GIS and remote sensing integrated environmental impact assessment of irrigation project in Finchaa Valley area

This research was conducted in order to assess the environmental impacts of Finchaa irrigation project using GIS and remote sensing techniques. Because of the limited resources only some environmental parameters were selected. These parameters are natural vegetation, soil/land, water quality, climate and health conditions. The normalized vegetation index (NDVI) analysis was used to detect the spatial and temporal change of vegetation biomass in the study area. The result indicated that the natural vegetation biomass is declining. This is mainly due to the expansion of agricultural land and escalating human made structures in the area. The water physico-chemical analysis demonstrated that the down stream water has more chemical substances and degraded physical properties than the up stream counterparts. The direct leakage of industrial liquid waste and the agro-chemicals from irrigation fields are supposed to contribute for this result. The GIS analysis of a 100 meter buffer around Major rivers and tributary streams is found to be a necessary action to mitigate the problem of pollution. The soil chemical and physical property analysis in the irrigated and non irrigated fields reveals that the soil samples taken from irrigated fields contain higher phosphorous, Nitrogen and organic carbon compared to its counter parts. The use of agro-chemicals in the irrigation fields contribute for the result. From the twenty two years rain fall, temperature and humidity data no abrupt inclining or declining trend is observed that could tell the possible impacts of the project. The post irrigation development years witness that some water born diseases and malaria case records have increased. It is also found out that expansion of irrigation fields and the respective Malaria case records are positively correlated. Generally, despite the significance of the Finchaa irrigation project, it has negative environmental repercussions. This is evident from vegetation cover distraction, water quality deterioration in the down stream area, alteration of soil physical and chemical components and increasing health threats. If the current condition continues the problems may out weight the benefits of the irrigation project. Thus in the project site and adjoining areas urgent environmental conservation is necessary. This helps to sustain the existing and revitalize the fading resources.