January, 2011

January, 2011   ||  Volume 15 No.1


Hydrogeomorphological Mapping at Village Level Using High Resolution Satellite Data and Impact Analysis of Check Dams in Part of Akuledu Vanka Watershed, Anantapur District, Andhra Pradesh

V.Raghu and K.Mruthyunjaya Reddy

A.P. State Remote Sensing Applications Centre (APSRAC)
8th Floor ‘B’ and ‘C’ Blocks, Swarnajayanthi Complex, Besides Maithrivanam, Ameerpet, Hyderabad – 500 038
E.mail: raghuvangeepuram@rediffmail.com

Anantapur District is a hot and arid District, falls in rain shadow zone with a very low annual rainfall of 520mm. The recurrence of drought increased considerably and unless collective measures are initiated on a permanent basis the situation will become grim in future. Akuledu Vanka watershed in Anantapur District is selected to demonstrate the capability of high resolution satellite data in ground water mapping at village level. This watershed is located in Survey of India toposheet Nos. 57F/5 and F/9. This watershed with an area of about 54 sq.km is underlined by hornblende-biotite gneiss and metabasalt traversed by dolerite dykes. Hydrogeomorphological mapping was carried out on 1:10,000 scale using IRS-P6 LISS-IV satellite data. The satellite data facilitates to update the extent of built-up area, road and drainage network. Further, the revenue villages enclosed in the watershed are digitized, mosaiced and superimposed on hydrogeomorphology map. This helps to give site specific recommendation on ground water prospects survey number wise i.e. for individual farmers. In addition, the impact analysis of check dams constructed in the watershed is also discussed. Studies showed that after construction of check dams the water levels in wells increased, abandoned wells got rejuvenated, new bore wells came up resulting increased irrigated area.


Spatiotemporal distribution of Weekly Hydroclimatic Potentialities of India – Monsoon period
A.A.L.N.Sarma and B.Sivaram1
Department of Meteorology & Oceanography, Andhra University
Visakhapatnam – 530 003.
1Birla Institute of Technology & Sciences, Pilani – Dubai (UAE)
E-mail: aalnsarma_met@rediffmail.com, sivaramboppe@yahoo.co.in

Hydroclimatic potentialities such as precipitation, potential evapotranspiration, actual evapotranspiration, water surplus, water deficit, soil moisture storage along with the indices such as humidity, aridity and moisture, soil wetness and soil moisture adequacy over India for the monsoon period on a weekly basis are reported by following the revised water balance model. The paper address the occurrence of varied degrees of drought and humid events for the selected stations drawn from the climate spectrum along with All India during the monsoon period and are of vital importance for crop scheduling especially in the context of increased climate variability..

Influence of vegetation cover on short distance variations of soil resistivity: An experiment on greyscale (digital) imaging and indexing

Sudip Dey, Chandrani Debbarma, Prasamita Sarkar and Sushmita Paul
Department of Geography and Disaster Management,
Tripura University, Suryamaninagar – 799 130, Tripura (West)
E.mail: sudip_geo@rediffmail.com

This paper attempts to assess the influence of vegetation cover upon physical character of soil within short distance. For that purpose a very small slope of 6m was selected which is covered by various types of natural vegetations like Cynodon dactylon, Lantana camara, Calamus tennis, and Acacia Arabia and Dracaena spicata. Soil resistivity metre was used for measuring the electrical conductivity of soil in this area. In the field 4 pin method was used and resistivity character of soil was calculated by r=2paR. A greyscale index of the soil resistivity was prepared within black to white range. Micrographic study of the soil particles were also done to understand the physical characters of the collected soil samples collected from survey points. Through the study it has been observed that though the area is very small, change of slope angle influenced upon the pattern and distribution of vegetation cover. This study also opens the fact that even within a small area though the general compositions of the soil are similar, resistivity character is influenced by the variation of vegetation cover.

Some aspects of the influence of North West Pacific systems on Indian Summer Monsoon Rainfall
Vinod Kumar, M.Satya Kumar1, D.K.U.R.Bhagat2, Shiv Ganesh3 and R.D. Mistry
Meteorological office, Chatrapati Shivaji International Airport, Mumbai – 400 099
1Meteorological center, Begumpat Airport, Hyderabad – 500 016
2Additional Director General of Meteorology, Pune – 411 005
3Director General of Meteorology Office, New Delhi -110 003
E-mail: vinodmanjusingh@gmail.com

Failure of southwest monsoon rainfall during 2002 highlighted again the need for examining the impact of intense low pressure systems (Tropical depression and above) over North West Pacific (NWP) on Indian Summer Monsoon Rainfall (ISMR) with a longer series of data. Month wise tracks of NWP intense low pressure systems, located west of 140°east from June to September for 38 years from 1963 have been considered. These include 27 All India normal/excess and 11 deficient monsoon years. These data have been analyzed with All India monsoon rainfall (AIMR) of the same years. It has been observed that NWP systems located west of 120°east and AIMR are positively correlated with correlation coefficient (CC) of +0.368. When an NWP system is located west of 120°east and a low pressure area (LPA) is observed over the Bay, monsoon depression (MD) forms over the Bay, otherwise an LPA forms over the Bay. Under these conditions east-west trough is seen up to 500 hPa and it continues up to the NWP system. The situation enhances the rainfall activity over India. It has been also observed that excess cyclone genesis over Northwest Pacific during summer monsoon is not the cause of monsoon failure over the country. Correlation coefficient (CC), computed between AIMR and total number of systems that crossed 30° north, are negatively correlated (-0.438). Both types of correlation coefficients suggest that NWP systems influence ISMR in both ways but they can not alter normal/ excess monsoon conditions into deficient monsoon conditions and vice versa.



Space weather event of 25 September 1998: Ionospheric Response
H.Chandra and R.G.Rastogi

Physical Research Laboratory, Ahmedabad - 380 009

Ground geomagnetic data at a chain of stations in India, interplanetary magnetic field, solar wind parameters and the ionospheric data at Thumba are examined to study the great geomagnetic storm of 25 September 1998. The geomagnetic storm is unique because of the strong counter electrojet in the morning, strong electrojet around noon and then counter electrojet in the afternoon hours caused by the enhanced solar wind density and velocity in association with the changes in IMF Bz. Disappearance of Esq in the morning hours, absence of ionization anomaly in the pre-noon hours, strong ionization anomaly near noon and later the absence of the post-sunset height rise and equatorial spread-F on 25 September 1998 are observed as a consequence of the imposition of electric fields associated with the space weather event.