Mapping Kerala's Coastal Defences: From Field Survey to Shoreline Management Plans

Article released on August 17, 2025

Disclaimer: The views expressed in this article are my own and do not represent those of any affiliated organizations or government bodies.

Kerala's coastline is as beautiful as it is fragile. Stretching over 593 kilometres, this narrow strip of land faces the Arabian Sea on one side and backwaters, lakes, and rivers on the other. For generations, fishing communities and coastal towns have thrived here. But today, the coast is under siege. Nearly 41% of Kerala's shoreline is eroding, placing lives, livelihoods, and infrastructure at risk.

In response, a vast network of seawalls, groins, and breakwaters has been built over decades to hold back the sea. Yet questions remain: How well are these structures working? Which stretches of coast are secure, and which remain vulnerable? 

Below is the table showing overall structure status statistics before we jump into the individual districts discussion.

Thriuvananthapuram, Kerala's southernmost district, has about 75 km of coastline, of which roughly 40% is lined with protection structures. These include long stretches of seawalls and nearly 70 groins built to break wave energy and hold sand in place.

Our survey showed a mixed picture of performance. About 14.5 km of seawalls were intact, doing their job well, while 7 km showed partial damage, and another 4.6 km had collapsed completely. The groins told a similar story: out of 68, nearly two-thirds were still standing strong, but the rest were either damaged or no longer effective.

In the field, we observed clear differences in how the coast responded. For example, intact seawalls at Panathura, Veli, and near Varkala still provided good protection. But places like Pozhiyur, Poonthura, and Shangumugham showed damaged seawalls with no visible beach in front of them, raising concerns about erosion. Some groin fields, such as those at Thazhampally, showed little sand trapped between structures, while stretches like Veli and Puthukurichi still had healthy beaches 10-20m wide.

These observations highlight that while structures remain the backbone of coastal protection, their condition directly affects how well they retain sand and shield communities. In Thiruvananthapuram, regular maintenance and complementary measures like beach nourishment could make the existing investments more effective.

Kollam has about 46 km of coastline, and it is one of the most heavily protected stretches in Kerala - more than 90% of it is lined with seawalls and groins. This makes Kollam stand out as the district with the highest percentage of coastal defences.

On the ground, our team found 27.8 km of intact seawall, but also 7 km showing partial damage, and about 2 km fully collapsed. Out of the 86 groins, only 39 were in good shape, while most others were partially damaged or not functioning as intended.

The effectiveness of these structures varied widely. Some stretches, like Paravur Thekkumbagam to Thottukuzhi, had beaches 10-15 m wide, showing that the seawalls and groins there were helping stabilise the shoreline. In contrast, key areas such as Thanni, Thangaserry, and Alappad showed little to no beach formation, even right next to the defences. This indicates erosion pressures are still high despite the heavy protection.

Interestingly, some groin fields - such as Kattil successfully trapped sand between their arms, creating usable beaches. But in other locations, like Alappad and Parayakkadavu, groins did not show the same effect, pointing to differences in how waves and currents interact along the district.

Overall, Kollam demonstrates both the strengths and limitations of a structure-heavy approach: while much of the coast remains shielded, erosion hotspots persist, reminding us that periodic maintenance and site-specific solutions are just as important as the presence of structures themselves.

Ernakulam's 45 km coastline is one of the busiest in Kerala, with fishing harbours, ports, and urban settlements packed close to the shore. To defend this stretch, about 79% of the coast is lined with seawalls and groins - a total of 37.4 km of seawalls and 41 groins.

On paper, this looks like strong protection. But our survey revealed a more uneven reality: only 12 km of seawalls are intact, while nearly 23 km showed partial damage, and another 2.5 km had broken down completely. Among the groins, 22 remained effective, while 16 were partially damaged and 3 had failed entirely.

The consequences of this are clear when we look at the beaches. From Kodamthuruthu to Fort Kochi, stretches of coastline had no beach at all, meaning waves were hitting the defences directly, accelerating wear and tear. In contrast, the section from Puthuvype to Elamkunnapuzha held beach widths of 5-40m, suggesting that the structures there were better aligned with natural sediment movement. But again, further north around Njarakkal, Cherai, and Munambam, beaches were absent, leaving the coast exposed.

