Saturday, December 3, 2022

Nijgadh airport site: A major sink of atmospheric and soil carbon

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This writing provides an overview of how Nijgadh proposed Second International Airport (NSIA) site acts as a carbon sink, its biogeography and locational proximity to the Nepal-India border. Issues like ecosystem services, water table, underground water recharge, surface run-off associated with the construction of the proposed airport have been covered in various media by different authors, thus, they are not covered here.


Deforestation releases carbon (C) into the atmosphere whereas reforestation (natural growth of vegetation), conservation and management, and afforestation (vegetation growth assisted by humans) greatly increase in-situ forest biomass and carbon (C) storage. A survey of literature published from the studies of similar sites like that of NSIA from 1979 to 2020 revealed that an increase in global C-biomass stock from reforestation and/or afforestation has helped carbon sequestration (carbon capture by green vegetation) and has contributed to the improvement of ecosystem services. 

Ecosystem services refer to the basic services from nature (often assisted through proper management) to serve better and make life comfortable on the earth from clean air and naturally filtered water as tree roots hold soil in place to prevent erosion by utilizing atmospheric and soil carbon. This process helps to ameliorate the rapidly changing global climate. Through the restoration of vegetation, humankind helps in recycling water, create fertilizer by capturing carbon to provide food and ecosystem services to people.

Through the restoration of vegetation, humankind helps in recycling water, create fertilizer by capturing carbon to provide food and ecosystem services to people.

These activities have helped to improve climates even in dry and the hostile environments. In many parts of the world, humans have started working on dry and deserted areas to reclaim land to sustain ecosystem services. Greening environment has helped to avoid the use of gray water (reusing retreated water that is flushed out from toilets, washing clothes, and industries) through the biological cleaning processes. It also helps to minimize surface run-off and recharge of underground reservoirs. Many specialized smart sustainable projects have been developed in many parts of the world through greening programs that help not only to sustain ecosystem services, but also to ameliorate global climate at local -regional-and-global scales.

Climate restoration processes

One of the major processes of ameliorating abnormal climate is through carbon farming. Earth atmosphere contains 750 billon tons of carbon, but soil, oceans, and geologic formation accumulate many folds of this amount. Additionally, human activities have released 500 billion tons of carbon into the atmosphere through industrial activities. Industrialized countries have vastly contributed to atmospheric carbon; for examples, China contributes 30 percent of the global carbon, the United States 15 percent, and India 17 percent. Additionally, emissions from the uses of fossil fuel and changes in land uses have been contributing to the global carbon over the last three centuries. Though industrial emissions and ocean surfaces are of less problems to landlocked Nepal because of its low level of industrialization, Nepal must bear the brunt of emissions from neighboring countries for no fault of its own.

Current annual rate of addition of carbon into the atmosphere is approximately 9 GtC (9 Arab tons of carbon which is represented as 109) per year to the atmosphere. Daily human activities on the earth, such as deforestation, construction, and agricultural farming, release a 19-36 percent of carbon, which otherwise would have been locked into the soil or oceans for decades to centuries. While the general increase in atmospheric CO2 can be assumed to positively influence above ground biomass (AGB) production, for the AGB to increase by utilizing the atmospheric and soil carbons, it must have the necessary conditions to grow and sink carbon, for example, proper slope (degree), aspect (degree), latitude (degree), longitude (degree) and altitude (m). Ideal natural factors help the restoration of carbon through the conservation and recovery of young planted and naturally regenerating forest stands. Mature natural forests appear more sensitive and vulnerable to the increasing temperature and decreasing precipitation than the young.

However, planted forests whose C dynamics are mainly affected by the increasing temperature, are not affected much by the changes in precipitation. Maintaining diversity in plantation forest is essential to enhance long-term C storage. Literature review from various parts of the globe for 1979 to 2020 period suggests enrichment (mixed) planting result into two-fold benefits– increasing the tree diversity and increasing the above ground biomass (AGB) production along with the storage of carbon.

A survey of literature published from 1979 to 2020 from the study of various geographic regions of the world suggests that to ameliorate climate, it is essential to properly manage vegetation in natural conditions as much as possible. These literatures further suggest that plantation forest can put above ground biomass (AGB) ranging between 5.00 ±1.15 Mg (ten lakhs grams) per hectare per year in young plantation forests, and 2.56 ± 0.38 Mg per hectare per year as they get to the middle ages.

This is possible only if such plantations are promoted with species-rich, unevenly aged, and are in the tropical and subtropical regions. In general, terrestrial vegetation ecosystems (e.g., forests, grasslands, croplands, shrublands, and savannas) absorb 112–169 PgC (1 Pictagram ~ 10-12 grams) of carbon each year from the atmosphere through a biogeochemical process called photosynthesis, which is related to the net primary production (NPP) over a period. NPP depends on various factors, such as nutrients, soil moisture, soil profile and landscape. NPP will be higher in warm conditions tropical conditions.

