scholarly journals FLOOD RISK ZONATION USING A MULTI-CRITERIA SPATIAL GROUP FUZZY-AHP DECISION MAKING AND FUZZY OVERLAY ANALYSIS

Author(s):  
M. Hasanloo ◽  
P. Pahlavani ◽  
B. Bigdeli

Abstract. In this study, a GIS based approach has been proposed for the flood risk zonation based on a multi-criteria spatial group fuzzy AHP decision making analysis and its integration with fuzzy overlay analysis. For this purpose, 10 layers affecting flood occurrence have been used including: the Digital Elevation Model (DEM), Slope, NDVI, Flow Accumulation (Flow Ac.), HOFD, VOFD, Topographic Position Index (TPI), Topographic Wetness Index (TWI), Curve Number (CN), Modified Fournier Index. Each layer was classified into 5 sub-classes and their preference at its layer was weighted by a group of experts using fuzzy analytical hierarchy processes (GFAHP) method. Finally, the risk map of the studied area with the weight of experts and fuzzy overlay method was product and divided into five categories.

2020 ◽  
Vol 954 (12) ◽  
pp. 20-30
Author(s):  
Yu.V. Vanteeva ◽  
Е.А. Rasputina ◽  
S.V. Solodyankina

The authors present the results of geoinformation mapping the Primorskiy Ridge landscapes using Landsat 8 satellite images, the digital elevation model SRTM and the factor-dynamic classification of geosystems. At the first stage, the remote sensing data for different seasons were classified using the ISODATA method. Then, using the digital elevation model, the landforms were classified basing upon the topographic position index. According to combining the classification parameters of one of the space images and digital elevation model, each polygon is automatically assigned to a certain preliminary type of landscapes using boolean expressions. Legend adjustments were made basing upon the fieldwork materials. As a result, a digital landscape map of the southern part of the Primorsky Ridge was created; it reflects the landscape structure at the level of facies groups and contains attributive information about the landform, altitude, slope and aspect, topographic wetness index. The analysis of the landscape pattern showed a high fragmentation of landscape polygons, formed due to overlay operations, which indicates the need for generalization of landscape contours.


2006 ◽  
Vol 63 (3) ◽  
pp. 262-268 ◽  
Author(s):  
Elvio Giasson ◽  
Robin Thomas Clarke ◽  
Alberto Vasconcellos Inda Junior ◽  
Gustavo Henrique Merten ◽  
Carlos Gustavo Tornquist

Soil surveys are necessary sources of information for land use planning, but they are not always available. This study proposes the use of multiple logistic regressions on the prediction of occurrence of soil types based on reference areas. From a digitalized soil map and terrain parameters derived from the digital elevation model in ArcView environment, several sets of multiple logistic regressions were defined using statistical software Minitab, establishing relationship between explanatory terrain variables and soil types, using either the original legend or a simplified legend, and using or not stratification of the study area by drainage classes. Terrain parameters, such as elevation, distance to stream, flow accumulation, and topographic wetness index, were the variables that best explained soil distribution. Stratification by drainage classes did not have significant effect. Simplification of the original legend increased the accuracy of the method on predicting soil distribution.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Natalya Krutskikh

Abstract The study of internal and external factors in the formation of an urban geosystem is determined by its complex structure and multiple connections. Based on geoinformation modelling, an analysis of the landscape structure of the city territory is carried out, which can be a basis for further geoecological research. Morphometric indicators, which make it possible to determine the elementary geochemical landscapes, are indicated according to the data of the digital elevation model. A standardised topographic position index (TPI) is used to determine locations. Spatial zoning according to the type of land use reflects the qualitative features of the external load and technogenic impact. The data on the composition of the lithogenic base show the properties of the depositing medium and determine the natural background. Number of categories of landscapes identified are 58, characterised by a homogeneous geological composition, technogenic load and conditions for the migration of matter. The ratios of various landscape zones have been calculated. The study area as a whole is characterised by the predominance of migration processes over accumulation.


2021 ◽  
Vol 10 (1) ◽  
pp. 3425-3437
Author(s):  
M. Nazish Khan ◽  
◽  
M. Kashif ◽  
A. Shah ◽  
◽  
...  

This study has been carried out in the Pathankot region, having strategic importance in terms of military operations. It explores the ability of remote sensing and GIS in assessing off-road trafficability which is integral part of terrain intelligence. Number of thematic layers has been prepared using Sentinal -2 satellite images and PALSAR Digital Elevation Model (DEM) viz. LULC, Slope, Topographic Wetness Index (TWI), Terrain Roughness Index (TRI) and ground conditions to assess the potential of off-road trafficability in the study area for military operations. Results clearly depict that most of the region is suitable for off-road movement. However, north western part is showing less suitability. Keywords PALSAR; Multi-criteria Decision Analysis; AHP; Trafficability


2014 ◽  
Vol 18 (9) ◽  
pp. 3623-3634 ◽  
Author(s):  
A. M. Ågren ◽  
W. Lidberg ◽  
M. Strömgren ◽  
J. Ogilvie ◽  
P. A. Arp

Abstract. Trafficking wet soils within and near stream and lake buffers can cause soil disturbances, i.e. rutting and compaction. This – in turn – can lead to increased surface flow, thereby facilitating the leaking of unwanted substances into downstream environments. Wet soils in mires, near streams and lakes have particularly low bearing capacity and are therefore more susceptible to rutting. It is therefore important to model and map the extent of these areas and associated wetness variations. This can now be done with adequate reliability using a high-resolution digital elevation model (DEM). In this article, we report on several digital terrain indices to predict soil wetness by wet-area locations. We varied the resolution of these indices to test what scale produces the best possible wet-areas mapping conformance. We found that topographic wetness index (TWI) and the newly developed cartographic depth-to-water index (DTW) were the best soil wetness predictors. While the TWI derivations were sensitive to scale, the DTW derivations were not and were therefore numerically robust. Since the DTW derivations vary by the area threshold for setting stream flow initiation, we found that the optimal threshold values for permanently wet areas varied by landform within the Krycklan watershed, e.g. 1–2 ha for till-derived landforms versus 8–16 ha for a coarse-textured alluvial floodplain.


