【作者】 郭睿；

【导师】 李凤民； 孙国钧；

【作者基本信息】 兰州大学 ， 生态学， 2012， 博士

【摘要】 中国黄土高原半干旱地区生态环境脆弱。对土地的不当使用——不合理的耕作、过度放牧和不合理的生态建设实践——都加剧了区域水土流失,水资源短缺,进而影响了整个地区的生态保护和农业发展进程,使区域可持续发展面临严峻挑战。本研究选取祖厉河流域为例,对农草土地的合理利用进行分析。在考虑了集水技术应用和水土流失预防的基础上,划分了祖厉河流域农草土地利用的适宜区域,具体包括：淤地坝的适宜建设区域分析；基于就地微集水技术的农田适宜区域分析；主要农作物及田间就地微集水技术(沟垄覆膜)的适宜区域分析以及苜蓿草地的区域适宜性分析,给出了全流域提高农草生产力并有效控制水土流失的农草土地利用结构。1.淤地坝具有拦截泥沙和集蓄降水的能力,是防治水土流失提高农业生产力的有效方法。研究通过实地调查,建立了淤地坝地理位置,功能状况,淤积年限,淤积库容,可淤积面积的数据库。采用径流曲线模型(Soil Conservation Service,SCS)模拟祖厉河流域径流量(经实测径流量数据验证,该模型有效)。以流域河网的200m缓冲区提取,以150m3／hm2和250m3／hm2径流量为界划分,得到了淤地坝的最适宜,中度适宜和不适宜三个区域。结果显示定西市白碌乡,石峡湾乡,称钩驿乡等乡均是淤地坝最适宜修筑的地区。与实际数据比较,其中93.5%的坝都建在适宜度最高的地区,仅有6.5%的坝坐落在本结果中度适宜和不适宜修建淤地坝的地区。划分结果与实际情况匹配,验证了划分结果的可靠性和有效性。其中大部分适宜建设淤地坝的区域在定西市境内,而会宁市部分地区不适宜用淤地坝来治理水土流失。根据该划分结果,以定西市城关乡为例,为淤地坝的建设提出了规划方案,并模拟了这些坝的淤积年限,淤积库容及可淤积面积,结果显示根据该规划方案可以有效的拦泥淤地。2.控制水土流失、改善生态环境不能仅依靠淤地坝的功能,其长久之计在于优化土地利用,合理利用降水资源。根据1989-2000年会宁、峻口、郭城驿和靖远水文站的实测径流量和输沙量数据构建回归模型,在GIS平台上模拟了土壤侵蚀空间分布。选择土壤侵蚀,径流量和坡度为评判标准,运用理想点法划分了5个等级,将第4级和第5级定义为祖厉河流域适宜进行农业耕作的地区；第1级定义为不适宜耕作的地区。根据该结果,与实际的土地利用状况对比,多数利用不合理的土地分布在流域的西北及东南部,对这些区域建议退耕还草。3.农作物的合理布局也是农牧业地区土地合理利用的关键。通过文献查阅收集该流域主要作物(小麦、玉米和马铃薯)对环境因素的需求。以作物最适宜生长的环境条件为评判标准,运用层次分析法建立模型,划分并通过地图形式表达了该流域三种主要作物的推荐种植区；结合流域半干旱的自然现状,研究了微集水技术(沟垄覆膜)对作物适宜种植区的影响,划分了微集水技术的适宜应用区域,结果表明该技术对流域东北大部分地区的影响最高,将该等级的地区定义为沟垄覆膜技术的最优推广区。该研究为流域应对市场需求变化时,快速准确的在合理区域进行农作物种植比例调整提供了解决方法,为农业产业化,农业整体决策提供科学依据。4.以苜蓿为例,分析了祖厉河流域退耕还草对生态环境的影响。选择苜蓿产量,土壤容重,土壤水分和土壤C、N含量为评判标准,采用熵权法建立评价模型,对苜蓿在流域北部和南部地区的生长年限分别做了综合比较分析。结果表明,在流域的北部种植苜蓿的年限最长以9年为宜,在流域的南部以6年为宜,推荐种植年限之后,综合指数显著下降。最后以地图形式表达了苜蓿在祖厉河流域的产量分布情况。该方法解决了苜蓿种植的合理年限问题,使苜蓿即改善了土壤环境又避免苜蓿的长期生长对土壤造成干层,也为其它区域苜蓿合理种植年限的确定提供方法。整个研究以土地的合理利用为基础,围绕着农业和牧业的高效利用展开,利用GIS为平台,为农田、农作物和牧草(以苜蓿为例)的合理利用进行了分析研究,最终达到减少土壤侵蚀,提高水资源的利用率,提高农业生产力的目的。更多还原

