Delineating soil landscape facets from digital elevation models using compound topographic index in a geographic information system

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 569 ◽  
Author(s):  
X. Yang ◽  
G. A. Chapman ◽  
J. M. Gray ◽  
M. A. Young

Soil landscapes and their component facets (or sub-units) are fundamental information for land capability assessment and land use planning. The aim of the study was to delineate soil landscape facets from readily available digital elevation models (DEM) to assist soil constraint assessment for urban and regional planning in the coastal areas of New South Wales (NSW), Australia. The Compound Topographic Index (CTI) surfaces were computed from 25 m DEM using a D-infinity algorithm. The cumulative frequency distribution of CTI values within each soil landscape was examined to identify the values corresponding to the area specified for each unmapped facet within the soil landscape map unit. Then these threshold values and CTI surfaces were used to generate soil landscape facet maps for the entire coastal areas of NSW. Specific programs were developed for the above processes in a geographic information system so that they are automated, fast, and repeatable. The modelled facets were assessed by field validation and the overall accuracy reached 93%. The methodology developed in this study has been proven to be efficient in delineating soil landscape facets, and allowing for the identification of land constraints at levels of unprecedented detail for the coast of NSW.

Author(s):  
Mosriula Mosriula

Analysis of land, its carrying capacity and development strategy of seaweed cultivation in Labakkang, Pangkajene Regency. This study attempts to: (1) analyze the suitability of coastal land that appropriate for seaweed cultivation, (2) determine the carrying capacity of the land for seaweed cultivation, (3) formulate strategies and policies that appropriate for seaweed cultivation. This study used biophysical field survey to assess the region, analyze the suitability of the land as well as the carrying capacity of the area by using a geographic information system. Furthermore, the research analyzed the strategy and policy of development of seaweed cultivation with A'WOT analysis approach. The results of the evaluation of the suitability of land for seaweed cultivation in coastal areas showed that Labakkang has potential approximately 1632.876 ha. The area is suitable for seaweed cultivation activities around 1035.54 ha, and unsuitable area around 597.336 ha. For carrying capacity of seaweed cultivation in the coastal area of Labakkang is for 40.55 units. The priority development strategy of seaweed cultivation is strengthening institutions to make a sustainable seaweed cultivation in Labakkang.


Author(s):  
Y. Singh ◽  
S. Bhandari ◽  
D. Tamang ◽  
A. Basnet ◽  
R. Shrestha ◽  
...  

Abstract. Digital Elevation Models are one of the important datasets of any Geographic Information System (GIS) and so are the parameters derived from them. One such parameter is slope, whose accuracy can have a significant effect on many engineering and construction works. This paper addresses the eight-slope calculation methods that are currently available to calculate slope value from a DEM and compares how these methods works on different slope range and values. These methods were applied to calculate slope from DEM of 30 m. To determine the method that calculates the most accurate slope value for a particular slope range by comparing them with actual slope value is the main objective of this paper. The methods 2FD, 3FD, 3FDWRD, Average Neighborhood, Constrained Quadratic Surface and FFD has given similar results across all slope range while the algorithms that appears to yield the most varying results are Maximum Max and Simple D. In addition, it is observed that the choice of algorithms is more important when grade slope is less than 10 percent. However, for terrains with above 10 percent slope, the choice of algorithms seems less important with only a difference of approximately 0.5 gradient.


Author(s):  
Gizachew Tiruneh ◽  
Mersha Ayalew

Accelerated soil erosion is a worldwide problem because of its economic and environmental impacts. Enfraz watershed is one of the most erosion-prone watersheds in the highlands of Ethiopia, which received little attention. This study was, therefore, carried out to spatially predict the soil loss rate of the watershed with a Geographic Information System (GIS) and Remote Sensing (RS). Revised Universal Soil Loss Equation (RUSLE) adapted to Ethiopian conditions was used to estimate potential soil losses by utilizing information on rainfall erosivity (R) using interpolation of rainfall data, soil erodibility (K) using soil map, vegetation cover (C) using satellite images, topography (LS) using Digital Elevation Model (DEM) and conservation practices (P ) using satellite images. Based on the analysis, about 92.31% (5914.34 ha) of the watershed was categorized none to slight class which under soil loss tolerance (SLT) values ranging from 5 to 11 tons ha-1 year-1. The remaining 7.68% (492.21 ha) of land was classified under moderate to high class about several times the maximum tolerable soil loss. The total and an average amount of soil loss estimated by RUSLE from the watershed was 30,836.41 ton year-1 and 4.81 tons ha-1year-1, respectively.Int. J. Agril. Res. Innov. & Tech. 5 (2): 21-30, December, 2015


2019 ◽  
pp. 1478-1485
Author(s):  
Osamah N. Al-Sheikh ◽  
Ayser M. Al-Shamma’a

The groundwater represents the main source of water in the study area due to lack of surface water. The Dammam unconfined aquifer represents the main aquifer in the study area and Southern desert because of the regional extent, the quantity and quality of water. Many groundwater wells have been drilled in the study area to coverage the huge demand of water for agricultural purposes. The Geographic Information System (GIS) was used to estimate the volume of water which calculated (25.6964 × 109 m3) within the study area , automate calculation of the area of Al Salman basin using digital elevation models, derive the thickness maps of AlDammam unconfined aquifer from Key holes (KH) and Bore holes (BH), draw the groundwater head and flow map in the study area. Such data derived from GIS can help authorities and researchers for groundwater management and further development within the study area.


