1. Introduction
Land use planning strategy, which is a deliberate process of defining land for various uses to balance social, economic, and environmental goals [
1,
2], is an approach for improving urban and environmental sustainability [
3,
4,
5,
6]. In this context, environmental sustainability is a condition for meeting the needs of current and future generations without jeopardizing the current and future health of natural ecosystems [
7]. The land use planning process varies widely at various scales, but the general process includes defining the goal and objectives, data collection and analysis, plan formulation, negotiation and decision-making, implementation, and monitoring and updating [
8].
Land use planning strategies have not been able to effectively address environmental sustainability problems (e.g., degradation of environmentally sensitive areas caused by urban expansion patterns) in the Global South, particularly in Sub-Saharan Africa [
3,
9,
10,
11]. For example, the past and current urban expansion patterns in the Abuja city-region, Nigeria are inconsistent with the land use plans as urban development expands into the land designated for non-urban development areas, including environmentally sensitive areas [
9]. This leads to the degradation of environmentally sensitive areas of many African city-regions, including Abuja, highlighting the need to guide urban development effectively using strategic actions such as land use planning strategies [
12,
13,
14]. Addressing the environmental sustainability problems caused by urban expansion patterns at the regional scale is useful in this regard, especially if used to guide local and urban planning processes [
3,
15,
16,
17]. This is, for example, recognized by the Nigerian Urban and Regional Planning Law of 1992 that made provision for the higher-order plans to provide a framework for the lower-order plans [
16]. In Sub-Saharan Africa, including Nigeria, the land use planning process at the regional scale is, however, often neglected [
16], which may lead to spatial inconsistencies (e.g., spatial conflicts) between urban and regional plans. Spatial conflict in this context can be regarded as a situation where a lower-order plan (e.g., an urban plan) deviates from the framework of a higher-order plan (e.g., a regional plan), which may result in e.g., urban development in those areas designated for non-urban development by the regional plan. This situation may contribute to the conflicts between urban developments and other land uses (e.g., intensive agriculture, productive forestry) proposed by the regional plan. The spatial inconsistencies between urban and regional plans, as well as the actual urban developments, hinder achieving the environmental goals of land use planning strategies [
9,
18].
To improve achieving the environmental goals of land use planning strategies, environmental assessments can be conducted using the Strategic Environmental Assessment (SEA) or para-SEA [
19,
20,
21,
22,
23,
24]. The SEA is an environmental planning and management instrument used for determining and mitigating the potential environmental impacts of policies, plans, and programs at both regional and urban/local scales [
24,
25,
26,
27,
28]. The para-SEA is an informal process of conducting the environmental assessment of strategic actions, whereby the administrative framework is not defined or considered and the process does not meet the formal specifications of SEA but has some of their characteristics [
24]. The SEA process aims to protect environments from strategic actions and promote environmental sustainability [
19,
29,
30,
31,
32,
33]. Applied SEA varies widely, but the general process includes screening, consideration of alternatives, description of the action, impact identification and scoping, prediction of impact magnitude and significance, identification of mitigation measures, preparing the documentation of the assessment, review, consultation, and public participation, decision-making, and monitoring implementation [
33]. According to Therivel [
32], the core of the SEA process includes environmental impact prediction, evaluation, and mitigation. The environmental impact prediction is to determine the scale, duration, and likelihood of the impacts, while evaluation is to determine whether the predicted impacts are significant or not, and mitigation is to reduce or eliminate the significant impacts [
32]. Unlike the classical Environmental Impact Assessment (EIA) process, which focuses on predicting, evaluating, and mitigating the environmental impacts of project actions [
26,
31,
34], the SEA process is used for predicting, evaluating, and mitigating the higher-level environmental impacts of strategic actions, including land use planning [
26,
31,
34,
35]. Implementing the SEA process has long-term benefits (e.g., environmentally-friendly development, a smoother planning process, greater plan transparency) that can vastly exceed the short-term cost, especially if it addresses environmental problems to support achieving the environmental goals of plans [
36]. In some parts of the world, particularly in the European Union, the SEA process has been implemented since 2001 [
37]. While implementing the SEA process in Sub-Saharan Africa, attempts were made in some countries, including Botswana [
27], South Africa [
38], and Ghana [
39]. However, in most countries of Sub-Saharan Africa, including Nigeria, the formal SEA process has not been implemented in all sectors [
40], including land use planning.
Theoretically, the relationship between land use planning and environmental assessments can be depicted using the socio-ecological idealism of spatial planning theory [
41] and the SEA framework for strategic decision-making [
32]. Socio-ecological idealism, which is a vision to reintegrate social and environmental problems into the planning process, has been used to broadly address the relationships among the human, built, and natural environments [
41]. In recent years, socio-ecological idealism in planning was partially drawn under the sustainability umbrella, where the economic aspect of spatial planning was integrated into the theory, thus planning at e.g., urban and regional scales adopt the principles of neighborhood, community, urban, and regional sustainability [
3,
41,
42]. Environmental assessment, which focuses majorly on the environmental aspect of sustainability, also considers both social and economic aspects [
19] and may foster the actualization of the socio-ecological idealism vision in land use planning. Socio-ecological idealism indicates to environmental assessment the holistic value and socio-environmental visions for the desired future in the evaluation of options in strategic planning [
41]. Therefore, environmental assessment and land use planning can be used to improve urban and regional environmental sustainability [
1,
3,
4,
5,
6,
19,
29,
30,
31,
32,
33]. While land use planning focuses on the spatial arrangement of land use, environmental assessment can be used to: reduce the environmental risk of the plan; streamline the project action of the plan; faster plan approval; and better plan implementation [
36] that reflects socio-ecological idealism in land use planning. The SEA framework for strategic decision-making, including land use planning strategy is used to describe: environmental baseline and identify alternatives land use plans; prepare scoping reports, predict and evaluate impacts of the alternative land use plans; mitigate the impacts of the chosen alternative land use plan; prepare the SEA report for formal decision, and; monitor the implementation of the chosen alternative land use plan [
32].
