Quantifying suitable dynamic water levels in marsh wetlands based on hydrodynamic modelling

The water level of marsh wetlands is a dominant force controlling the wetland ecosystem function, especially for aquatic habitat. For different species, water level requirements vary in time and space, and therefore ensuring suitable water levels in different periods is crucial for the maintenance of biodiversity in marsh wetlands. Based on hydrodynamic modelling and habitat suitability assessment, we determined suitable dynamic water levels considering aquatic habitat service at different periods in marsh wetlands. The two-dimensional hydrodynamic model was used to simulate the temporal and spatial variation of water level. The habitat suitability for target species at various water levels was evaluated to obtain the fitting curves between Weighted Usable Area (WUA) and water levels. And then suitable water levels throughout the year were proposed according to the fitting curves. Using the Zhalong Wetland (located in northeastern China) as a case study, we confirmed that the proposed MIKE 21 model can successfully be used to simulate the water level process in the wetland. Suitable water levels were identified as being from 143.9–144.2 m for April to May, 144.1–144.3 m for June to September, and 144.3–144.4 m for October to November (before the freezing season). Furthermore, proposed water diversion schemes have been identified which can effectively sustain the proposed dynamic water levels. This study is expected to provide appropriate guidance for the determination of environmental flows and water management strategies in marsh wetlands.     

西宁市老年人口分布与养老资源错位研究

健康中国战略下,积极应对老龄化、建立健全养老和医疗等相关设施,成为许多城市关注的问题。目前相关研究很少关注西北城市的老龄人口的空间分布及养老资源错位的现象。本研究以西宁市主城区为研究区域,基于2010—2018年西宁市公安局各街镇人口数据和兴趣点（POI）数据,选用老年人口系数、赡养率、增长率和地理集中率四个指标,利用综合老龄化指数（CAI）模型、核密度函数模型和空间错位指数模型对西宁市主城区人口老龄化空间分布及养老资源（医疗资源、老年设施）空间错位现象进行探索分析,结果表明：（1）9年间西宁市主城区人口老龄化程度不断加深,已步入老年型社会。（2）通过老龄化综合指数可知：主城区外围街镇人口老龄化增长速度大于城区中心的街道,其中小桥街道、朝阳街道、马坊街道与乐家湾镇人口老龄化最为严重,2018年综合老龄化指数增长速度超过中心城区街道,西宁市主城区人口老龄化严重程度已从中心街道向外围街镇扩散。（3）通过空间错位指数计算可得知：城中区的养老资源数量充足但过于集中,城北区的养老资源分布合理但是数量较少,行政区之间的养老资源与老年人口分布存在较大空间错位问题。     

纳入动态数据的改进FLUS模型在城市增长边界划定中的应用

城市增长边界是管控城市建设用地无序扩张的有效手段,科学合理划定城市增长边界是当前研究关注的重要课题。本研究试图引入百度动态交通时间和POI数据改进FLUS模型,以长沙市中心城区为例,采用2000、2010和2018年3期土地利用数据对比验证改进FLUS模型模拟精度,并利用改进FLUS模型设置2种情景,模拟2030年长沙市中心城区土地利用变化,结合用地适宜性评价划定城市增长边界。结果显示：① 纳入动态数据的改进FLUS模型模拟2010年和2018年土地利用相比原模型KAPPA系数提高了2.90%和2.74%,总体精度提高了1.79%和1.83%,表明改进模型具有更高模拟精度;② 利用改进FLUS模型模拟的2030年长沙市中心城区土地利用变化,基准情景和生态保护情景建设用地规模分别为930.06 km²和881.36 km²,均以耕地转为建设用地比例最大;③ 长沙市中心城区刚性增长边界范围为1479.59 km²,占中心城区总面积的37.38%,边界内包含了芙蓉区、天心区、雨花区、岳麓区和开福区的大部分区域;④ 基准情景和生态保护情景下,长沙市中心城区弹性增长边界面积分别为799.35 km²和742.92 km²,建设用地扩张空间主要为长沙县和望城区,结果与2010版长沙市城市总体规划拓展方向一致。纳入动态数据的改进FLUS模型多情景模拟划定城市增长边界,能更高精度的为规划决策提供科学依据。     

