatial distribution of bear remains. The maps demonstrate that Ursus deningeri entered the cave through a now-sealed High Level Chamber entrance at the back of the cave in the middle Pleistocene, whereas Ursus arctos accessed the cave in the late Pleistocene through the now-sealed Northeast Gallery entrance. The denning areas are reconstructed as Labyrinth/Bear's Den for U. deningeri and Vestibule/Great Chamber for U. arctos. Considerable post-mortem re-distribution of the remains of both species is indicated.  相似文献   

14.
Cemeteries give evidence for a continuous change in sepulchral culture and provide insights into the application of characteristical rock materials used for tombstones during different times. Four selected cemeteries in Dresden (the Eliasfriedhof/Elias Cemetery, the Trinitatisfriedhof/Trinity Cemetery, the Johannisfriedhof/Johannis Cemetery, and the Städtischer Urnenhain/Municipal Urn Grove), which are of considerable cultural and historical importance, have been investigated within an ongoing mapping project. First results of this project focussing on the tombstone inventory of the mentioned graveyards and thus the use of building and decoration stones therein between 1680 and 1945 are presented in this paper. It can be demonstrated that the choice, variety, and application of rock material depends on the infrastructure and transport possibilities, but is also strongly influenced by sepulchral cultural trends and the prevailing zeitgeist. Until the middle of the 19th century, nearly solely Elbe sandstone (from the area of the Elbsandsteingebirge/Elbe sandstone mountains), that was transported on the Elbe river by ship, is found as rock material for tombstones in Dresden cemeteries. Rapid construction and development of the railway network starting around 1840 improved the availability, at first, of regional rock material (e.g., from the Lausitz/Lusatia) and, later on, from about 1880, of national and international—especially European—rock material (e.g., from Franken/Franconia, France, Scandinavia). Furthermore, the Friedhofsreformbewegung/cemetery reform movement at the beginning of the 20th century, with its significant effect on the selection of rock types used for tombstones, marks another historical breakthrough.  相似文献   

15.
In the present investigation, an effort has been made to identify the critical sub-watersheds for the development of best management plan for a small watershed of Eastern India using a hydrological model, namely, AVSWAT2000. A total of 180 combinations of various management treatments including crops (rice, maize ground nut and soybean), tillage (zero, conservation, field cultivator, mould board plough and conventional practices) and fertilizer levels (existing half of recommended and recommended) have been evaluated. The investigation reveled that rice cannot be replaced by other crops such as groundnut, maize, mungbean, sorghum and soybean since comparatively these crops resulted in higher sediment yield. The tillage practices with disk plough have been found to have more impact on sediment yield and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in the case of zero tillage, conservation tillage, field cultivator, moldboard plough, and conservation tillage as compare to conventional tillage. Lowest NO3–N loss was observed in zero tillage in all the fertilizer treatments, whereas field cultivator, moldboard plough and disk plough resulted in increase of NO3–N loss. As compared to conventional tillage, the losses of soluble phosphorus were increased in moldboard plough. The losses of organic nitrogen were also increased as fertilizer dose increased. After zero tillage the conservation tillage preformed better in all the fertilizer treatments as per loss of organic nitrogen and organic phosphorus is concerned. It can be concluded that the sediment yield was found to be the highest in the case of disk plough followed by moldboard plough, field cultivator, conventional tillage, field cultivator and least in zero tillage practices. The nutrient losses were found to be in different order with tillage practices, resulted highest in disk plough tillage practices. In view of sediment yield and nutrient losses, the conservation tillage practice was found to be the best as the sediment yield is less than the average soil loss whereas nutrient loss is within the permissible limit.  相似文献   

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 Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological (surface and groundwater) and geochemical aspects have been studied for the development and management of water resources in drought-prone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About 91 000 ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about 47 000 ha is irrigated by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators for the irrigation practices. Groundwater assessment studies revealed that 584 million m3 of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or the application of fertilisers. Received: 10 June 1998 · Accepted: 15 November 1998  相似文献   

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基于RS与GIS技术的西藏多龙矿集区生态环境监测研究   总被引:3,自引:0,他引:3  
西藏多龙矿集区铜多金属矿产资源丰富,铜储量约2500万吨,排名中国第一。矿集区矿产资源的开发能带来巨大的社会经济效益,但青藏高原地区生态环境承载力有限,矿山开发容易造成生态环境的不可逆破坏。本文基于高分二号、Landsat8等遥感影像数据,采用人机交互解译方法提取多龙矿集区有关人类活动、水文、荒漠化、金属氧化物污染及草地覆盖等信息,进而分析研究区生态环境现状。分析结果表明:研究区生态环境整体仍处于较原始状态,未遭受过大型工业活动及人为活动破坏;区内主要植被类型为高原草原和高原草甸,高草地覆盖区面积较小且分布较集中;研究区荒漠化形势较为严峻,主要荒漠化类型包括沙漠化、石漠化及盐碱化等;矿区地表出现大面积褐铁矿化及孔雀石化,周边土壤及水系金属及重金属矿物含量超标;区内砂金矿盗采、超载放牧及地质勘探等人类活动均对当地生态环境造成一定影响。利用RS与GIS技术开展多龙矿集区生态环境调查研究,可为矿山的绿色选址及绿色矿山开发建设提供建议及技术支持。  相似文献   

