Spatio-Temporal Dynamics of Land Use Units in the Kadzel Sub-Catchment Basin in Diffa, Niger

Environmental degradation linked to land occupation and use, such as climate change and anthropogenic activities, has led to the modification of the landscape units of the Kadzel sub-watershed. The objective of this study is to analyze the dynamics of land use units in the Kadzel area in Diffa between 1992 and 2022 and to propose a future scenario for sustainable environmental management. The approach used relies on remote sensing and geographic information systems to analyze the dynamics of land use units. Additionally, the Markov Cellular Automata (CA) model was used to predict future land use. The land cover maps were produced from a supervised classification by maximum likelihood based on the true and false color compositions of bands 4/3/2 (TM5), 3/2/1 (ETM+) and 7/5/4 (8 OLI). Ten occupation classes were discriminated. Between 1992 and 2022, there was a decrease in the areas of irrigated crops (4.91% and 2.88%), of shrubby tree steppes (14.31% and 9.48%), field-fallow complexes (22.23% and 10.52%), and degraded areas. Grassy steppes (25.76% and 13.32%). However, this reduction has been beneficial for wastelands, urban areas and bodies of water. Based on predictive modeling, it is predicted that by 2052, urban areas, fallow field complexes and bare soils will constitute the main types of housing units. The regressive trend in natural resources appears to continue into the future with current land use practices.

非洲中部Bongor盆地与Lake Chad盆地烃源岩发育特征差异性探讨

Bongor盆地和Lake Chad盆地是位于非洲中部且地理位置较近的盆地,但两者在烃源岩的发育特征方面却存在着明显的差异:Bongor盆地的烃源岩主要发育于下白垩统湖相泥岩中,Lake Chad盆地的烃源岩则主要发育于上白垩统海岸—滨海相泥页岩中。通过对2个盆地的区域构造背景分析,认为烃源岩发育的差异性是2个盆地所处的区域应力场不同所致。Bongor盆地位于中非裂谷系,其油气成藏特征受中非剪切带的影响;Lake Chad盆地属于西非裂谷系,油气成藏特征受西非张裂带的影响。中非裂谷系和西非裂谷系2大不同的区域地质背景,造就了2个盆地差异性较大的烃源岩发育特征,了解这种油气成藏的差异性特征对中国南海未来的油气勘探有一定的启发作用。

非洲Lake Chad盆地上白垩统层序地层及沉积特征

综合利用测井、录井和地震资料对非洲乍得的LakeChad盆地上白垩统进行了三级层序划分，在此基础上对层序’内部体系域沉积相类型及其特征进行了研究。LakeChad盆地的上白垩统可划分为2个地层组，对应3个三级层序、6个体系域，但只有下部的层序1发育较为完整，主要为河流相、三角洲相和滨一浅海相沉积，沉积物源主要来自于盆地东部、南部和西部的古隆起。

乍得湖盆地构造特征与油气成藏规律初探

以前人的研究为基础，结合研究区及邻区地球物理资料、岩矿特征、钻井资料，分析了盆地结构特征、构造样式、演化序列以及油气成藏规律。研究表明，乍得湖盆地为伸展断～坳型裂谷盆地，断裂、褶皱构造发育；经历了前裂谷（侏罗纪以前）、同裂谷（135～23．5Ma）、后裂谷（23．5Ma以后）三个演化阶段；主要发育白垩纪和古近纪两套含油气系统。

乍得湖盆地典型区域降雨入渗补给地下水试验

针对尼日利亚北部乍得湖盆地降雨入渗补给地下水的问题,选择典型区域开展土壤剖面取样工作,采用氯离子平衡法计算各剖面降雨入渗补给量,并结合野外调查、钻探等工作研究影响降雨入渗补给的主要因素。结果表明:4个取样点(Y1、Y2、Y3、Y4)土壤剖面年平均降雨入渗补给量分别为4.9、1.5、7.9、26.2 mm/a,平均值为10.1 mm/a,年平均降雨入渗补给率仅为0.72%、0.22%、1.17%、3.87%,平均值为1.49%;研究区降雨入渗补给量很少,降雨对地下水资源的补给有限,地下水的主要补给来源为Hadejia河;研究区蒸散发量大,植物根系发达、吸水能力强,地表入渗水分多在表层土壤中或泥质层与风积砂层交界面上消耗于蒸发蒸腾,最终散失到大气中。在人类活动严重改变Hadejia河水文情势的背景下,研究区这种独特的地下水补给特征导致地下水位快速下降,使得区内正面临较严重的地下水资源枯竭问题。