Land use and land cover (LULC) change has become a critical issue for decision planners and conservationists due to inappropriate growth and its effect on natural ecosystems. As a result, the goal of this study is to identify the LULC for the Vembanad Lake system (VLS), Kerala, in the short term, i.e., within a decade, utilizing three standard machine learning approaches, random forest (RF), classification and regression trees (CART), and support vector machines (SVM), on the Google Earth Engine (GEE) platform. When comparing the three techniques, SVM performed poor at an average accuracy of around 82.5%, CART being the next at accuracy of 87.5%, and the RF model being good at the average of 89.5%. The RF outperformed the SVM and CART in almost identical spectral classes such as barren land and built-up areas. As a result, RF-classified LULC is considered to predict the spatio-temporal distribution of LULC transition analysis for 2035 and 2050. The study was conducted in Idrisi TerrSet software using the cellular automata (CA)-Markov chain analysis. The model's efficiency is evaluated by comparing the projected 2019 image to the actual 2019 classified image. The efficiency was good with more than 94.5% accuracy for the classes except for barren land, which might have resulted from the recent natural calamities and the accelerated anthropogenic activity in the area.

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Spatio-temporal classification and prediction of land use and land cover change for the Vembanad Lake system, Kerala: a machine learning approach

Physical model studies on damage and stability analysis of breakwaters armoured with geotextile sand containers

Dynamic interaction analysis of structure-water-soil-rock systems under obliquely incident seismic waves for layered soils

Geotextile sand containers (GSCs) gained popularity recently as a modern age coastal protection measure. Its usability as an ecofriendly alternative for traditional breakwaters overcomes issues such as scarcity and quarrying prohibition of natural rocks. The current work involves a 1:30 scaled physical experimentation on the hydraulic performance of an emerged, nonovertopping breakwater model with GSCs. Four configurations of GSC structures are analyzed for their runup, rundown, and reflection characteristics confining to wave parameters of Mangaluru. The study revealed that the reflection coefficient (Kr) for GSC structures could range from 0.26 to 0.69. In addition, reducing GSC fill percentage from 100 to 80 is found to be more effective (up to 64%) in reducing reflection, runup, and rundown rates, than altering GSC size. These results can serve as a practical guideline for designing GSC breakwaters. 

Experimental Investigation of the Hydraulic Performance of Breakwater Structures with Geotextile Armor Units

Breakwaters are essential constructions providing tranquility to ports and harbour structures, when there is a lack of natural protection measures. Traditionally these massive structures are constructed using natural rocks weighing tonnes. In the present scenario, obtaining huge natural rocks are difficult as well as non-eco-friendly. Geotextiles sand containers (GSCs) emerges as a suitable alternative for the rock armour units of breakwaters and various literatures supports its efficacy. The present investigation aims at analysing the performance of GSCs when filled with a calculated amount of cement and sand. The Hydraulic performance and stability analysis of cement and sand filled geotextile breakwater models are carried out in a 1:30 scaled monochromatic wave flume. When GSC breakwaters are filled with sand and cement, up to 43% increased stability is observed with a considerable decrease in wave runup, rundown and reflection, than sand-alone filled units. As a result, cement-sand filled GSC units can be suggested as a possible alternative to sand alone filled units where vandalism has to be countered. 

https://www.nature.com/articles/s41598-022-19673-9.pdf

Preliminary investigation on stability and hydraulic performance of geotextile sand container breakwaters filled with sand and cement

Maritime countries like India face serious coastal erosion issues. Over 1200 km of Indian coastline is identified as eroding. Unavailability and high cost of natural rocks remain as a major hindrance for construction of conventional hard options like breakwaters, seawalls and groynes. This has forced coastal engineers to find nature friendly and economical alternatives. Experiences from Australia, Germany and United States prove the efficacy of geotextile containment systems in coastal protection. This chapter aims at reviewing Indian examples of protection works using geosynthetic and geotextile containment systems from early 1980s. Geosynthetic protection structures include groynes, submerged reefs, seawalls and breakwaters. Benefits and difficulties in implementation of protection works are identified by reviewing prominent works conducted in the east and west coast of India. Experiences at Hamla, Dahanu and Pentha helped in replacing conventional structures with geotubes. Equilibrium beach profile is attained using near-shore geotube reef system at Hamla and Dahanu, Maharashtra, whereas reef constructed using geotextiles at Candolim, Goa suffered serious damage due to vandalism and toe scour. Geosynthetic systems along with gabions and rock armours improve the stability, wave dissipation and reflection characteristics as seen in Pentha, Odisha and Uppada, Andhra Pradesh. Lack of proper design criteria and deliberate destruction by vandals remains as the major threat. Countering these challenges, geosynthetic containment systems offer a cost-effective alternative to conventional coastal protection methods in India.

Tom Elias

Papers

Physical model studies on damage and stability analysis of breakwaters armoured with geotextile sand containers

Coastal Protection Using Geosynthetic Containment Systems—An Indian Timeline

Effect of armour unit layers and placement mode in the determination of stability of geotextile sand container (GSC) breakwaters