Evaluation of morphometric parameters and hypsometric curve of Arkavathy using RS and GIS techniques

Conclusions

The study of hypsometric curve reveals that Arkavathy river basin is close to young but not old type of basin. Hence, the basin possesses considerable scope for erosion in future. The presence of flatter terrain in midlands in between uplands and lowlands is confirmed by hypsometric curve. And that puts existing reservoirs and water bodies across midlands at risk of sedimentation and loss of crucial live storage which will lead to accentuation of water stress in the basin.

Morphological characteristics of the basin indicate variation in different stream orders that confirms the anomalous basin development and local variation in topography in the basin. The dendritic to sub-dendritic pattern indicates uniform resistance to drainage pattern by major rock types in the basin such as intrusive acidic rock and banded gneissic rock. Along with the combination of factors such as human intervention and intensity of precipitation, flooding is expected across stream orders 3 and 5 due to lower bifurcation ratios, whereas stream orders 1, 2, and 4 possess increased scope for infiltration that facilitate building water harvesting and recharge structures. The steeper slopes at highlands and lowlands depicted by hypsometric curve, particularly at the regions across stream orders 3 and 5, have the potential to conserve water through large surface water harvesting structures.

The areal aspects of the Arkavathy river basin confirm that the basin is elongated and as a consequence Arkavathy river basin experiences low peak flows of runoff for longer duration despite flood risk. Lower drainage density and length of overland flow in the basin confirm longer concentration times for runoff particularly in the regions of lower relief. Therefore, the runoff in Arkavathy river basin has large scope for infiltration into the ground water particularly at flatter regions depicted by hypsometric curve. However, as Arkavathy river basin possesses moderate- to low-water-bearing aquifer systems such as granite and gneiss rock types, the water infiltrated can only be stored across fluvial deposits across the valley floors and stream channels of the drainage network or in rock fractures. As the aquifer systems in Arkavathy basin are not high-water-bearing systems, considering the water budget of the basin, the cause of loss of water in a basin can be deduced as evapotranspiration. It can be concluded that due to high time of concentration of runoff in the basin, as a consequence of its morphometry, the loss of water due to evapotranspiration rates leads to the persistent water scarcity in the basin.

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Taxonomy

• River Basin management