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71.
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。  相似文献   
72.
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.  相似文献   
73.
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.  相似文献   
74.
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.  相似文献   
75.
气候舒适的程度及持续时间的长短,是影响旅游发展和人类居住环境适应性的重要因素。基于1981 2010年普洱市10个县区气象站的日平均气温、相对湿度及风速等常规气象观测资料,对季节划分、气温极值和平均气温空间分布进行了分析,计算舒适度指数(包括温湿指数、风寒指数、人体舒适度指数),研究了普洱市的宜居气候舒适性。结果表明:普洱市夏季90%的区域平均气温为20~24℃,仅有东部和中部少数河谷地带超过24℃;冬季90%的区域平均气温均在10℃以上。冬半年全市最低气温低于0℃的年平均日数不足1天,夏半年全市最高气温高于35.0℃的年平均日数不足4天。因此普洱市"冬无严寒、夏无酷暑",全年有6~9个月的春秋宜人气候,是典型的全年"人体感觉舒适"的宜居气候区,尤以夏半年最为舒适。近10年普洱市快速增长的旅游总人数和完成的GDP进一步说明普洱市的宜居和旅游的气候适宜性。  相似文献   
76.
对农村居民点布局适宜性评价方法的探讨,不仅能丰富农村居民点布局研究的理论体系,也有利于开展农村居民点规划和整理工作。以江苏省宜兴市为例,综合考虑其社会经济和农村居民点布局特点,从自然地理条件、区位条件、生产条件以及生态环境条件4个方面建立评价指标体系,基于灰靶模型研究农村居民点布局适宜性,并据此提出相应的分类调控对策。研究结果表明:宜兴市农村居民点适宜性等级总体较高;在空间上呈现中、北部平原地区的农村居民点布局适宜性整体高于南部丘陵山区的分布特征。针对不同适宜等级提出的分类调控对策可以为当地农村土地整治、村庄规划等实际工作提供一定的参考。  相似文献   
77.
安徽升金湖国家级自然保护区水鸟生境适宜性变化   总被引:3,自引:2,他引:1  
水鸟是湿地生态系统健康的指示生物,人类活动对其影响日益严重.研究自然保护区内的水鸟生境适宜性变化可以为湿地恢复提供帮助.通过层次分析法确定水鸟生境影响因子的权重,建立生境适宜性指数模型,根据TM遥感影像图和相关数据计算出安徽省升金湖国家级自然保护区1986-2011年5个年份的水鸟生境适宜指数,并结合GIS空间分析生成的水鸟生境适宜性分级图,分析升金湖建立保护区后水鸟生境适宜性变化.结果表明:升金湖地区在1986年建保护区后的几年间水鸟生境适宜性相对平稳,但是仍然有较为明显的下降;1990s后期,该地区水鸟生境适宜性开始显著恶化,一直持续到2000年之后才有小幅度的回升.水鸟生境适宜性最好的区域由片状分散逐渐转变成小范围聚集,适宜区域也在由实验区和缓冲区向核心区迁移的过程中显著缩减.本文还讨论了在研究中存在的不足,并提出一些恢复水鸟生境的建议.  相似文献   
78.
RCCC-WBM水量平衡模型在北方典型流域的适用性研究   总被引:1,自引:0,他引:1  
流域水文模型是开展环境变化影响分析和水资源评价的重要工具。以山西省的5个不同尺度的代表性流域为研究对象,分析了RCCC-WBM模型在山西省的区域适用性。结果表明:RCCC-WBM模型能够较好地模拟出山西省径流年内分配特征和年代际变化特点,对典型流域月径流量模拟的Nash-Sutcliffe模型效率系数超过65%,水量模拟误差也较小,该模型在山西省具有较好的适用性,可以用于山西省水资源评价等方面的科学研究。  相似文献   
79.
目前针对受震灾威胁、地质灾害频发的山地环境下的农村居民点布局研究尚不多见。该文以彭州市龙门山镇银厂沟流域为例,首先在总结分析区内地质灾害发育特征的基础上,基于8项指标进行地质灾害危险性分区; 然后,将地质灾害危险性区划结果作为影响农村居民点用地适宜性评价的首要因素,再结合地形条件、社会经济和生态环境等方面,以地质灾害极高危险区、单体地质灾害危害范围、坡度≥25°和基本农田保护区为限制性条件,构建地质灾害威胁下的农村居民点用地适宜性评价指标体系; 最后,采用模糊综合评价法对彭州市银厂沟流域内居民点用地适宜性进行评价分级。研究结果表明: 高度适宜区占研究区总面积的4.2%,中度适宜区占11.4%,低度适宜区占10.5%,不适宜区占73.8%; 农村居民点用地“适宜”区域主要沿公路分布,并存在多个“块状”集中分布区,这些地区地形平坦,交通条件便利,可为新农村住宅位置的选择提供指导意见。  相似文献   
80.
黄健文 《地震工程学报》2019,41(4):1060-1065
当前新型乡村抗震防灾适宜性规划分析中通常采用地质分区方法对勘测点进行分析,在分析过程中忽略了GIS空间的复杂性,且未对评价指标加权分析,导致抗震适宜性评价指标量化过程过于主观,存在计算结果与实际结果拟合度低的问题。据此,提出基于ANSYS的新型乡村抗震防灾适宜性规划模型分析。考虑到GIS的空间复杂性,采用ANSYS在GIS空间进行有限元结构场修正操作,结合Logistic非线性回归模型,对乡村土地抗震防灾适宜性规划中的二分类变量数据进行非线性回归分析。为了防止计算数值过于主观,采用组合熵系数模型对Logistic方程计算得来的评价指标加权,由此完成基于ANSYS的新型乡村抗震防灾适宜性规划模型分析。经过实例分析证明,所提方法求出的计算结果与实际结果拟合度较高,能成功完成评价指标的量化,对乡村抗震防灾适宜性规划分析更加客观。  相似文献   
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