http://117.252.14.250:8080/jspui/handle/123456789/5675 2026-04-05T19:44:14Z http://117.252.14.250:8080/jspui/handle/123456789/5691 Contents National Institute of Hydrology 1992-01-01T00:00:00Z http://117.252.14.250:8080/jspui/handle/123456789/5690 1-Analysis of Pumping Test Data on Large Diameter Wells Using Optimization Technique. Singh, V. S.; Gupta, C. P. The pumping phase data on large diameter wells, particularly in hard rock terrane, usually show negligible aquifer response indicating that most of the water is pumped from the well storage. Therefore, the recovery data should also be taken into account to estimate the hydrogeological parameters. The observed time-drawdown recovery datais matched with the analytically or numerically drawn theoretical type curves to estimate the hydrogeological parameters. In case of a numerical method, forward modeling is carried out wherein the parameters are progressively varied so as to obtain a close match with the observed time-drawdown/recovery curve. However, a visual match is naturally subjective and biased. Besides, the process of ploting and matching is a long drawn one. An alternative approach is presented here which ensures an unbiased, objective, and fast interpretation of the pumping test data on a large diameter well. The technique essentially consists in the minimization of the drawdown function which is the sum of squares of difference between the observed and computed drawdowns. The non-linear drawdown function is linearized around initially guessed hydrogeological parameters. The partial derivatives of this function with respect to hydrogeological parameters result into a set of simultaneous equations giVing new values of these parameters. The guess values of parameters are replaced by these newly estimated parameters. This iterative process is continued till a pre-set convergence criteria is achieved. This technique eliminates the need for a manual matching of field and computed time-drawdown curves. An illustration for interpreting the pumping test data on a large diameter well in a eranitic terrane is described in detail. 1992-01-01T00:00:00Z http://117.252.14.250:8080/jspui/handle/123456789/5689 2-Characterization of Groundwater Recharge in a Crystalline Watershed Through Recharge Process and Groundwater Flow Models. Reddy, T. Narasimha; Prakasam, P.; Subrahmanyam, G. V.; Goud, P. V. Prakash; Rao, V. V. S. Gurunadha; Gupta, C. P. Parkal watershed with an extent of about 12.35sq.km. is a hard rock granitic aquifer system and is situated in Warangal district, Andhra Pradesh. The recharge to the aquifer mainly occurs due to rainfall during monsoon season and has been estimated using a recharge process model. The recharge has been estimated as a balance component after accounting for interception losses, surface runoff, evapotranspiration based on agroclimatological conditions and soil moisture status. Surface runoff has been estimated from SCS (Soil Conservation Service) curve number model. Aquifer parameters viz., transmissivity and specific yield have been estimated through pump tests at four locations. The aquifer system has been modeled as a single weathered leaky aquifer using integrated finite difference method on a nested squares grid. Steady state condition of the aquifer system has been simulated assuming an equilibrium condition during June, 1981. The average annual recharge estimated over 10 years period has been fed as input to the aquifer. During the steady state calibration, the transmissivity values assigned at various meshes have been modified in some pockets to match the computed and observed water level contours. At some places minor changes have been resorted in the draft distribution arrived from well inventory and pumping hours. Irrigation return seepage has been found to be contributing significantly to the groundwater regime in the ayacut area of Damera cheruvu. The monthly recharge estimates of the recharge model have been fed as input to the aquifer model in the transient condition. The aquifer model has been refined after several trials and the monthly recharge estimates were found to be adequate for simulation of the water table behaviour. 1992-01-01T00:00:00Z http://117.252.14.250:8080/jspui/handle/123456789/5688 3-Data Base Management - Retrieval of Groundwater Level Fluctuation Data. Kumar, K. J. Anandha; Das, Sanjiv A network of more than thousand observation wells.has been established by Central Ground Water Board, all over the state of Orissa. Since 1988 PC/XT is being used for storage and retrieval of voluminous data using programs in D Base III plus which was earlier done manually. Now with advanced computer facilities provided' by N.I.C.,Bhubaneshwar, the data are stored in NEC-S-1000,working under the control of ACOS. After each measurement of network hydrograph stations, reports are prepared in the form of tables showing districtwise frequency of water level fluctuatios as compared to similar periods of the previous water year, as also premonsoon period of the current water year. This presents, at a glance, the number and percentage of wells falling in different flin.tuation intervals with maximum and minimum rise and fall . This Is an easy way to depict changes in groundwater regime in response to recharge or draft. Earlier the computation and generation of frequency table was done manually. Now this table is obtained ,using a software developed by N.T.C. The paper discusses generation of the frequency tables showing groundwater level fluctuation using this software. 1992-01-01T00:00:00Z