“一带一路”倡议下老挝沙湾区土地适宜性评价

为了对老挝沙湾区土地适宜性进行评价,本文选择了地形、土壤、水利、区位和生态5类13项指标,建立了老挝沙湾区土地适宜性评价指标体系;将层次分析法(AHP)与GIS技术相结合,对老挝沙湾区农业用地、林业用地和建设用地进行适宜性评价。研究结果表明:宜农用地占土地面积的30.16%,主要分布在海拔较低、坡度较小的沙湾拿吉大平原以及湄公河沿岸;宜林用地占土地总面积的60.07%,主要分布在东部和北部山区;宜建用地占土地总面积的4.62%,主要分布在平原地区,湄公河沿岸,以及交通较发达地区;不适宜用地占总面积的2.32%,主要分布在甘蒙省西北部以及东部。研究方法和研究结果可以为老挝沙湾拿吉省土地利用规划和相关研究提供科学依据与支持,同时为老挝今后的土地资源开发奠定基础。     

Assessing potential land suitable for surface irrigation using groundwater in Ethiopia

Although Ethiopia has abundant land for irrigation, only a fraction of its potential land is being utilized. This study evaluates suitability of lands for irrigation using groundwater in Ethiopia using GIS-based Multi-Criteria Evaluation (MCE) techniques in order to enhance the country's agricultural industry. Key factors that significantly affect irrigation suitability evaluated in this study include physical land features (land use, soil, and slope), climate (rainfall and evapotranspiration), and market access (proximity to roads and access to market). These factors were weighted using a pair-wise comparison matrix, then reclassified and overlaid to identify suitable areas for groundwater irrigation using a 1-km grid. Groundwater data from the British Geological Survey were used to estimate the groundwater potential, which indicates the corresponding irrigation potential for major crops. Results indicated that more than 6 million ha of land are suitable for irrigation in Ethiopia. A large portion of the irrigable land is located in the Abbay, Rift Valley, Omo Ghibe, and Awash River basins. These basins have access to shallow groundwater (i.e., depth of groundwater less than 20 m from the surface) making it easier to extract. The comparison between available groundwater and total crop water requirements indicate that groundwater alone may not be sufficient to supply all suitable land. The study estimates that only 8% of the suitable land can be irrigated with the available shallow groundwater. However, groundwater is a viable option for supplementing surface water resources for irrigation in several basins in the country.     

安徽省人口年龄结构特征及其社会经济影响研究

根据人口普查和抽样调查的数据资料,采用对比分析、聚类分析等研究方法分析了1953~2015年安徽省人口年龄结构时间特征、空间特征。从时间上看,安徽省人口年龄结构不断演变,少儿人口数量从不断增加转变为不断减少,劳动适龄人口比重比较稳定,人口老龄化程度不断加深,总抚养系数和少年儿童抚养系数大幅度下降,老年抚养系数上升;从空间上看,人口年龄结构存在较大地区差异。安徽省人口年龄结构对社会经济发展的影响主要表现为：① 人口老年化导致劳动生产率和经济增长速度的减缓,家庭规模小型化,并对社会养老保障和医疗卫生的挑战;② 少儿人口的不断减少影响教育资源的配置;③ 人口年龄结构的区域差异进一步加剧了安徽区域发展的不平衡性。为了尽可能地减缓人口年龄结构演变对安徽省社会经济发展的不利影响,建议采取如下措施：一是充分利用“人口红利”机遇期,加快经济发展,不断促进社会进步;二是要加强引导,因地施策;三是完善社会保障制度,努力扩大社会保障制度的覆盖面,力争全覆盖,尽量减小城乡差距;四是大力发展养老产业,探索建立满足居家养老、社区养老、机构养老等多种方式需求的政府主导、政策扶持、社会参与、市场运作的社会化养老服务体系。     

2000-2010年广州市人口老龄化空间分异及形成机制

分析2010年广州市人口老龄化空间分布特征,并采用因子生态分析方法、聚类分析方法划分老年人口社会空间地域类型,将两者叠加分析,得出广州市人口老龄化空间分异可划分为8种类型区并呈圈层和扇形分布的特征。通过与2000年的人口老龄化空间分异进行比较,归纳出广州市人口老龄化空间分异的变化具有历史继承性、随城市开发进程而结构趋于复杂化、出现类型更新和类型区范围变化等特征。广州市人口老龄化空间分异模式主要分为四种：老城区延续发展模式、中心城区更新转变模式、近郊区急剧转变模式、远郊区分异发展模式。最后从城市历史发展传承、城市规划建设引导、住房等制度变迁影响、房地产发展等方面探讨了广州市人口老龄化空间分异形成机制。     

