Saturday, November 21, 2009

Technical Report on Canacona Disaster

Satellite Data Study: Canacona Disaster a synergy of Climatic, Geological and Human Induced Factors

High resolution satellite data, coupled with Geographical information Systems and Global positioning Systems, revealed that the Canacona Disaster was a synergy of climatic changes, coupled with meteorological, geological [lithology and structure of outcrops], geomorphologic, hydrological and human invasive factors.

A comprehensive study undertaken by Dr. Joseph S. Rauto De Souza, Chief Scientist of the State Science & Technology Council and Dr. F M Nadaf, Sr. Faculty in Geography, DPM's Shree Mallikarjun College of Commerce, Canacona, have revealed that incessant precipitation has resulted in triggering of land slides and flash flooding in Canacona. The Integrated Disaster Management Plan, synergizing the Integrated Flood and Land slide Management Plan, has been prepared for revitalizing and resurging the taluka.

The study reveals that the cause of the land slides in the upper catchments was primarily due to human invasion and climatic changes, resulting in excessive water infiltration, causing an increase in the soil pore pressure, which prevented the release of water movement, to an unsaturated area. This caused the sediment grains to slip incessantly, causing stress within, resulting in slope failure along weak slip surfaces. This reduced the frictional strength of the outcrops, owing to external loading. This further caused the down slope movement of rock and mud debris, boulders, pebbles, silt and lateritic outcrops and increased stress concentrations within the mass, causing progressive failure as also as the slope gradient was also greater than 35%.

Likewise, the weight of the super-imposed load decreased the stability of the slope and reduced the shearing strength of the material, by the increase in excess of moisture. The disturbance in the equilibrium between the stress and strength of the material was also an important string factor. The high water ground table due to super saturation of the water table also contributed to the landslide catastrophe.

A paradigm shift and changes in land use pattern from forest to Kumeri cultivation, increase in open space due grazing pasture lands, as also, deforestation on hill slopes, increased the open space, in the source region of Talpon. This has resulted in alterations in hill slope gradient, change in surface and sub surface drainage and topography, causing incessant seepage and infiltration in the strata, resulting in increase in the sediment load.

The hanging streams also increased large rain water seepage within the pores, joints, fractures and fissure zones [lineaments] in the region, which effectively contributed to the infiltration which contributed to the landslides / mudslides / rock falls.

Likewise, extensive siltation of the rivers has resulted in a large and prominent spit formation (Talpona) and hook formation (Galgibag) on the mouth of both the rivers, which have arrested the smooth water flow into and from the Arabian Sea. Bunds and bhandaras were also choked and blocked due to the sediment deposition and tree and plantations brought by the slides.

However, unfortunately, the proliferation of mangroves in the rivers, (although an ecological asset), waste and debris into the rivers, have resulted in reducing the carrying capacity of the Talpona and Galgibag rivers, causing a change in water levels. Contrary, the destruction of mangroves within the river banks, have resulted in excessive back wash of the high tide. Traditional dwellings were also located near the bank of the rivers.

Coincidently, both the tidal rivers experienced a very high tide at around 09:34 am, when the down pour commenced, which also flushed in large saline water, however this could not drain upstream comfortably due to the heavy down stream precipitation and runoff load. Thus, there was a breaking point or super saturation point where the tidal water and the rain water intersected, causing a sudden water flash, which aggregated the flooding.

In order to assess the damage and propose remedial prescriptions to revitalize the region as also to avert any disaster, the elements of water and flood resources, land-use practices, coastal zone components, landslide and demographic aspects have been integrated to develop an Integrated flood and landslide Management Plan synergized into an Integrated Disaster Management Plan, using the components proposed under the Parker’ Model, for the Canacona Taluka.

An Integrated Disaster Management Plan, synergizing Flood and Landslide Management approach is proposed for the Canacona Taluka and envisage the same for the entire State of Goa, to avert any disaster or rather to adopt preventive and preparedness measures.

Relief, topology, land use pattern, river catchment and drainage, slope, soil, structural fragmentation, geology, hydrology, demography, distance from the banks of the river and coasts are some of the preliminary parameter adopted for the data analysis.

Two approaches have been suggested in order to effectively address the calamity, a Bottom-up and Top-down. The “bottom-up” approach suggests and addresses risks fragmentation rather than integration, whilst the “top-down” approach suggests the contribution of the local community towards subverting responsibility for overall management of the disaster. It is suggested that both the approaches be supplemented and complimented in the management approach.

