KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 毛里塔尼亚努瓦克肖特地区土地沙漠化过程及其驱动环境研究 | |
| 周娜 | |
| Subtype | 博士 |
| Thesis Advisor | 雷加强 |
| 2017-05-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 新疆乌鲁木齐 |
| Degree Discipline | 理学博士 |
| Keyword | 沙漠化土地 沙漠化过程 西非地区 驱动环境 模拟预测 Desertification Land Desertification Progress West Africa Driving Environment Simulation Prediction |
| Abstract | 毛里塔尼亚伊斯兰共和国位于非洲西撒哈拉地区，素有“沙漠共和国”之称。毛里塔尼亚首都努瓦克肖特是全国最大的城市，同时受到海洋与沙漠的双重威胁。在气候和人类活动因素的共同作用下，该地区环境出现了一系列严重问题，沙漠化的危害尤其严重。所以研究努瓦克肖特地区土地沙漠化现状及其时空分布格局，探讨沙漠化发展的驱动环境，预测沙漠化发展趋势，对于将来更好的开展荒漠化防治工作，以及该地区的可持续发展有着重要而深远的意义。本研究选取努瓦克肖特首都地区，通过对研究区 5 个时期（1985 年、1988年、2000 年、2006 年和 2010 年）沙漠化土地和不同土地利用类型的遥感解译与分类处理，研究了该地区 1985 年-2010 年五期沙漠化土地时空变化特征，并在整理分析长时间序列气象、人口与牲畜数据基础上，进一步分析了影响土地沙漠化时空变化的驱动力，通过 Geo-SOS 模型模拟，对该地区未来 10 年的土地沙漠化状况进行了预测研究。结果表明：研究区从 1985 至 2010 年间，沙漠化土地发展趋势以 2000 年为分界点，呈现二段式分布。1985-2000 年间，沙漠化过程处于正向发展阶段，2000-2010 年间，沙漠化过程处于逆向减少阶段。沙漠化土地转化较为频繁的类型是极重度沙漠化土地与重度沙漠化土地。非沙漠化土地中，城镇用地与人工绿地一直处于增长趋势。从空间分布来看，沙漠化土地发生逆转的区域主要分布于城镇用地的周边和东南部区域，而发生沙漠化正向进程的地区则主要分布与城市的东北部及东南部区域。从自然驱动力来看，通过对该地区最高温、最低温、降雨的趋势及周期变化分析，气温的升高，降雨的减少，使该地区气候向暖干的方向发展，在这种气候环境下，极有可能促进土地沙漠化的发展；但是由于该地区有雨季和旱季之分，所以气候变化对土地沙漠化的影响存在着季节差异。该地区平均风速具有明显的阶段性，可分为偏强期和偏弱期。1980 年为转折年份，在 1960 年至 1980 年，该地区风速偏弱；1981 年到 2011 年为偏强期。流动沙丘的动态变化作为沙漠化进程的主要表征之一，其景观的斑块数量与形态的破碎度与沙漠化程度有这一定关系，流动沙丘的景观斑块数量破碎化的增大，会促使沙漠化程度的加剧。通过对该地区沙丘粒度的研究，发现该地区纵向沙丘物质组成主要以细沙和极细沙为主，该地区沉积环境则以风成和沿岸盐沼沉积为主。结合自然驱动力，在降雨量多的年份，降雨会成为该时期植被恢复的主要因素；但在降雨少或者无降雨的时期，人类活动作为沙漠化的驱动因素之一则成为了沙漠化正逆发展的主要影响因素。人口的增长，GDP 的增长，城市土地的扩张，畜牧业的发展，无一不对土地利用产生巨大的压力，特别是本身就很脆弱的沙漠化土地，这都为土地沙漠化进程ᨀ供了潜在的有利条件。综上，通过 Geo-SOS 模拟得到 2021 年模拟预测结果，结果表明在气候条件与 2000-2010 年相似等情况下，2021 年努瓦克肖特地区沙漠化土地面积总体上将呈减少趋势。 |
| Other Abstract | Mauritania located in the western Sahara, which not only is one of the world's poorest countries, but also is the driest country in Africa. Nouakchott is capital and the largest city of Mauritania, but this city suffers erosion from both ocean and desert. Under the combined effect of climate and social economic factors, the environment of this area is in serious troubles, especially the desertification was recognized as the greatest threat to life. Therefore, the study on process of desertification in Nouakchott and analysis the driving factors could facilitate desertification prevention, and could bring important and far-reaching significance for sustainable development of the region. In this study, high-resolution remote sensing image obtained during the winter in 1985, 1988, 2000, 2006 and 2010 in Nouakchott were selected for interpretation and classification. By analyzing the types of desertification land and land use, we have revealed the temporal and spatial characteristics of five periods from 1985 to 2010. According to the temporal and spatial variation in the study area, we further analyzed the factors driving the spatial and temporal changes of desertification, and carried on simulation study about land desertification in the next 10 years in this region. The results show that the desertification trend had divided from 2000. Specifically, desertification process was in a positive development phase from 1985 to 2000, while the desertification process was in reverse reduction stage from 2000 to 2010. The desertification transformation frequently occurred in extremely severe desertification land and severe desertification land. In normal region, the area of urban land and artificial green land has been in a growth trend. From the view of spatial distribution, the desertification reversal area mainly distributed in the neighboring and Southeast of urban, while the process of desertification mainly occurred in southeast and northeast area of city. By analyzing the periodic variation trend of the highest temperature, the lowest temperature and rainfall, we found the temperature rising and rainfall reducing warmed and dried the climate in this region. Such climate environment is likely to aggravate land desertification. Because there are rainy season and dry season in this region, so the impact of climate change on land desertification has seasonal differences. The periodicity of average wind speed in this region can be divided into strong and weak period. Weak wind period occurred from 1960 to 1980, while strong wind period occurred from 1981 to 2011. The dynamic change of mobile dune is one of the main characters of desertification process, the increased landscape fragmentation number of mobile dune will lead to an increasing of desertification. Through the research on the size of the sand dunes, we found the longitudinal sand dune mainly consisted of fine and very fine sand, while the environmental sediments mainly consisted of Aeolian deposit and coastal salt marsh. Combined with the natural driving force, in the year with more rainfall, the rainfall will become a maJor factor derived vegetation restoration; but in less rainfall or non-rainfall period, human activities which act as one of the driving factors of desertification has become the main influencing factors in desertification development. Population growth, GDP growth, city land expansion, and the development of animal husbandry, all of them extremely stressed land use, especially to fragile desertification land. Thus, these processes could be the potential accelerator of land desertification. Based on the above results, we also offered simulation results by using GeoSOS. This simulation results shown that if the climate condition in 2021 could be similar to it in year 2000 -2010, the area of desertification land would decrease in general. |
| Subject Area | 自然地理学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/14797 |
| Collection | 研究系统_荒漠环境研究室 研究系统_空间对地观测与系统模拟研究室 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 周娜. 毛里塔尼亚努瓦克肖特地区土地沙漠化过程及其驱动环境研究[D]. 新疆乌鲁木齐. 中国科学院大学,2017. |
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