Remote sensing and GIS based analysis of temporal land use/land cover and water quality changes in Harike wetland ecosystem, Punjab, India

摘要

Wetlands help in maintaining ecological balance in an area, but are shrinking fast all over the world. A study was conducted on the Harike wetland in Punjab state of India to analyze temporal changes in land use/land cover (LULC), water spread area and water pollution by using RS and GIS techniques. The LULC map of Harike wetland ecosystem covering an area of 22213.91 ha was prepared through on-screen visual interpretation of multispectral Resourcesat 2 LISS-IV satellite data (2014 and 2018) having spatial resolution of 5.8 m. Area under agriculture, forest and built up increased and that under waste land, water bodies and wetland decreased during 2014-18. The rate of increase in agricultural land was quite high (18.87 ha/year) during 2006-2014, but reduced to 3.53 ha/year during 2014-2018. The built up land increased comparatively at low rates (0.87 and 0.90 ha/year). Areas under waste land, water bodies and wetland decreased at the rate of 4.32,1.61 and 13.80 ha/year during 2006-2014 and 2.37, 0.34 and 1.71 ha/year during 2014-2018, respectively. The water spread area of Harike wetland which was 4073 ha and 4166 ha in year 2002 and 2006 reduced to 3918.98 ha and 3910.56 ha in the year 2014 and 2018, respectively. However, wetland ponded area shrinked at a rate of 30.37 ha/year during 2006-2014 and 2.11 ha/year during the period 2014-2018. The area under low and medium turbidity increased by 22.02% and 15.2%, respectively, but decreased by 49% under high turbidity during 2014-18. Wetland water was observed to be rich in macro and micronutrients. The pH, BOD and COD of wetland water increased by 0.51, 9.7 mg/1 and 24 mg/1, respectively, during 2002-14 and by 0.03, 2.0 mg/1 and 5.92 mg/1, respectively during 2014-18. Interaction between land use, water quality, water inflow, ground water and wetland area has also been studied. Intensive cultivation and declining groundwater levels in the area are negatively affecting the wetland. This necessitates regular monitoring of wetland structural components and water quality along with an urgent plan in place for conservation, rehabilitation and management of Harike wetland ecosystem in participatory mode.