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81.
引入社会资本理论,从网络、信任和规范3个维度,建构社会资本与名镇保护间的一个分析框架,剖析保护背后的社会资本困境及其内在根源。基于对苏州周庄等3个名镇的实证研究发现:① 社会资本主要通过其3个关键要素从组织基础、制度体系、精神动力对名镇保护沟通机制、约束机制与合作机制进行作用;② 当前名镇社会资本呈现网络弱化、信任缺失、规范不足现象,致使名镇保护中各多元主体协商遇冷、合作受限、行为失范;③ 提升社会资本、推动自下而上参与模式,是解决名镇保护的社会问题、走出保护困境的有效途径。 相似文献
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83.
Ecohydrologic separation alters interpreted hydrologic stores and fluxes in a headwater mountain catchment 总被引:1,自引:0,他引:1
Recent studies have demonstrated that compartmentalized pools of water preferentially supply either plant transpiration (poorly mobile water) or streamflow and groundwater (highly mobile water) in some catchments, a phenomenon referred to as ecohydrologic separation. The omission of processes accounting for ecohydrologic separation in standard applications of hydrological models is expected to influence estimates of water residence times and plant water availability. However, few studies have tested this expectation or investigated how ecohydrologic separation alters interpretations of stores and fluxes of water within a catchment. In this study, we compare two rainfall‐runoff models that integrate catchment‐scale representations of transport, one that incorporates ecohydrologic separation and one that does not. The models were developed for a second‐order watershed at the H.J. Andrews Experimental Forest (Oregon, USA), the site where ecohydrologic separation was first observed, and calibrated against multiple years of stream discharge and chloride concentration. Model structural variations caused mixed results for differences in calibrated parameters and differences in storage between reservoirs. However, large differences in catchment storage volumes and fluxes arise when considering only mobile water. These changes influence interpreted residence times for streamflow‐generating water, demonstrating the importance of ecohydrologic separation in catchment‐scale water and solute transport. 相似文献
84.
T.V. Makhubela J.D. Kramers D. Scherler H. Wittmann P.H.G.M. Dirks S.R. Winkler 《地球表面变化过程与地形》2019,44(15):2968-2981
In situ cosmogenic nuclides are an important tool for quantifying landscape evolution and dating fossil-bearing deposits in the Cradle of Humankind (CoH), South Africa. This technique mainly employs cosmogenic 10-Beryllium (10Be) in river sediments to estimate denudation rates and the ratio of 26-Aluminium (26Al) to 10Be (26Al/10Be), to constrain ages of sediment burial. Here, we use 10Be and 26Al concentrations in bedrock and soil above the Rising Star Cave (the discovery site of Homo naledi) to constrain the denudation rate and the exposure history of soil on the surface. Apparent 10Be-derived denudation rates obtained from pebble- to cobble-sized clasts and coarse-sand in soil (on average 3.59 ± 0.27 m/Ma and 3.05 ± 0.25 m/Ma, respectively) are 2-3 times lower than the bedrock denudation rates (on average 9.46 ± 0.68 m/Ma). In addition, soil samples yield an average 26Al/10Be ratio (5.12 ± 0.27) that is significantly lower than the surface production ratio of 6.75, which suggests complex exposure histories. These results are consistent with prolonged surface residence of up to 1.5 Ma in vertically mixed soils that are up to 3 m thick. We conclude that the 10Be concentrations accumulated in soils during the long near-surface residence times can potentially cause underestimation of single-nuclide (10Be) catchment-wide denudation rates in the CoH. Further, burial ages of cave sediment samples that consist of an amalgamation of sand-size quartz grains could be overestimated if a pre-burial 26Al/10Be ratio calculated from the surface production is assumed. © 2019 John Wiley & Sons, Ltd. 相似文献
85.
Understanding the interactions of vegetation and soil water under varying hydrological conditions is crucial to aid quantitative assessment of land-use sustainability for maintaining water supply for humans and plants. Isolating and estimating the volume and ages of water stored within different compartments of the critical zone, and the associated fluxes of evaporation, transpiration, and groundwater recharge, facilitates quantification of these soil–plant-water interactions and the response of ecohydrological fluxes to wet and dry periods. We used the tracer-aided ecohydrological model EcH2O-iso to examine the response of water ages of soil water storage, groundwater recharge, evaporation, and root-uptake at a mixed land use site, in northeastern Germany during the drought of 2018 and in the following winter months. The approach applied uses a dynamic vegetation routine which constrains water use by ecological mechanisms. Two sites with regionally typical land-use types were investigated: a forested site with sandy soils and a deep rooting zone and a grassland site, with loamier soils and shallower rooting zone. This results in much younger water ages (<1 year) through the soil profile in the forest compared to the grass, coupled with younger groundwater recharge. The higher water use in the forest resulted in a more pronounced annual cycle of water ages compared to the more consistent water age in the loamier soil of the grasslands. The deeper rooting zone of the forested site also resulted in older root-uptake water usage relative to soil evaporation, while the grassland site root-uptake was similar to that of soil evaporation. Besides more dynamic water ages in the forest, replenishment of younger soil waters to soil storage was within 6 months following the drought (cf. >8 months in the grassland). The temporal evaluation of the responsiveness of soil and vegetation interactions in hydrologic extremes such as 2018 is essential to understand changes in hydrological processes and the resilience of the landscape to the longer and more severe summer droughts predicted under future climate change. 相似文献
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87.
