中国县域粮食产量与农业劳动力变化耦合关系研究（英文）

In this paper we establish a model that expresses the coupled relationship between grain yield and agricultural labor changes in China, and present a preliminary discussion of the coupled processes involved in changes in these factors at the county level. Thus, we develop two coefficients on the basis of county-level statistical data for grain yield and agricultural labor for the years 1991, 2000, and 2010, namely, the grain-labor elasticity coefficient(GLEC) and the agricultural labor-transfer effect coefficient(ALTEC). The results of this study show that during the transformation process of agricultural development in China, different kinds of coupled relationships between grain yield and agricultural labor changes co-existed at the same time. For example, between 1991 and 2010, counties characterized by three different coupled modes(i.e., increasing grain yield and decreasing agricultural labor, increasing grain yield and agricultural labor, and decreasing grain yield and agricultural labor) account for 48.85%, 29.11%, and 19.74% of the total across the study area, respectively. Interestingly, a coupled relationship between increasing grain yield and decreasing agricultural labor is mainly concentrated in the traditional farming areas of China, while a coupled relationship between increasing grain yield and agricultural labor is primarily concentrated in pastoral areas and agro-pastoral ecotones in underdeveloped western China. At the same time, a coupled relationship between decreasing grain yield and agricultural labor is concentrated in areas that have experienced a rapid development transition in agriculture, especially the developed southeastern coast of China. The results of this study also show that between 1991 and 2010, 1961 counties experienced a decline in the proportion of agricultural labor; of these, 1452 are also characterized by increasing grain yield, 72.38% of the total. This coupled relationship between grain yield and changes in the proportion of agricultural labor shows a stepped fluctuation and has continually strengthened over time. Data show that mean values for the GLEC and ALTEC increased from –0.25 and –2.93 between 1991 and 2000 to –0.16and –1.78 between 2000 and 2010, respectively. These changes in GLEC and ALTEC illustrate that the influence of agricultural labor changes on increasing grain yields has gradually diminished. Finally, the results of this study reveal that the ‘Hu Huanyong Line' is a significant boundary sub-dividing this coupled relationship between grain yield and changes in agricultural labor.     

The spatio-temporal variations of frost-free period in China from 1951 to 2012

The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFFD and LFD is beneficial to reduce the harmful impacts of climate change on agricultural production and enhance the agricultural adaptation. This study examined daily minimum temperatures for 823 national-level meteorological stationscalculated the values of FFDLFD and FFP for station-specific and region-specific from 1951 to 2012estimated the gradients of linear regression for station-specific moving averages of FFDLFD and FFPand assessed station-specific time series of FFP and detected the abrupt change. The results as follows: at both the station level and the regional levelthe FFP across China decreases with the increase of latitude from south to northand with the increase of altitude from east to west generally. At the station levelthe inter-annual fluctuations of FFDLFD and FFP in south and west agricultural regions are greater than those in north and east. At the regional levelexcluding the QT regiontemporal changes of FFP are relatively small in both the low-latitude and the high-latitude regionsbut for the mid-latitude regions. According to the linear trend gradients of the moving average values of station-specific FFDLFD and FFPFFD was delayedLFD advancedand FFP extended gradually over the 80% of China. Furthermorethe change magnitudes for FFDLFD and FFP in the north and east agricultural regions are higher than that in the southern and western. Among the 659 station-specific time series of FFP examined by the Mann-Kendall test341 stationslocated mainly in the north regionhave one identifiable and significant abrupt change. And at the 341 stations with identified abrupt changesmost(57%) abrupt changes occurred during 1991–2012followed by the periods of 1981–1990(28%)1971–1980(12%)and 1951–1970(3%). The spatio-temporal variations of FFDLFD and FFP would provide important guidance to agricultural practices.     

