Quantitative morphometric analysis was carried out for Megech-Dirma, sub-basin of the Blue Nile, by estimating (1) linear, (2) aerial, and (3) relief aspects. An endeavor has been made to measure the Megech-Dirma watershed’s morphometric characteristics to implement conservation methods for soil and water properly. ASTER DEM has been used as input data for extracting morphometric parameters. Strahler’s classification scheme was used to classify the extracted drainage network in ArcGIS extension ArcMap 10.4. The watershed covers a total surface area of 1309.56 km². The shape of the watersheds as calculated from elongation, circularity, and form factors reveals the elongated shape and the watersheds parade dendritic pattern. The sub-watersheds include third-order for Megech and sixth-order streams. Lower stream orders, in particular first-order streams, dominate the sub-watersheds. The length of overland flow has a higher value (1.06) for Megech indicates low relief, whereas the values of length of overland flow, which are relatively low (0.20) for Dirma, indicate high relief. The drainage density of the study watershed was morphometrically analyzed and obtained 0.47 km/km² for the Megech sub-basin, which indicates the basin is highly permeable and result in better underground water storage capacity and 2.46 for the Dirma sub-basin indicating very coarse and coarse channel, respectively. The ruggedness number for Megech and Dirma sub-basins was 0.56 and 0.07, respectively, indicating moderate and long, rugged topography, which could be susceptible to flash flood and soil erosion. The dissection index values for Megech 0.40 and 0.36 for Dirma show river sub-basins are moderately dissected. The ruggedness number is 0.56 for Megech implies moderate soil erosion probability, whereas the high infiltration number (14.29) for Dirma river shows the high runoff potential in the sub-basin. The findings of this study include drainage morphometry data that can be used to better understand watershed characteristics and serve as a framework for better planning, management, and decision-making to ensure the long-term use of watershed resources of water and soil.

The present study has been carried out to analyze the relationship between faulting and geomorphology of the Wadi Atyaruh to reveal the effect of structures on the morphology and distribution of the different karst features. Geographical Information System (GIS) and Remote Sensing (RS) techniques were applied to investigate morphological and topographic characteristics of Wadi Atyaruh, based on ASTER Global Digital Elevation Model (ASTER GDEM) Version 3 (V3) data. Dextral strike-slip fault is the main faulting type in the valley. Conjugate faults system has been found in the study area, which reveals the orientations of the principal stresses. Wadi Atyaruh consists mainly of Dernah formations (Eocene) and Quaternary deposits. Two types of Karren have been recognized, they are Rillen karren and solution basis which are well distributed in Darnah formation. Caves are found in the Darnah formation, the passages and chambers of these caves show a phreatic bedding plane, elliptical shape, laminar profiles, and rectangular and rounded top vadose profiles. The drainage system of this valley is sub-parallel drainage pattern to dendritic drainage pattern, indicating that the area has affected by strike-slip movement (Dextral), joints and it has steep slopes. interpretation of DEM of study area indicate moderate and high relief, low run off and high infiltrations due to the nature of the fracture carbonate rock, the basin have early mature stage of erosion development. Geomorphic parameters such as hill shade, slop, aspect, area shaded and elevation maps, was produced to describe geomorphic forms and processes of the Wadi Atyaruh. The complete morphometric analysis of drainage basin indicates that the given area is having good groundwater prospect.

The study assessed the accuracies of globally available Digital Elevation Models (DEM’s) i.e., SRTM v3, ASTER GDEM v2 and ALOS PALSAR DEM with respect to Topo-DEM derived from topographic map of 5m contour interval. 100 ground control points of the elevation data were collected with the help of kinematic hand held GNSS (Global Navigation Satellite System), randomly distributed over the study area. The widely used RMSE statistic, NCC correlation and sub-pixel-based approach were applied to evaluate the erroneous, correlation, horizontal and vertical displacement in terms of pixels for the individual Digital Elevation Model. Following these evaluations, SRTM DEM was found to be highly accurate in terms of RMSE and displacement compared to other DEMs. This study is intended to provide the researchers, GIS specialists and the government agencies dealing with remote sensing and GIS, a basic clue on accuracy of the DEMs so that the best model can be selected for application on various purposes of the similar region.

Watershed ecosystem monitoring and evaluation indicators need to factor in land cover/use change rationally and adaptively. Vegetation canopy greenness can be utilized to seek an accurate solution to various land cover/use change issues, for example, by applying the Normalized Difference Vegetation Index (NDVI) algorithm. This research set out to analyze the relationship between the spatial pattern of canopy greenness and small island watersheds’ hydrological characteristics. It used NDVI algorithm extraction and BFLOW+ 3.0 filter in the HydroOffice 12.0 program and then examined the two resulting datasets using correlation analysis. The results showed that the spatial pattern of canopy greenness derived from NDVI changed significantly near the river mouth. The densely populated settlements in the coastal stretch continued to sprawl towards mountainous regions, which naturally function as recharge zones. Meanwhile, the hydrological characteristics displayed a fluctuating trend during the observation period (2015-2019). Based on the correlation analysis, canopy greenness patterns and hydrological features form a positive and relatively strong relationship (38.8%). For this reason, ecological shifts in small island watersheds require climate change mitigation and adaptation measures.