Comparative geomorphometric approach to understand the hydrological behaviour and identification of the Erosion prone areas of a coastal watershed using RS and GIS tools

Assessment of the geomorphometric parameters using Remote Sensing (RS) and Geographic Information System (GIS) tools forms an important part in routing the runoff and other hydrological processes. The current study uses a geospatial model based on geomorphometric parameters for the categorization of surface runoff and identification of the erosion-prone areas in the watershed of the Kuttiyadi River. The 4th order Kuttiyadi river is dominated by a dendritic to semi-dendritic drainage pattern in the subwatersheds. The linear aspect of the subwatersheds indicates towards the presence of permeable surface and subsurface materials with uniform lithology. The aerial and relief aspects of the subwatersheds shows fine drainage texture, gentle slopes, delayed peak flow, flatter hydrograph, and large concentration time which shows that subwatersheds are quite capable of managing flash floods during storm events. The estimated values of surface runoff (Q) and sediment production rate (SPR) are range from 2.13 to 32.88 km2-cm/km2 and 0.0004–0.017 Ha-m/100km2/year respectively and suggest that Subwatershed 1 (SW1) will generate more surface runoff and is prone to soil erosion followed by subwatershed 2 (SW2) in comparison to other subwatersheds. This paper aims to fill the knowledge gap regarding categorization of flow and erosion dynamics in a coastal river watershed. We believe that our work may work help in providing the crucial information for decision-makers and policymakers responsible for establishing suitable policies and sustainable land use practices for the watershed.

GIS & Remote Sensing Based Morphometric Parameters and Topographic Changes of the Lower Orashi River in Niger Delta

In watershed hydrology, the morphometric features of a river basin are vital to examine the lower Orashi River basin morphological and hydrological aspects, as well as its flood potential, based on their morphometric characteristics using remotely sensed SRTM data that was analyzed with ArcGIS software. The areal, linear, and relief aspects of the Orashi River basin were examined as morphometric parameters. The lower Orashi river basin, according to the findings, has a total size of 625.61 km2 and a perimeter of 307.98 km, with a 5th order river network based on Strahler categorization and a dendritic drainage pattern. Because of low drainage density, the drainage texture is very fine, the relief is low, and the slope is very low. Bifurcation ratio, circularity ratio, drainage density aspect ratio, form factor, and stream frequency values indicate that the basin is less elongated and would produce surface runoff for a longer period, while topographic changes show that the river is decreasing with depth in the land area at about the same elevation as a result of sand deposited due to lack of maintenance by dredging, which implies that the basin is morphometrically elevated and sensitive to erosion and flooding. To understand geohydrological features and to plan and manage watersheds, morphometric analysis based on geographic information systems and remote sensing techniques is beneficial.

Assessment of Groundwater Recharge Potential Depending on Morphologic Analysis in East of Wasit, Southeastern Iraq

Modern technologies are used for watershed management to cope with drought risks in arid and semi-arid regions. The study aimed to conduct a morphometric analysis and know potential groundwater recharge areas in the eastern region of Wasit Province. Remote sensing and GIS data were used for morphometric analysis. The morphometric analysis results adopted the Digital Elevation Model. The results of the analysis were verified by matching the results with what exists in reality. The area of the first basin was 1482.017, as it is the largest basin from the area, with a percent of 51.228% of the total area of all basins. The percentage of first-degree flows reached 83.37% in the first basin, 74.14% percent in the second basin, 75.51% in the third basin, and 75.75% in the fourth basin from all streams in each basin. The bifurcation rate (3.135-4.233), Stream frequency range values (0.543-0.332), drainage texture coarse, low drainage density that ranged between 0.986-1.14 km/km2 elongation ratio ranging from 0.348-0.624 form factor (0.095-0.316). The basins' circularity (0.105-0.238) relief value (951-112) m infiltration number value (0.369-0.535). All basins have a longitudinal shape and lead to the formation of floods and rapid currents, which exposes the region to rapid seasonal floods and the creation of flash floods that cause soil erosion and analyses the drainage intensity results. It was low, and this is an indication that the ground has high permeability. The flow frequency results indicate that the area is semi-arid and exposed to small amounts of rain and coarse drainage texture by comparing the result parameters from morphometric analysis results for each basin. The potential recharge areas of groundwater in the study area can be known, n as the analysis results showed that recharge potential occurs in all basins. The highest groundwater recharge is possible in the third basin and the lowest in the first basin. Morphometric analysis was performed by ARC-GIS(Arc-map10.4).

