GIS and remote sensing approach is an effective tool to determine the morphological characteristics of the basin. Gilgel Abay watershed is stretched between latitude 10.56° to 11.22° N and longitude 36.44° to 37.03° E which is one major contributing river of Lake Tana which is the source of Blue Nile. The present study addressed linear and areal morphometric aspect of the watershed. The study deals with emphasis on the evolution of morphometric parameters such as stream order, stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, elongation ratio, circularity ratio, and form factor ratio. The morphometric analysis of the basin revealed that Gilgel Abay is firth-order drainage basin with total of 662 drainage network, of which 511 are first order, 111 are second order, 30 are third order, 9 are fourth order, and 1 is fifth-order stream. The total length of stream is longer for first order and decrease with increasing stream order. The mean bifurcation ratio is 5.16 which is greater than the standard range, and it indicates that basin is mountainous and susceptible to flooding. Low drainage density is observed which is 0.6 km⁻². It indicates that basin is highly permeable and thick vegetation cover. Areal aspect of the morphometric analysis of the basin revealed that the basin is slightly potential to flooding and soil erosion, indicating that runoff generated from the upland area of the watershed is significantly infiltrated at the gentle downstream part and contributing to groundwater potential. Further studies with the help of GIS and remote sensing with high-resolution remote sensing data integrating with ground control data in the field are more effective to formulate appropriate type of natural resource management system.

GIS和遥感方法是确定流域形态特征的有效工具。Gilgel Abay 流域位于北纬 10.56° 至 11.22° 和东经 36.44° 至 37.03°之间，是青尼罗河源头塔纳湖的主要河流之一。本研究涉及流域的线性和区域形态测量方面。该研究侧重于形态测量参数的演变，如河流顺序、河流长度、分叉比、排水密度、河流频率、纹理比、伸长率、圆度比和形状因子比。流域形态测量分析表明，吉尔格尔阿拜为一级流域，共有662个流域网，其中一级流域511个，二级流域111个，三级流域30个，四级流域9个，1 是五阶流。一阶流的总长度较长，随着流阶的增加而减少。平均分叉比为5.16，大于标准范围，说明盆地为山地，易受洪水侵袭。观察到低排水密度为 0.6 公里^－2．表明该流域透水率高，植被覆盖较厚。流域形态测量分析的面积方面显示该流域有轻微的洪水和水土流失潜力，表明流域高地地区产生的径流在温和的下游部分显着渗透，并有助于地下水潜力。借助GIS和遥感，将高分辨率遥感数据与实地地面控制数据相结合，进一步研究可以更有效地制定适当类型的自然资源管理系统。