Characterization and Classification of Soil Map Units by Using Remote Sensing and GIS in Bahar Al-Najaf, Iraq

Abstract

The Bahar Al-Najaf Lands is located in the west of the Al-Najaf Governorate. It is extended between 31° 39′ 16″–32° 08′ 08″ N and 43° 47′ 11″–44° 30′ 15″ E with a total area of 2,000.2 Km2. This chapter aims to find out the possibility of using Remote sensing (RS) and Geographic Information Systems (GIS) techniques in contributing to soil surveys by selecting soil map units drawing and calculating spectral reflectance by satellite image of Landsat 8 provided with two Sensors; Operational Land Imager (OLI) and Thermal Infrared (TIRS). The image was acquired on 07/13/2014 from the USGS site and shows the nature and interference effect of the relationship between some of the soil physical and chemical properties on its spectral reflectance values by choosing false-color composite RGB (753), which is a specialist for studying soils and minerals and deducting study area using ERDAS imagine 2013. Some enhancements have been made (radiation, spectral and spatial) add to unsupervised classification, as well as using earth indicators (EIs). The used EIs include soil color, texture, natural plants and topography. These EIs are used in determining the researcher movement paths to select 16 Pedon’s sites with 21 auger holes to a depth of 75 cm for surveying and isolating expected soil individuals within the study area which are identified using GPS. The unsupervised classification approach has shown considerable potential in the distribution of soil classes are close to supervised classification. The pedons revealed and described, according to the (Soil Survey Staff 1999). Disturbed soil samples were selected from each horizon, air-dried, crushed and passed through sieve openings of 2 mm diameter for execution physical and chemical analysis. The results of particle size analysis show that there is no specific pattern distribution of soil particles whether within the pedon itself or between the pedons. There was no observed variations in textures classes for the vertical direction within the same pedon as in (P9, P4A, P10) or got little changes as in P4B. Horizontally variations observed among sites which returns to the nature of sedimentary additives and helps to occur the Lithological discontinuities in soils. All the pedon’s horizons were strongly calcareous, while they varied in gypsum content in surface and subsurface horizons. Depending on the US modern classification, All the studied soils are within the Entisol order, which classified into two of Suborders. The first is Fluvents including great soil group Torrifluvents and subgroup Typic Torrifluvents which includes 9 Soil series ME1, DW56, TW964, DM44, MW3, TE354, DW124, DE47, DE126. The second is Psamments including two great soil groups, The first Torripsamments containing subgroup Typic Torripsamments including DE33, DE34, DE74, TE334, TW446 soils series. The other quartzipsamments include subgroup Typic quartzipsamments containing two soil series ME1, DM14. The soil series are classified according to the proposed (Al-Agidi 1976). for alluvial Iraqi soils classification, It was diagnosed nine families and 15 soil series in the study area.