For Ernakulam, the lesson is sharp: high urban and industrial pressure make the coastline less forgiving. Defences here not only need to be maintained, but also designed with changing coastal dynamics in mind. Otherwise, we risk losing beaches altogether - something already visible along several stretches.

Thrissur's 61.5 km coastline shows a patchwork of protection and exposure. About 45% of its length is covered by seawalls and a handful of groins - specifically 27.5 km of seawalls and just 3 groins. Compared to the southern districts, the coverage here is lower.

Our survey found that only 5 km of seawalls were intact, while 6.7 km were partially damaged, and a worrying 15.8 km had fully disintegrated. The groins offered little resistance; just one remained intact, two were partly damaged, and none were fully effective.

On the ground, the picture was striking. In areas like Kara and Padinjare Vemballor, seawalls had been pushed out of place by strong waves, leaving communities exposed. Other completely broken stretches were visible from Vadanapally to Ganeshamangalam. Only short sections, such as Koolimuttom and Moonupeedika, still had an intact seawall.

When it came to beaches, Thrissur revealed both promise and concern. North of Munambam, wide beaches of nearly 350 m were present, tapering to 25 m near the tsunami colony - an indicator that sediment was accumulating well in these stretches. But further south, from Arattuvazhy to Perinjanam, beaches disappeared entirely in front of the seawalls. Interestingly, older seawalls at Moonupeedika and Palapetty were associated with beaches 40-120 m wide, showing that age and design can sometimes work in favour of stability. 

Overall, Thrissur's coast highlights how erosion and protection don't follow a single pattern - some areas have thriving beaches, while others face severe loss. It reinforces the need for district-specific shoreline strategies rather than one-size-fits-all approaches.

Malappuram's 50.8 km coastline has some of the highest coverage of protection structures in the state, with about 73% of its length shielded. This includes 36.9 km of seawalls and 3 groins. On paper, that sounds like strong defence, but in reality, many of these structures are struggling.

Our survey found only 11.1 km of seawalls intact, while 15.3 km were partially damaged, and another 10.5 km had completely collapsed. The groins were in even worse shape - none intact, two partly damaged, and one entirely gone. These figures underline how high coverage doesn't always mean high protection.

Field visits confirmed this vulnerability. Along stretches like Kappirikkad, Veliancode, Puthuponnani, Ponnani beach, and Puthiya Kadappuram, seawalls were visibly broken and scattered.  Yet, in between, there were pockets of resilience - for example, intact walls near Padinjarekka, Azhikkal, Tanur fishing harbour, and Vallikunnu still held their ground, though often flanked by weaker stretches.

The beaches told an equally mixed story. From Kappirikad to Ponnani lighthouse, beaches were almost absent, except for narrow 10-20m strips at Puthuponnani and Mylaichikadu. Further north, however, there were brighter stops - beaches 15-20 m wide at places like Paravanna, Thottumpuram, Alungal, and Anangadi, suggesting sediment was still accumulating in patches. Yet, other locations such as Unniyal, Ottumal, and Kadalundi Nagarm showed no such formation, leaving communities exposed.

In sum, Malappuram illustrates the challenge of relying heavily on structures: even with widespread coverage, the condition and functionality matter most. The district's coastlines are a patchwork of protection and vulnerability, needing urgent repairs and smarter planning. 

Kozhikode's 78 km coastline is also one of the most heavily engineered in Kerala, with 53 km of seawalls and 16 groins. On paper, this means over 70% of the coast has some form of defence. But as our survey showed, the real picture is mixed.

Only about 10.5 km of seawalls remain intact, while 28.1 km are partly damaged and 14.4 km are in poor or collapsed condition. The groins fared slightly better, with 5 intact and 11 partially damaged, but none fully non-functional. This uneven performance highlighted how structures built for defence can themselves become weak points over time.

On the ground, we found long stretches where protection was visibly compromised - including Calicut South, Bhatt Road, Thuvvapra, Kolavi beach, Vatakara, and Kuriyadi. At the same time, pockets of strength were evident around Godhishwaram, Elathur to Kappad, Kodikkal, and Payyoli, where intact seawalls still held their line against the sea.

