ANNOUNCEMENTS
Throughout the country, many seasonal streams have been turning into effluent carrying drains due to sewage and industrial waste discharge. Hydrological interactions of these streams with the aquifers lead to transport of contaminants from surface water to groundwater. Hindon is one such monsoon rain fed stream whose flow is generated entirely by effluents in the non-monsoon season. It originates in Saharanpur district of Western Uttar Pradesh and joins River Yamuna near Delhi. Saharanpur has seen rapid urban growth with industrial clusters being present throughout the district. The drains carrying urban and industrial discharges release the waste load to Hindon. Shallow aquifer system which provides drinking water to the region is in high risk of contamination due to contaminant transfer from the stream. So a study is conducted by considering one of the blocks of Saharanpur district through which Hindon flows by. Numerical modeling is used to simulate stream aquifer interaction by using Visual MODFLOW software. The hydraulic parameters required for modeling has been computed through experimental procedure. The soil of the region was found to belong to sandy loam category. Hydraulic conductivity of soil was found to be about 0.603 m/day. Hydraulic conductivity of the river bed was found to be 0.00587 m/day. Low hydraulic conductivity of river bed indicates deposition of organic matter leading to clogging of river bed. Bulk density of soil was found to be about 1492 kg/m3and percent porosity was found to be about 43.7 percent. Secondary datasets have been used for monitoring data and hydrological inputs into the model. Model has been conceptualized by considering a 6000m by 6000m area. Considering two pumping regimes of 250 m3/day and 500 m3/day, the model is run initially in a steady state. MODPATH program has been used to trace path line of particles from river to the aquifer. At 250 m3/day pumping, the particles start getting captured by wells. At 500 m3/day pumping, all particles from the river get captured by wells. Considering these two pumping schedules, transient state groundwater flow model is run for a time period of 365 days. The flow model of the region shows the movement of groundwater from North West to South East direction. Groundwater heads decreases in the pre monsoon season and increases due to rainfall recharge and increase of river stage in the monsoon season. Post monsoon groundwater heads are found to be nearly similar to pre monsoon groundwater heads for 250 m3/day pumping condition. However, for 500 m3/day pumping condition, post monsoon groundwater heads are seen to fall below the pre monsoon groundwater heads. MT3DMS is used to convert the flow model to a contaminant travel model. Transport of TDS and Nickel from river to the aquifer is simulated for a model run time of 365 days. At both the pumping regimes, TDS gets captured by the wells adjacent to the river. Concentration of Nickel is found to be insignificant. Concentrations for both contaminants were within permissible limits. TDS, being a conservative contaminant, does not undergo retardation reaction. Nickel, being a heavy metal, undergoes sorption-desorption reactions with soil. Hence Nickel undergoes retardation, decreasing its concentration in groundwater. However, if the concentration of contaminants in the river increases, or the pumping rate increases due to increase in the number of pumping wells, greater concentration of contaminants will get captured by wells and pose threat to the health of the population residing in villages near the stream. Since remediation of groundwater is a complex process, it is essential to regulate the contaminant load in streams. The capability of soil to attenuate contaminants need to be explored in detail. Knowledge of attenuation mechanisms of contaminants in different geological conditions and utilizing numerical modeling for creation of different scenarios, better formulation of groundwater pollution control and management plans can be achieved.
Keywords: Saharanpur, Hindon, Visual MODFLOW, Contaminant Transport.
