Sustainable Global Water Management

Humid conditions and equatorial forest in the Congo Basin have allowed for the maintenance of significant biodiversity and carbon stock. The ecological services and products of this forest are of high importance, particularly for smallholders living in forest landscapes and watersheds. Unfortunately, in addition to deforestation and forest degradation, climate change/variability are impacting this region, including both forests and populations. We developed three case studies based on field observations in Cameroon, the Central African Republic, and the Democratic Republic of Congo, as well as information from the literature. Our key findings are: (1) the forest-related water cycle of the Congo Basin is not stable, and is gradually changing; (2) climate change is impacting the water cycle of the basin; and, (3) the slow modification of the water cycle is affecting livelihoods in the Congo Basin. Developmental and environmental actions in the Congo Basin need to properly consider the slight modification of this water cycle in watersheds that affect products and services from the forest. Full article

In many areas of southern Europe, the scarcity of water due to climate change will increase, making its availability for irrigation an even more limiting factor for agriculture. One of the main necessary measures of adaptation of the vineyards in these areas will be the implementation of water-saving irrigation strategies and technologies to improve WUE (water use efficiency). The objective of the present study was to evaluate the long-term economic viability/profitability of different deficit irrigation techniques such as regulated deficit irrigation (RDI) and partial root-zone irrigation (PRI) with low water volume/fertilizer applied in a Monastrell vineyard in southeastern Spain to plants grafted on different rootstocks, and to assess the productive, social, and economic efficiency in these semiarid conditions. Through a cost/benefit analysis, socio-economic and environmental criteria for the selection of optimal deficit irrigation strategies and tolerant/water use efficient rootstocks for the vineyards in arid environments are proposed. Our analysis shows a clear conflict between productivity and quality in wine grape production. Productive and economic indices, such as yield, productive WUE (kg m⁻³), economic efficiency (€ m⁻³), break-even point (kg ha⁻¹), and water productivity (€ m⁻³), were inversely related with berry quality. Besides, high berry quality was closely related with higher production costs. Under the current market of low-priced grapes, if the grower is not rewarded for the quality of the grapes (considering technological, phenolic, and nutraceutical quality), the productivity vision will continue and the cost-effective option will be to produce a lot of grapes, even if at the expense of the berry and wine quality. In this situation, it will be difficult to implement optimized deficit irrigation strategies and sustainable irrigation water use, and the pressure on water resources will increase in semiarid areas. Public policies should encourage vine growers to invest in producing high-quality grapes as a differentiating character, as well as to develop agronomic practices that are environmentally and socially sustainable, by the grapes more adjusted to their real quality and production costs. Only in this way we can implement agronomic measures such as optimized low-input DI (deficit irrigation) techniques and the use of efficient rootstocks to improve WUE and grape quality in semiarid regions in a context of climate change and water-limiting conditions. Full article

Food security is often threatened by droughts during rice production. Although most of the rice is produced in lowland or irrigated “wet” rice fields, terraced paddy fields are important in the rice production system in island or mountainous countries. With the intensifying frequency of El Niño periods in recent decades, there has been a risk of droughts in terraced paddy areas. To mitigate drought, remote sensing data analysis could be an efficient and reliable tool for obtaining scarce ground monitoring data. In this study, crop water stress index (CWSI) and temperature vegetation dryness index (TVDI) were applied to evaluate the drought intensity, and hydrological monitoring data was provided as a support for the evaluation. The results indicated that droughts normally occurred during the dry season, and intensified during El Niño periods. CWSI and TVDI were visible to predict drought occurrences in the watershed area. TVDI overestimated the drought inside Keduang watershed compared to CWSI because of the complex condition of the terraced paddy area, including the hydrology in this area. The complex topography, high groundwater table, and continuous plot-to-plot irrigation helped to maintain the water availability and mitigated the drought impact for rice production in the studied terraced paddy field. Full article

Rice, wheat, corn, soybeans, and sorghum are the five major crops in China, which account for 92% of the country’s total grain production and 33% of its water consumption. Combining water footprint analysis tools with sustainability assessment tools, the water sustainability of the five major crops can be analyzed. Based on ecological economics theory, this paper constructs a sustainability evaluation system of China’s five major crops’ water footprints and analyzes the national and provincial diversity of the sustainability of the five major crops’ water footprints using three dimensions: scale, distribution, and equity. We find that the interprovincial distribution equity sustainability divergence is the key bottleneck factor that restricts sustainability (more than scale and configuration). One key strategy is to arrange grain production at the national level, on the basis of considering the differences of water-resource endowment between different provinces to break through the bottleneck of the water-resource distribution sustainability of these five major food crops. This paper determines a general management model that can improve the sustainability of water resource management at the interprovincial level by comparing and analyzing the most sustainable and least sustainable provinces for the water footprint production of these five major crops. Full article