Towards landslide assessment, the integration and synthesis of slope morphometry, [greater the high slope - more are the landslides] soil distribution, geology [bearing on soil], drainage, landforms, lineaments and land use pattern in the region, in a GIS environment by overlay analysis was the criterion established. The degree of slope was a very criterion factor, followed by soil and landuse pattern. The zonation maps were grouped into highly susceptible, moderately susceptible, and low susceptible regions

Towards flood protection in the region, structural and non-structural measures have been proposed. The non-structural measures suggest the establishment of an effective monitoring and flood-warning system, coupled with an education awareness raising and training program and prescribes evacuation routes and sites. It also addresses issue related to safeguarding the infrastructure in the region from being affected by flood, etc. The approach is with an effect in restricting the damage caused by the flash floods. Whereas, the structural approach proposes to undertake and adopt repairs and reconstruction of all damaged bunds and embankments along the banks of the Rivers Talpona and Galgibag and restoration of water diversion channels, for facilitating smooth water flow.

Likewise, the strengthening of financial instruments and logistics, like insurance schemes, loans for the affected community, should also be revitalized alongwith mobilization of calamity funds in a sustainable manner.

Viable management prescriptions have been suggested in the areas of hill and hill slopes, water and soil, food and nutrition, livestock, engineering and flood resistant control, community health and causality, beach, coasts and dune management, economic indicators and viability, strengthening institutional mechanism and administrative response as also capacity building. Information Education and Communication (IEC) has been suggested as a major communication tool towards disaster preparedness

Corrective measures to sustain beach and river ecology, forest and agriculture ecology and restoration of livelihood of the affected population, at large need to be undertaken. Medical teams should periodically visit and monitor the area to ascertain any vector borne diseases outbreak, including physiological disorders. Furthermore, earnest efforts need to be made to ensure that the houses partly damaged are repaired or retrofitted with flood resistant inputs and those houses within the flood risk zone be evicted and reconstructed to higher locations. The silted regions need to be cleaned up and water systems be disinfected. Several prescriptions towards the management of hill and hill slopes, water and soil, food and nutrition, livestock, engineering and flood resistant structure, community health and causality, beach, coasts and dune management, economic viability, institutional mechanism, administrative response and capacity building have been suggested in the recommendations. The concerned authorities should re-consider the norms for release of compensation, considering the steep rise in the economy.


Towards flood protection in the region, structural and non-structural measures have been proposed. The non-structural measures suggest the establishment of an effective monitoring and flood-warning system, coupled with an education awareness raising and training program. It prescribes evacuation routes and sites and addresses issue related to safeguarding the infrastructure in the region from being affected by flood. The approach is with an effect in restricting the damage caused by the flash floods. Whereas, the structural approach proposes to undertake and adopt repairs, retrofitting of damaged house holds and reconstruction of all damaged bunds and embankments along the banks of the Rivers Talpona and Galgibag and restoration of water diversion channels, for facilitating smooth water flow.

However, an effective administrative response framework with integrated machinery system should be recognized, and the approach should be from response to preparedness.


Flood resistance of buildings potentially at risk, should also be secured. No new constructions should be constructed on lower regions and in the flood risk region. However construction should be encouraged in higher elevations and beyond the flood risk zone. The construction should be undertaken adopting foundations, preferably with a plinth upto 1.0 meters. Stilts of concrete pillars / beams can be constructed to provide smooth flow of water, beneath, at time of rise in water due to floods. No structures should be permitted within the NDZ (CRZ-I).

In order to protect the ecological sensitive wetland, any further reclamation to wetlands in the region should be arrested. Mixed agriculture cropping with due crop rotation practices, may be adopted to enrich the soil fertility. Forest plantations will also help in carbon storage and help to regulate climate changes. Timber trees should be planted on hill slopes

To restore beach ecology, be restored and enhanced. As such, mitigation measures towards trapping and binding the sand through nourishing and replenishing the sediments at Galgibag and other beaches of Canacona, with native pioneer coastal sand dune vegetation like sand binders, creepers, may be undertaken. In order to protect the turtle nesting sites at Galgibag, a buffer zone of around 500 meters radius from the site should be strictly maintained, being hyper ecologically sensitive. Tourism should be undertaken in a sustainable manner. The number of shacks should not be increased beyond the carrying capacity if beaches in Canacona.

Alternatively, towards improvement of the sand replenishment, possibility of promoting artificial dune concept which may help as a natural protection may be examined.

Bunds and embankments that are destroyed should be re-stabilized with civil and engineering approaches. Intensive mangrove plantations should be undertaken along the banks of the River Talpona, Galgibag and Saleri. The streams, drains and channels clogged and chocked should be cleaned up immediately.