Various findings have reported that NPP is 12.5 PgC in tropical climatic conditions whereas it remains low (1.64 PgC) in temperate and alpine conditions. Many countries are concurrently protecting their naturally regrowing secondary and remaining old-growth forests to offset anthropogenic CO2 emission and to create a significant temporary carbon (C) sink hoping to increase further in the future.

Carbon stock in the above ground biomass (AGB) can increase effectively in tropical and subtropical forests. Though ABG and carbon capture also is possible at temperate, sub-alpine, and alpine climatic conditions, over five hectares of land areas are needed to serve the same purpose that a hectare area can serve in tropical and subtropical areas under ideal conditions. The carbon turnover rates decrease as the elevation increases in the case of Nepal. Carbon turnover is a process of entering carbon into plant body and leaving plant body into the atmosphere while converting carbon into biomass like the energy needs for an active person vs. sedentary person.  

Many natural mature tree stands have become saturated where the NPP is in the process of decline and so is the C-storage. However, tree species richness (a combination of different species of various ages in tropical and subtropical environment) helps in soil moisture retention, evapotranspiration, forest productivity, resulting large biomass and the creation of large quantity of C-pools while mitigating the atmospheric conditions.

By comparing literature with similar geographic and climatic situations, Nijgadh’s biogeography can be contextualized and compared as a rich ecosystem to produce above ground biomass (AGB) and in-situ carbon storage.

Nijgadh biogeography 

Nijgadh has both natural and plantation forests in subtropical and tropical savanna types of climates. Probably, this area is one of the major carbon store houses of Nepal. In fact, a part of the Parsa National Park also extends up to this area and contributes to C-storage significantly. In a national park, natural ecosystems are conserved where naturally regenerating forests are highly biodiverse. By comparing literature with similar geographic and climatic situations, Nijgadh’s biogeography can be contextualized and compared as a rich ecosystem to produce above ground biomass (AGB) and in-situ carbon storage. This contextualization suggests that from the climate amelioration perspective, it will be worth to conserve Nijgadh forest rather than converting it into a concrete airport.

The annual precipitation of Nijgadh area ranges from 1,100~1,700 mm, with precipitation maxima occurring between June and September. Maximum annual mean temperatures range from 32.0°C to 37°C, and minimum annual mean temperatures range from 9°C to 25°C. The area has been historically forested but have been heavily deforested since the 1960s after the construction of the East West Highway. As developmental activities started in the Tarai region with the eradication of malaria, exodus started from the Mountain and Hills. Many neighborhood effects were seen on the fringes of forested areas as many nearby large chunk of the forested lands were granted as Birta to clear and convert dense forest into private farmlands by the erstwhile royal decrees. Such large chunks of forests were granted to royal coteries, political supporters, and to a few Indians.

After the onset of multi-party democracy in 1990s, political parties started using forest resources as their vote banks and destroyed many impenetrable forests to achieve their political goals. Nonetheless, in recent decades, the forested area of the region has increased because of the out migration for remittance purposes. While the entire country has green cover of over 40 percent after mass exodus started to remain safe from the countrywide insurgency launched by the Maoist Party.

The exodes became remitters. The additional mass exodus helped to increase the green coverage all over the country, forest coverage in the Nijgadh area however has decreased due to unplanned whimsical mega projects like the Nijgadh Second International Project and illegal felling and selling of trees to nearby border in India. Often such activities are  encouraged by some political parties to enrich their coffers and attract cadres through political patronage.

Rich Biodiversity

Forests in the Nijgadh area are composed of mixed deciduous broadleaved species. Dominant native species accounting for over 50 percent includes Shorea species, Terminalia species, Dalbergia species, Acacia species and others. The tree species encompass both naturally regenerated and planted forests across different successional stages, from stand initiation to mature forests (stand age >100 years). The oldest planted forests of sissoo in the area were established after the 1970s onwards but most forest plantations are much younger as they are planted inside the taungya basti. Thus, most of these forest plantations are around ~20 years old, while their tallest trees already reach heights almost 45m. The hardwood stands above 5 cm diameter contribute to the conservation of carbon in above ground biomass and soil depth.

By all environmental factors such as slope (degree), aspect (degree), latitude (degree), longitude (degree) and altitude (m), all these factors became ideal for the restoration of carbon in Nigadh forested areas.  Specific relationships can be contextualized with the forest stands of Nijgadh based on the stand age and above ground biomass [(log10(AGB)]. The richness of species, density and canopy cover all suggest Nepal cannot afford to lose the existing vegetation cover of Nijgadh if Nepal were to ameliorate the changing global climate that is predicted to rise by 20 C because of the accumulation of greenhouse gasses in the atmosphere.

