Impact of Climate Variability on Agricultural Productivity and Food Security in Banke, Nepal: Insights from 1990–2020

24 Apr 2025 -

This paper explores how climate variability—including changes in temperature, rainfall, and sunshine hours—affects agricultural productivity and, consequently, food security in the Western Terai region of Nepal, specifically Banke District. It provides insights into long-term trends, crop yield responses, and adaptive farming practices, offering a foundation for climate-resilient agricultural strategies in vulnerable lowland regions.

Abstract

Nepal’s diverse climate, spanning from subtropical lowlands to arctic high mountains, poses significant challenges for its predominantly agriculture-dependent population. This study examines the impact of climate variability on agricultural productivity and food security in Banke, Nepal, over the period 1990–2020. Analysis of long-term climatic data revealed a steady increase in average temperature (0.0946°C per year), a significant upward trend in sunshine hours (15.15 hours per year, R² = 0.3125), and a modest rise in accumulated rainfall (approx. 1.94 mm per year). Sunshine hours had a significant positive effect on crop yield (r = 0.417, p = 0.017), while rainfall and temperature showed weaker, non-significant relationships. A linear regression model explained 24.2% of the variation in crop yield. Farmers in Banke have adopted adaptive strategies such as year-round irrigation, which has improved yields compared to rainfed systems. The findings highlight the dominant role of solar radiation in driving productivity and stress the need for integrated, climate-resilient agricultural strategies.

Introduction

Nepal’s geographic and climatic diversity makes it highly susceptible to the impacts of climate change, particularly in the agriculture sector, which supports nearly two-thirds of its population. Variations in temperature, rainfall, and extreme weather events such as droughts and floods affect crop production, food security, and livelihoods. Moreover, climate change exacerbates issues related to pests and diseases, which further threaten productivity.

Past studies underscore the sensitivity of crops to climate variability. Maize, for instance, shows better yield responses in mountainous regions than in the Terai. While moderate climate changes may temporarily boost productivity in certain areas, extreme variability poses persistent risks. According to Kang et al., food security hinges on availability, access, utilization, and stability—all of which are vulnerable to climate extremes.

The Western Terai region, including Banke, has experienced a yearly temperature rise of 0.040°C. Inadequate irrigation infrastructure and monoculture practices have contributed to food deficits, with Banke reporting a deficit of -1767 MT in 2015-16. This study addresses knowledge gaps by evaluating the relationship between climate variables and crop yields over three decades, with a focus on Janaki Rural Municipality.

Study Area and Methodology

Study Area

Study area (Janaki Rural Municipality, Banke, Nepal)

Janaki Rural Municipality is located in Nepalgunj, Banke District, Nepal. It lies at an elevation of 165 meters and is bounded by Nepalgunj Sub-Metropolitan City (east), Kohalpur Municipality (north), Khajura Rural Municipality (west), and India (south). The climate is temperate with flat terrain. Average annual rainfall is 1445.58 mm, and temperature ranges from 4.5°C to 46°C.

Out of 5,063 hectares of cultivable land, 2,532 ha are utilized. Landholding patterns are diverse, with many households owning less than 1 hectare. Agriculture is the primary livelihood source.

Results and Discussion

This study examined the interplay between climate variability and agricultural productivity in Banke and Janaki Rural Municipality over the period 1990–2020. Our analysis revealed a minor but steady increase in average temperature (0.0946°C per year), a significant upward trend in sunshine hours (15.3 hours per year, R² = 0.3376), and a modest annual increase in accumulated rainfall (approximately 1.94 mm per year). Notably, sunshine hours were found to have a significant positive correlation with crop yield (r = 0.417, p = 0.017), while rainfall and temperature exhibited weaker and statistically non-significant relationships with yield. The linear regression model, incorporating these climate variables, explained 24.2% of the variation in crop yield, indicating moderate explanatory power.

In parallel, the agricultural profile of the region is characterized by a high reliance on monoculture, with limited crop diversification and minimal institutional support, despite overall sufficient food production. Shifts in crop calendars, particularly the delayed sowing and harvesting of major crops such as paddy, wheat, mustard, lentils, and pigeon pea, reflect farmers’ adaptive responses to irregular monsoons and broader climatic shifts.

Moreover, the irrigation analysis underscores that while 93.3% of the land depends on rainfed irrigation, year-round irrigation—though practiced on a limited scale—significantly enhances crop yield (7868.63 kg/ha compared to 5450.43 kg/ha under rainfed conditions, t(132) = 2.696, p = 0.008).

Collectively, these findings underscore the dominant role of solar radiation in driving crop productivity and highlight the complex challenges posed by climate variability. They also reveal critical vulnerabilities in the current agricultural practices, particularly the dependence on rainfed irrigation and monoculture systems, which may exacerbate the impacts of climate-induced stresses.

Conclusion

To ensure long-term agricultural sustainability and food security, there is an urgent need for integrated climate-resilient strategies that include improved irrigation infrastructure, diversified cropping systems, and enhanced institutional support.

Keywords: Climate Variability, Agricultural Productivity, Food Security, Irrigation, Crop Yield, Climate Change Adaptation

Corresponding Author: Madan Sigdel, KCRE & Central Department of Hydrology and Meteorology, TU, Nepal

Received: March 31, 2025; Accepted: April 10, 2025; Published: April 14, 2025