Non-structural Flood Management -
Cost Effective Options
Abstract
BS Ahuja
commissioner (PP) Ministry of Water Rersources
It has been an established fact that floods have an intricate relationship with environment degradation which could be appropriately termed as manmace disaster rawer tnan a natural disaster India being one of the richest in water resources, is continuously suffering from the menace of floods and droughts due to ooor management of this nch resource. lnsp(te of increased allocation of funds and its expenditure on flood protection measures dunng Eighth Five Year Plan, the struggle to deal with the disaster has become more difficult, structural measures have although been successful in providing incidental relief but non-structural and decentralised measures like flood plain zoning, flood proofing precictions and forecasting could prove to be much more cost effective and people participatory than the structural measures Paper highlights the facts on flood situations in India and measures taken so far by the Government of India
unplanned, development has been the major cause of floods and poor water resource management in India. Landuse planning nas never been integrated into the watershed management and eco-systems for exposed planning of a development programmes cost of structural measures have been exorbitant and always evaiuated as much larger than the benefits realised over a period of time. Hence, for sustainable future, the paper emphasises need for decentralised mechanisms Of using non-structural measures like flood plain zoning and prediction - systems to take preventive actions. It highlights need for risk assessment through identification and mapping of risk prone areas and distribution of population in resonance with the water resource management pro gramma
Introduction
It is aptly said that ‘Flood are acts of God, but acts of man cause fl000 aamage”. It is natural for a river to over-flow its banks in the event of heavy rainfall in its upper catchment and spill into the flood plains, which are basically its right of way. Extensive and often unplanned use of flood plains, disregarding the basic fact tnat it is a part and parcel Of the river, leads to flood damage. Thus, the uncontrolled and indiscriminate development of flood plains due to pressure of population can be considered as one of the main factors responsible for the ever increasing flood damage reported from different parts of the country in spite of substantial investment in the flood sector during the last four decades
Due to financial constraints, no flood control structure can be constructed to provide total or absolute protection against all conceivable magnitudes of floods. Moreover not all ‘flood-prone’ areas are amenable to protection through conventional flood control measures due to a variety of reasons. In some situations it may not be economically justified to build flood control structures, as the cost would far exceed the benefits, in other cases it may result in false sense of security leading to extensive economic activity in tne area it is, tnerefore, necessary to suitably ‘manage floods” with a view to reduce the damage potential and property losses and minimise if not avoid loss to lives of humans and cattle. It is possible to achieve this by a suitable blend of structural measure like embankments etc., togetnerwith non-structural measures like flood plain zoning and flood forecasting and warning.
Flood Plain Management
me structural measures have been emphasizing on the attempts to modify the floods The non-structural measure on the other hand lay stress on attempts to modify the susceptibility to flood damage and attempts to modify the loss burden. They strive to keep the people away from flood waters, bearing in mind the stark reality that the flood plains in fact, belong to the river and that the floods are not only a curse, but also a blessing in disguise In some ways. It contemplates use of flood plains judiciously, simultaneously permitting vacating of the same for use
of the river whenever the situation calls for This technique allows the use of flood plains reducing the hazard, while retaining its beneficial effects
in view of cost effectiveness of the non-structural measures and speedier implementation, as more and more human encroachments and activities are taking place in the flood plains in our country, the main thrust is now on the non-structural flood management measures.
The non-structural measures can be broadly grouped under two categories as follows;
Flood Plain Management which would comprise of;
• Flood Plain Zoning
• Flood Proofing including Disaster Preparedness and Response Planning
• Flood Forecasting and Warning
Modifying Loss Burden
• Disaster Relief
• Flood Fighting including Puolic i-iealtn Measures
• Flood insurance
Of all the non-structural measures for flood management which rely on the modification of susceptibility to flood damage, the one which is gaining increasedl sustained attention of the planners and acceptance of the public is the flood forecasting and warning. Other measures particularly the flood plain zoning have to oe tackled witn more vigor so that a long-term solution to flood problem can be achieved in conjunction with structural measures wherever necessary.