The spit and hook landforms developed at the mouth of Talpona and Galgibag respectively, need to be scientifically treated to minimize their size and shape so as to enable smooth flow and discharge of water up and down stream

Dug wells may have been infected, as such, it is proposed that all the drinking water sources like; wells and tanks should be disinfected. Furthermore, to combat any out break of mosquitoes borne diseases, open spaces need to be fumigated. The soil can be enriched with nutrients wherever possible. Furthermore, transmission of communicable diseases, due to contamination of water and food supplies as also disruption of sewage disposals system need to be frequently monitored to avoid any epidemic outbreak.

Further the study opines that due to the recent economic crises and structure, the rates, process, procedure, criteria and norms of compensation and relief disbursal should be restructured and revised.

Road Map for future Improvement:

 The study suggests that disasters can be abridged through earnest efforts and concerted interface between the Central Ministries and State Government, towards impact reduction on life; economy, environment, through a well established early warning well established and effective alert and trigger mechanism, superlative predictability, through adaptation of viable preventive and preparedness measures and ameliorative planning at time of an eventuality, disaster proofing is also an integral of the approach with enhancement of the integrated communication system.

 Optimizing or complementing available technological means, in flash flood forecasting in the given socio-economic context of the participating communities is a pre requisite.

 Further, improvement in the tide gauge systems, and strengthen surface observations and assessment systems, including, high speed recording systems. Taluka level preparedness and response plans should be prepared made available at all Taluka Headquarters through a dedicated Help Line.

 An independent Disaster Management Authority (DMA) need to be constituted and should identify disaster prone areas, using high-end Geo Informatics and related advanced systems, related to water and climate anomalies, chemical related, nuclear related, geological and biological related, human induced, accident and industrial related, and other disasters and prepare a blue print “Disaster Vision Document”.

 The study further entails that there is a need to strengthen communication links, forecasting and control room facilities by augmenting the existing facilities at Taluka levels. Awareness and sensitization drives along with mock drills, supported with sophisticated communication networking as part of the integrated management system, using print and electronic media is imperative.

 The study also suggests research promotion in climatic, metrological, geological and related sciences leading to disasters. Disaster crisis software, simulation models nee do be developed, specially related to climate change and human alterations towards early disaster predictions, warning and resurgence systems, and brings on board the IPCC report recommendations and cautions on the need to view coastal disasters, critically.

 Scope for further enriching the report is also a welcome gesture the investigators opined.

Thursday, November 12, 2009

Friday, October 16, 2009

Friday, July 3, 2009

Water Resources of Canacona

Water is essential to all lives. Water is found in three forms that is Liquid, Solid, Gas. During Monsoon season Canacona experiences heavy rains resulting into rich reserves of water, but unfortunately the rain water is not harvested properly. Hence in the following paragraph an attempt has been made to highlight the important river system of Canacona (Figure 2.3).
Saleri River System: River Saleri takes its birth near Barcem and Gocoldem and flow for 12 Kms. Padi Nalla (4 Kms), Agonda Nalla (7.5 Kms), and Molorem Nalla (6 Kms) are the chief tributaries of this river. This river has also developed a small spit near its mouth.
Talpona River System: River Talpona is a well-known river of Canacona taluka. It emerges from the impenetrable woods of Rivona Dongar. This river system is nearly 31 Kms long with 40 hectares of catchment area. River Talpona has four branches that are, Nadke Nalla (15 Kms long), Gaondongrem Nalla (15 Kms long), Bhatpal Nalla (6 Kms long), and Khalwade Nalla (6 Kms long). River Talpona has developed a spit and a bar near its mouth. On the bank of this river one can find thick and rich growth of mangroves.
Galgibag River System: This is yet another main river system of Canacona which originates in the state of Karnataka. The river is just about 15 Kms in length with a catchment of 20 hectares. Maxem Nalla (10 Kms long) and Loliem Nalla (2.5 Kms long) are the key tributaries of the River Galgibag. River Galgibag has developed one of the rare coastal feature namely a hook near its mouth.

Climate of Canacona

The climate of Canacona is healthy and pleasant and characterized by hot and humid conditions. Since Canacona is bordered by Arabian Sea it experiences marine type of climate. Normally there is not much difference between day and night temperatures. Generally May is the hottest month when the temperature reaches 340C and December is the coolest month when the temperature falls to 180C.

The relative humidity in Canacona is high as 97 percent during monsoon season. During January to March the humidity comes to 50 percent but it never goes below this mark.

About 90 percent of the total rain occurs during monsoon season between June and September. In an average Canacona receives 3000 mm of rain annually. Rain occurs in 120 days. The highest rainfall of 22 cm was recorded in 1994. July and August are the rainiest months. Rainfall starts decreasing from the month of September. The general pattern of wind from June to September is southwest to northeast and reverse during other months. Canacona also experiences local winds namely land breezes and sea breezes.

