Chure-Tarai and climate changeRampant excavation of riverbed materials has led to dire environmental consequences.
The Chure-Tarai region extends east to west along the southern part of Nepal. The Tarai plains adjoin the Indian border and are often called the country's food basket. Immediately to the north, the Chure range forms the southernmost foothills of the Himalaya. Geologically, this is part of the Gangetic plain composed of fine sediments of rivers that are tributaries of the Ganga. The Chure hills are the youngest hills that are building up with the rise of the Himalaya.
After the eradication of malaria in the Tarai region in the 1960s, the population started to increase slowly. The trend accelerated after the building of the East-West Highway. Forest encroachment skyrocketed due to rapid settlement growth and the use of firewood for cooking increased illegal logging and deforestation for expanding urbanisation in the Tarai-Chure region.
As the population in the Tarai increased due to migration from nearby hilly districts and adjoining Chure hills, infrastructure development also spread that led to a massive expansion of road networks, highways, bridges and concrete houses in the last two decades. This put immense pressure on the local geo-resources and groundwater resources, mainly riverbed materials. As the economic value of riverbed materials increased due to their use as construction materials, the pressure on geo-resources increased. This led to machine excavation of riverbed materials and disturbances to the natural course as well as previously deposited river terraces and their natural settings. Moving far beyond livelihood support for individual families, the use of geo-resources has grown into a business, and heavy machinery like excavators and dump trucks are being used for riverbed excavation.
The illegal excavation of riverbed materials has become big business. All political parties and leaders of all levels are involved directly or indirectly in establishing crushers across the country with their turnover running into billions of rupees. The situation became even more alarming after the establishment of a three-tier federal system. The exploitation of river resources became the main and only source of income for many local governments in the Tarai and Chure regions. There is huge competition to generate the most income among neighbouring municipalities which ruthlessly exploit the upstream and downstream sections of the same river. In some municipalities, border disputes have emerged due to the revenue generation from river-bed materials and the amount of deposits.
This has led to extreme environmental consequences in many places in the Chure-Tarai region. River courses have been modified and many villages are flooded during the monsoon. There is widespread siltation problem on agricultural lands, impacting soil health and soil-forming processes. Not only this, the natural ecosystem that thrives on the geological substrate has been impacted badly. Riverbed materials are not only important as construction materials, but they are also important as the geological substrate that maintains the natural health of the ecosystem as rivers are an integral part of the ecosystem. The water storage capacity of riverbanks has almost been lost, and this has caused a total modification of the local environment, badly affecting the local environment and making the land surface vulnerable to atmospheric interactions of the surroundings.
Not only this, the riverbeds have dropped more than five metres in various locations of many rivers by the use of heavy machines which can be seen on the rivers crossing the Chure-Tarai region. This has caused a total inversion of the river water and groundwater interaction. The consequences are that many shallow tube wells in the region which were mainly used by individual households for pumping out groundwater for drinking purposes are drying up, threatening the water security of the local poor people and increasing pressure on deep aquifer systems.
The Chure-Tarai region encompasses the first forest ecosystems after the vast agroecosystem of the Tarai region, where farm practices have shifted from native crop systems to cash and high-value crops. This has led to excessive use of chemical fertilisers and pesticides, which ultimately releases into the river systems and possibly shallow aquifer systems. This has caused the loss of many aquatic species, a decrease in pollinators and poor soil health. Development activities are directly going against natural systems and disturbing natural flows. This has led to increased hydrometeorological disasters and significantly weakened the climate change resilience capacity of this region. This goes very much against the recently adopted approach of using nature-based solutions.
The climate change resilience capacity of this region is decreasing rapidly due to over-exploitation and unmanaged excavation of geological substrates, the sole part of the fragile landscape which is the major part of protecting the climate change resilience capacity of the land. Human activities such as construction by modifying the riverine ecology and its associated biodiversity, lowering the groundwater level, decreasing soil health and water holding capacity, encroaching on forests and removing native forest species, and introducing new management in community forests are major detrimental factors responsible for the decline of the resilience capacity.