Soil and Water Resources and Land Sustainable Productivity in the Catchment Area with Intensive Management in Hilly Red Soil Regions,China

Taking an example of Majiayu Catchment Area (14.15 ha) in Taoyuan County of HunanProvince, the soil and water resources dynamics, fertility evolution characteristics andland productivity changing situation were studied. Fixed observation results from 1993to 2002 showed that pools covering about 15% of total area could store up 10% of surfacerunoff, keep 78.1% of eroded soil and 65.4% of lost nutrients. The yearly ratio ofinterception and evapotranspiration in land, storage in pools and drainage was 7:2:1,which ensured the resources and nutrients equilibrium and a benign recycle in thecatchment area system, and benefited the aquatic culture and helped to resist seasonaldrought. Moreover, the results showed that soil erosion modulus decreased significantly,equal to or lower than soil loss tolerance (≤500 tkm-2) in reddish yellow soil regions.Soil organic matter, total and available N content in sloping land, dryland and paddyfield increased steadily (>10%); water storage enhanced by more than 20% in sloping landand dryland in drought season; crop production increased by more than 20%; and productionof trees, fruits, tea and fish as well as land productivity increased yearly.

Analysis of Climate Variability and Its Influence on the Hydrological Response of the Catchment Area of Kadey (East Cameroon)

Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.

Distribution of Macro-elements and Natural Radionuclides in the Bottom Sediments and Soils of the Catchment Areas of Small Lakes in the Baikal Region

The examination of macroelements and natural radionuclides in the bottom sediments of small lakes and soils in the catchment areas of the Baikal region allows for the study of the mechanism of inflow and the source of these materials.On the basis of the results of rentgenostructural analysis lake sediments are divided into four types:terrigenous,carbonate, terrigenous-carbonate and organogenic.Through the analysis of gamma-ray spectrometry and ato-

Zavkhan River and Its Catchment Area Delineation Using Satellite Image

The purpose of this research is to define initial parameters of Khyargas Lake-Zavkhan River and its catchment area using satellite images. The study has been done by two datasets: 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and lake position, outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and initial parameters of the Zavkhan River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research, and with the reality. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Zavkhan River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.

Tuul River and Its Catchment Area Delineation from Satellite Image

The purpose of this research is to define basic parameters of Tuul River and its catchment area using satellite images. The study has been done by two datasets 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and basic parameters of the Tuul River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Tuul River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.

The scaling method of specific catchment area from DEMs

Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.

Measuring COVID-19 vaccination coverage: an enhanced age-adjusted two-step foating catchment area model

Background:There are only limited studies on access to COVID-19 vaccines and identifying the most appropriate health centres for performing vaccination in metropolitan areas.This study aimed to measure potential spatial access to COVID-19 vaccination centres in Mashhad,the second-most populous city in Iran.Methods:The 2021 age structure of the urban census tracts was integrated into the enhanced two-step foating catchment area model to improve accuracy.The model was developed based on three diferent access scenarios:only public hospitals,only public healthcare centres and both(either hospitals or healthcare centres)as potential vaccination facilities.The weighted decision-matrix and analytic hierarchy process,based on four criteria(i.e.service area,accessibility index,capacity of vaccination centres and distance to main roads),were used to choose potential vaccination centres looking for the highest suitability for residents.Global Moran’s index(GMI)was used to measure the spatial autocorrelation of the accessibility index in diferent scenarios and the proposed model.Results:There were 26 public hospitals and 271 public healthcare centres in the study area.Although the exclusive use of public healthcare centres for vaccination can provide the highest accessibility in the eastern and north-eastern parts of the study area,our fndings indicate that including both public hospitals and public healthcare centres provide high accessibility to vaccination in central urban part.Therefore,a combination of public hospitals and public healthcare centres is recommended for efcient vaccination coverage.The value of GMI for the proposed model(accessibility to selected vaccination centres)was calculated as 0.53(Z=162.42,P<0.01).Both GMI and Z-score values decreased in the proposed model,suggesting an enhancement in accessibility to COVID-19 vaccination services.Conclusions:The periphery and poor areas of the city had the least access to COVID-19 vaccination centres.Measuring spatial access to COVID-19 vaccination centres can provide valuable insights for urban public health decisionmakers.Our model,coupled with geographical information systems,provides more efcient vaccination coverage by identifying the most suitable healthcare centres,which is of special importance when only few centres are available.

