A student is investigating the relationship between population growth and food production in the delta region of Country G in South Asia. The delta is forme...

(a) Population of the delta in 1980: 75 million [1]. Population in 2020: 155 million [1].

(b) The area of farmland has decreased steadily from 42,000 km² in 1980 to 33,000 km² in 2020 [1]. This represents a continuous loss of 9,000 km² of farmland over the 40-year period [1].

(c) Calculating the percentage decrease in farmland:

Decrease = 42,000 - 33,000 = 9,000 km² [1]

\[\text{Percentage decrease} = \frac{9\,000}{42\,000} \times 100 = 21.4\%\] [1]

(d) Total rice production increased between 1980 and 2010 despite shrinking farmland because:

1. The rice yield per km² increased significantly from 280 to 450 tonnes per km², meaning each unit of land produced much more rice [1].
2. This was achieved through the adoption of high-yield crop varieties and improved farming techniques developed during the Green Revolution [1].
3. The large increase in fertiliser use (from 45 to 210 kg per km²) boosted growth rates and yields on each unit of land, compensating for the area lost [1].

(e) Total production decreased slightly between 2010 and 2020 because:

1. Although yield per km² continued to rise (450 to 480), the area of farmland fell from 35,500 to 33,000 km² - a loss of 2,500 km² [1].
2. The additional loss of farmland to housing, industry and saltwater intrusion outweighed the gains from higher per-area yields, producing a net decline in total production (from 15,975 to 15,840 thousand tonnes) [1].

This illustrates a critical tipping point: yield improvements can only compensate for land loss up to a point. Beyond that, food production begins to fall.

(f) Two environmental problems from increased fertiliser use [2 marks each: 1 for identifying, 1 for explaining]:

1. Eutrophication: Excess fertiliser washed into rivers and the sea by rainfall causes eutrophication. Nutrient enrichment triggers algal blooms that block light and reduce dissolved oxygen when the algae die and decompose, killing fish and other aquatic organisms [1+1].
2. Groundwater contamination: Chemical fertilisers (particularly nitrates) can leach through the soil and contaminate groundwater supplies, making drinking water unsafe and harming human health. Nitrate contamination is linked to health problems including blue-baby syndrome in infants [1+1].

(g) How rising sea levels could reduce food production:

1. Saltwater intrusion: Rising sea levels push saltwater further inland, contaminating freshwater supplies and the soil used for growing rice. Most rice varieties cannot tolerate salt, so crop yields decline sharply [1].
2. Permanent flooding: Low-lying coastal farmland would be permanently submerged, removing productive land from cultivation entirely [1].
3. Storm damage: More frequent and severe storm surges would destroy standing crops and damage the irrigation systems that farmers depend on [1].

(h) Two social problems from mass displacement [2 marks each: 1 for identifying, 1 for explaining]:

1. Urban overcrowding: Large numbers of displaced people moving to cities would overwhelm housing capacity, leading to the growth of informal settlements with poor sanitation and limited access to clean water [1+1].
2. Employment crisis: Competition for jobs in cities could lead to widespread unemployment and poverty among displaced communities who lack the urban skills needed for non-agricultural work [1+1].

(i) The delta population has continued to grow rapidly because:

1. High birth rates: The average household size is 5.2 people and the annual growth rate is 1.8%, meaning the number of births far exceeds deaths in this young population [1].
2. No viable alternatives: Farming is the primary livelihood and many people lack the resources, skills or connections to relocate to safer areas. They remain because they have no realistic option to leave [1].

(j) Three strategies to protect food production and people [2 marks each, max 6]:

1. Flood defences: Build embankments and sea walls along the coast to protect farmland and settlements from rising sea levels and storm surges [1+1].
2. Salt-tolerant crops: Invest in developing salt-tolerant rice varieties that can grow in areas affected by saltwater intrusion, maintaining food production on land that would otherwise become unusable [1+1].
3. Planned resettlement: Create properly planned resettlement areas inland with housing, services and employment for communities displaced from the most vulnerable coastal zones [1+1].

Other valid strategies include: improving irrigation and water management, promoting family planning, or developing early warning systems for floods.