Tourism-oriented revitalization of historic districts has been identified as a form of sustainability which is believed to contribute to both conservation and development. Comprehensive assessments of the effects of such tourism-oriented revitalizations in historic districts are thus a great challenge, and are needed to support sustainable development and management efforts. In this study criteria and indicators were identified by using the AHP method with experts scoring four aspects on two levels. We assess a case in China using this system and outputs indicated infrastructure and environment performed best, while the score for residents’ living condition and participation was the lowest. Finally, we offer some suggestions to improve the relatively poor status in order to assist historic districts in achieving sustained revitalization. 相似文献
88.
A survey of a Ligurian tourist harbour was carried out during winter 2006 and summer 2007 in order to study the organic matter (OM) turnover through extracellular enzymatic activity. Seawater and sediments were sampled at six stations, three inside the port boundaries, one outside the port and two in an area influenced by the outflow of a minor river (Boate). The seawater showed OM turnover times similar to other oligo-mesotrophic coastal areas, and low concentrations of chlorophyll-a and inorganic nutrients. The sediments, instead, revealed high OM loads and a predominance of proteolysis. A significant reduction of the OM loads was observed in the outside station, indicating that the OM accumulation was due to the structures and activities of the harbour and to the Boate influence. The OM biotic recycling via enzymatic activity was enhanced especially during summer. Although the carbohydrates were probably highly refractory, their turnover was notably faster, due to glycolytic enzymatic activity that was enhanced more than the proteolytic in both the sediment and in the seawater. This suggested that the removal and recycling of OM were potentially efficient, and prevented the shift to eutrophication of the Rapallo harbour area. 相似文献
89.
XIANG HongFa WAN JingLin HAN ZhuJun GUO ShunMin ZHANG WanXia CHEN LiChun DONG XingQuan 《中国科学D辑(英文版)》2007,50(3)
Tectonically,the large-scale right-lateral strike-slip movement along the Red River fault zone is characterized at its late phase with the southeastward extension and deformation of the Northwestern Yunnan normal fault depression on its northern segment,and the dextral shear displacement on its central-southern segment.Research of the relations between stratum deformation and fault movement on the typical fault segments,such as Jianchuan,southeast Midu,Yuanjiang River,Yuanyang,etc.since the Miocene Epoch shows that there are two times dextral faulting dominated by normal shearing occurring along the Red River fault zone since the Miocene Epoch.The fission track dating (abbreviated to FT dating,the same below) is conducted on apatite samples collected from the above fault segments and relating to these movements.Based on the measured single grain's age and the confined track length,we choose the Laslet annealing model to retrieve the thermal history of the samples,and the results show that the fault zone experienced two times obvious shear displacement,one in 5.5 ±1.5 MaBP and the other in 2.1±0.8 MaBP.The central-southern segment sees two intensive uplifts of mountain mass in the Yuanjiang River-Yuanyang region at 3.6-3.8 MaBP and 1.6-2.3 MaBP,which correspond to the above-mentioned two dextral normal displacement events since the late Miocene Epoch. 相似文献
90.
A re-assessment of the historic seismicity of the central sector of the Colombian Eastern Cordillera (EC) is made by revision of bibliographic sources, by calibration with modern instrumental earthquakes, and by interpretations in terms of current knowledge of the tectonics and seismicity of the region. Throughout the process we have derived an equation to estimate Mw for shallow crustal earthquakes in Colombia using the length of isoseismal VIII, LVIII:
We also derived an equation to evaluate Mw for Colombian crustal earthquakes using the rupture length, L, estimated generally from the aftershock distribution of strong earthquakes:
We calculated average attenuation parameters for intermediate depth and shallow earthquakes that may be used, combined with other observations, to estimate the focal depth of historical events. Our final picture shows three distinct regions of the Colombian Eastern Cordillera (EC) where historical earthquakes are distributed. (a) The southern sector, from the Páramo de Sumapaz down to the Colombian Massif where the largest crustal earthquakes have occurred (1827, M 7 3/4; 1967, Mw = 7.0). (b) The central sector, between the Páramo de Sumapaz and Tunja with moderate to large earthquakes associated to the reverse faults on the piedmonts (the 1805 earthquake, M 6 3/4, on the western flank, and the 1743, 1923 and 1995 with M 6 1/2, 6 3/4, and 6.5, respectively, on the eastern flank). (c) The northern sector, to the north of Tunja, which is characterized by recurrent earthquakes probably associated with major reverse faults in the axial zone (e.g., 1646, I0 = VIII; 1724, M 6 3/4; 1755, I0 VIII; and 1928, M 5 3/4). Two events appear to be related to the axial faults to the south of Bogotá: those in 1644 (M 6) and 1917 (M = 7.1). The 1785 earthquake might have been an intraplate event in the subducting plate under the EC. Events in 1616 and 1826, which caused damage along the axial zone of the Cordillera near Bogotá, have no historical records precise enough to allow the estimation of their location and size, but their epicentres are probably not farther than some tens of kilometers from Bogotá. 相似文献