考虑末端出行的城市轨道交通就业可达性

在轨道交通与城市融合发展的背景下,基于地铁站点的步行影响范围和由共享单车订单数据识别所得的骑行影响范围,测算站点到居住小区和就业兴趣点(POI)的步行和骑行时间,提出考虑末端出行的两步移动搜索法.结合洛伦兹曲线和基尼系数,测算和分析北京市六环内城市轨道交通站点的就业可达性及其公平性,量化末端出行对二者的影响.结果表明,在步行和骑行2种末端出行方式下,各站点的末端出行时间平均为18.6、8.6min,占总出行时间的29%、16%,且第一公里耗时略高于最后一公里.城市轨道交通就业可达性由中心城区向外围沿圈层递减,呈现明显的廊道特征.整体上基尼系数达到0.16、0.17,就业可达性分布较公平,但低房价站点存在明显的可达性劣势,局部上四环外和低房价类型站点的可达性分布相对更不均衡.相较于传统方法,利用改进方法所得的结果显示,考虑末端出行后可达性平均变化20%、9%,且外围站点变化更大,公平性的变化程度达到10%、2%.

基于汇水盆地法化探异常信息提取的综合应用——以西昆仑赞坎地区1∶5万水系沉积物地球化学测量为例

地球化学测量是一种有效的找矿技术方法,基于汇水盆地的水系沉积物地球化学异常提取可以有效减少表生地球物理和地球化学作用造成的异常漂移,进而明确找矿方向。以西昆仑赞坎地区为研究区,使用高精度DEM划分汇水盆地,基于汇水盆地法对1∶5万水系沉积物Au、Cu、W、Mo因子得分进行了异常信息提取。以汇水盆地面积作为泥沙输移比校正残差值,在此基础上得到AuCu、W-Mo校正残差值分布图。与传统化探数据处理方法相比,基于汇水盆地法处理的水系沉积物异常范围明显变大,异常强度得到增强,异常的分布更符合研究区的地形特征。本次研究结果显示,利用该方法提取的高异常范围与研究区已知矿点匹配度高于传统处理方法,能够为该地区找矿工作提供依据。

广州市降雨强度和汇水面积对降雨径流污染的影响

随着城市点源污染得到有效解决,降雨径流产生的面源污染逐渐成为城市水环境的主要污染源。利用Infoworks ICM软件构建广州市猎德涌流域排水系统的水力水质模型,系统分析了降雨强度和汇水面积对降雨径流污染的影响。结果表明,当最大降雨强度达到50 mm/h时,初雨径流污染达到峰值;当汇水面积小于100 hm^(2)时,管渠排放具有明显初雨效应,当汇水面积超过100 hm^(2)后,初雨效应会逐渐削弱。通过定量化表征降雨强度、汇水面积与降雨径流污染的关系,为城市雨水处理设施布设和面源污染治理提供参考。

秘鲁铜元素地球化学空间分布及对成矿远景区的预测

秘鲁位于南美洲西岸,作为安第斯成矿带的重要组成部分,矿产资源丰富,铜矿资源储量和产量位居世界第二。本文首次对秘鲁开展全国范围全球尺度地球化学调查工作,获得汇水域沉积物样品共416件,秘鲁全境铜元素含量为2.38~495μg/g,背景值(中位数)为24.0μg/g。秘鲁全境、沿海带、安第斯山区和亚马孙平原的表层(深层)汇水域沉积物中铜元素平均含量依次为31.4(31.6)、45.6(32.2)、47.5(48.2)和21.3μg/g(24.9μg/g)。地球化学图显示,秘鲁铜空间分布整体呈现出西高东低的趋势,西部沿海带和中部安第斯山区含量较高,东部亚马孙平原区含量较低的特征。本文选用75%累积频率作为异常下限值,圈定出5处铜地球化学异常,其中两处达到地球化学巨省规模,两处达到地球化学域规模。同时,讨论铜地球化学异常的来源和影响因素,解析与之对应的矿产资源响应,秘鲁良好的构造演化环境,为大型、超大型铜矿床的形成提供有利条件。太平洋纳斯卡板块向南美大陆不断俯冲变换,致使洋壳发生部分熔融,产生强烈而广泛的中酸性岩浆活动,且岩浆中铜含量大规模富集,局部地区在特定环境下富集成矿。这一构造运动导致铜元素在秘鲁空间分布上呈现出多个地球化学块体,可能也是铜地球化学异常形成的原因之一。这些巨大的地球化学块体发现可用于未来寻找铜矿集区或大型、超大型铜矿床,圈定找矿远景区,并可以降低找矿风险,提高找矿效率,缩短找矿周期。研究圈定的地球化学找矿远景区,可为秘鲁铜矿勘查开发利用提供基础资料和数据。

Particle Size Characteristics of Soil in Karst Area with Different Land Use Pattern—A Case Study of Shuifang Spring,Jinfo Mt.,Chongqing