Geo-informatics based Morphometric Analysis of a Reservoir Catchment in Shivalik Foothills of North-West India

The present study examined 35 morphometric parameters related to stream/drainage network, catchment geometry, and relief aspects for hydrological characterization of the Thana Dam catchment using geospatial tools and techniques. The dam catchment was delineated using the high-resolution Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) Digital Elevation Model (DEM) data in ArcGIS 10.4.1 software using the Arc Hydro tools. The catchment is comprised of 4th order stream, obtained using a stream threshold value of 100 m length. The lower values of elongation ratio (0.61), circularity ratio (0.22), and form factor (0.29) indicated higher soil erosion potential, mainly due to their inverse relationship with land erodibility. Moreover, the higher values of stream frequency (15.7), drainage density (>5.0), drainage texture (7.48 km-1), and mean bifurcation ratio (4.08-6.33) indicated higher runoff potential, which would intensify the soil erosion, mainly due to their direct relationship with erodibility. Bifurcation ratio, elongation ratio, circulatory ratio, form factor, altogether indicated an elongated shape of the catchment with a fine drainage texture. The higher values of bifurcation ratio and texture ratio of the catchment also indicated severe overland flow (low infiltration rate) with a limited scope for groundwater recharge in the area, which in turn might significantly encourage the soil erosion. Overall, it was concluded that the catchment has a huge runoff potential resulting in high soil erosion due to its fine texture, impermeable subsurface material, steep slope, low infiltration rate, limited vegetation, longer duration of overland flow, and higher surface runoff. The morphometric analysis was found to be suitable for identifying catchment shape and the factors affecting hydrologic conditions and erodibility of the catchment. Thus, Geo-informatics based morphometric analysis of a reservoir catchment can be useful to study the erosion potential in relation to hydrologic (rainfall-runoff relationship) and other related land characteristics (e.g., relief, slope, infiltration rate, etc.).

Use of Geospatial Tools in Morphometric Analysis and Prioritisation of Sub-Catchments of the Soungrougrou (Casamance Basin)

The prioritisation of catchments, particularly in the context of catchment plans and management programmes, is part of water resources development. In fact, morphometric analysis assisted by geospatial technology is carried out by prioritising sub-catchments according to their natural resource availability characteristics. Information on the geomorphology and erosion factors of the study area is used in the area in the preparation of local models of ungauged sub-catchments, which otherwise lack an adequate hydrological database. The objective of this paper is to use geographic information systems (GISs) in morphometric analysis to prioritise sub-catchments of the Soungrougrou (a tributary of the Casamance River). In this respect, the integrated methodology involving morphometric aspects from geospatial technology is used. To carry out the geospatial research, basic mathematical equations used in a GIS environment were used to measure a series of aspects of hydrology such as flow length, flow length ratio, bifurcation ratio, drainage density, drainage texture, flow frequency, elongation rate, circularity ratio, form factor, relief and relief ratio. The results divided the whole catchment into three priority areas, namely high, medium and low. The results are relevant for establishing soil and water conservation plans in the Soungrougrou basin, as well as adequate groundwater production and management. The high category (sub-basins 6, 8, 14, 17 and 18) is subject to maximum soil erosion, which requires immediate intervention to avoid possible natural hazards.

Prioritization of Flash Flood-Prone Areas in Small Coastal Basins around the Mediterranean Using Geomorphological Variables

The present study aims to model flash flood risk in small coastal watersheds in areas that are characterized by Mediterranean climate through extensive morphometric analysis which can prove invaluable for the investigation of flood risk, in ungauged watersheds, where flash floods are frequent. The available topographic data (EU-DEM) are analyzed through Geographic Information Systems (GIS) to produce all the secondary variables that are necessary for this morphometric analysis. Watershed prioritization techniques that are applied on geomorphological variables have proven to be an effective way of estimating the relative flash flood risk in a sub-watershed level. A series of morphometric parameters are used (bifurcation ratio, drainage frequency, drainage density, drainage texture, length of overland flow, circularity ratio, form factor, elongation ratio) which have an effect on flood risk. In small watersheds, with intermittent runoff, this effect can be different than in larger watersheds, so our methodology differs significantly from the methodology other researchers use. The compound factor is calculated by aggregating the assigned ranks of these morphometric indices and the sub-watersheds are prioritized according to their flash flood risk. The study area is located in the island of Samos, in Eastern Greece, where flood events are usual and pose a risk to villages and infrastructure around the island. The selected watershed (Imvrasos river) is divided into several sub-watersheds (W-1 to W-8) and a series of morphometric indices are calculated and evaluated through statistical procedures and by applying prioritization techniques, in order to locate the sub-basins that have the highest risk to flash floods. Sub-watersheds W-2 and W-3 (on the southern part of Imvrasos area) show the highest prioritization values, and should be prioritized for better watershed management planning.

