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>

Remote Sensing and GIS Based Comparative study of watershed of different Physiographic Conditions, Wainganga Sub Basin, Maharashtra

The present study carried by a Wainganga river basin is of critical importance for Maharashtra to preserve its watershed, drainage, relief, soil, forests, wildlife, and tribal population dependent on it. Protecting the basin however does not seem to be priority for the state. The very lifeline of the Wainganga River is being subjected to growing pressure. Its flow has already been obstructed at several places with dams and barrages. By 2012 there were as many as 149 dams built in Wainganga basin. The river in its initial reaches flow westwards and thereafter southwards in M.P. State and continues to flow Southwards in Maharashtra State. Several studies related to different aspects of channel cross section and longitudinal profile river have been carried out from different parts of the country and abroad. Recent emphasis is placed on quantitative geomorphology of drainage basin by various methods and measures to establish the interrelationship of cross section and longitudinal profile river and to impact on river morphology. Water is not only for sustains of life but also determines the quality of life. Assessing water quality is important as quantity in water resources planning and management. It may be observed that the existence of human being a lot of serious problem to disturbance of quality and quantity of water. There are several reasons for scarcity of water and most important things to the increasing population and changing environment condition in the local as well as world level. For sustainable development requirement to that fresh water is indispensable for human survival. Water is being transferred to irrigation and urban industrial uses, putting additional stress on the performance of the irrigation sector. Keeping in mind the scarcity of water resources to cater to the multi various needs of the growing population along the Wainganga River with the vagaries of monsoon precipitation and dearth for quality of water. The purpose of the present research work is to describe the physical condition in Wainganga drainage basin as a system unit resulting from the interaction between landuse & landcover and topography, which is an impact of socio economic condition and surrounding area or region.

Evaluation of morphometric characteristics and watershed prioritization of Bhadar basin of Saurashtra region, Gujarat

Morphometric analysis is one of the important aspects of quantitative geomorphology which is primarily used to study the geometrical aspects of the landforms. The study was undertaken with the objectives of evaluating morphometric characteristic and prioritizing the watersheds of Bhadar basin based on its morphometric characteristics. Linear, relief and aerial aspects were calculated for watershed characterization. The watersheds were ranked on the basis of high values of linear parameters and low values of shape parameters. A total of 16 watersheds 5G1B1, 5G1B2, 5G1B3, 5G1B4, 5G1B5, 5G1B6, 5G1B7, 5G1B8, 5G1B9, 5G1B10, 5G1B11, 5G1B12, 5G1B13, 5G1B14, 5G1B15 and 5G1B16 were identified in the Bhadar basin and morphometric characteristic of each watershed was determined. Highest priority indicated the greater degree of erosion in the particular watershed and it therefore priority should be given in applying soil conservation measures. It was concluded that the watershed 5G1B15 should be given highest priority because of higher erosion problems over other watersheds of Bhadar basin while 5G1B4 should be given the least priority.

Determination of Evolution Stages of Landform: A Comparative Study of Mountain-Plain (Kosi, Bihar) and Plateau-Plain (Kangsabati, WB) Regions of Tropical India

The major aim of quantitative geomorphology is to understand the geomorphological stages of evolution of any area. The quantitative revolution and the development of remote sensing and GIS techniques have brought greater attention to this field of analysis. We have used a morphometric analysis, which is an important indicator to understand the geomorphic stages of evolution of any drainage basin, to compare the drainage basin characteristics and related stages of evolution of a mountain-plain and plateau-plain drainage basin in tropical India. The Kosi basin has been selected for the mountain-plain area and Kangsabati basin is the chosen region for the plateau-plain area. Different drainage morphometric parameters and measurements related to linear, areal, relief characteristics have been determined through the use of SRTM (Shuttle Radar Topographic Mission) GeoDEM and ARC GIS 10.1. Area-altitude relationship and hypsometric characteristics have also been accessed to identify the stages of geomorphic evolution. All the relief characteristics indicate Kosi in a young or rejuvenated stage when compared to the mature plateau region of the river of Kangsabati. Morphometric characteristics also indicate that there are high geologic and geomorphological controls on river basin characteristics.