Basic farmland protection area based on morphological optimization and boundary identification
MUZhenglong, SHIPeiji, LIUChunfang, ZHENGHaisong College of Geography and Environment Science of Northwest Normal University, Lanzhou 730070, China 通讯作者:通讯作者:石培基,E-mail: xbsdspj@163.com 收稿日期:2017-03-27 修回日期:2017-10-10 网络出版日期:2018-01-20 版权声明:2018《资源科学》编辑部《资源科学》编辑部 基金资助:国家自然科学基金项目(41771130) 作者简介: -->作者简介:慕正隆,男,甘肃庆城人,硕士生,主要研究方向为城市与区域发展、国土整治。E-mail: mzlxbsd@163.com
关键词:耕地质量;空间集聚;基本农田保护区;边界识别;榆中县 Abstract Delimitation of basic farmland protection area is an important measure ensuring national crop security and improving comprehensive grain production capacity. However, the 2011 amendments to the “Regulations on the Protection of Basic Farmland” emphasized that high-quality farmland is only included in basic farmland protection areas. It did not make clear requirements for the protection region as well, which contributes to a large number of protected areas, long and obscure boundary lines, virtually increasing the risk of basic farmland being occupied. Therefore, taking country cultivated land in 2015 as an example, we adopted the method of step-by-step multi-factor comprehensive evaluation to optimize the basic farmland protection area based on farmland in Yuzhong County of 2015 and Moran' s I index spatial autocorrelation analysis and GIS. We found that the quality of cultivated land in Yuzhong County is at a moderate level, with an overall amount of 79.76% for high-quality farmland and middle-leveled farmland. High-quality (HH) and low-quality (LH) agglomeration area can be allocated as basic farmland protection area. After boundary identification, 11 designated basic farmland protection areas can be delimitated, with a total area of 75 878.17 hm2 including three plain areas, five hilly areas, and three mountainous areas. Compared with areas before optimization, we reached the goal of completing the overall land use planning to reduce the number of patches when patch unit area increases and the boundary line is shortened and cleared. The landscape pattern is optimized as well. Our research process and methodology provides a reference for the development of relevant work.
Keywords:cultivated land quality;spatial agglomeration;basic farmland protection area;boundary recognition;Yuzhong County -->0 PDF (9508KB)元数据多维度评价相关文章收藏文章 本文引用格式导出EndNoteRisBibtex收藏本文--> 慕正隆, 石培基, 刘春芳, 郑海松. 基于形态优化和边界识别的基本农田保护区研究[J]. 资源科学, 2018, 40(1): 22-31 https://doi.org/10.18402/resci.2018.01.03 MUZhenglong, SHIPeiji, LIUChunfang, ZHENGHaisong. Basic farmland protection area based on morphological optimization and boundary identification[J]. RESOURCES SCIENCE, 2018, 40(1): 22-31 https://doi.org/10.18402/resci.2018.01.03
榆中县地处甘肃省兰州市,地理位置介于35°34′20″N-36°26′30″N,103°49′15″E-104°34′40″E之间(图1),总面积3295km2,占兰州市的24.97%。地势南高北低,中部凹,呈马鞍形,地貌分南部山地、中部河谷川滩盆地、北部黄土梁峁沟谷丘陵区。耕地主要分布在梁峁顶部、沟谷底部以及河谷川滩盆地较平坦的区域[15]。全县由于地形复杂,降雨量分布极其不均,由东南向西北减少,东南部年均550mm以上,西北部却低于250mm[16]。地表水年总径流量5349万m3,主要有发源于南部马衔山、兴隆山的自产水和入境黄河客水,形成南山自流灌区、中部和西北部电灌区,是全县农业生产最宝贵的水资源[16]。榆中县现辖20个乡镇、168个行政村。2015年年末人口总数44.50万人,其中农业人口39.61万人,农民人均纯收入8100元。全县耕地面积111 926.29hm2,占兰州市总耕地面积的40%,有效农田灌溉面积占33.87%,是全市重要的农业县和国家高标准农田建设示范县。 显示原图|下载原图ZIP|生成PPT 图1研究区地理位置 -->Figure 1Location of the study area -->