Irriga ◽  
2002 ◽  
Vol 7 (2) ◽  
pp. 91-97
Author(s):  
Sergio Campos ◽  
Thiago Godinho dos Santos ◽  
Cristiane Lopes da Silva ◽  
Zacarias Xavier de Barros ◽  
Lincoln Gehring Cardoso

CAPACIDADE DE USO DAS TERRAS DA BACIA DO RIBEIRÃO ÁGUA FRIA – BOFETE (SP)  Sérgio CamposThiago Godinho dos SantosCristiane Lopes da SilvaZacarias Xavier de BarrosLincoln Gehring CardosoDepartamento de Engenharia Rural, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, CP 237, CEP 18603-970, Botucatu - SP, E-mail: [email protected].  1 RESUMO              A determinação da capacidade de uso das terras numa bacia é muito importante para o planejamento e uso do solo, pois o uso inadequado e sem planejamento dessas terras provocam a baixa produtividade das culturas.  Este trabalho visou definir as classes homogêneas de capacidade de uso da terra da bacia do Ribeirão Água Fria - Bofete (SP)  para atender ao planejamento de práticas de conservação do solo desta área.  A bacia situa-se entre as coordenadas geográficas 22o 58' 30`` a 23o  04' 30`` de latitude S e 48o 09' 30`` a 48o 18' 30`` de longitude W Gr., apresentando uma área de 9.180,12 hectares.  A carta de capacidade de uso da terra da bacia foi elaborada a partir da carta clinográfica  obtida por Santos et al. (1999), mapa pedológico do Estado de São Paulo (Oliveira et al., 1999), da tabela de julgamento de classes de capacidade de uso do solo (França, 1963) e das recomendações constantes no manual para levantamento utilitário do meio físico e classificação das terras no sistema de capacidade de uso (Lepsch et al., 1983).  A discriminação, o mapeamento e a quantificação das áreas das classes e subclasses de capacidade de uso pelo Sistema de Informação Geográfica - IDRISI apresentaram os seguintes valores:  IIIe,s - 517,020 ha (5,63%); IIIs - 863,150 ha (9,40%); IVe - 846,730 ha (9,23%); VIe - 871,110 ha (9,49%) e VIIe - 6082,115 ha (66,25%). Os resultados permitiram concluir que a bacia essencialmente constituída por 2/3 pela subclasse VIIe, ou seja, são terras que podem ser utilizadas por pastagens com uso moderado ou florestas, pois apresentam problemas complexos de erosão por causa de sua declividade. O Sistema de Informação Geográfica IDRISI permitiu através de seus módulos discriminar, mapear e quantificar as áreas das classes e subclasses de capacidade de uso das terras da bacia com rapidez e confiabilidade.   UNITERMOS: Capacidade de uso, unidades de solo, classes de declive, bacia hidrográfica.   CAMPOS, S., SANTOS, T.G., SILVA, C.L., BARROS, Z.X., CARDOSO, L.G.  LAND USE CAPACITY OF AGUA FRIA STREAM BASIN – BOFETE (SP)  2 ABSTRACT              The land use capacity determination is considered to be very important on land use planning, since its inadequate utilization can lead to low crop productivity. This work aimed to define the homogeneous classes of land use capacity of Agua Fria stream Basin – Bofete (SP) in order to help the soil conservation procedure planning in this area. The Basin is located from 22°58’30’’ to 23° 04’30’’ southern latitude and 48° 09’30’’ to 48°18’30’’ western longitude, in a 9180.12 ha area. The chart of land use capacity was established based on the clinographic chart by Santos et al. (1999), São Paulo state pedological map (Oliveira et al, 1999), class determination chart of soil use capacity (França, 1963) and the recommendations from the manual for physical environmental utilitary survey in the using capacity system (Lepsch et al, 1983). The determination, mapping and quantification of class and subclass areas of using capacity by the Geographic Information System – IDRISI presented the following values: IIIe,s – 517.020 ha (5.63%); IIIs 863.150 ha (9.40 %); IVe – 846.730 ha (9.23%); VIe – 871.110 ha (9.49 %) e VIIe – 6082.115 ha (66.25 %). The results allowed to conclude that the Basin is 2/3 essentially constituted by VIIe subclass, i.e., land that could be used for moderate grazing or forests, since it has complex erosion problems due to its slope. The Geographic Information System IDRISI by its modules enabled to discriminate, map and quantify the land use capacity class and subclass areas of the basin fast and reliably.  KEY-WORDS: Using capacity, soil unit, sloping class, hidrographic basin.


1970 ◽  
Vol 19 (2) ◽  
pp. 25-42
Author(s):  
Krishna Prasad Poudel

Not available.Key words: Geographical Information System; Hill-slope; Upper Madi; Kaski; Nepal Tribhuvan University Journal Vol. XIX, No. 2, 1996 Page: 25-42 Uploaded Date: 29 October, 2010


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