Water Productivity

The long-term performance of various systems was determined and the economic aspects of solar hot water production were investigated in this work. The effect of the collector inclination angle, collector area and storage volume was examined for all systems, and various climatic conditions and their payback period was calculated. It was found that the collector inclination angle does not have a significant effect on system performance. Large collector areas have a diminishing effect on the system's overall efficiency. The increase in storage volume has a detrimental effect for small daily load volumes, but a beneficial one when there is a large daily consumption. Solar energy was found to be truly competitive when the conventional fuel being substituted is electricity, and it should not replace diesel oil on pure economic grounds. Large daily load volumes and large collector areas are in general associated with shorter payback periods. Overall, the systems are oversized and are economically suitable for large daily hot water load volumes.

Cenozoic deep-sea sedimentation in the southwest Pacific area was controlled by large changes in the patterns of bottom-water circula-tion and erosion. The circulation patterns were largely controlled by the development of the Circum-Antarctic Current south of ...

In this study, we compare three desalination based alternatives for water supply in off-grid areas, and assess their environmental footprint. The three options are: (a) a solar still, (b) a photo-voltaic (PV) powered reverse osmosis (RO) unit, and (c) water delivery by truck from a central RO plant. By use of life-cycle analysis (LCA), a comprehensive environmental modeling of the three systems is carried out. The basic systems, components and processes are modeled, and then varied, in order to offer a deeper insight into the robustness of the model.Our findings indicate that energy generation and materials usage are critical parameters when the considered alternative options are compared. Of the three options, PV-RO is found to have the least environmental impact. The usefulness of this study is that it provides policy-makers insights into renewable energy desalination for clean water production and, thus, it promotes the deployment of low-carbon desalination technologies.► Three desalination-based alternatives were assessed for environmental footprint. ► The life-cycle analysis (LCA) approach was used. ► A comprehensive environmental modeling of the three systems is carried out. ► Main finding: PV-RO has the least environmental impact.

This study investigated the optimum irrigation scheduling and the best application rate of compost under rotational distribution system in sandy soils conditions to mitigate water stress on apple trees for improving yield, water productivity and quality traits. The obtained results indicated that applying optimum irrigation scheduling (adding Water Irrigation Requirements (WIR)) for apple in three and four days as irrigation interval) and increasing the application rate of compost up to 25 ton per fed, increase water and fertilizers uptake rate with good growing conditions. Meanwhile, the fruit yield, quality trait, and water productivity of apple were increased. In apple cultivation and other crops which follow the bilateral irrigation rotation, the irrigation requirements should be splitted in three days per week along with increasing the application rate of compost up to 25 ton fed-1 with drip irrigation system to mitigate the negative effect of water stress on apple trees.

Una river receives a great contribution of sediments from its eroded margins, bad road construction and vast areas of degraded pastures that transports large volumes of sediments to Rio Paraíba do Sul affecting water quality for urban use. The creation of the environmental database of the Una Watershed (area of 476 km²) was important due to the high number of

In the last 10 years the Sri Lankan government has changed its policy regarding its remaining rain forest from one that promoted commercial exploitation to one of conservation. The growing importance of uplands as catchments for water production, biodiversity conservation and other downstream services has been recognized by the Sri Lankan government. It is therefore timely that we review 15

Desalination of seawater accounts for a worldwide water production of 24.5 million m3/day. A “hot spot” of intense desalination activity has always been the Arabian Gulf, but other regional centers of activity emerge and become more prominent, such as the Mediterranean Sea and the Red Sea, or the coastal waters of California, China and Australia. Despite the many benefits the technology has to offer, concerns rise over potential negative impacts on the environment. Key issues are the concentrate and chemical discharges to the marine environment, the emissions of air pollutants and the energy demand of the processes. To safeguard a sustainable use of desalination technology, the impacts of each major desalination project should be investigated and mitigated by means of a project- and location-specific environmental impact assessment (EIA) study, while the benefits and impacts of different water supply options should be balanced on the scale of regional management plans. In this context, our paper intends to present an overview on present seawater desalination capacities by region, a synopsis of the key environmental concerns of desalination, including ways of mitigating the impacts of desalination on the environment, and of avoiding some of the dangers of the environment to desalination.

A spatial decision support system (SDSS) based on multi-criteria and multi-objective decision analysis is applied in a case study in Ethiopia to reduce soil erosion on the basis of reallocation of crops according to their capacity to protect the soil. The case study is carried out in the Adwa district. The SDSS has been implemented using the widespread GIS software IDRISI 32 (release 2) and with the direct involvement of local stakeholders in defining factors and constraints. These are based on land cover-land use, altitude, potential erosion, proximity to roads, water and the relative soil protective capacity of each crop species. A reduction of soil loss from an average of 4.5 t ha−1 yr−1 to values below the risk threshold of soil degradation (1 t ha−1 yr−1) would be achieved through the application of the SDSS results. The biggest impediment to the reallocation exercise, however, is the shortage of cultivable land suitable for cultivation.

Water resources for agriculture are rapidly declining in the North China Plain because of increasing industrial and domestic use and because of decreasing rainfall resulting from climate change. Water-efficient agricultural technologies need to be developed. Aerobic rice is a new crop production system in which rice is grown in nonflooded and nonsaturated aerobic soil, just like wheat and maize. Although an estimated 80,000 ha are cultivated with aerobic rice in the plain, there is little knowledge on obtainable yields and water requirements to assist farmers in improving their management. We present results from field experiments with aerobic rice variety HD297 near Beijing, from 2002 to 2004. The crop growth simulation model ORYZA2000 was used to extrapolate the experimental results to different weather conditions, irrigation management, and soil types. We quantified yields, water inputs, water use, and water productivities. On typical freely draining soils of the North China Plain, aerobic rice yields can reach 6–6.8 t ha−1, with a total water input ranging between 589 and 797 (rainfall = 477 m and water application = 112–320 mm). For efficient water use, the irrigation water can be supplied in 2–4 applications and should aim at keeping the soil water tension in the rootzone below 100–200 kPa. Under those conditions, the amount of water use by evapotranspiration was 458–483 mm. The water productivity with respect to total water input (irrigation plus rainfall) was 0.89–1.05 g grain kg−1 water, and with respect to evapotranspiration, 1.28–1.42 g grain kg−1 water. Drought around flowering should be avoided to minimize the risk of spikelet sterility and low grain yields. The simulations suggest that, theoretically, yields can go up to 7.5 t ha−1 and beyond. Further research is needed to determine whether the panicle (sink) size is large enough to support such yields and/or whether improved management is needed.

The effects of irrigation management on yield and water productivity of inbred, hybrid, and aerobic rice varieties G. Lu, R. Cabangon, TP Tuong, P. Belder, BAM Bouman, and E. Castillo The objective of this study was to compare the effects of water-saving irriga-tion regimes on yield, ...