耕地质量是多层次的综合概念,是指对耕地的自然、环境和经济等因素水平的综合评价[27]。内容包括耕地的地力质量、工程质量、空间质量、生态环境质量等[28]。本文以土地变更调查成果中的耕地图斑作为评价单元,拟从以上四个方面,同时考虑耕地的稳定性,构建耕地质量综合评价指标体系,借鉴张忠[3]、边振兴[29]、宋戈[30]等人百分赋值指标量化方法及取值区间的研究成果,确定本文指标量化结果。 (1)地力质量、工程质量依据农用地质量分等成果分别选取地貌类型、耕地坡度、年平均降水量、有效土层厚度、土体构型(土地的剖面结构)、土壤有机质含量、耕作层土壤质地7个指标[6,7,29,30]和灌溉保证率、田间道路通达度2个指标[3,8,28,31]。 (2)空间质量反映农田的区位条件,影响耕地的生产效率,选取田块距村庄的距离,田块距主干道的距离2个指标[9,10],其中田块距村庄的距离利用ARCGIS软件中的NEAR工具实现,田块距主干道的距离利用BUFFER工具实现。 (3)生态环境质量反映耕地可持续利用水平和农产品品质,选取土壤污染程度作为评价指标[11],依据环保部门提供的环境污染企业监测信息,征求环保部门意见,以污染企业为原点,一定距离为缓冲区半径,确定土壤污染范围,分为无污染和污染两种类型。 (4)耕地的稳定性反映耕地被占用或破坏的风险,选取规划用途、地质灾害2个指标[12,32,33],其中规划用途按土地利用总体规划确定,分为耕地用途和非耕地用途;地质灾害以灾害隐患点为原心,按照一定的半径和规则划定缓冲区,缓冲区之内确定为地质灾害区,耕地易受灾害损毁,分为灾害区和非灾害区。 指标权重采用层次分析法和德尔菲法综合确定。指标及其量化结果见表1。 Table 1 表1 表1耕地质量评价指标体系量化及权重 Table 1The quantification and weight of index system of cultivated land quality evaluation
榆中县耕地质量综合评价分值在9.71~94.62之间,平均值68.69,耕地整体质量中等。利用等距法,将榆中县耕地质量分为四种类型(图3a,见27页),分别为高等地、中等地、中下等地、低等地四种类型。高等地(分值73.4~94.62)占43.85%,中等地(分值52.17~73.39)占35.91%。高、中等地在平原区主要分布于中部盆地、宛川河谷地及西北部的青城镇,依靠黄河进行灌溉;在丘陵区主要分布于黄土梁、峁、沟谷中比较平坦的区域,集中在北部的309国道、324县道沿线的花岔乡、贡井乡、中连川乡和县域东南角的高崖镇、龙泉乡,该区域虽无灌溉,但由于交通便利,村庄集中,耕作条件成熟,是全县优质的旱作农业区;在山区主要分布于南部兴隆山和马衔山之间的沟谷地带,主要依靠山区冰雪融水形成的自流灌溉系统灌溉。中下等地(分值30.95~52.16)占耕地总面积的17.36%,低等地(分值小于30.95)占耕地总面积的2.88%。中下等地、低等地多分布于北部、东南部山区,中部县城规划区和南部兴隆山自然保护区范围内,田块零碎散乱。 显示原图|下载原图ZIP|生成PPT 图3基本农田保护区优化各阶段成果 -->Figure 3Basic farmland protection area optimization of the various stages of the results -->
优化后基本农田保护区与优化前榆中县土地利用规划(2009—2020年)、榆中县城市周边和全域基本农田划定成果相比:从目标上看,优化后保护区内基本农田面积占优化前的104.84%,能够完成土地利用总体规划确定的目标;从布局上看,空间布局与全域基本农田划定成果重合比占95.44%,与实际划定成果相符。优化后,图斑数量减少,单位面积增大,保护区边界线长度大大降低且明晰;景观分维数、边缘密度、形状指数都有所降低,景观形态得到进一步优化。从地貌单元来看,增大了平原区基本农田比例,将平原区集中连片的优质耕地划入了基本农田,同时依据规划用途为城市建设预留了一定的发展空间;减少了丘陵区和山区的基本农田数量,主要是北部生态脆弱和南部兴隆山林区低质量、分散的耕地。因此,基本农田保护区形态优化和边界识别,使得基本农田更加集中连片,边界清晰规整,同时为城市建设预留了发展空间、避让了重要生态区。优化前后对比见表2。 Table 2 表2 表2基本农田保护区优化前后结果对比 Table 2Comparison of the results of the optimization of the basic farmland protection area
(1)本文采用逐级修正多因素综合评价、基于Moran's I指数的局部空间自相关分析、基于GIS的空间分析相结合的方法,以甘肃省榆中县为例,划定优质稳定、集中连片、保护边界清晰的基本农田保护区。与农用地分等成果相比,本文选择的耕地质量综合评价方法具有明显的优势,不仅考虑了农用地分等评价中的因素(地力质量、工程质量),还在此基础上增加了空间质量、生态环境质量、耕地的稳定性指标,主要原因是能够入选基本农田的优质耕地,不仅要求自然条件与农业工程措施良好,而且还要耕作半径适度、土壤未遭受污染、无地质灾害和城市建设不占用的耕地。与直接选择高质量耕地集中连片区作为基本农田保护重点区域相比,本文基于耕地的空间异质性特征,采用局部空间自相关分析方法,可以自动得到HH、HL、LH、LL四种类型。同时,从集聚区的结果来看,LH区穿插于HH区之中,将其纳入基本农田重点区域,可以减少保护区内部的空洞和边界长度,划入后便于统一管理。 (2)从耕地质量来看,榆中县耕地质量平均值68.69,整体中等。耕地质量共划分为高、中、中下和低四种类型,其中高等地与中等地合计占79.76%,是全县优质和稳定性高的耕地,在各地貌单元中均有分布。平原区分布于中部和西北角,丘陵区分布于北部和东南部黄土山梁、峁、沟谷中较平坦的区域,山区分布于南部两山之间的沟谷地带。从耕地质量集聚特征来看,共划分成HH、HL、LH、LL四种类型,其中HH、LH共有耕地75 071.65hm2,可作为划入基本农田的重点区域。 (3)经过边界识别,全县共划定11个基本农田保护区,总面积75 878.17hm2。其中平原区3个,占30.46%;丘陵区5个,占55.80%;山区3个,占13.74%。与形态优化前相比,本次划定的保护区能够满足土地利用总体规划确定的目标,图斑数量减少,图斑面积增大,保护区边界线长度降低,边界更加容易辨别,景观形态得到进一步优化。优化后,增大了平原区优质基本农田的数量,剔除了丘陵区和山区生态区的耕地,使得保护区内耕地更加集中连片,质量优良,便于开展高标准农田建设和管理。 The authors have declared that no competing interests exist.
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