Central Ground Water Board, India
Online published on 12 January, 2016.
Sitanadi is one of the west flowing river of Udupi district and drains an area of 650 sq.km. in the taluks of Udupi, Karkala and Kundapura. The eastern part of the basin is partially under western ghats and western part lies in the coastal midan land. Physiographic ally the basin can be broadly divided into three well defined, identifiable and genetically significant units. Soil survey of the basin shows that, based on the morphological characteristics of various soil profiles 18 soil series are established and 24 soil units are recognised which are combinations of sandy clay, silty clay and gravely clay soils. Sitanadi is a sixth order river, the bifurcation ratio is 4.2 indicating mature basin. The drainage density is 1.78 km/sq.km. The basin is elongated with a form factor 0.26, circularity ratio 0.30 and elongation ratio 1.06. General pattern of rain fall over the basin was that eastern part received more rainfall compared to the western part of the basin. Based upon the origin, Geological diversities and relative groundwater potentialities in the aquifers belonging to different geological formations two hydrogeological units have been identified as consolidated and unconsolidated formations. Groundwater potential in the basin is evaluated by conducting resistivity surveys in different parts of the basin. Based on apparent resistivity, total longitudinal conductance, specific yield, transitivity and observation well data, the basin is divided into high, medium and low potential regions. The quality of groundwater from both domestic and irrigation wells is generally good and well within the limited both for domestic and irrigation purposes except few wells in the lower reaches during premonsoon periods where quality of water deteriorates due to salt water intrusion. Seasonal variation of water quality shows that there is a significant cyclic variation in quality characteristics between premonsoon and post monsoon period. Salt water Ingression studies indicate that ingression goes up to and beyond 20.5 km from the river mouth. Correlation studies between salinity ingression verses stream discharge as a function of distance indicates that the stream discharge increases as salinity decreases and as stream discharge decreases, salinity increases. Rate of salt water ingression is inversely proportional to the rate of stream flow in the river.