过去百年尼泊尔耕地时空变化（英文）

In order to advance land use and land cover change(LUCC) research in Nepal, it is essential to reconstruct both the spatiotemporal distribution of agricultural land cover as well as scenarios that can explain these changes at the national and regional levels. Because of rapid population growth, the status of agricultural land in Nepal has changed markedly over the last 100 years. Historical data is used in this study, encompassing soils, populations, climatic variables, and topography. Data were revised to a series of 30 m grid cells utilized for agricultural land suitability and allocation models and were analyzed using a suite of advanced geographical tools. Our reconstructions for the spatiotemporal distribution of agricultural land in Nepal reveal an increasing trend between 1910 and 2010(from 151.2 × 10~2 km~2 to 438.8 × 10~2 km~2). This expanded rate of increase in agricultural land has varied between different eco, physiographic, and altitudinal regions of the country, significantly driven by population changes and policies over the period of this investigation. The historical dataset presented in this paper fills an existing gap in studies of agricultural land change and can be applied to other carbon cycle and climate modeling studies, as well as to impact assessments of agricultural land change in Nepal.     

改革开放以来中国农业政策效果的时空计量分析

Since reform and opening up, how much contribution has China’s implementation of new agricultural policy made to agricultural output? This paper is trying to establish an agricultural policy output econometric model for doing a quantitative analysis of China’s new agricultural policy. The results show that China’s agricultural policies on agricultural output have an average contribution rate of about 7% since 1978, which is consistent with the OECD’s basic forecast. There are obvious temporal and spatial differences. Generally speaking, we can divide the contribution of agricultural policy into three periods, which are the start-up phase from 1978 to 1991 (14 years), the stationary phase from 1992 to 2002 (11 years) and the rising phase from 2003 to 2008 (6 years). In space, the contribution of agricultural policy underwent a process from the all-low in the start-up phase, the gradual increase in the stationary phase to the all-high in the rising phase. Northern and western regions are more sensitive to policies. There are three major factors that can affect the contribution of regional agricultural policies, which are the process of national industrialization strategy, terrain and the level of local finance.     

Preface

<正>China has a 5000 year history of agricultural civilization.Diversified natural and cultural features across regions have led to a variety of agricultural heritage systems,which continue to inspire sustainable development.In 2005,the Qingtian Rice-Fish Culture System was selected as one of the first Globally Important Agricultural Heritage Systems(GIAHS)pilot sites by the FAO,which opened new prospects for research and practiceon agricultural heritage conservation.This new period of research     

中国农业劳动力变化与农业经济发展及其对乡村振兴的启示（英文）

Based on panel data from 1991, 2000 and 2010 at the county level in China, this study analyzed the coupling characteristics and spatio-temporal patterns of agricultural labor changes and economic development under rapid urbanization using quantitative and GIS spatial analysis methods. Three primary conclusions were obtained.(1) During 1991–2010, China's agricultural labor at the county level showed a decreasing trend, down 4.91% from 1991 to 2000 and 15.50% from 2000 to 2010. In spatial distribution, agricultural labor force has evolved by decreasing eastward and increasing westward.(2) During 1991–2010, China's agricultural economy at the county level showed a sustained growth trend, with a total increase of 140.13%, but with clear regional differences. The proportion of agricultural output in national GDP gradually decreased, characterized by decreases in eastern China and increases in western China.(3) The coupling types of economic-labor elasticity coefficient are mainly growth in northwest China, for both the agricultural economy and labor, and are intensive in southeast China, with growth of the agricultural economy and reduction of agricultural labor. Regions with lagged, fading, and declining coupling types are generally coincident with the high incidence of poverty in China. However, different coupling types had a positive developing trend for 1991–2010. Finally, based on the coupling types and spatial distribution characteristics of economic-labor elasticity coefficients, some policy suggestions are proposed to promote the integration of the primary, secondary, and tertiary industries and the vitalization of rural economies.     