Concepts of Flood Plain Zoning
The basic concept of fiood plain zoning is to regulate tne land use in the flood plains in order to restrict the damage by floods, which are bound to occur from time to time. iPefer figure 1 and 21 Flood plain zoning, therefore, aims at determining the locations and tile extent of areas likely to be affected by floods of different magnitudes! frequencies and to develop those areas in such a fashion that the resulting damage is reduced to the minimum
FLOOD PLAIN ZONING
it therefore, imposes limitations on indiscriminate and unplanned development of both the unprotected as well as protected areas. In the former case, boundaries of restricted areas are established to prevent indiscriminate growth, while In the protected areas only such categories of development can be allowed which will not involve unduly heavy damage in case the protective measures fail. Flood Plain Zoning can certainly help In minimising flood damage while ensuring that the valuable flood plains are simultaneously put to developmental use.
Flood plain zoning is not only necessary in the case of fioods by rivers but is also useful in reaucing the damage caused by drainage congestion particularly in urban areas, where on grounds of economy and other considerations, urban dralnage may not be designed for the worst possible conditions and presupposes some damage during storms wnose magniruoe exceeos mar br which the drainage system is designed
Broad Methodology
The steps Involved In implementation of flood zoning measures could be broadly indicated as follows
1. oemarcatlon Of areas liable to floods.
2. Preparation of detailed contour plains of such areas to a large scale (Preferably 1;50001 showing contours at an interval of 0.3 to 0.5 meters.
3. FIxation of reference river gauges and determination of areas likely to be Inundated for different water levels and magnitudes of floods.
4. DemarcatIon Of areas ifable to flooding by floods Of different freguencies like once in two years, five years, ten, twenty, fifty and hundred years. Similarly areas likely to be affected on account of accumulated rainfall lire, 5,10, 25 and 50 years
5. Delineation of the types, of use of which the Flood Plains can be put to In the light of lii and 14) above wIth Indication of safeguards to be ensured.
in the existing developed areas possibilities of protecting relocations/exchanging the sites of vital installation like electricity substations/power houses, telephone exchanges etc, should be seriously examined, so that these are, always safe from possible flood damage. Similarly, the pump station Of tube-wells for drinking water supply should be raised above the high flood levels corresponding a 100 year flood.
SimIlarly, possibility of removing buildings/structures obstructing existing natural drainage lines should be seriously considered, in any case, with immediate effect unplanned growth shall be restricted so that no constructions obstructing natural drainage, resulting in increased flood hazard Is allowed.
in future buildings, the following regulations may be stipulated
al Plinth levels of all buildings should be nearly 0.75 to one meter above the drainage/flood submersion lines
bI In the areas liable to floods, all the buildings, a stairway snoula invariaoly be providea to tne roofs so that temporary shelter can be taken there. The roof levels of the single story buildings and the First floor level in double story buildings should be above flood levels of 1 to 400 frequency so that the human lives and the movable property can tare temporary shelter tnere when necessary during the periods of floods.
Attempts in the past
The need for Flood plain zoning has received recognition
at various levels in the past As far back as in 1973-74
Central water Commission preparea guiaellnes for 900c
Dubai International Award - 2000 for Best Practices (DIARP)
Call for submission of Best Practices
To encourage, recognise and enhance awareness of outstanding and sustainable achievements in improving the quality of life in human settlements, the Dubal Municipality has announced the third cycle for the oubal International Award - 2000 for ten Best Practices (OIABP) tO be selected globally.
The Ministry of urban Development, Government of inoia, nas designated the Human Settlement Management Institute (HSMII, the Research and Training wing of Housing and Urban Development Corporation (HUDCO) as the National Level Nodal Agency for Best PractIce documentation as well as for submission of Best Practice entries for the Awards of Excellence Instituted by the Dubai Municipality, in association with UNCHS.