This paper tried to analyze the particle size characteristics of the soil samples in Shuifang Spring catchment area,Jinfo Mt.,Chongqing with different land use patterns that are horse race grassland, rhododendron bush,bamboos,and the grassland near the Shuifang spring.The different land usepattern in karst area is of great affection to the particle size characteristics of soil.The median diameter of the karst surface layer soil becomes gradually smaller and smaller in following sequence:horse race grassland,grassland near the Shuifang Spring,

Catchment Management and Its Effects on Arable Lands of Zimbabwe: A Look beyond the Fast Track Land Reform Program

This study was carried out in selected districts of Mashonaland East and Central provinces of Zimbabwe in 2011 to determine the effects of soil erosion on arable lands and how this related to catchment management. Results show that the highest contribution is 53% and is obtained from arable land codes 5 and 7. These fields show signs of excessive sheet and gully erosion. The least contribution is 0.8% and this is on arable land codes 3, 4 and 8. These fields have properly done conservation works existing. 33% of the assessed arable lands have conservation works in place whilst 67% are not protected and as such the fields are eroded. Soil erosion results in the washing away of the precious top soil, responsible for plant growth and infiltration of rain or irrigation water. This reduces the usefulness of such affected arable lands as crops grown on it can’t thrive due to lack of soil fertility. The paper recommends that government policies focus more on promoting sustainable land use through integrated catchment area management. This will go a long way in achieving sustainable development in Zimbabwe.

基于就医活动推断的老年人公交就医可达性研究

为准确评估老年人公交就医出行的实际可达性,本文基于老年卡数据构建公交出行链,提出基于公交出行链的老年人就医活动推断方法,获取老年人的实际就医出行需求和出行时间。引入公交实时到站数据以反映公交实际运营水平对就医可达性的影响,构建面向出行全过程的实际出行成本矩阵,包括等候时间、乘车时间、换乘时间。考虑不同医院服务供给能力差异构建综合服务能力指标,引入分级服务半径和高斯距离衰减函数,提出基于改进两步移动搜索法的老年人公交就医可达性计算方法。以北京市六环内区域为例进行实证分析,结果表明:老年人公交就医可达性整体呈现由中心向外围递减的趋势,在城市外围区域其分布也存在空间异质性,五环路外的东部和西部区域可达性较好,而北部、东北部区域的可达性相对较差;各区域高峰时段的平均可达性均明显低于平峰时段的平均可达性。本文可为提升老年人就医出行可达性和公交系统适老化水平提供支撑。

供需协调视角下城市应急救援可达性评估--以郑州“7·20”特大暴雨为例

日益频繁的特大暴雨对城市造成愈加严重的影响,亟须关注应急救援需求的变化特征以及与之对应的应急救援可达性水平,以此提升城市应急救援的动态响应能力。以郑州市中心城区为例,通过社交媒体数据识别求救点和道路阻碍点,分析“7·20”特大暴雨背景下应急救援需求的时空分布特征。基于供需协调的视角,利用高斯两步移动搜寻法评估城市应急救援可达性。研究结果表明,应急救援需求具有动态集聚分布特征,同时应急救援可达性存在供需错位。最后,从完善应急救援通道网络、建立应急救援可达性智能评估平台、优化应急救援资源的空间布局三方面提出优化策略。

秦汉新城渭河1#雨水出口系统优化方案研究与实践

针对西安市西咸新区秦汉新城渭河1#雨水出口流域面积过大,存在系统内涝安全风险的问题,研究1#雨水出口系统优化方案。依据陕西省省级城市内涝治理实施方案,分析1#雨水出口系统存在的一系列问题以及优化原则和目标,重点分析了大汇水分区下雨水系统安全以及雨污分流改造的思路,为解决城市水安全、水环境以及水资源利用提出了应对措施与建议。

基于改进高斯两步移动搜索法的西南山地乡村居民医疗设施可达性评价——以重庆市九龙坡区为例

近年来,乡村医疗资源的数量和质量都有显著提升,但不同地区乡村居民在获得医疗机会、就医成本等方面存在较大差异,医疗设施布局不合理问题仍存在。医疗设施可达性作为衡量医疗设施空间布局是否合理的关键指标,为解决医疗资源分配不合理和改善医疗资源分配不公等问题提供了重要依据。针对传统高斯两步移动搜索法(Gaussian-Based 2SFCA)对于山地乡村地区医疗资源可达性在供给与需求思考不足的问题,将其进行改进,从而更为科学客观地评价可达性。研究选取重庆市九龙坡区乡村地区为研究对象,借助Arcgis平台分析乡村医疗设施供需情况,引介改进高斯两步移动搜索法分析设施可达性,在此基础上,借助SPSS软件进行K聚类分析,揭示乡村医疗设施可达性影响因素。研究发现:第一,各类医疗设施的可达性数值综合层面上的高可达性区域主要是由于临近医疗资源高供给能力的县综合医院和乡镇卫生院所贡献的,而村级医疗设施对综合可达性空间差异影响较小;第二,山地乡村地区公共医疗设施配置存在医疗资源与人口分布的空间不匹配的情况,主要体现在村级医疗设施;第三,区域可达性水平与交通通达性高低没有必然联系,受人口需求(人口规模、人口密度)、医疗设施供给服务能力及分布的影响更大。最后针对不同可达性区域提出优化策略。本研究为西南山地乡村地区医疗设施可达性评价提供了一套具有实践操作性的方法体系。