Monthly calibration and optimization of ?ngstr?m-Prescott equation coefficients for comprehensive agricultural divisions in China

?ngstr?m-Prescott equation (AP) is the algorithm recommended by the Food and Agriculture Organization (FAO) of the United Nations for calculating the surface solar radiation (R_s) to support the estimation of crop evapotranspiration.Thus,the a_s and b_s coefficients in the AP are vital.This study aims to obtain coefficients a_s and b_s in the AP,which are optimized for China’s comprehensive agricultural divisions.The average monthly solar radiation and relative sunshine duration data at 121 stations from 1957–2016 were collected.Using data from 1957 to 2010,we calculated the monthly a_s and b_s coefficients for each subregion by least-squares regression.Then,taking the observation values of R_s from 2011 to 2016 as the true values,we estimated and compared the relative accuracy of R_s calculated using the regression values of coefficients a_s and b_s and that calculated with the FAO recommended coefficients.The monthly coefficients,a_s and b_s,of each subregion are significantly different,both temporally and spatially,from the FAO recommended coefficients.The relative error range (0–54%) of R_s calculated via the regression values of the a_s and b_s coefficients is better than the relative error range (0–77%) of R_s calculated using the FAO suggested coefficients.The station-mean relative error was reduced by 1%to 6%.However,the regression values of the a_s and b_s coefficients performed worse in certain months and agricultural subregions during verification.Therefore,we selected the a_s and b_s coefficients with the minimum R_(s )estimation error as the final coefficients and constructed a coefficient recommendation table for 36 agricultural production and management subregions in China.These coefficient recommendations enrich the case study of coefficient calibration for the AP in China and can improve the accuracy of calculating R_s and crop evapotranspiration based on existing data.     

中国山区耕地利用边际化过程机理——基于成本和收益变化的分析（英文）

Farmland marginalization has become the main trend of land-use change in the mountainous areas of China. Using annual survey data of major agricultural production costs and earnings at national and provincial levels in China, this study aims to analyze the reasons and mechanism behind farmland marginalization in mountainous areas. We find that farmers on plains are able to reduce their per mu labor input effectively through intensive use of agricultural machinery, which has minimized the impact of the increase in labor price. However, it is extremely challenging for farmers in mountainous areas to use the same method owing to the rough terrain. Thus, per laborer farming area in these areas has increased relatively slowly, causing a widening gap in agricultural labor productivity between the two regions. With the rapid rise in labor costs since 2003, the marginalization of cultivated land in mountainous areas is evident. In 2013, the net profit of agricultural production in mountainous China fell below zero. Since 2000, the land-use and land-cover change in these areas was characterized by the reduction of farmland area, reforestation, and the enhancement of the NDVI value. The high correlation between the NDVI change rate and the ratio of change in farmland(r = –0.70) and forest(r = 0.91) in mountainous areas at provincial level further attests to the trend of farmland marginalization there. Finally, we summarize the mechanism of such marginalization against the backdrop of the rapid increase in the opportunity cost of farming and the rapid fall of agricultural labor forces in mountainous areas. This study contributes to a deep understanding of the development process of farmland marginalization and abandonment as well as forest transition in Chinese mountainous areas.     

湘江中下游农田土壤和蔬菜的重金属污染

A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.     

生态退耕对中国农田生产力的影响(英文)

The changes in cropland quantity and quality due to land use are critical concerns to national food security, particularly for China. Despite the significant ecological effects, the ecological restoration program (ERP), started from 1999, has evidently altered the spatial patterns of China’s cropland and agricultural productivity. Based on cropland dynamic data from 2000 to 2008 primarily derived from satellite images with a 30-m resolution and satellite-based net primary productivity models, we identified the impacts on agricultural productivity caused by ERP, including "Grain for Green" Program (GFGP) and "Reclaimed Cropland to Lake" (RCTL) Program. Our results indicated that the agricultural productivity lost with a rate of 132.67×104 t/a due to ERP, which accounted for 44.01% of the total loss rate caused by land use changes during 2000-2005. During 2005-2008, the loss rate due to ERP decreased to 77.18×104 t/a, which was equivalent to 58.17% of that in the first five years and 30.22% of the total loss rate caused by land use changes. The agricultural productivity loss from 2000-2008 caused by ERP was more attributed to GFGP (about 70%) than RCTL. Although ERP had a certain influence on cropland productivity during 2000-2008, its effect was still much less than that of urbanization; moreover, ERP was already converted from the project implementation phase to the consolidation phase.     

