April, 2010

April, 2010   ||  Volume 14 No.2


GIS based study of Spatio-Temporal changes in groundwater depth and quality in Kaithal district of Haryana, India 

S.K.Goyal and B.S.Chaudhary

Dept. of Geophysics, Kurukshetra University, Kurukshetra - 136 119
E-mail: sanjayktl@gmail.com

The study has analyzed the spatio-temporal changes in groundwater depth and quality from 1992 to 2007 in Kaithal district of Haryana state to understand the hydrological behavior and status of the area. Pre- and post- monsoon depth to water level below ground level (bgl), electrical conductivity (EC) and Landsat remote sensing data were used in the study. Spatial distribution of depth and EC in the study area were mapped and classified into standard zones in GIS environment for 1992, 1997, 2002 and 2007. Change detection maps, seasonal fluctuation maps and groundwater prospects maps were generated using cross and difference operations in Integrated Land and Water Information System (ILWIS 3.6) to identify critical as well as potential groundwater zones in the district. The study revealed a decline in average groundwater depth from 9 m bgl in 1992 to 16 m bgl in 2007. Average EC of groundwater in the district was also found to degrade from 1722 µS/cm to 2267 µS/cm in the corresponding period. The changes in depth and quality were more prominent in two-third part of the district (upland plains) under Gulha, Siwan, Kaithal and Pundri blocks. In the remaining low lying part in southern region, depth and EC were almost stable in 3-10m and 2500-9000 µS/cm range respectively. Due to high EC (>4000 µS/cm), the groundwater in a part of Rajaund block was found unsuitable for irrigation. Also, it had low public acceptability for drinking. Entire Pundri block along with a part of the adjoining Kaithal block (about 32% of total area) was identified as the zone of good groundwater prospects. Western part in Siwan block (about 8% of total area) was found critical due to fast depleting groundwater levels. The depletion of levels and worsening of groundwater quality in general, can be attributed to over-exploitation of groundwater and excessive use of agrochemicals in addition to natural factors. High EC (2500-9000 µS/cm) and a nearly shallow water table observed in Rajaund and Kalayat blocks can be understood to be a combined effect of inadequate groundwater withdrawal, poor drainage conditions, effect of leaching, and geohydrological setting of the area.


Predictability of solar activity using fractal analysis
R.Gayathri and R. Samuel Selvaraj1
Dhanalakshmi Srinivasan College of Engg. & Tech., Poonjeri, Mamallapuram,
Chennai - 603 104
1Dept. of Physics, Presidency College, Chennai - 600 005
E-mail: r.gayathri77@rediffmail.com

Various new techniques like neural networks, learning nonlinear dynamics and others are used by researchers to predict solar activity. But we are yet to obtain reasonably good results. This is mainly because the reason of the variation of solar activity is still unknown. Hence it is important to analyze the characteristics of the data. This paper considers sunspot numbers as an index of solar activity. The daily sun spot number data is analyzed using fractal technique and examined to determine the predictability of solar activity. For the period 1990 to 2004, the average fractal dimension for periods of 10 days or less was about 1.43. But during the same period, the average fractal dimension was 1.72 for periods longer than 10 days. Hence the result is encouraging for short-term prediction (i.e.) within about 10 days, but discouraging for medium-term prediction (longer than 10 days).

Seasonal forecast of southwest monsoon rainfall – District level

Onkari Prasad, O.P.Singh1 and S.K.Subramanian2
43 Ritu Apartments, A-4 Paschim Vihar, New Delhi - 110 063
1 India Meteorological Department, Lodi Road, New Delhi - 110 003
2 New No. 3 ( Old No. 13), East Tambaram, Chennai - 600 059
Email: onkariprasad06@yahoo.com; op_singh54@yahoo.com; sksubramanian@gmail.com

An empirical model has been proposed for district level seasonal forecast of rainfall during southwest monsoon season. Results relating to meteorological subdivision of Tamilnadu and Pondicherry are discussed. Cloud and rainfall data for a period of 36 years (1972-2008 except 1978) have been used in the study. It has been shown that different features of cloudiness over near equatorial regions of Indian Ocean during pre-monsoon months of April and May contain signals indicating likely performance of subsequent southwest monsoon. These features have been quantified by assigning an index called South Indian Convergence Zone ( SICZ ) Activity Index ( SAI ). SAI varies from 1 to 20. Verification of the forecasts has shown that the proposed model is capable of producing ‘Useful’ forecasts of seasonal rainfall for meteorological sub-division of Tamilnadu and Pondicherry and its districts. 

