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Disasters
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Satellite Surveillance for Disaster Mitigation
Causes of Floods
- Heavy Downpour
A careful look on the rainfall data for the past three flood affected years i.e. 198,1993, 1995 indicated that the highest rainfall was received during rainfall was received during 1995 (Fig. 2). The rainfall during 1995 was concentrated in the end of August and first week of September. The rain fall observed during 28th, 29th and 30th August was 67.5, 72.0 and 62.0 mm and during 2nd, 3rd and 4th September was 86,115 and 135mm respectively (Fig. 3). Hence, this heavy rainfall within very short time caused floods in the area.
Figure 2 Annual rainfall, Rohtak district
Figure 3 Monthly Rainfall during 1995 Rohtak District
- Non-maintenance and Breaching of Drain No. 8.
The drain No. 8 covers whole of the Rohtak district. The salutation and growth of vegetation in the bed of the drain blocked the rain water which caused breaching of the drain. This became the main reason of floods in the district.
- Presence of Localised Depressions
Few localised depression in the district got flooded due to heavy precipitation. These are the low lying areas which get water logged during the monsoon season and have no proper drainage.
Flood Management
On the basis of extensive study on extent and causes of floods in the district, it is possible to suggest appropriate measure based on avove findings. But the floods can not be totally controlled it is not possible to provide protection against all magnitudes of floods. The repetition of catastrophe that had occur in the study areas can be minimized by taking various structural or non-structural measured (Ramamoorthy, 1989).
- Desolation and Deweeding of Dran No. 8
The drain no-8 which was bult to drain out the excess water from the district into the Yamuna river should be desalted down to its original depth and the vegetative growth should be removed so that its actual water carrying capacity may be restored.
- Proper Maintenance of Embankments
Weak points on the rivers banks should be identified and an effective technique should be adopted to re-enforce soft zones, Geotextiles not only effectively control soil erosion but also facilitate drainage and stabilize river banks. The vegetation cover can be carpeted to reduced breaching and soil erosion.
- Construction of Ring Bunds
All the major settlements should be identified in the flood affected areas and should be surrounded by ring bunds to protect from floods. This will save human life, their cattle stocks and property to a large extent.
Conclusion
The study demonstrates the capability of satellite
data for mapping and management of flood inundated areas. Moreover, the provides clues for effective management of such areas. Till now structural methods have been adopted for planning of flood affected area but with the advent of satellite based information system, including all weather satellites, priority may be given to non-structural methods such as disaster preparedness, relief and rehabilitation.
References
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Chaudhary, B.S.; Arya, V.S.; Beniwal, Ashok; Babu, T.P. and Ruhal, D.S. 1996. Space Application for disaster management: Floods in Hisar, Sept., 1995. Presented in Seminar on Environmental Management - Challenges and Strategies, Hisar (India).
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De Brouwer, J.A.M. 1994. Flood study in the meghna Dhonagoda polder, Bangladesh. Proc. 15th Asian conference Remote Sensing Vol. II pp C-7-1 to C-7-6.
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Florezano, T.G. 1989. Flood management using Remote Sensing data. The Brazilian experienced. Space and flood management. I.A.F. 40th congress, Malaga spain, pp 31-46.
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Hood, R.S.; Hooda, I.S. and Arora, B.K. 1995. Remote sensing based monitoring and management of floods in parts of Harya using satellite data. Proc. Intl. Conf. On Remote Sensing and GIS, Hydrabad, India. Pp. 221-225.
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