Egypt’s population growth, scarce resources, and a struggling economy threaten its capacity to achieve food security. Water is of particular interest at this juncture given impending development projects under increasingly uncertain climate conditions. The main objective of this research is to forecast grains production in Egypt under different productivity scenarios, based on annual data from 1980 to 2017, to estimate and forecast cultivated area. Findings suggest that the potential reduction in the Nile flows into Egypt will adversely impact agricultural production, especially during the summer season, reducing cultivated areas and decreasing crop yields. These findings suggest that Egypt’s reliance on imports will continue and grain imports will increase as the population grows and opportunities to reclaim lands remain limited. If food security and concerns about reliance on food imports persist among leaders, future policy options should focus on increasing water-use efficiency and raising productivity of both land and water. Full article

Efforts to understand the political complexities of water governance must include critical hierarchical or bureaucratical perspectives. The River Chiefs System, China’s national mechanism which has evolved from local attempts, values more political control than governance efficiency. Water governance, which is regarded as a political task, is allocated from river chiefs at higher levels to lower levels. The River Chiefs System stipulates that local river chiefs fully mobilize and integrate various technical and administrative forces to achieve environmental goals. However, the strengthening of local authority enables local river chiefs to combat or eliminate state power. Although public involvement in the River Chiefs System is encouraged to some extent, “government-dependent” public participation hardly ensures real public involvement and supervision. Full article

Climate change is a proven fact. In the report of 2007 from IPCC, one can read that global warming is an issue to be dealt with urgently. In many parts of the world, the estimated rise of temperature (in a very near future) is significant. One of the most affected regions is the Iberian Peninsula, where the increasing need for water will very soon be a problem. Therefore, it is necessary that decision makers are able to decide on all issues related to water management. In this paper, we show a couple of mathematical models that can aid the decision making in the management of an agricultural field at a given location. Having a field, in which different crops can be produced, the solution of the first model indicates the area that should be used for each crop so that the profit is as large as possible, while the water spent is the smallest possible guaranteeing the water requirements of each crop. Using known data for these crops in Portugal, including costs of labour, machines, energy and water, as well as the estimated value of the products obtained, the first mathematical model developed, via optimal control theory, obtains the best management solution. It allows creating different scenarios, thus it can be a valuable tool to help the farmer/decision maker decide the crop and its area to be cultivated. A second mathematical model was developed. It improves the first one, in the sense that it allows considering that water from the rainfall can be collected in a reservoir with a given capacity. The contribution of the collected water from the rainfall in the profit obtained for some different scenarios is also shown. Full article

From the perspective of system science, in China, an assignment system of initial water entitlements at the river basin-level can be divided into two subsystems, namely the assignment subsystem of initial water entitlements at the province-level and government reserved water at the river basin-level. Under the new backdrop of implementing the strictest water resources management system (SWRMS), we propose a novel methodological framework for addressing the in-coordination of pre-allocation plans between two subsystems for Lake Tai Basin, China. First, considering total water use, pollutant discharge and water use efficiency, we establish several criteria for the discriminant analysis of pre-allocation plans. Whilst based on these criteria, we built a comprehensive discriminant criterion to further verify coupling and coordination of pre-allocation plans between two subsystems. Second, according to uncoordinated or less coordinated situations, we propose adjusted strategies to decide the direction (increase or decrease) of the adjustment for pre-allocation plans of two subsystems. Third, taking coupling and coordination as optimal objectives, and considering total water use, total pollutant discharge and water use efficiency as constraints, we built an adjusted decision-making model for the assignment of initial water entitlements of the basin. Finally, the results of this novel discriminant analysis methodology that were applied to the Lake Tai Basin show that under the water frequency of 75%, in the planning year 2030, Jiangsu Province is assigned the most initial water entitlements at the province-level, followed by Shanghai and Zhejiang Province. In this paper, results are generally in accordance with pilot plans released by China’s Ministry of Water Resources. Apart from pilot plans, our findings also show the assignment plans for government reserved water at the river basin-level, which is coordinated and coupled with assignment plans for initial water entitlements at the province-level. The novel methodological framework of this paper can also be applied as a reference to other similar river basin. Full article