基于改进两步移动搜索法的合肥市中心城区综合公园可达性评价

为提高城市综合公园布局均衡性地定量评估的准确性,以合肥市中心城区为例,提出一种基于改进多出行模式的两步移动搜索法,利用高德地图的路径规划模型,结合双变量局部空间自相关、洛伦兹曲线以及基尼系数等方法,在手机信令数据的基础上对不同时间阈值下的城市综合公园的可达性及供需情况进行分析,进一步揭示中心城区综合公园布局的合理性。结果显示:合肥市中心城区综合公园的可达性空间差异显著,可达性较高区域通常分布在新城区以及综合公园周边地区,并且随着时间阈值的提高,可达性水平的空间分布呈现均衡态势;合肥市中心城区在15 min与30 min时间阈值下均只有近5%的居住网格处于供需匹配状态;近7%的居住网格处于供需显著不匹配状态,主要集中于老城区西部以及滨湖区北部区域,居住区密度与综合公园数量是影响供需匹配的重要原因。研究结果表明,通过利用手机信令数据与高德路径规划数据作为数据源对传统可达性的计算方法以及两步移动搜索模型进行改进,建立微观尺度下城市综合公园的可达性评价框架,能够精确地评估城市综合公园的可达性;通过优化城市交通的通达程度以提高居民综合公园游憩出行的阈值,能够显著促进城市综合公园整体的空间分布合理性。

基于两步移动搜索法的福州市公园绿地主客观可达性研究

公园绿地的可达性对于提升民生福祉、环境公平及城市高质量发展具有深远意义。综合考虑公园绿地的主观和客观供给能力,基于公园绿地规模、网络好评度、高德地图API路径规划等数据,运用高斯两步移动搜索法测度了居民单一出行及多交通出行模式下福州市公园绿地的客观和主观可达性,得出以下结论:(1)同一出行模式下公园绿地的主客观可达性差异大,客观可达性的高值区主要分布在非中心城区,而主观可达性的高值区大多分布在中心城区;(2)不同交通出行模式下主观和客观可达性也存在差异,步行出行模式下的公园绿地可达性低于驾车和公共交通出行模式的可达性,综合出行模式的可达性分布与驾车可达性分布相似,尚未形成公共交通主导的公园绿地发展模式;(3)公园绿地主客观供需平衡的县域少,供需不平衡的县域多,高人口密度县域存在公园绿地供给小于需求问题,非中心城区县域公园绿地主客观供需比普遍较低;(4)步行、驾车、公共交通出行模式下的高客观供需比-高主观供需比的公园绿地仅三坊七巷和福州市贵安新天地休闲旅游度假区,超过70%的公园绿地属低客观供需比-低主观供需比类型。本研究不仅关注公园绿地的空间可达性,也基于人的感受对公园绿地的主观可达性加以测度,为可达性评价提供新的研究思路,同时也为福州市公园绿地资源配置和存量绿地的质量提升提供建议。

城市内涝灾害对应急救援服务可达性的影响评估

【目的】城市化进程加快和气候变化导致内涝积水频发,造成道路封闭和交通堵塞,给城市应急救援响应的时效性带来严重影响。为了准确评估暴雨内涝下的城市应急救援响应能力,【方法】以荔湾区为例,通过构建内涝水动力模型,模拟不同设计降雨情景下的内涝积水,识别道路积水风险,明确阻断道路,并结合两步移动搜寻法(2SFCA)对不同脆弱性的兴趣点(POI)的应急救援服务可达性进行评估。【结果】结果显示:随着降雨重现期从1 a一遇增大到100 a一遇,内涝积水面积增大,平均积水深度从0.08 m增大到0.20 m。受积水影响道路数量持续增加,阻断道路长度从11 km上升至49 km,增长了超过300%。随着阻断道路的增多,应急救援可达的POI数量呈现下降趋势,并且在不同时间阈值内平均下降40%以上,可达性呈明显下降趋势。【结论】内涝模型耦合城市路网得到的道路积水可以揭示阻断道路的总体格局,可达性模型可以快速估算出应急救援的时效性。结果可为应急救援响应能力的评估提供参考。