Morphometric Study of Dhatarwadi River Basin Using RS and GIS Techniques

Aims: Morphometric study of Dhatarwadi river basin. Place and Duration of Study: This study is a work done for the research work in Ph.D. degree at College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh, Gujarat, India. Methodology: Morphometric analysis involved determination of linear, aerial and relief aspects of the Dhatarwadi river basin, which was carried out using 30 X 30 m SRTM DEM in ArcGIS 10.5 software using standard formulae. Results: The obtained results revealed that the Dhatarwadi river basin is 6th order drainage basin. The total number of 1327 streams were identified out of which 1st, 2nd, 3rd, 4th, 5th and 6th order streams are counted as 1036, 239, 42, 7, 2 and 1 number, respectively. The mean bifurcation ratio value is 4.31 for the study area which indicates that the geological structures are not distorting the drainage pattern. Stream length ratio varies between 0.14 and 2.14 indicates late youth geomorphic stage. The length of overland flow was found as 0.3084 km which also indicates very less structural disturbance, low runoff conditions and having higher overland flow. The stream frequency of the basin is 1.5448 km-2, indicates that this basin is having high permeable geology, low relief and the almost flat topography. The form factor, elongation ratio, circularity ratio and compactness coefficient are found as 0.3951, 0.7094, 0.3126 and 1.7882, respectively of the study basin is suggests that the Dhatarwadi river basin shape is elongated. The drainage texture is 7.1426 km-1 which shows that the Dhatarwadi river basin has short duration for peak flow. The relief, relief ratio and relative ratio of the basin are found as 0.438 km, 0.009372 and 0.2352, respectively. Conclusion: All these parameters indicate that the Dhatarwadi river basin is of flat terrain with small hillocks/inselbergs having low to medium runoff potential.

Approach for analyzing landslide and torrential flow hazard conditions in relation to landscape evolution in the northern Colombian Andes

<p><span>Colombia is an equatorial country located in the northwestern corner of South America with characteristic and complex climatic and geologic settings, which contribute to a great diversity of landforms in the Colombian Andes. 65% of the Colombian population is concentrated in this mountainous terrain, where landslides and torrential flows are common. These natural hazards led to several tragic events over time. Their occurrence is favored by a very dynamic landscape made up of weak and highly weathered materials and affected by tectonic stress. In this study, we aim to gain a better understanding of morphometric control on the occurrence of landslides and torrential flows through process geomorphology and information derived from Digital Elevation Models (DEMs). Several morphometric indices related to drainage network, basin geometry, drainage texture, relief characteristics, asymmetry factor and others were calculated over 168 drainage basins in the northern Colombian Andes. We used quantitative geomorphology to find patterns of anomalies associated with landscape evolution and the occurrence of landslides and torrential flows. Understanding morphodynamics from morphogenesis is important to assess landslide and torrential flow hazard conditions in relation to landscape characteristics and evolution, to support hazard assessment, and consequently to reduce human and economic losses.<br>Keywords: Landslide, torrential flow, morphometric indices, mountainous terrains.</span></p>

Identifikasi Aktivitas Petani Dan Sifat Fisik Tanah Sawah Di Desa Detusoko Barat Kecamatan Detusoko Kabupaten Ende

This study aims to determine the activity of farmers and the physical properties of soil on rice fields in the village of Detusoko Barat, Detusoko District, Ende Regency. The research method used is the method of purposive sampling. The research was carried out in paddy fields in the village of Detusoko Barat and in the soil chemical laboratory of the Faculty of Agriculture, Undana. Farmer activity variables observed were rice cultivation such as seedbed, land preparation, planting, fertilizing, maintaining, harvesting. Variable physical characteristics that are analyzed temperature, rainfall, humidity, drainage, texture, effective depth, slope, surface rock, rock outcrop. The results showed that the activities of farmers in the village of West Detusoko carried out rice cultivation twice a year, tillage using a tractor and fertilizing using inorganic fertilizer. The physical properties of soil in the ciherang rice variety in Detusoko Barat village are generallyclassified as very suitable (S1) class. And in rice varieties, Bengawan also generally belongs to the (S1) class very appropriate.

Estimation of Morphometric Parameters of Karatoya sub-River Basin in Bangladesh using GIS and Remote Sensing Techniques

Morphometric analysis identifies the relationship of various aspects in the basin area, and plays an important role for understanding the geo-hydrological characteristics of a basin. The Karatoya River is ecologically and economically significant for Dinajpur region of Bangladesh. In this study, the morphometry of a sub-portion of Karatoya River in Birganj upazila was assessed by using GIS and remote sensing. The secondary data from ASTER DEM data and DEM data of Bangladesh were used to represent the morphologic and geo-hydrologic nature of the basin. The study computed and assessed more than 31 morphometric parameters in all aspects of the river basin. Morphometric analysis of the river network and the basin revealed that the Karatoya sub-basin was in the 6th order river network (as Strahler’s classification) with a dendritic and parallel drainage pattern and fine grain in drainage texture. This type of analysis will lead to develop the sustainable framework for agricultural and watershed management to be used by the local administration.