18.
The purpose of this research is to evaluate the groundwater quality in Dindugal district of Tamil Nadu based on the water quality index by geographic information system (GIS) and statistical analysis. This area consists of 80 functional tanneries around Dindigul town with a capacity to process about 200 Mt of hides and skins as leather. In 13 villages, as many as 1090 houses were damaged by tannery contamination. A total of 66 groundwater samples were collected to identify the geochemical sources and contamination. The order of major cations is Na > Ca > Mg > K, while that of anions is Cl > SO4 > HCO3 > F > PO4. CaCl2, MgCl2, and (CaHCO3)2 types suggested that the mixing of high-salinity water was caused by irrigation return flow, domestic wastewater, and septic tank effluents, with existing water followed by ion exchange reactions. Moreover, Gibbs plots indicated that groundwater contamination was derived from the weathering of granitic gneisses as well as the leaching of evaporated and crystallized ions from agricultural and industrial effluents. The water quality index (WQI) exhibited 8 % of the groundwater samples were not suitable for drinking purpose. The GIS maps showed that the poor water quality decreased toward the southern part of the study area. WQI of TDS, fluoride, sodium, potassium, and bicarbonate were high in groundwater. Multivariate statistical analyses (principal component analysis (PCA), factor analysis (FA)) suggested that the groundwater chemistry was changed by the weathering of source rocks ion exchange and leaching of inorganic components and addition from anthropogenic effluents. Finally, it is thought that the monitoring and assessment works are very useful to understand the degree and sources of groundwater contamination.  相似文献   

19.
A geomorphologic approach, combined with GIS spatial analysis, was used to investigate a 90-km long coastal sector in Southern Sicily, Italy, affected by important erosive processes. Applied methodology allowed the creation of a database involving a range of coastal characteristics thereby providing helpful information on coastal processes and general sediment circulation patterns. Coastal erosion, mainly linked to the construction of ports and harbours, has been locally mitigated by the construction of solid structures which themselves generate significant environmental stress in downdrift areas. In recent times, several nourishment projects have been planned to solve existing erosive problems, yet there is still a lack of a general erosion management plan based on the installation of port and harbour by-passing systems and including the phasing out of current beach cleaning and port maintenance procedures that produce a great quantity of sediments.  相似文献   

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《Applied Geochemistry》1986,1(1):139-151
The principal marble quarries of Italy for the past 2000 years have been those of Carrara. In Roman times, the marble was exported all over the ancient world. Renaissance quarries were opened up in Seravezza; both the Seravezza and the Carrara quarries have been exploited until today. The correct identification of Carrara marble has always been a problem because it was traded so widely in Roman times and was later used to fabricate broken or lost pieces of classical statuary. Many types of geochemical analysis have been tried in order to find distinctive signatures for the recognition of classical marbles, including trace elements, ESR spectroscopy of Mn, thermoluminescence, and stable isotopic ratios. To date, the most promising has been isotopic ratio analysis of oxygen and carbon.In this study, stable isotopic signatures were investigated as a means for distinguishing: (1) the principal quarry areas of the Carrara Commune: Fossacava, Miseglia, and Torano, and the Seravezza Commune; (2) or merely the largely classical quarries of Carrara from the Renaissance quarries of Seravezza; (3) and, most important, the Carrara quarries from other quarries of Greece, Turkey, Italy, and Tunisia in the classical marble data base.Discriminant analysis (DA) of the isotopic analyses showed that the three quarry areas of a Carrara could not be told apart but that they could be told easily from Seravezza. In addition, a “mineralized” Carrara quarry at Mandria, with buff to yellow rather than white marble, was also distinctive. DA also suggests that Carrara can be told from those quarries with which it is presently confused: Paros, in the Aegean Sea; Marmara, in Turkey; and Pentelikon, near Athens.Sr isotopic analysis showed a range in the Carrara and other marbles of Hettangian (Lower Jurassic) age from 0.70778 to 0.70810 which is very different from values found in Paros and Pentelikon. This suggests that Sr might make a good third discriminator for classical marble.  相似文献   

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