Impact of land use change on soil resources in the peri-urban area of Suzhou city

The Yangtze delta area is among the fastest developing areas in China. Here there are mega-cities like Shanghai, Nanjing and the attached urban areas of different sizes including those along the lower reaches of the Yangtze River from Shanghai up to Nanjing as well as their satellite cities and towns, forming one of the most densely distributed urban areas in China. This is a case study done in Suzhou city at the center of the Yangtze delta to reflect the impact of urban sprawl on soil resources using satellite images and digital soil databases. The extent of the developed land in the studied area and the impact of development on soil resources at 1:100,000 scale are estimated and the soil types impacted most by urbanization development are determined through overlaying the soil map on the satellite images (Landsat-7) of the studied area at different times (1984, 1995, 2000 and 2003). The methodology for this study consists of analyzing data resulting from using a geographic information system (GIS) to combine urban land use maps of different times derived from satellite images with data on soil characteristics contained in the established soil databases by which some results come into being to present the fast expanding trend of urbanization in the Yangtze delta area, the urban spread and the soils occupied by the urbanization process, and also the quality of the occupied soils.     

长江三角洲地区城市空间扩展研究

城市化是建设用地扩展的主要驱动因素,分析建设用地时空演化格局已成为学者研究城市化过程的重要视角。采用空间自相关等方法,测度了1985年以来长江三角洲地区城市空间扩展的集聚特征并分析其演变过程;并结合格网建设用地密度频率的变化特点,将空间划分为不同的景观梯度地带,以此研究城市空间在不同地带中的扩展特点。研究结果表明,长三角城市空间扩展聚集程度先降后升,城市化区域融合趋势明显,并在城市空间扩展中表现出以上海、南京和苏州等为代表的3种模式,反应了长三角内部不同的经济发展特点。此外,在不同景观梯度下,长三角城市空间扩展表现出典型的阶段性特征。2000年以前在各个景观梯度下城市空间扩展差异较小,表现为较强的拓展性扩展;2000年以后,在城市核心区扩展强度加强,表现为填充式扩展加快。同时,城乡过渡区面积增加迅速,表明随着城市空间扩展的加速,长江三角洲地区城市土地不集约利用现象已较为突出。     

长江三角洲地区城市用地增长的时空特征分析

以Landsat MSS、TM、ETM 卫星影像为主要数据源,利用遥感和GIS 手段,提取了长江三角洲地区5 个时相(1979 年、1990 年、1995 年、2000 年、2005 年) 城市用地信息,分析了城市用地扩展速度、扩展强度、空间结构的变化特征,进而探讨了长江三角洲1979 年以来的城市空间生长过程。结果表明：① 1979 年以来,长江三角洲城市用地增长呈明显的加快趋势,城市用地总体扩展强度也表现为不断提高。不同行政等级城市用地的扩展强度表现为直 辖市> 地级市> 副省级市> 县(县级市)。② 长江三角洲城市用地空间结构的分维和稳定性特征具有一定的波动性。城市用地的空间结构特征与城市用地增长过程和发展阶段具有一定的联系。③ 长江三角洲城市生长表现出“一核二带”、“二核三带”、“四核四带”和“五核五带”的空间轨迹。     

城市化对南京地区土壤多样性影响的灰色关联分析

随着城市化的发展,越来越多的土壤资源被侵占。本文借助RS和GIS技术,根据1984年、1995年、2003年3期TM遥感影像 (30m×30m),采用多时相连续对比法对南京地区近20年来城镇扩张情况进行了分析;结合南京地区土壤图,利用生态学领域中的多样性测度方法计算了城市化背景下南京地区的土壤多样性指数 (HP)、土壤均匀度指数 (Jsw) 和土壤丰富度指数 (R₂),进而在镇级尺度上对1984~2003年南京地区土壤多样性时空变化特点进行了研究;利用灰色系统理论中的灰色关联分析方法,对南京地区各级行政区划单位的扩张对土壤多样性的影响进行了初步探讨。分析结果表明,各级行政区划中村庄的扩张对土壤多样性指数的影响最广,约占研究区总面积的60%;镇、县和市的扩张对土壤多样性的影响逐渐减少,各占研究区总面积的26%、7%和7%。     

