![Flood Management Therefore it is important to evolve flood management technique so as to minimise loss of lives and property on account of release of water from the dam and also to store the flood water in the reservoir. Two types of measures Structural measure Non-structural measures [A] Structural measures: Protection works Flood embankments [B] Non-structural measures Flood forecasting Flood warning Flood plain zoning](https://image.slidesharecdn.com/3-floodpresentation-110228094551-phpapp01/85/Gujarat-flood-presentation-7-320.jpg)
Gujarat flood presentation
- 1. Flood, Flood Control Cell, Flood Forecasting
- 2. Total dams under flood monitoring 193 Major Medium Minor Total North Gujarat Central Gujarat South Gujarat Kachchh Saurashtra Total 193 Gated: Ungated:
- 3. Occurrence of flood: Heavy and wide spread rain persists in the contributing catchment area of the river system. (Quantity and duration of rainfall) Flash floods in smaller river basins occur due to concentrated spells of heavy rain/ cloud bursts in short periods When carrying capacity of river channel is insufficient Wetness of the underlying surface at the time of rainfall Course of monsoon system causing rain and the direction of river flow.
- 4. Floods due to breaches: Failure of structures/ embankments of reservoirs and rivers/ operational mistakes Breaches in the embankment Sudden release of water from the dam Failure of reservoirs
- 5. Floods due to meteorological situation : Tropical storms and depressions Active monsoon situation Break monsoon situation
- 6. Effect of Flood Any flood occurred due to either release from the dam or natural river flow causes loss of life, damage to the properties, damage to standing crops, polluting drinking water sources, disruption to road/ rail transportation system and communication system.
- 7. Flood Management Therefore it is important to evolve flood management technique so as to minimise loss of lives and property on account of release of water from the dam and also to store the flood water in the reservoir. Two types of measures Structural measure Non-structural measures [A] Structural measures: Protection works Flood embankments [B] Non-structural measures Flood forecasting Flood warning Flood plain zoning
- 8. Among the above measures, the non-structural measures particularly flood forecast is more important The need of hydrological forecasts is more and more felt and reliable forecast service becomes a necessity both for a means of flood damage reduction and reservoir regulations. The need of flood forecasting
- 9. Flood forecasting system can be effectively evolved by Setting up improved/ computerised flood control cell Setting up effective instrumentation for observation of hydrological and hydro-meteorological data. Setting up of effective communication system for transferring data even under most adverse conditions. The data to be transmitted and processed Rainfall, weather forecast, river gauges, reservoir level and releases through gates.
- 10. Decisions to be taken at flood cell : Computation of inflow forecasts to reservoirs Decide releases from the dams Issue Flood warnings for down stream localities
- 11. Flood cell shall maintain the following basic data Information: List of project under monitoring with its detail Basin map of each project. Flood memorandum:- keep ready the chapters related to your dam. Data of history of past flood. Area - capacity table. Weather forecast Equipments: Wireless set - Its link periodical checking. Mobile. Computer - Xerox / Fax machine. Internet facility. Detail of rainfall / river gauge station in the C.A.
- 12. (Contd…) Telephone/ mobile Nos of of related authority e.g. Revenue authority i.e. collector, D.D.O., Mamlatdar Police M. L. A. Vilage Sarpanch, Talati
- 13. Duties of flood operator : Sitting in the chair of operation of flood, the followings are to be kept in mined. (i) P W L (ii) Present storage. (iii) Any warning from IMD, CWC or from other authority for rainfall, flood etc. (iv) Rule level of the particular day. (v) Cushion available in the dam w.r.t. rule level & F R L. (vi) Present inflow / outflow.
- 14. For effectively reservoir operation, the operation of flood shall keep the following details in mind. Fully acquivant with the basin. Size, type, extent. General slope, vegetation cover. Rainfall station. Distance from the dam site. Representation catchments area. Communication of rainfall data to dam site, flood control cell. River gauging station: Correlate the gauge level and its river discharge. Details of upstream dam (if any) w.r.f. its storages, max. release capacity, travel time of flood from U/S dam to our dam site, arrangement of communication of release of flood. Travel time of flood upto dam site.
- 15. Unexpected situations A very difficult situation arises when the official responsible for formulation of forecast is handicapped because of: Non availability of all the desired data/ information, and Deviation from the defined boundary conditions. Breach in flood embankments of river Rain of very high intensity at location in between the base and the forecasting stations. Unexpected regulation of control structures.
- 16. During very severe floods communications may fail and the only information available at the dam may be reservoir water level and the rate of rise. Unexpected situations
- 17. Present flood forecasting system : For inter-state rivers CWC is responsible for making observation and issue of forecasts for reservoir regulation and important cities. For rivers of the state Focal officers/ officers in charge of the dam decides the quantum of flood reaching the dam site at a particular point of time.
- 18. Action to be taken at the time of unexpected situation Decide the rate of rise of water level and period of filling cushion available in the reservoir. Decide the inflow rate Decide the period of filling cushion available in the reservoir Check the data of historical flood Decide the release keeping in view the inflow rate, time to fill the flood cushion and historical flood.
- 19. Release of Water and flood warning : Safety of the reservoir Safe carrying capacity of river channel Keeping in view the inflow rate, water level in the reservoir, Rule levels, cushion available in the reservoir, storage position of d/s reservoir When the release of water from more then one reservoir in the same river, care shall be taken to restrict the flow within the banks, storage position of the d/s dam. The tidal position at the time of release of water. As far as possible release the water during ebb period. Avoid releasing flood during nights as far as possible. Manage the release of water in such a way that it can be avoided during Night. Warning of release water to the d/s area shall be well in advance following the guidelines laid in flood memorandum. As far as possible warning regarding quantum of flood water should be given comparing same amount of flood in past. Inform the concern Revenue, Police, MLA, Concerned village Sarpanch/ Talati, Railway authority , Highway authority etc.
- 20. Weather forecast: Issued by IMD Last 24 hr data Five day Rainfall forecast (Districtwise) Qualitative forecast for next 24 hrs showing the trend of storm movement and rain fall. Satellite image
- 21. Thank You