CAJ | 학술논문

卫星遥感是进行洲际或者全球尺度内陆水体信息提取的最有效、最为切实可行的技术手段。作为全球水资源较为匮乏的大洲，以遥感技术进行非洲内陆水体信息提取研究具有重要的应用价值。文章以2010年Landsat TM/ETM+卫星遥感影像数据为基础，辅以 MODIS 遥感影像，基于面向对象的分类方法，选用归一化差值水体指数（Normalized Difference Water Index，NDWI）及波段组合（Band 4/Band 2）进行水体信息提取。并根据不同气候区，选取4个典型区，监测年内水体的变化情况。结果表明：1）非洲内陆水体面积为311479.2 km2，其中湖泊总面积为209018.5 km2，占水体总面积的67.1%；河渠总面积64550.1 km2，占20.7%；水库坑塘总面积37910.7 km2，占12.2%。非洲拥有水库211个，总面积13438.7 km2。2）撒哈拉以南的非洲是水体主要的分布区，统计分析表明约97%的水体分布在该地区。3）热带沙漠气候区湖泊面积呈减少趋势，热带草原气候区湖泊受干湿季节影响上下波动较大，热带雨林气候区和地中海气候区湖泊面积变化较小，总体上4个典型区水体面积变差系数＜10%。
위성요감시진행주제혹자전구척도내륙수체신식제취적최유효、최위절실가행적기술수단。작위전구수자원교위궤핍적대주，이요감기술진행비주내륙수체신식제취연구구유중요적응용개치。문장이2010년Landsat TM/ETM+위성요감영상수거위기출，보이 MODIS 요감영상，기우면향대상적분류방법，선용귀일화차치수체지수（Normalized Difference Water Index，NDWI）급파단조합（Band 4/Band 2）진행수체신식제취。병근거불동기후구，선취4개전형구，감측년내수체적변화정황。결과표명：1）비주내륙수체면적위311479.2 km2，기중호박총면적위209018.5 km2，점수체총면적적67.1%；하거총면적64550.1 km2，점20.7%；수고갱당총면적37910.7 km2，점12.2%。비주옹유수고211개，총면적13438.7 km2。2）살합랍이남적비주시수체주요적분포구，통계분석표명약97%적수체분포재해지구。3）열대사막기후구호박면적정감소추세，열대초원기후구호박수간습계절영향상하파동교대，열대우림기후구화지중해기후구호박면적변화교소，총체상4개전형구수체면적변차계수＜10%。
An object-oriented classification approach was applied in this study to extract surface water area across the African continent based on Landsat TM/ETM+ imagery acquired in 2010, combined with MODIS images to examine the water surface arealfluctuation caused by seasonality. Normalized Difference Water Index (NDWI) and band ratio (band 4/band 2) were used as the major input for eCognition software package to extract surface water area. Further, surface water area was extracted over four typical regions determined from various climatic zones to investigatethe surface water areal fluctuation due to precipitation and runoff variability.Our results showed that the surface waters area totaled 311479.2 km2across the African continent. The lake area was 209018.5 km2,accounting for 67.1% of the total inland waters area, while river and channels area 64 550.1 km2, accounting for 20.7%, and reservoirs and ponds area 37 910.7 km2, accounting for 12.2% of the total inland waters across the African continent.Altogether, there were 211 reservoirs distributed all over the continent, and the area amounted to 13 438.7 km2. Inland surface waters for Africa were mainly distributed across regions sitting down to the south of Sahara.Our investigation also showed that inland waters decreased about 100 km2 in the target area from tropical desert climatic zone.A large areal fluctuation was observed for the target region from tropical steppe climatic zone, and the surface waters area changed in a range of 1000 km2. Comparatively, surface waters showed small variation due to seasonality, andthe areas only changed in a range of tens of square kilometers. As indicated by the coefficient of variation (less than 4.85%) in these four target regions, the surface water areal fluctuation across the African continent might be less than 10%.