Ionospheric precursors observed during some earthquakes
A.K.Gwal, Santosh Kumar Jain, Gopal Panda 1 and S.K.Vijay 2
Space Science Laboratory, Department of Physics Barkatullah University, Bhopal – 462 026
1Department of Engineering Physics, RKDF Institute of Science and Technology, Bhopal – 462 026
2Department of Physics, Govt. Geetanjali Girls College, Bhopal – 462 026
E-mail: ak_gwal@yahoo.co.in

Ionospheric anomalies in association with earthquakes were derived using foF2 records from ionospheric stations. The present study reports the ionospheric perturbations, if any, observed over the related ionospheric station prior to occurrences of five earthquakes during last three years at various locations. Initially, foF2 data were analyzed with upper and lower bound and the observed anomalous changes related to geomagnetic disturbances were filtered out. Then the remaining perturbations were analyzed in relation to the occurrence of seismic activities. Hence period considered in this study comes under the quiet geomagnetic conditions. The results of the study showed some unusual perturbations. These anomalies are strongly time dependent and appeared some days before the main shock. The possible mechanism to explain these anomalies is the effect of seismogenic electric field generated just above the surface of the earth within the earthquake preparation zone well before the earthquake.



Study of Ionospheric Perturbations during Turkey – Central Earthquake of December 20, 2007
Gopal Panda, Santosh Kumar Jain, S.K.Vijay 1 and A.K.Gwal

Space Science Laboratory, Department of Physics, Barkatullah University, Bhopal - 462 026
1 Department of Physics, Govt. Geetanjali Girls College, Bhopal – 462 026
E-mail : gopal­_panda007@yahoo.com

Present paper deals with variation of foF2 (critical frequency) in F-region of ionosphere before seismic shock of Turkey-Central earthquake on December 20, 2007. A statistical analysis of variation in foF2 before earthquake has been presented. We analyzed foF2 data using bound method. The observed anomalous changes related to geomagnetic disturbances are filtered out (using Dst index). Assuming the remaining disturbances are due to earthquake which may be used as an earthquake precursor. 



Simultaneous observation of VLF and VHF wave in the presence of ionospheric irregularities
R.P.Patel, K.Patel1, A.K.Singh1 and R.P.Singh1

Department of Physics, M.M.H. College, Ghaziabad - 201 009
1Atmospheric Research Lab., Physics Department, Banaras Hindu University, Varanasi - 221 005
Email: abhay_s@rediffmail.com; rppatel12@yahoo.co.in

The propagation of electromagnetic waves through the ionosphere in the presence of irregularities is differently affected in different frequency ranges. Very high frequency waves are scattered whereas very low frequency waves are guided through the ducts formed by the irregularities under suitable conditions. To study these effects, we have analyzed VLF and VHF waves recorded at Varanasi during the period January 1991 to December 1999. VLF waves from natural lightning discharges and VHF amplitude scintillations of signals at 250 MHz transmitted from FLEETSAT geo-stationary satellites have been used. The occurrence rate of VLF waves is low and sporadic and they are generally observed during nighttimes. The VHF scintillations at Varanasi are also generally observed during nighttimes. The whistler waves generally propagated along the magnetic field lines, which is dipolar and lies in the ionosphere for the Varanasi station. A correlation study of these two simultaneously recorded signals has been carried out. The recorded events of VLF whistlers/emissions and VHF scintillations are largely uncorrelated. However, there are a number of days when these two events are simultaneously observed. Analysis of these correlated events show that at time and under certain suitable conditions, the ionospheric irregularities may help VLF wave propagation and also cause scattering of VHF signals resulting into either weak or strong scintillations.