南京大都市区建设用地扩张特征与机理

作为全球城市化最快的地区之一,中国建设用地的扩张引起了广泛的关注。以长三角北翼中心城市南京为例,利用遥感、土地利用调查等数据研究大都市区建设用地扩张的过程、格局与机理。研究表明,1985-2007年南京市在工业化、城市化和国际化的推动下经济快速增长,引致了建设用地的扩张,年均增长率为3.14%。2001年后随着城市发展模式由单中心向多中心转换,建设用地呈加速扩展趋势。南京市建设用地扩展具有明显的沿长江和南北交通走廊轴向发展的特征。开发区和新城建设是南京市建设用地扩张的主要方式。区、县尺度的回归分析表明,人口增加、全球化是城镇工矿用地扩张的重要推手;经济的服务业化有利于土地集约利用,减少对用地的需求,这种影响在城区更大;在分权化竞争中,都市区政府具有更强的控制力。     

长三角地区城市土地与能源消费CO2排放的时空耦合分析

探究城市土地与碳排放的时空耦合关系,是协调城市土地与生态环境亟待解决的重要问题。基于重心模型、总体耦合态势模型和空间耦合协调模型,使用建成区面积、能源消费和DMSP/OLS夜间灯光等数据,分析了1995—2013年长三角地区城市土地与能源消费碳排放的时空耦合特征,并考虑空间因素的影响,构建空间滞后面板Tobit模型分析其驱动因素。结果表明：① 1995—2013年,建成区面积与碳排放量总体上均呈增加趋势。建成区面积由1251 km ²,增加至4394 km ²,碳排放量由30389.49万t,增加至90405.22万t。城市土地与碳排放间呈显著的正相关;② 城市土地与碳排放空间差异明显,上海、南京、杭州、苏州和无锡的城市建成区面积相对较大,碳排放相对较高;③ 长三角地区城市土地与碳排放耦合关系总体上呈减弱-增强-波动的态势。协调关系处于不断演化过程中,低协调阶段的城市数量明显减小,高协调阶段的城市数量明显增加,且呈集聚分布特点。南京、无锡、苏州、杭州和宁波处于高协调阶段;④ 空间滞后面板Tobit模型结果表明：城镇化对城市土地与碳排放耦合协调度具有驱动和制动的双重作用。同时,人口密度、经济水平、产业结构和空间因素对其也具有重要影响。     

南京市区建设用地扩张模式、功能演化与机理

以南京市区不同时段遥感影像为基础,在综合凸壳方法与公共边方法基础上,通过矩阵分析对1985-2007年南京市区建设用地扩张模式进行划分,探讨不同扩张模式的空间结构特征。结果表明：① 1985年以来,南京市区建设用地扩张迅速。其中,填充扩张由主城区逐渐向外推移,飞地扩张分散在远离主城区的开发区、工业园及大学城内,蔓延扩张则介于二者之间,多表现为前期扩张的继续发展。② 功能上,填充扩张由居住主导向居住与工业混合转变;蔓延扩张由居住与工业混合向工业主导转变;飞地扩张一直以工业主导,并伴随科教的区域性集中。③ 驱动机理,填充与蔓延扩张属于收益驱动型,飞地扩张更多地受成本制约。随着城市空间向外拓展,建设用地扩张的成本约束作用均逐渐加强;而城市建设用地中工业用地比重的增加,又使三种扩张模式的收益驱动作用加强。     

