基于GIS和RUSLE的滇南山区土壤侵蚀时空演变——以云南省元阳县为例

滇南山区土壤侵蚀时空演变研究对于水土保持规划及世界文化遗产区的生态保护具有重要意义。本研究基于RUSLE模型和GIS/RS空间信息技术,分析元阳县2005—2015年间土壤侵蚀状况的时空变化趋势,以及其侵蚀成因和影响机理。结果表明: 研究期间,元阳县土壤侵蚀空间分异显著,流失区主要集中于县域东南部、西南部,藤条江沿岸区域侵蚀广泛,极强度和剧烈侵蚀呈点状分布。元阳县2005—2015年平均土壤侵蚀模数为11.06 t·hm^-2·a^-1,微度和轻度侵蚀所占面积比例近80%,而轻度和中度侵蚀则构成了近50%的全年土壤侵蚀总量,是县域水土流失治理的重点侵蚀级别。研究期间,随着森林覆盖率的提高,县域水土流失有减缓趋势。元阳县地形复杂多变,土壤侵蚀分布与海拔、坡度有很大的相关性,这种分布格局的形成受自然和人为因素的共同影响,海拔500 m以下、1500 m以上且坡度25°～45°的山地区是水土防护治理的重点区域。

Spatial-temporal variations of soil erosion in Southern Yunnan Mountainous Area using GIS and RUSLE: A case study in Yuanyang County,Yunnan Province,China

It is of great significance to understand the spatial-temporal change of soil erosion in the Southern Yunnan Mountainous Area, especially for soil and water conservation planning and ecolo-gical protection in the world cultural heritage area. Based on the RUSLE model and GIS/RS space information technology, we examined the spatial-temporal variation of soil erosion and its relationship with environmental factors in Yuanyang County from 2005 to 2015. The results showed that, during the study period, the spatial differentiation of soil erosion in Yuanyang County was substantial. The soil erosion area was concentrated on the southeast and southwest region. Erosion widely distributed among both sides of Tengtiao River. Extreme and severe erosion presented a point distribution pattern. The average soil erosion modulus was 11.06 t·hm^-2·a^-1 from 2005 to 2015. The erosion level was basically slight and mild, accounting 80% of the total. Mild and moderate erosion contributed nearly 50% of total annual soil erosion, which was the key level of soil erosion control. During the study period, soil erosion had been slowed down with the improvement of forest cover. The terrain was complicated and changeable in Yuanyang County, and soil erosion distribution had a prominent correlation with altitude and slope. The formation of this distribution pattern was driven by numerous natural and human factors. The key area of soil and water protective governance were below 500 m, above 1500 m and slope located at 25°-45°.