【Abstract】 The eco-environment is fragile in semi-arid areas of the Loess Plateau, China. Improper uses of land like unreasonable farming, overgrazing aggravate soil erosion and the shortage of water resource. All of the above influence the sustainable development of ecology, agriculture and eco-safety. In this study, the Zuli River Basin was selected to study the rational use of agricultural and grass land. Combining water harvesting techniques and soil erosion prevention, the suitable areas for agriculture and grass were analyzed. The study includes:suitable areas for silt storage dams; suitable areas for farmlands; suitable areas for the main crops and micro-water harvesting techniques; suitable areas for alfalfa. Overall, the rational land use for agricultural and grass which can improve the productivity and control soil erosion was delineated.1. The silt storage dam has the ability to intercept sediment and harvest precipitation is an effective way to control water and soil losses. Through field investigation, the databases of location, status, year et al were established. The runoff simulated by Soil Conservation Service (SCS) model and verified by the measured data. Then taking150m3/hm2and250m3/hm2as the boundaries, the suitable areas for silt storage dam were divided by200m buffer of gullies. The results show that the most suitable areas for silt storage dam are in Dingxi Bailu country, Shixw country, Chenggy country and so on. Compared with the actual data,93.5%of the dams are built on the most suitable regions and only6.5%of the dams are built on the moderately suitable and unsuitable regions. Through comparison simulation results and actual result, this method is proved to be reliable. Then, according to this result, a plan scheme for the construction of silt storage dams was proposed in Chengguan country Dingxi city, and the years, capacities and areas for dams were also simulated, the results show that the dams could intercept soil effectively under this planning scheme.2. A long-term solution to control soil erosion and improve the ecological environment is to optimize land use and use precipitation rationally. The spatial distribution of soil erosion was simulated and validated by the measured runoff and sediment data in Huining, Chankou, Guochengyi and Jingyuan stations during1989-2000. Select soil erosion, runoff and slope as criteria, the suitable areas for agriculture was divided by the ideal point method into5levels, class4and5were defined as suitable areas for farmlands and calssl was defined as unsuitable regions. According to this result, the reasonable and unreasonable land uses were analyzed comparing with the actual land use, most of which were in the northwest and southeast of the basin.3. The rational distribution of crops is also the key when it comes to rational land use for agriculture. Based on literatures, the crops’demands for environment were collected. Based on the standard of the most suitable environmental conditions for crops, the suitability maps for these chief crops (wheat, corn and potato) were obtained by the Multi-Criteria Evaluation Approach. Considering the basin is in semi-arid areas, the effect of the technology of double ridges and furrows on the suitable areas for crops was also analyzed. The result shows the most suitable areas for this technology are in northeast of the basin. This study delineated the suitable areas for chief crops which offer consults and scientific basis to adjust agricultural production.4. Taking alfalfa as an example, the impact of returning cropland back to grassland on ecological environment was analyzed. Select soil bulk density, soil moisture, soil contents of C, N and yield as the standards, the effect of alfalfa’s growth year on environment was analyzed by the Entropy Method in the northern and southern, respectively. The results show that the appropriate year for planting alfalfa in the northern of the basin is9years, and the appropriate year for planting alfalfa in the southern of the basin is6years, after the appropriate year, the composite index decreased significantly. Finally, the distribution of the yield of alfalfa in Zuli River Basin was displayed in the form of map. The method provides reasonable planting years for alfalfa to not only improve the soil environment but also avoid the dried layer of soil that could use for reference in other regions.The entire study centered around the effective use of agriculture and husbandry has highlighted the concept of taking the rational use of land as the foundation, analyzing the rational use of farmland, crop with its technology of double ridges and furrows and alfalfa to achieve the objective of reduce soil erosion, improve water utilization and productivity.更多还原