Assessment of Soil Salinity Risk on the Agricultural Area in Basrah Province,Iraq:Using Remote Sensing and GIS Techniques

This study presents an integrated study of expansion process of salinized land in Basrah Province, a typical salt-affected area in southern parts of Iraq, by using geo-information techniques. Satellite images （Landsat TM 1990） and thematic maps （ETM 2003） were used to provide comprehen- sive views of surface conditions such as vegetation cover and salinization detection. With ERDAS soft- ware, the normalized differential salinity index （NDSI） and salinity index （SI） were computed and then evaluated for soil degradation by salinization. ARC/INFO software was used along with field observa- tion data （global positioning system） for analysis. During the past 13 years, the salinized land in study area increased by 6 579.1 km2 and in 2003 covered 34.5% of the total area; in the meantime, vegetation cover has decreased by 4 595.9 km2 and in 2003 covers only 24.1% of the study area. Environmental changes show that, between 1990 and 2003, 37.5% of vegetation cover and 45.9% of marshlands were transformed into salty meadow and wet salty crust, respectively. In addition, there was 16.6% of sand lands converted into dry puffy salty crust. Results using spatial analysis methods showed that 7 894.9 km2 （41.4%） of land had no risk of environment degradation by soil salinity, 4 595.9 km2 （24.1%） bad slight risk, 4 042.8 km2 （21.2%） had moderate risk, and 2 536.3 km2 （13.3%） of the total land area was at a high risk of environment degradation by soil salinity. In conclusion, the study area was ex- posed to a high risk of soil salinity.

Remote Sensing and GIS Application in the Detection of Environmental Degradation Indicators

The main aim of this research is to highlight the environment change indicators during the last 20 years in a representa-tive area of the southern part of Iraq(Basrah Province was taken as a case) to understand the main causes which led to widespread environment degradation phenomena using a 1:250000 mapping scale.Remote sensing and GIS's software were used to classify Landsat TM in 1990 and Landsat ETM+ in 2003 imagery into five land use and land cover(LULC) classes:vegetation land,sand land,urban area,unused land,and water bodies.Supervised classification and Normalized Difference Vegetation Index(NDVI),Normalized Difference Build-up Index(NDBI),Normalized Difference Water Index(NDWI),Normalized Difference Salinity In-dex(NDSI),and Topsoil Grain Size Index(GSI) were adopted in this research and used respectively to retrieve its class boundary.The results showed a clear deterioration in vegetative cover(514.9 km2) and an increase of sand dune accumulations(438.6 km2),accounting for 10.1,and 10.6 percent,respectively,of the total study area.In addition,a decrease in the water bodies' area was de-tected(228.9 km2).Sand area accumulations had increased in the total study area,with an annual increasing expansion rate of(33.7 km2·yr·1) during the thirteen years covered by the study.It is therefore imperative that Iraqi government undertake a series of pru-dent actions now that will enable to be in the best possible position when the current environmental crisis ultimately passes.