吉林省人口老龄化时空分异特征及成因

本文基于地理信息软件ArcGIS 10.1,选取老年人口系数为人口老龄化指标,运用人口重心模型、空间自相关和半变异函数等分析方法,对吉林省第四次、第五次、第六次人口普查数据进行分析,探讨1990-2010年吉林省人口老龄化时空分异特征,并采用多元线性回归方法解释其形成原因。研究结果表明：①吉林省各县市人口老龄化差异明显,进程加快,重心由西北向东南方向移动,但移动速度减缓;②吉林省人口老龄化存在正的空间自相关性,在空间的集聚呈现先弱后强的变化趋势;③人口老龄化高—高区向东部集聚,低—低区向西部集聚的趋势比较明显;④总体上吉林省人口老龄化空间的结构化分异较为明显,随机性因子引起的空间异质性程度较弱,人口老龄化的空间差异主要体现在东—西方向上;⑤出生率始终是影响吉林省人口老龄化的主要因素,迁出率对人口老龄化发展起关键作用,人均GDP年对人口老龄化呈负相关,城市化率对人口老龄化的推动作用愈发显著。     

Regional differentiation of ecological conservation and its zonal suitability at the county level in China

China’s investments, financial incentives and deductions in terms of ecological conservation are based at the county level. Therefore, the monitoring and assessment of the effects of ecological conservation at the county level is important to provide a scientific basis for the assessment of the ecological and environmental quality at the county scale. This paper quantitatively estimated the dynamics of high-quality ecosystems and vegetation coverage over the past 15 years, and their relationships with the number of ecological conservation programs at the county level were analyzed. Then, the effects of ecological conservation measures on ecological changes at the county level and their regional suitability were assessed and discussed. The results showed that counties with a percentage of high-quality ecosystems greater than 50% were primarily distributed in northeastern China, southern subtropical China and the southeastern Qinghai-Tibet Plateau, and those with a percentage lower than 20% were mostly distributed in northwestern China, the southwestern karst region and the North China Plain. In recent decades, ecological conservation has focused on ecologically fragile regions; more than five ecological conservation programs have been implemented in most counties of the Three River Source Region in Qinghai Province, southeastern Tibet, western Sichuan, the Qilian Mountains, southern Xinjiang and other western regions, while only one or zero have been implemented in the eastern coastal area of China. Over the past 15 years, the proportional area of high-quality ecosystems has increased in approximately 53% of counties. The vegetation coverage of counties in the Loess Plateau, Huang-Huai-Hai Plain, Beijing-Tianjin-Hebei (Jing-Jin-Ji), Sichuan-Guizhou-Chongqing, and Guangdong-Guangxi provincial-level areas has increased significantly. However, it decreased in northern Xinjiang, central Tibet, central and eastern Inner Mongolia, the Yangtze River Delta and other regions. The relationships between the numbers of ecological conservation programs and the indicators of ecosystem restoration response, such as high-quality ecosystem and vegetation coverage, do not show positive correlations. These results suggest that ecological conservation programs should be planned and implemented according to the distribution patterns of high-quality ecosystems and that restoration measures such as afforestation should follow natural principles and regional differentiation under the background of climate change.     

Comprehensive Evaluation of the Suitability of Agricultural Land in Myanmar

Myanmar is a country with an economy based on agriculture. It has rich agricultural resources and great potential for development. The development of agriculture in Myanmar is becoming increasingly important to international food security. Assessments of agricultural land resources in Myanmar are the basis for the country’s agricultural development and for food security evaluations. In this paper we used the MaxEnt model to analyze the relationship between the suitability of land for agricultural reclamation and the main environmental variables in Myanmar, and then constructed a model to comprehensively evaluate the suitability of land for agriculture in Myanmar. The results show that: 1) the overall accuracy of the MaxEnt model is high (AUC>0.8), which means there is a high correlation between the database of selected environmental indicators and the true distribution of cultivated land in Myanmar. 2) Soil depth is the most important factor affecting the suitability of land for agriculture in Myanmar. When the thickness of soil layer is less than 100 cm, the suitability of land for agriculture is low. With respect to topographic conditions, slope is the main factor affecting suitability. When the slope is greater than 20 degrees, the suitability of land for agriculture is low. With respect to climate conditions, precipitation is the main influencing factor. There is a positive correlation between river network density and land suitability. 3) Currently, 400 000 km² of the land resources in Myanmar are suitable for agriculture, and of this amount 290 000 km² are highly suitable, accounting for nearly 40% of the country's land area. The highly suitable land is distributed mainly in Magway, Sagaing, Ayeyarwady and Yangon provinces. The provinces are also important grain production areas in Myanmar, and this serves to validate the effectiveness of the method used in this paper.