Geology of Canacona

Geology of Canacona mainly consists of Granite, Meta-basalt, Gneiss and Dykes. The oldest rock of Goa, which is dated back to 3,200 million years known as Anmod Tranjamite gneiss, is found in Canacona at Char Rasta. The area between Palolem and Patnem is known for intrusion of dykes into granite and gneiss.

As far as mineral wealth of Canacona is concerned it is very poor. Bauxite is the only mineral, which is found in Canacona, but the deposits are very small and they cannot be exploited, as they are economically unviable. Large quantity of sand is also available especially at Rajbag and Polem.

Physical Landscape

It is already mentioned that geography of Canacona is very rich and diversified. Canacona is one of those rare places on the world map, where the Sea and the forest meet at one place (Palolem). Canacona taluka is characterized by hilly topography, indented Coastline headlands, beaches, islands and wetlands.

Geographers are more interested in understanding the physiography or physical landscape of any area because the growth of population, growth of urban centers, density and distribution of population and many other components are directly dependent with it. Broadly Canacona taluka can be divided into three physiographic divisions.
1. The Coast
2. The Ghats
3. The Wetlands
The Coast of Canacona lies to the south of river Sal and to the north of river Kalinadi. The Coast of Canacona is not smooth like the Coast of Salcete. The Coast of Canacona is full of bays and headlands. Rama’s bay, Canacona bay, Kolam bay are the most prominent bays of Canacona, whereas Cape Rama has the most developed cliff. The height of Canacona varies from sea level to 646 meters mean above sea level. In the north the highest elevation is 448 meters, which is known as east peak, whereas in the south the highest elevation is to the east of Loliem which 172 meters. The most elevated part of Canacona is located at the center with 646 meters that is very popular as Canacona peak, found behind Karmal Ghat section.

In the Arabian Sea contour of 10 meters depth is found much close to the cliff of Cape Rama whereas the same contour is 3 km away at Agonda and 4 kilometers away from Palolem. The 20 meters depth is uniformly found at 9 km along the Coast of Canacona. The highest high tide that occurs in Canacona is 1.58 meters and the lowest is 0.82 meters.

The Westernghats are undoubtedly the most important physiographic division of India. Canacona happens to be a part of this ecosystem. The Westernghats section of Canacona is hilly and is covered by very dense jungle and it houses numerous species of plants and animals. The Westernghats section of Canacona has a wildlife sanctuary known as Cotigao Wild Life Sanctuary that covers 89.5 sq. km of area.

This is another important integral part of Canacona. Wetlands of Canacona are found in Galgibag, Talpona, Agonda and around Chaudi i.e. around Railway station and in front of New Kadama Bus Stand. They are considered to be ecologically very productive. During winter season these wetlands attract a large number of migratory birds.

Location of Canacona

Canacona is located in the southernmost part of Goa between the latitudes of 140 55’00’’ to 150 10’ 00’’ North of the equator and 730 55’ 00’’ to 740 15’ 00’’ to the east of Greenwich (Figure 2.1, and 2.2). Canacona Taluka covers an area of 352.02 square kilometer, which is 9.50 percent of the total geographical area of the state or 17.90 percent of the total area of South Goa District. According to 2001 census Canacona taluka has a population of 43,997 people. In terms of area Canacona occupies third rank after Sanguem and Satari whereas, in terms of population it occupies 11 positions.

For administrative purpose Canacona taluka is divided in to seven village Panchayats and one municipal council. Chaudi is the headquarters of Canacona taluka. Chaudi is about 37 Kms from Margao and 37 Kms from Karwar. The town is located on National Highway No. 17, which connects New Mumbai (Panvel) to Cochin. Of the total geographical area of Canacona i.e., 352.02 sq kms about 17.6 sq kms area is urban.

Canacona Taluka is surrounded by many neighbors. In the north Canacona is bordered by Quepem taluka, in the east with Sanguem Taluka and in the south it shares its border with Uttar Kannada district of Karnataka and on the west Canacona is washed by waves of Arabian Sea.

Canacona - An Introduction

Goa - the 25th full-fledged state of Indian Union has 11 talukas. Canacona is one among them. Geographically Canacona has occupied a vital position. Canacona is known for its rich cultural heritage, unity in diversity and rich physical environment.
From the available historical sources, the word Canacona is derived from the Sanskrit word “Kanvapuram”. It is believed that Canacona was a dwelling place for “Kanvarush”. Kanvarushi lived in the thick forest of Canacona around the present Shree Mallikarjun temple at Shristal. For meditation “Kanvarushi” would go to “Tarpon” or in other words to river Talpona. Canacona is a land blessed by Kanvarushi therefore it became kanvapuram and from kanvapuram it later become Canacona.