https://stm2.bookpi.org/TPMDRHSIVSSL/issue/feed 2025-12-31T10:41:18+00:00 Open Journal Systems <p>Climate change presents an intense and growing challenge to global food security, with its impacts severely felt in the agricultural systems of nations like Sierra Leone. Increasingly erratic rainfall patterns, prolonged dry spells, and seasonal floods threaten the livelihoods of the nation's smallholder farmers, underscoring an urgent need for effective adaptation and mitigation strategies.</p> <p>Sierra Leone, however, possesses significant natural advantages for agriculture. The country is situated at the northern limit of the equatorial rainforest zone, endowed with a hot, humid tropical climate and abundant land and water resources. It is one of Africa's most humid countries, with a mean annual rainfall ranging from 1,900 mm to over 4,000 mm, averaging 2,526 mm per year. This plentiful water supply underpins the great potential for sustainable agricultural intensification. A pronounced dry season from December to March and receiving only 6 to 7 per cent of the annual rainfall, which coincides with high solar radiation and lower humidity, highlighting the critical need for water conservation and irrigation. It is here that the country's extensive lowlands, particularly the network of Inland Valley Swamps (IVS), become especially promising. These fertile wetlands offer a reliable opportunity for water storage, irrigation, and year-round crop production, serving as a vital bulwark against seasonal climate variability. Recognising this potential, various IVS development initiatives have been undertaken across the country. These have often centred on water control structures to manage hydrology for cultivation. In recent years, pilot projects have introduced earth dams, structures larger and more robust than traditional head bunds as a means of harvesting and storing rainwater within these valleys. While these micro-dam systems have demonstrated promise, their implementation has yielded mixed results, with successes moderated by technical, social, and maintenance challenges.</p> <p>This book presents a focused investigation into one such micro-dam rainwater harvesting system. It moves beyond a simple case study to provide a critical analysis of the system's performance. By examining its agronomic benefits, hydrological impact, and socio-economic dimensions, this work illuminates both the tangible advantages and the practical constraints encountered. Ultimately, it aims to bridge the gap between pilot-scale experimentation and widespread, sustainable adoption. The insights and evidence-based recommendations contained herein are intended to guide policymakers, developers, and farming communities in optimising these systems, thereby unlocking the full productive potential of Sierra Leone's Inland Valley Swamps and enhancing resilience for its agricultural future.</p> https://stm2.bookpi.org/TPMDRHSIVSSL/article/view/764 2025-12-31T10:41:18+00:00 Mohamed Matthew Blango [email protected]

<p>Major opportunities to improve food security and household incomes are being missed in Sub-Saharan Africa (SSA) because of inadequate management of agricultural water, especially in rain-fed systems. Moreover, there are challenges of coping with water scarcity and stress due to climatic variability. Land degradation resulting from soil erosion by wind and water, and poor management of soil fertility, also contributes to low rainwater use efficiency. Sierra Leone receives a lot of rain, with an annual average of 2526 mm. During the wet season, typically between April and November, there is an excess of water; more than the requirement for crop production. However, the situation changes drastically in the dry season (December to March) when the total rainfall is most times 6-8% of the annual rainfall. Rainwater is an important input factor for healthy and productive ecosystems. Rainwater harvesting (RWH) in a watershed context has a role and an impact on several aspects of ecosystems and human well-being. In Sierra Leone, irrigation plays a minor role as almost all farming activities are rainfed. This study takes an integrated approach towards agricultural water management with specific objectives designed to optimise the availability and utilization of water and move the focus from local field level to basin or watershed scale. This research was conducted in an Inland Valley Swamp at Njala University, located in the Southern region of Sierra Leone. A micro-dam with a reservoir of capacity, 26,500 m³ was evaluated to know the extent to which it can improve cropping intensity and extend the cropping season. Losses by seepage was high, amounting to 34% and 27% of stored water during 2014/15 and 2015/16 dry season respectively. The reduction in seepage could be attributed to the addition of a layer of soil with high clay content on the upstream of the dam. Despite the seepage, there was sufficient water to support a second crop with supplementary irrigation. Yields from the dry season crop were generally higher than those of the rainy season. This throws more light on the potential for higher yields not just in the lowlands as against the uplands, but also getting better yields in the dry season as compared to the wet season. To further improve the performance of the RWH system, a novel approach was undertaken to improve rice yields and save water during irrigation, with the addition of Biochar. In doing so, the effect of biochar on water productivity under various management practices was investigated. Many studies have demonstrated that using biochar as a soil amendment can improve the soil carbon content and water retention. The water management practices included: the Alternate Wetting and Drying (AWD) method, Aerobic Rice System (ARS) and the Continuous Flooding (CF) practice. In a period of three years (2014-2017), rice was cultivated twice a year, wet and dry season. The highest measured wet and dry season yields, 3.2 t ha^-1and 4.7 t ha^-1, occurred during the 2015/2016 cropping season. In general, dry season yields were higher than wet season yields, plots with biochar had higher yields than plots without biochar, and CF plots had higher yields than ARS plots, which in turn had higher yields than AWD plots. The water management practices had significant effect on water productivity, with the yields under the ARS being significantly higher during the dry season of 2015/16 (p = 0.001) and 2016/17 (p= 0.003) than the CF and AWD. As the small reservoir (or pond) is a key component of the watershed and is affected by various hydrologic variables, it is critical to understand the impacts of impending climate change on its functionality. Typically, this is done using physically-based hydrologic models coupled with future climate data from General Circulation Models (GCMs). Simulated volume of water in the pond from the Soil and Water Assessment Tool (SWAT) was calibrated with observed data for the same period. (2014/15 dry season). A Nash Sutcliffe Efficiency (NSE) value of 0.82 was calculated during the validation of the model. The model also predicted a reduction in the volume of stored water by the end of the century (2081-2100 as compared to a baseline period (1961-2000).</p>

2025-12-31T00:00:00+00:00 Copyright (c) 2025 Author(s). The licensee is the publisher (BP International).