The beaches reinforced this contrast. Some areas, such as Chaliyam to Koyiland harbour, displayed 10-25 m wide beaches, especially near Godhishawaram, Kozhikode beach, Vellayil, Puthiyappa, and Kappad. These stretches suggested reasonably effective sediment retention. But elsewhere at Kadduka bazar, Vakkadavu, Bhatt Road, and Thuvvapara - beaches had vanished, leaving walls directly exposed to waves. Further north, from Kovali beach to Sand Banks, beaches were patchy, with 10-30 m widths at places like Palithazhe, Kodikkal, and Payyoli, but absent in locations such as Urupyakavu temple, Mukhacherry, and Choombala harbour.

Kozhikode's coast is thus a study in contrasts: some areas well-stabilised, others stripped bare. It shows how even within a single district, coastal protection is never uniform - success depends on both structural maintenance and natural processes.  

Kannur's 69 km coastline is defended with 44.1 km of seawalls and 13 groins. This means over 60% of the shoreline is lined with structures. Yet, much like elsewhere in Kerala, the condition of these defences raises concern.

Our survey showed that only a small fraction of seawalls were intact. Instead, 31.8 km were partially damaged, and another 9.3 km had completely disintegrated. The groins reflected this pattern of decline: 5 intact, 5 partially damaged, and 3 fully collapsed. 

The picture along the shore was striking. In stretches such as Hussanmotta to Thalaserry harbour, Kizhunna to Thottada, Thayyil to Mappila Bay, and Ettikulam to Payyambalam, seawalls stood broken or weakened. Entirely washed-out segments were seen from Kokkapuram to Thalassery market and south of Kizhunna, leaving vulnerable gaps.

When we looked at beaches, Kannur's coast revealed its mixed fortunes. Many stretches, especially between Pettipalam and Dharmadom, had no visible beach at all, exposing seawalls directly to wave attack. But there were also bright spots. The famous Muzhappilangad drive-in beach offered 20-30 m wide sandy shores, continuing northward to Azhikkal breakwater. Similarly, from Ezhimala to Valiyaparamba, stretches of 10-25 m wide beaches were observed, showing that sediment still finds places to accumulate.

Overall, Kannur demonstrates the fragility of Kerala's coastal defences. Despite extensive seawall coverage, damage is widespread, and beach formation remains patchy. The district's experience underlines the need for maintenance, hybrid solutions, and sediment management, rather than relying solely on hard structures.

Looking across all nine districts of Kerala, some clear patterns emerge:

• Where seawalls stand, beaches often (not always) vanish. These hard defences stop waves, but they also cut off the natural supply of sand. Many stretches now have seawalls fronted by nothing but water.

• Groins work in some places, fail in others. Well-maintained groin fields can trap sand and create beaches - but many in Kerala are partially damaged or poorly designed, leaving gaps that allow erosion to continue.

• Maintenance matters. A seawall or groin is not a one-time fix. Neglect quickly turns these structures into rubble, which not only fails to protect the coast but sometimes worsens the problem for nearby communities.

These lessons went beyond academic insight. They directly shaped Kerala's first Shoreline Management Plan (SMP) - a statewide roadmap for better coastal protection and planning. The survey data, structure assessments, and functional evaluations became the evidence base for prioritising interventions and guiding policy.

The Kerala survey was more than a one-state exercise. It was a pilot that set the template. The methods we developed - combining structural assessment with functional evaluation of beaches have since been extended to Andhra Pradesh, Tamil Nadu, and Puducherry, forming a basis for their own Shoreline Management Plans.

For us as a team, the Kerala survey was also an unforgettable field experience. Ten scientists, split into four groups, covered nearly 600 km of coast in just weeks, often walking under the blazing sun, talking to fishing communities, and collaborating with KID officials. The knowledge we gathered was not just technical - it was human, grounded in the lives of people who depend on the sea every day.

Looking back, this work shows how detailed local surveys can feed directly into policy. The data became a foundation for sustainable planning, while the lessons learned in Kerala are now shaping coastal management across India.

If you'd like to explore the full details, you can read the published article: https://link.springer.com/article/10.1007/s11852-025-01124-y

Murali, M.G., Veeravalli, S.G., Alluri, S.K.R. et al. Statewide field assessment of coastal protection structures in Kerala, India: structural and functional insights. J Coast Conserv 29, 39 (2025). https://doi.org/10.1007/s11852-025-01124-y