2014 ◽  
Vol 14 (7) ◽  
pp. 1819-1833 ◽  
Author(s):  
A. Candela ◽  
G. Brigandì ◽  
G. T. Aronica

Abstract. In this paper a procedure to derive synthetic flood design hydrographs (SFDH) using a bivariate representation of rainfall forcing (rainfall duration and intensity) via copulas, which describes and models the correlation between two variables independently of the marginal laws involved, coupled with a distributed rainfall–runoff model, is presented. Rainfall–runoff modelling (R–R modelling) for estimating the hydrological response at the outlet of a catchment was performed by using a conceptual fully distributed procedure based on the Soil Conservation Service – Curve Number method as an excess rainfall model and on a distributed unit hydrograph with climatic dependencies for the flow routing. Travel time computation, based on the distributed unit hydrograph definition, was performed by implementing a procedure based on flow paths, determined from a digital elevation model (DEM) and roughness parameters obtained from distributed geographical information. In order to estimate the primary return period of the SFDH, which provides the probability of occurrence of a hydrograph flood, peaks and flow volumes obtained through R–R modelling were treated statistically using copulas. Finally, the shapes of hydrographs have been generated on the basis of historically significant flood events, via cluster analysis. An application of the procedure described above has been carried out and results presented for the case study of the Imera catchment in Sicily, Italy.


2012 ◽  
Vol 43 (1-2) ◽  
pp. 135-145 ◽  
Author(s):  
Bin Yong ◽  
Li-Liang Ren ◽  
Yang Hong ◽  
Jonathan J. Gourley ◽  
Xi Chen ◽  
...  

The topographic wetness index (TWI), frequently used in approximately characterizing the spatial distribution of soil moisture and surface saturation within a watershed, has been widely applied in topography-related geographical processes and hydrological models. However, it is still questionable whether the current algorithms of TWI can adequately model the spatial distribution of topographic characteristics. Based upon the widely-used multiple flow direction approach (MFD), a novel MFD algorithm (NMFD) is proposed for improving the TWI derivation using a Digital Elevation Model (DEM) in this study. Compared with MFD, NMFD improves the mathematical equations of the contributing area and more precisely calculates the effective contour length. Additionally, a varying exponent strategy is adopted to dynamically determine the downslope flow-partition exponent. Finally, a flow-direction tracking method is employed to address grid cells in flat terrain. The NMFD algorithm is first applied to a catchment located upstream of the Hanjiang River in China to demonstrate its accuracy and improvements. Then NMFD is quantitatively evaluated by using four types of artificial mathematical surfaces. The results indicate that the error generated by NMFD is generally lower than that computed by MFD, and NMFD is able to more accurately represent the hydrological similarity of watersheds.


2017 ◽  
Vol 8 (2) ◽  
pp. 828-832
Author(s):  
M. C. Pineda ◽  
C. Perdomo ◽  
R. Caballero ◽  
A. Valera ◽  
J. A. Martínez-Casasnovas ◽  
...  

Precision agriculture (PA) requires reasonably homogeneous areas for site-specific management. This work explores the applicability of digital terrain classes obtained from a digital elevation model derived from UAV-acquired images, to define management units in in a relative flat area of about 6 ha. Elevation, together with other terrain variables such as: slope degree, profile curvature, plan curvature, topographic wetness index, sediment transport index, were clustered using the Fuzzy Kohonen Clustering Network (FKCN). Four terrain classes were obtained. The result was compared with a map produced by a classification of soil properties previously interpolated by ordinary kriging. The results suggest that areas for site-specific management can be defined from terrain classes based on environmental covariates, saving time and cost in comparison with interpolation of soil variables.


Author(s):  
O. M. Kunah ◽  
O. S. Papka

<span>The role of geomorphological ecogeographical variables have been shown, which are received by means of the digital elevation model created on the basis of remote sensing data as markers of an ecological niche of weeds on an example common milkweed (</span><em>Asclepias syriaca</em><span> L.). The research range chooses territory which is in settlement Vovnjanka district (the Poltava region). The range has the linear sizes of 26 kilometres in a direction from the east on the west and 15 kilometres in a direction from the north on the south, the range total area makes 390 км</span><sup>2</sup><span>. As geomorphological variables the topographical wetness index, topographic position index, mass balance index, erosion LS-factor, direct and disseminated insolation, altitude above channel network, multiresolution valley bottom flatness, multiresolution ridge top flatness index, vector ruggedness measure have been considered. It is established, that on set of the geomorphological indicators received by means of digital model of a relief, it is possible to assert, that within a separate agricultural field a wide variety of microconditions which is caused by relief features is formed. Possibly, the variation of thermal and water modes, moisture redistribution, and also productivity mechanical processings of soil and efforts under the control of number of weeds make a background in which limits there is possible a moving of weed plants, including common milkweed.</span>


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