1. Introduction
Despite the contributions of irrigation to poverty reduction and food security, irrigated agriculture contributes less than 12% of the total cropped area in Nigeria. Low crop water productivity in upstream farms and high crop water productivity in downstream farms suggest the need for improved technical efficiency, especially among the farms located upstream. Disparities in access to irrigation are serious challenges for the sustainability of the large-scale irrigation project in Nigeria. Bridging thus gap in equality can increase rice production substantially, thereby reducing poverty and food insecurity and increasing income.
Irrigation plays a critical role in the livelihood of farming communities all over the world [
1]. Many works have indicated that distributional heterogeneity prevents large-scale irrigation projects from reaching their full potential [
2]. Disparities in farmers’ abilities to benefit from irrigation resources are likely to cause distributional conflicts and factionalism [
3]. Insufficient irrigation water supply (IWS) downstream mostly leads to lower crop yields compared to the farms located upstream. Downstream farmers in some irrigation systems cannot plant water-intensive crops such as rice; therefore, they instead cultivate crops with lower water requirements like corn and soybeans [
4]. Numerous studies have indicated that downstream farmers face more uncertainty and risk because they receive less water than farmers located upstream [
5,
6]. Therefore, some studies [
7,
8,
9,
10] have opined that unless water quotas are carefully enforced, upstream farmers will continue to consume more water at the expense of downstream farms.
Access to irrigation water and water productivity has a cause/effect relationship [
11]. Excess irrigation can result in less water productivity due to over-irrigation and unproductive water outflows, seepage, percolation, and evaporation. Acute water shortages can also lead to less water productivity due to moisture stress, while moderate water use can enhance water productivity and water use efficiency. Therefore, access to irrigation water is a necessary but not sufficient condition for higher crop water productivity.
Other factors that enhance crop water productivity include good agronomical practices and judicious use of other inputs, including the use of improved cultivars and the efficient use of fertilizers. Increased output may arise from improved yields, reduced crop loss, improved cropping intensity, and increased cultivated areas. Reliable access to water enhances the use of complementary inputs, such as high-yielding varieties and agrochemicals, which also increase output levels and improve crop water productivity [
12]. In many large-scale irrigation projects, water is available but does not produce potential gains due to lower water productivity. Resource mismanagement, especially by upstream farmers, and acute inadequate water downstream are the main causes of lower productivity. Reliable access to irrigation water not only raises output levels and water productivity but also reduces variance in output across seasons [
13].
A plethora of research on irrigation management has claimed that upstream farmers tend to over-irrigate their fields without considering their downstream counterparts [
6,
14,
15]. According to [
14], downstream farmers are enraged by upstream farmers who use water directly from the distributary and drainage canals to cultivate their paddy fields. The most troublesome issues for downstream water users are illegal water drawing and the consequent farmer discord [
16]. A Study by [
10] postulated that water distribution disparity, in addition to transportation losses and technological constraints, leads to farmer conflicts. However, inefficient management and unequal distribution of water have led many experts to conclude that large irrigation projects, especially in the developing countries like Nigeria, fall short of achieving their targeted objectives [
17].
The linkage between irrigation, poverty, and food security in developing countries had been widely discussed by researchers and policy makers [
18,
19,
20,
21]. However, competition for limited water resources and disagreements over water distribution among diverse water users are significant challenges to the sustainability of large-scale irrigation system management across developing countries [
22]. Although Nigeria has made considerable progress in irrigation water resources and development towards improve food security, income, and economic growth [
23], empirical findings indicate that large-scale irrigation projects in the country have favored some farmers, particularly those upstream, expanding wealth disparity [
1].
The Hadejia-Jama’are River Basin Development Authority established the Kano River Irrigation Project (KRIP) in 1976. The KRIP and other large-scale irrigation schemes have been mandated to increase the country’s aggregate food and raw material production while increasing farmers’ incomes, livelihoods, and food security [
24]. Increased revenue will improve the quality of life of farmers and others engaged in the value chain generated by irrigation. Reference [
25] claimed that examining the internal and external aspects affecting water supply performance downstream is vital to understanding each scheme’s unique potential. The KRIP has 18 sectors, each with a main canal (MC), branch canals (BCs) and distributary canals (DCs). The project was designed to distribute water equitably to all farms in the project area via gravity. However, due to managerial problems, siltation, and farmers’ attitudes towards breaking the field canal, the downstream farmers receives less water, making them prone to crop failure and receiving less income than their counterparts. Furthermore, In the 1970s and 1980s when Nigeria was seeing substantial income from oil exports, the government was able to offer cash for maintenance and operation (M&O) of the irrigation project. Therefore, the farming community handed off responsibility for this task to the government. However, due to competing demands from other sectors of the economy and the diminishing oil income, these subventions gradually dwindled each year. Thus, the water distribution infrastructure deteriorated as it went without maintenance for too long. This led to a decline in the scheme’s effectiveness, eventually affecting the farmers’ livelihoods. Reference [
26] showcased that there is a positive relationship between water inequality and income inequality and between water inequality and rural poverty.
References [
6,
27,
28] have shown that water availability, dependability, efficiency, and equity negatively affect the performance of downstream farmers. However, few studies have proven how water access affects productivity and income inequality [
4,
29]. Similarly, numerous studies have also used various indicators to measure water delivery performance [
30,
31,
32,
33,
34,
35,
36]. References [
37,
38] employed quantitative analytical methodologies to evaluate the access to irrigation water in large-scale public irrigation.