长三角城市群城镇化与生态环境质量优化研究

以2003—2016年的长三角城市群26个城市为研究对象,分析长三角城镇化和生态环境的时空变化特征,运用STIRPAT模型探讨城镇化对生态环境影响。结果表明:① 2003—2016年,长三角城镇化与生态环境质量均有提升,且城镇化水平的地区差异大于生态环境质量。长三角形成以上海、南京和杭州为中心的城镇化水平高值集聚,生态环境质量整体提升明显且空间差异小。② 长三角城镇化明显改善本城市生态环境质量,对相邻城市的生态环境质量有一定的负面影响。对本城市而言,多维的城镇化从人口、经济、土地、社会层面疏解生态环境压力,加强生态环境治理,优化提升生态环境质量。以人口集聚和结构优化为特征的人口城镇化,促进消耗集中、排放集中,提升了资源使用效率和污染治理效率。以产业集聚和经济发展为特征的经济城镇化,通过产业集中布局和创造经济效益,在资源配置和污染治理上发挥集聚效应,并为生态环境改善提供资金支持。对相邻城市而言,城市的城镇化“虹吸效应”大于“扩散效应”,城市的产业转型和环境规制会使污染向相邻城市转移,从而对相邻城市生态环境质量有一定的负面影响。     

中国中、东部典型样区不同发展水平下土壤与土地利用多样性的对比分析(英文)

Two typical provincial capitals (Nanjing and Zhengzhou) and two counties (Rugao and Yuanyang) in east (Jiangsu Province) and central (Henan Province) China were chosen respectively as the developed and less developed comparative cases for pedodiversity and land use diversity correlative analysis by borrowing the recently better developed pedodiversity methodology. Land use classification was worked out using remote sensing images in three different periods (1986-1988, 2000-2001 and 2004-2006) for these studied case areas before the calculation of the constituent diversity index and spatial distribution diversity index modified after Shannon entropy in 2 km×2 km grid scale of the soil and land use pattern were conducted and then a connection index was proposed to evaluate the relationship between soil and land use diversity. Results show that during the years from 1986 to 2006, the composition and spatial distribution of regional land use pattern had changed greatly. The agricultural land area of all the studied case areas decreased obviously in which Nanjing has the highest decrement of 895.98 km 2 mainly into urban use while the other land use type area changes show the same trend. The connection index of four typical soil family types and typical urban land use types, i.e., urban construction land, transportation land and industrial and mining area all increased in this period. In the studied case areas, there is the highest soil constituent diversity in Zhengzhou at 0.779 while the simplest soil constituent diversity in Rugao at 0.582. Meanwhile we have higher land use diversity in the more urbanized Jiangsu Province than Henan Province, Nanjing is ranking the first that has been getting higher and higher in the three periods at 0.366 in 1986-1988, 0.483 in 2000-2001 and 0.545 in 2004-2006. Finally, the connection index figures to evaluate the relationship between soil and land use diversity of the studied areas were compared to show the similar phenomenon that this figure grows fastest in Nanjing followed by Zhengzhou and other places.     

城市化过程中土地利用变化对区域滞洪库容量的影响研究——以南京市河西地区为例

通过对两期LandsatTM遥感影像进行监督分类,提取近20年南京市河西地区土地利用变化状况,用转移矩阵、迁移概率和迁移量比重模型来说明河西地区的土地利用变化,并根据地表状况和土壤的压实程度提出了不同土地利用类型的区域滞洪库容量计算模型,从而估计土地利用变化对水分调节功能的影响。研究发现:①河西地区土地利用变化的主要特征为以其他土地利用类型向建筑用地的转移为主,旱地内部的转移和水田向旱地(主要是菜地)的转移也占有一定的比重;②由于地表封闭和种植结构的改变导致区域滞洪库容量大量损失,1986年到2003年总滞洪库容量减少了550.40万m³其中因建筑用地面积的增加使地表封闭而减少的滞洪库容量高达482.15万m³,相当于整个研究区域86mm水深;③局部范围的土壤压实只对局部的滞洪库容量产生影响而对区域的总的滞洪库容量的影响不大,1986年到2003年因土壤压实而减少的滞洪库容量只有3.12万m³,只占总滞洪库容减少量的0.54%。研究表明减少地表封闭是防止城市瞬时洪涝灾害的重要方面。