Studying evidence of land degradation in the Indian Ganga River Basin-a Geoinformatics approach.

Land degradation is a long-term loss of ecosystem function and productivity which takes place due to a wide variety of land processes, namely soil erosion, soil sodification, green-cover loss, and soil conditions such as soil infertility that leads to productivity loss. About 41% of the land in India is under different forms of land degradation in which a major part lies in the Indian Ganga River Basin (IGRB). In this work, we evaluated the evidence of land degradation in the IGRB by analyzing (i) the changes in the forest cover and land use (FCLU) between 1975 and 2010, (ii) forest fragmentation status for the same time period, and (iii) decline in rain-use efficiency (RUE) during 2000-2010. The FCLU-type mapping for the year 1975 and 2010 was carried out using 216 Landsat satellite scenes that derived 40 vegetation and 7 non-vegetation classes. The highest negative change (loss) was observed in the dry deciduous forest of mixed forest formation (4699.9 km2) and gregarious formation (1337.6 km2), and a major gain in settlement (5396.3 km2) and managed lands (3408.4 km2). An increase in forest fragmentation was observed in all the forest classes with the highest rise in the deciduous forest of the central basin. A consistent decline in RUE was observed highest in the South-Western semi-arid IGRB (0.02-0.15) that stretched up to the central basin. All the three analyses showed evidence of active land degradation in the form of green-cover loss, fragmented forests, and declined primary productivity with visual evidence for some of the severely degraded areas. The use of Geoinformatics to analyze land degradation using surface indicators is promising and provide possibilities of further improvements using better resolution data.