Geographic location of the Nijgadh area is characterized by lower altitude on less steep slopes. These conditions support more favorable growth conditions for plantation and natural forests. A review of literature from similar biophysical areas suggests that the above ground biomass (AGB) for natural forest could range between 250 ± 203 Mg (ten lakh grams) per hectare while plantation forests could be slightly lower [215 ± 200 Mg] due to monocropping.

Need for an Alternative Site 

It is very essential to conserve Nijgadh area from environmental perspective. This area helps to ameliorate climatic conditions through the conservation of carbon as it has both mixture of diverse natural forests, and mixed plantation forests. In addition to the environmental aspects, the proximity to the Indian border also warrants finding an alternative for Nijgadh for the construction of Second International Airport. Proponents of Nijgadh airport have been arguing the possible economic opportunities it offers while serving 27 Asian countries and other countries creating thousands of direct and indirect jobs. However, the confusion over whether India will allow to use its nearby sky is not clear.

Currently, India has allowed only limited routes to Nepal, despite previously agreeing to provide four routes. During the recent visit of Nepal’s Prime Minister, Sher Bahadur Deuba, to India, he proposed to Indian PM Modi for additional air routes, but PM Modi did not open his lips on this issue. Unless the Nepali and Indian Governments make clear to have Nepal additional air routes through the Indian sky, it will be uncertain to provide regular air services from the proposed Second International Airport in Nijgadh. More suspicion has been raised after the recent Indian Prime Minister Modi strategically avoided landing at the Gautam Buddha International Airport (GBIA) in Bhairahwawhile visiting Lumbini on Buddha Poornima.

It might be that Modi might have chosen a helipad built a few kilometers away from the GBIA for security reasons while visiting Lumbini. However, the suspicions are that PM Modi did not use GBIA on purpose to avoid a precedent of using Indian sky to and from GBIA. Though the nitty gritty of PM Modi’s security are unknown as the Indian Foreign Secretary replied in a convoluted manner to a question asked by a journalist, PM Modi not landing at and flying from GBIA sends some chilling news.  Any airplane requires at least 100 nautical miles sky distance from the airport to get to 29,000 ft cruise height, Nijgadh airport does not meet this requirement.

Assurance from the Indian Government to use Indian sky before attaining 29,000 ft. cruise height or descending from 29,000 ft. would eliminate the doubt whether Nepali airplanes can utilize the Indian sky before they attain the cruise height. Without an assurance from the Indian side, at present, only the Gautam Buddha (Regional) International Airport (GBIA) in Bhairahwa with an east-west runway can be the ideal site should an international airport be in the southern part of Nepal. From the geospatial perspective, GBIA is located at the center of Nepal. Geographically, Nepal extends between 800 and 880 east longitudes. Given that 10 longitudes at 260 – 300 North latitudinal location of Nepal measures 110 kilometers, Bhairahwa location almost in the middle of Nepal makes 409-km from the western Nepal-India border, and almost at the same distance from the eastern Nepal-India border.

Should a runway be constructed north south, a large size airplane cannot fly from any airport located in the Tarai region without using Indian sky. These issues need to be resolved before tempting to clear fell 2.4 million tree stands from the proposed Nijgadh Second International Airport.

Any airplane taking off or landing at GBIA will have east west span of 100 nautical miles to ascend and descend to and from 29,000 ft elevation. Nijgadh does not meet this requirement if an airplane must descend or ascend from the eastern side of Nepal to take off and land on the east-west runway.  Should a runway be constructed north south, a large size airplane cannot fly from any airport located in the Tarai region without using Indian sky. These issues need to be resolved before tempting to clear fell 2.4 million tree stands from the proposed Nijgadh Second International Airport. Instead of clear felling 2.4 million trees in such an uncertainty, an extension of the existing Simara Airport can solve the purpose. If traffic remains high at the Simara airport, and a possibility exists to develop Nijgadh an aviation hub for South Asian country, Simara airport can be extended eastward up to Nijgadh.

Since the perception of the idea of constructing Nijgadh Second International Airport, political parties have made many whimsical plans such as Build-Operate-Transfer (BOT) and construction of largest metropolitan smart city. Various aggressive statements of political parties reveal that there is a deep interest in felling and selling large volume of timber and distributing clear-felled forest land to nearest political coteries to fill coffers of political parties in the name of constructing Second International Airport at Nijgadh. This will be environmentally disastrous if proper transparencies are not maintained.      

The writer is a Professor of Geoscience at the University of Central Missouri, US and he can be reached at [email protected]

Published on 22 May 2022