Criteria for submission of Best Practices
The criteria for submission of Best Practices are’
Partnership Between at least two representatives of the public, non-governmental and/or private sectors;
Impact Positive and tangible improvements in people’s living conditions;
Sustainability In its environmental, social, economic and cultural aspects.
Th6 Oubai Declaration also stresses that due consideration be given to issues of leadership, community empowerment and gender,
Eligibility
The Award is open to all organisations and indivIduals from Governments, local authorities, internatIonal and non-governmental and community-based organisations, the private sector and other representatives of civil society. The Oubal International Award will be presented to ten outstanding Initiatives on the occasion of the world Habitat Day in the year 2000. Each award will consist of a cash prize of US $ 30,000/-, a trophy and a certificate In addition, Dubai Municipality will cover the travel and accommodation costs for upto two representatives of each award-winning best practice
All interested organisations, institutions, and individuals are invited to submit best practices for the 2000
Dubai International Award as per Reporting Format. All proposals should reach the Executive Director, Human
Settlement Management Institute (HSMI), HLJDCO House, Lodhi Road, New Delhi 110 003, by 31~ December,
1999. For further information, please contact Shri J.S. Marwaha, Senior Fellow, HSMI contact Numbers:
4369534/4369535/4369536/4368501/456$657/436841$/4369104 Fax Nos. 4565292/ 4369538
plain zoning which were approved by the Central Flood control Board. Since the implementation of these guidelines needed statutory backing, central water commission also prepared a model draft, wnicn was circulated by then Ministry of Irrigation in 1975 to all the states for enacting legislation.
The Rashtrtiya Barh Ayog (19801 in its report also recommended that Flood Plain Management measures should be undertaken where-ever necessary legislation exists and suitable legislation enacted in other states. However, the response from states except Manipur has not been encouraging Manipur enacted a legislatIon in 1978 which came into force in December,1 985.
Flood Proofing
Flood proofing measures help greatly in the mitigation of distress and provide immediate relief to the population in flood prone areas. It is essentially a combination of structural change and emergency action, not involving any evacuation The techniques adopted consist of providing raised platforms for flood shelter for men and cattle and raising the public utility installation above flood levels.
in case of urban areas, certain measures that can be put into action as soon as a flood warning is received involve’
Installation of removable covers such as steel or aluminum bulk heads over doors or windows, permanent closure of low level windows or other openings, keeping store counters on wheels, closing of sewer well, anchoring machinery, covering machinery with plastic sheet, seepage control, etc.
Flood proofing also tends to encourage persistent human occupancy of flood plains Flood proofing measures taken in the past In India consisted of raising of a few flood prone
villages, above pre-determined flood level and connecting them to nearby roads or high lands under this programme, several villages were raised in uttar Pradesh in West Bengal and Assam also, land fills were attempted in villages to keep houses above flood levels In some areas even though nearby agricultural lands were liable to inundation. The programme of raising of villages taken up in the Second Plan Period, was subsequently discontinued aecause it was ooserved that this metnod did not provide any protection at all to the surrounding agricultural areas.
Flood Forecasting and Flood Warning
Out of the various non-structural measures, ‘Flood Forecasting & warning- is recognised as one of the most important, reliable and cost effective methods Central water Commission organises flood forecasting at 157 stations in t~e country of which 132 are for water stage forecast and 25 for inflow forecast for certain major reservoirs. River stage forecast of 132 statIons covers 62 nver basins/sub basins. The Flood Meteorological Offices {FMO) also provide Information regarding general meteorological situation, rainfall amount of last 24 hours ana neavy rainfall warning for the next 24 hours for different regions and range Of quantitative precipitation forecasts for various river basins to the respective flood forecasting centres of Central water Commission. All the data is also simultaneously transmitted tO the circle headquarters supervising forecasting worits for overall scrutiny, monitoring, analysis and compilation. The final forecasts are then communicated to the concerned administrative and engineering authorities of the State and other user agencies connected with flood protection and management work on telephone or by special messenger/telegram/wireless depending upon local factors like vulnerability of the area and availability of communication facility etc.