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CONCLUSION
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CONCLUSION |
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In the present study, the ecological investigations of selected streams and eight tributaries in the Sharavathi river basin, Western Ghats was undertaken. The streams were selected from Nandiholé, Nagodiholé and Yenneholé sub-basins of Sharavathi. The eight tributaries of upstream of Sharavathi river basin were selected for the study. The ecological investigations included the land use pattern of the catchment, physico-chemical and biological analysis of water, hydrological assessment and physico-chemical analysis of soil samples. The land use pattern analysis was analysed using remote sensing data. The hydrological assessment included stream flow analysis and rainfall computation. Vegetation analysis of the catchment was done by random transect cum quadrat method to investigate the influence of vegetation on the water quality, soil quality and stream discharge. The analysis of soil and water was done by standard methods. The results of the ecological investigations revealed
• Land-Use pattern : Among the eight sub-basins of Sharavathi upstream catchment, Nagodiholé had the maximum evergreen and semi-evergreen forests (52.14%) followed by Hilkunji (43.27%) > Yenneholé (37.89 %) > Hurliholé (32.78%) > Sharavathi (19.16%)> Mavinholé (4.37 %) > Nandiholé (3.31 %) > Haridravathi (2.28%). The agricultural lands present in the sub-basins were Haridravathi (18.19%) > Nandiholé (11.33%)> Sharavathi (10.33%) > Mavinholé (9.81%) > Hilkunji (4.18%) > Hurliholé (1.97%) > Yenneholé (1.37%) > Nagodi (1.08%). The Land use pattern analysis shows that the forest areas have been replaced with agricultural activities in the sub-basin.
• Water quality of the Tributaries: The physico-chemical and biological analysis of the eight tributaries in the Sharavathi upstream catchment showed that all the parameters were within permissible limits. But electrical conductivity, total dissolved solids, turbidity, sodium and potassium values were relatively high in Nandiholé, Haridravathi and Mavinholé. The Palmer algal index showed high scores values in Nandiholé indicating organic pollution during the sampling period. This is mainly due to the agricultural activities in the catchment.
• Micro – level assessment: The micro-level assessment included the vegetation analysis, water quality, stream discharge and soil quality of selected streams in three sub-basins of Nandiholé, Nagodiholé and Yenneholé. The results are as follows
• Vegetation Analysis of the sub-basin: The vegetation analysis of the stream catchment of the three sub-basins of Nandiholé, Yenneholé and Nagodiholé revealed that Nagodiholé catchment had high endemism, evergreeness and total basal area followed by Yenneholé and Nandiholé. The characteristic feature of an undisturbed forest is high endemism and evergreeness but agricultural and other anthoropogenic activities in the Nandiholé have resulted in the loss of endemic and evergreen species.
• Stream water quality: The physico-chemical and biological analysis of the water quality revealed that the streams of Nandiholé sub-basin showed high values of TDS, turbidity, electrical conductivity, sodium and potassium values. All the streams in this sub-basin were also faecally contaminated. This is due to the increased anthropogenic pressure in Nandiholé compared to Yenneholé and Nagodiholé.
• Stream flow: The streamflow measurement varied radically between the first and second order streams of the three sub basins. The two out of the four streams in Nandiholé dried during the study period (i.e., during January and February of 2004). The other two streams of this sub-basin showed very low discharge values when compared with streams of Nagodiholé and Yenneholé. The results reveal that the stream flow varies according to the topography and rainfall pattern and forest cover in the catchment. The catchment with high forest cover like Nagodiholé and Yenneholé shows a high stream discharge, whereas catchment area with highest agricultural land shows a low stream discharge.
• Soil quality: The soil quality analysis revealed that the soil was productive in the Nagodiholé and Yenneholé sub-basins whereas the parameters like low organic content, high bulk density, etc revealed that the soils of Nandhiholé sub-basin were degraded.