Moreover, a comprehensive study of access to irrigation water in large-scale public irrigation among the diverse water users in Nigeria is not yet available. This article intends to: (a) assess upstream and downstream equity in water distribution and its impact on paddy output and water productivity in the Kano River Irrigation Project, Kano State, Nigeria, (b) provide empirical evidence of the degree of water productivity between the upper- and downstream farmers, (c) present some promising pathways for improving water distribution and equity for poverty reduction among irrigated farmers, and (d) suggest policy measures that will provide solutions that help to close the productivity gap, expand irrigation water availability, reduce resource mismanagement, and boost agricultural production across the board. In light of these concerns and pursuits, this study aims to test the following hypotheses:
H1. The distribution of irrigation water use is the same across location categories.
H2. The distribution of access to irrigation water is the same across farm location categories.
H3. The output produced is the same across farm location categories.
Conceptual Framework
To eradicate poverty, improve food security, and spur economic growth among irrigated farmers, farmers should have equal access to irrigation water and the benefits that come with it [
26]. Recently, in Sub-Saharan Africa, there has been a resurgence of interest in the subject of how irrigation expansion might help reduce poverty [
39]. However, more robust policy interventions are needed to reduce the disparity in the distribution of social and economic gains among farmers in irrigation areas, as wealth creation alone does not always alleviate poverty. These persisting inequalities may limit the possibilities for additional poverty reduction through economic growth and compromise the impact of governmental measures [
40].
Reference [
41] opined that the availability and accessibility of irrigation water is a necessity, but not a guarantee, for alleviating poverty. They further claimed that the final result depends on the relationships between water and non-water sector concerns and processes, which can either alleviate or exacerbate poverty. Reference [
42] outline five broad factors that influence the impact of poverty eradication on irrigated agriculture. These include: (a) equitable land acquisition; (b) irrigation infrastructural management; (c) irrigation water availability and equity in access to irrigation water; (d) production technology, cropping patterns, and crop diversification; and (e) input- and output-based support measures.
Figure 1 presents a nexus between poverty traps and inequality in access to irrigation water among irrigated farmers.
Irrigation water disparity can lead to low productivity and low income, leading to low levels of demand and savings (as shown in
Figure 1). Low savings and low market demand can lead to low physical and human capital investments, resulting in increases in poverty levels and long-term food insecurity.
Reference [
11] claimed that the incidence and severity of poverty among resource-poor irrigated farmers depend on their level of control over water resources rather than on their resource endowment. They cited an example from Eastern India, which is endowed with a very large groundwater reservoir and substantial surface water resources; however, people lack the resources to exploit these water sources, resulting in poverty in the upstream regions of India. Reference [
30] demonstrated that, although the underlying causes of poverty vary based on farming systems, the increasing scarcity and competition for water pose a threat to future advances in poverty reduction in many countries, especially in the South Asia and SSA. Indeed, most of the areas of persistent poverty can be described as “water scarce”. However, many irrigated areas with large-scale systems remain home to large numbers of poor people in both absolute and relative terms. This is largely due to inequity in access to land and water resources, resulting in low productivity, particularly in downstream areas [
43]. Reliable access to agricultural water not only raises crop output levels but also usually reduces variance in output and income over time. For instance, in Brazil, the entropy index of rice yield dispersion, which is a measure of yield variability, has declined from 5.3 in 1975 to 2.7 in 1995 in irrigated areas, while in rain-fed areas, it has increased from 8.0 to 13.7 over the same period. Lower entropy index values indicate a lower yield variability, while higher values indicate a higher yield variability. Moreover, the mean yield difference between irrigated and rain-fed areas has also widened [
44].
4. Conclusions
Even though the inequitable distribution of irrigation water is a serious challenge in the KRIP mission of poverty reduction and increasing food production, irrigation is widely pushed in rural Nigeria as an integral approach for increasing food security, income, and livelihoods. This study used a combination of quantitative and physical water measurements to estimate irrigation water usage and test for water accessibility amongst categories of farmers depending on their farm location (upstream, middle, and downstream). Kruskal–Wallis and post-hoc tests were used to evaluate the assumptions that the canal water is evenly distributed and that crop yields (in KRIP) across the location are equal. The determinants of the output were assessed using logistic regression. These findings confirmed the belief that a farmer’s location places them at an advantage or disadvantage due to unequal distribution of irrigation water, which could have a negative impact on downstream farmers’ incomes, food security, and livelihoods.
The quantity of irrigation water use, access to irrigation water, and paddy yield across the locations rejected all the hypotheses. The result of the analysis confirmed that the worst-off farmers are located downstream. Furthermore, the results indicated that the paddy output between the downstream and middle farms was not statistically significant. Farm location, quantity of irrigation water, access to irrigation water, and water usage instructions were all found to increase paddy output.
5. Policy Recommendations
More water for the poor, efficient use of water, and more equitable management are all part of the agricultural water agenda for development. The most effective strategy to alleviate poverty in Sub-Saharan Africa and some parts of Asia and North Africa is to increase overall water productivity though equitable distribution of water resources among the users of large-scale irrigation projects, irrespective of their location (upstream or downstream). Water is the only resource whose scarcity can lead to 100% crop failure. The most pressing policy and intelligent questions for the next few decades will be regarding access to water and water management, which might help to alleviate poverty in the aforementioned regions. Based on the findings of this study, the following policy options are recommended:
The project management should allow farmers, especially those located downstream, to access conjunctive water use. This is very important, as the current project management does not allow farmers to use tube wells in the catchment area. Lining the field canals to reduce seepage and conserve water should be implemented, thereby improving water access for downstream farmers. Fines should be imposed on farmers who break the field canals to acquire more water. Lastly, the management should work closely with the water users’ association for better management of the existing water systems.
The limitation of the study lies in the fact that the study was restricted to only one irrigation project in Nigeria; as such, the result cannot represent the entire situation of irrigation projects in Nigeria. However, it can serve as an eye-opener to investigate similar projects in the country and develop policy options that will improve water accessibility across different locations.