Assessment of Land Use and Land Cover Changes (LULC) in the North Talihya River Watershed (Lubero Territory, Eastern DR Congo)

On the Equator, the Talihya North watershed is a vast area of nearly 581.7 km2 that extends from the Cool Highlands on the Congo-Nile Crest in Lubero Territory to the Rift Valley in the Virunga National Park in Beni Territory. This vast territory has an agropastoral vocation. Indeed, agricultural activities combined with the high population density in this watershed generate modifications in the landscape structure. The objective of this paper is to study the dynamics of land use from 1987 to 2020. To achieve this, two Landsat TM+ and ETM+ images and one Sentinel-2 image were analyzed. After the classification of the images based on the Maximum Likelihood algorithm, this study shows that two processes are evident in the landscape of the North Talihya watershed: deforestation and savannization. Forests that occupied 253.11 km2 in 1987 have decreased to 201.12 km2 in 2001 and to 123.04 km2 in 2020. These area balances indicate that the natural forest formations in the North Talihya watershed have been converted primarily to croplands and fallows. The estimated annual deforestation rate between 1987 and 2020 is 2.18%. With this high rate of deforestation, mechanisms to restore degraded forest ecosystems in this watershed will need to be put in place. The sustainable management of residual forest ecosystems that have escaped human pressure is necessary for the conservation of biodiversity for future generations.

大型三角洲-深水沉积盆地油气地质与成藏特征比较分析

三角洲-深水沉积体系是世界上大中型油气田形成的重要场所,独特的沉积环境为油气生成和聚集提供了良好的生储盖与圈闭条件,不同的构造与沉积背景具有不同的成藏特点。为进一步研究该类盆地成藏特征与油气分布规律,指导油气勘探,特选取马哈坎三角洲盆地、尼罗河三角洲盆地和刚果扇盆地3个世界级富含油气区,采用比较分析的研究方法,通过对盆地构造与沉积演化、沉积特点、烃源岩、成藏组合及油气成藏特征等方面对比分析,对3个类型的大型三角洲-深水沉积盆地的油气地质与成藏特征进行总结。结果表明,3大盆地均形成于被动大陆边缘稳定沉积背景,均发育了规模巨大的三角洲-深水沉积体系,石油地质条件非常优越;由于形成时期不同的古气候、古沉积与古构造条件,3大盆地在沉积模式、烃源岩、主要成藏组合、油气类型、油气运移及油气藏类型等方面又具有明显差异性;其未来主要勘探领域与勘探方向亦不同,马哈坎三角洲盆地以深水为主,尼罗河三角洲盆地以深层为主,刚果扇盆地以深水中浅层为主。