LAND COVER AND LAND USE ANALYSES |
Land cover and land use analyses was done using remote sensing data as well as collateral data.. Geographic Information System (GIS) has been used for integrating remote sensing data with collateral data. Supervised classification approach using Gaussian maximum likelihood classifier is used for classification of remote sensing data. This is done by collecting a training data (GCP) from the study area and GCP’s were uniformly distributed all over the study area. Normalized Difference Vegetation Index (NDVI) is the most commonly used Vegetation Index (VI) for land cover analyses. The results show that area not under vegetation ranges from 39 % - 46 % while area under vegetation ranges from 54 % - 61 % in the Sharavathi basin.
Land-use change is significant to a range of themes and issues central to the study of cumulative impact assessment. The alterations it effects in the surface of the earth hold major implications for sustainable development and livelihood systems. Land-use change analyses help to understand (i) the driving forces (exogenous variables) of land use as they operate through the land manager; (ii) the land-cover implications of land use; (iii) the spatial and temporal variability in land-use/cover dynamics; and (iv) impacts on biodiversity and ecosystem functioning. Land use analyses of the upper river basin show that 25% of the area is under moist deciduous, followed by category II (21%, consisting of grass land, scrub, cultivable waste) , evergreen to semi-evergreen (16%), plantations (9.7%), agriculture (8.5%), water body (7.1%), class I (7.14%, habitation, roads, rocky area, etc.) and dry reservoir bed (5.4%).
Human interventions in the ecosystem have resulted in erosion of biodiversity in the recent past in the river basin. The loss in biodiversity has been attributed to habitat loss and fragmentation of the natural landscapes. The analyses revealed extensive fragmentation in the river basin as a consequence of damming the river, conversion of forestlands to agricultural lands, and encroachment etc. Fragmentation has resulted in the remnant areas of native vegetation surrounded by a matrix of agricultural, horticultural and other human impacted lands. These in turn have important influences on the biota within the remnant patches, especially along the edges of the remnant patches as well as in the surrounding matrix. The fragmentation is fuelled by anthropogenic activities, which are degrading the forest habitat of the critical watershed areas. Such human pressures have caused fragmentation of large, unbroken tracts of forests into, smaller isolated patches. This process has lessened the value of the forest as a habitat for many of the plant and animal species native to the Sharavathi river basin, from where, it is feared that many are lost forever. These consequences vary with the distance from the patches and connectivity with the other patches. The physical distances and influences modify the size, shape and the position in the patch and its constituents. The characteristics of the patch along with the spatial and temporal changes in the landscape were done to quantify the extent of damages. The remote sensing data in conjunction with GIS and GPS helped in landscape characterisation. Land use changes, Landscape dynamics and Landscape characterisation have been analysed from patch to river basin level to understand the temporal changes due to developmental activities in the river basin. Landscape analysis showed that the indices of shape, richness and diversity provided an additional evaluation of land cover spatial distribution within the complex mountain landscape. The landscape analysis has provided an outline of the degree of propagation of the disturbance from the non-biotic sources and fragmentation. It is revealed that fragmentation has caused loss of connectivity, ecotones, corridors and the metapopulation structure.
As a result of the development programme based on ad-hoc decisions, considerable changes in the structure and composition of the land use and land cover in the region have been very obvious during the last four decades. Pressure on land for agriculture, vulnerability of degraded ecosystems to the vagaries of high intensity of rainfall and high occurrence of steep erosion and landslide-prone areas, lack of integrated and coordinated land use planning are some of the reasons for rapid depletion of the natural resource base. These changes have adversely affected the hydrological regime of river basins resulting in diminished river / stream flows. Frequent landslides damage the infrastructure and threaten human lives. In this situation, in order to resolve present problems and to avoid a future crisis, a comprehensive assessment of land use changes, its spatial distribution and its impact on hydrological regime is required and accordingly, appropriate remedial methods should be employed for the sustainable utilization of the land and water resources of the catchment.