Land use planning strategies and environmental assessments are faced with various challenges in the Global South, including Sub-Saharan Africa [
27,
43,
44,
45]. Lack of financial capacities challenges land use planning in Lagos, Nigeria, and the Takoradi and Bolgatanga regions of Ghana [
43,
45]. Political interference is a key challenge facing land use planning in Kampala in Uganda and Kigali in Rwanda [
46]. Additionally, customary land tenure, lack of law enforcement, and distrust in government are barriers to effective land use planning in Ghana [
45]. In Malawi’s main urban centers, lack of human and technological capacity, corruption, and outdated legal and policy frameworks pose significant challenges to land use planning [
44]. Regarding environmental assessment at the sub-regional level, a lack of legislation, inadequate awareness, and low technical standards have been shown to burden and render the SEA process in Botswana suboptimal [
27]. Retief et al. [
38] demonstrate that a lack of focus, lack of integration with decision-making processes, and lack of assessment furthermore hinder the SEA practice in South Africa. According to Ofori [
39], lack of legal or institutional frameworks, developing alternative strategic actions, lack of organized baseline data are amongst challenges facing the SEA process in Ghana. Outside the Sub-Saharan Africa region, Slunge and Tran [
47] posit that inadequate training, financial resources are key challenges to institutionalizing SEA in Vietnam. Addressing these key challenges may be helpful to improve the environmental sustainability of city-regions, but may not be the answer to all problems, considering the fast rate of urbanization [
48,
49,
50,
51] that planning cannot keep up with and the challenges to control such urbanization by local, regional, and national governments. However, the development of the Abuja city-region from scratch using land use planning strategies [
52] makes it the best-case study for investigating land use planning and environmental assessment challenges, considering the long-term benefits of the SEA process that can vastly exceed the short-term cost [
36].
We aim to combine Geographic Information Systems (GIS)/Remote Sensing (RS) and survey-based data to investigate the key challenges of land use planning and its environmental assessments for the purpose of improving the urban and environmental sustainability of city-regions. Specifically, we investigate (1) the spatial inconsistencies and the causes between urban and regional plans, as well as the associated conflicts between the built-up areas and other land uses; (2) the state of land use planning; (3) the state of environmental assessments of land use planning, and; (4) the ways to address these challenges for effective land use planning. Our findings help to identify key challenges of land use planning, including spatial inconsistencies between urban and regional plans, as well as the associated conflicts between the current/future urban growth and land use proposed for intensive agriculture and productive forestry. Also, we identified the causes of the spatial inconsistencies between urban and regional plans, including conflicts in administrative boundaries, conflicts in funding the land use planning process, and lack of good coordination. Additionally, our study shows that implementing the SEA process of land use planning in such a way to avert the challenges (e.g., overlapping functions between the government ministries and agencies) facing the current EIA process would improve achieving the environmental goals of land use planning. Therefore, this paper contributes to land use planning as a strategic instrument for guiding and controlling urban expansion patterns and improving the urban and environmental sustainability of city-regions.
5. Conclusions
We combined GIS/RS and survey-based data to investigate key challenges of land use planning and its environmental assessments for the purpose of improving the urban and environmental sustainability of city-regions.
Perhaps, most alarming are the multiple inconsistencies (e.g., spatial conflicts) between urban and regional plans and the associated built-up areas caused by a lack of good coordination, conflicts in administrative boundaries, insufficient data, and professionalism/incompetence. While investigating the state of land use planning, our study showed that land use planning failed to address the inconsistencies between the plan and actual development, poor resettlement and integration, poor planning projection, and the emergence of informal settlements. However, the achievements of land use planning are the well-designed urban development plan of the capital city, provision of basic infrastructures, and mass housing developments. The process of land use planning contributing to haphazard urban expansion in peri-urban/satellite settlements is attributed to the inadequate implementation of land use plans. The inadequate implementation of land use plans is caused by insufficient funding, lack of political will, inadequate manpower, interference (e.g., local governments, local people, developers), and corruption. While investigating the state of the environmental assessment of land use planning, our study showed that there is a lack of formal SEA process or/and para-SEA process caused by weak political will, ignorance of the policy-makers, and a lack of technical capacity/professionalism problems. However, the environmental assessments of land use planning as a strategic action are being implemented using the EIA instrument, which is primarily designed for assessing the environmental impacts of project actions. The impact prediction and evaluation as the core process in the current environmental assessment of land use planning are being challenged by inadequate manpower/dearth of professionals, inadequate relevant tools for analysis, insufficient data availability. The mitigation as an additional core process in the environmental assessment of land use planning is being challenged by not following the suggested mitigation measures, no strong environmental agencies/lack of monitoring by the agencies, and overlapping functions between the government ministries and agencies. Our findings on addressing the key challenges (e.g., consistency between a well-developed plan and implementation) for effective land use planning and integrating the SEA or Para-SEA process into the land use planning process would probably improve achieving the environmental goal of land use planning.
The baseline information provided in this study is crucial to improve strategic planning and urban/environmental sustainability of city-regions in Sub-Saharan Africa and across the Global South, where land use planning faces similar challenges to address the haphazard urban expansion patterns. Future research should incorporate the urban plans of peri-urban/satellite settlements to quantify the spatial inconsistencies between urban and regional plans, and the associated built-up areas of the entire city-region and investigate the state of public participation in the processes of land use planning and environmental assessment.