Application of Data Envelopment Analysis to Evaluate Investments in the Modernization of Collective Management Irrigation Systems in Valencia (Spain)

Climate change and increased competition for water resources are generating growing concern about how to improve water-use efficiency in agriculture. In turn, this has prompted substantial investments in the installation of water-saving technologies in irrigation systems. The first aim of this research is to use data envelopment analysis to quantify, in terms of gross water savings (GWS), the local-scale efficiency of the irrigation policies adopted in an area of Spain suffering from a structural water deficit. Second, the cross-efficiency method is used to produce a ranking of the irrigation organizations analysed, in order to identify patterns of water-use efficiency performance that can guide future lines of investment. The results reveal that water-use efficiency prior to modernization is a key determinant of the efficiency achieved in terms of GWS at local scale. However, the investments targeted at irrigation modernization often have objectives other than water savings. These and other aspects should be taken into account when allocating public funds to irrigation modernization.

Adaptive Crop Management under Climate Uncertainty: Changing the Game for Sustainable Water Use

Water supplies are projected to become increasingly scarce, driving farmers, energy producers, and urban dwellers towards an urgent and emerging need to improve the effectiveness and the efficiency of water use. Given that agricultural water use is the largest water consumer throughout the U.S. Southwest, this study sought to answer two specific research questions: (1) How does water consumption vary by crop type on a metropolitan spatial scale? (2) What is the impact of drought on agricultural water consumption? To answer the above research questions, 92 Landsat images were acquired to generate fine-resolution daily evapotranspiration (ET) maps at 30 m spatial resolution for both dry and wet years (a total of 1095 ET maps), and major crop types were identified for the Phoenix Active Management Area. The study area has a subtropical desert climate and relies almost completely on irrigation for farming. Results suggest that there are some factors that farmers and water managers can control. During dry years, crops of all types use more water. Practices that can offset this higher water use include double or multiple cropping practice, drought tolerant crop selection, and optimizing the total farmed area. Double and multiple cropping practices result in water savings because soil moisture is retained from one planting to another. Further water savings occur when drought tolerant crop types are selected, especially in dry years. Finally, disproportionately large area coverage of high water consuming crops can be balanced and/or reduced or replaced with more water efficient crops. This study provides strong evidence that water savings can be achieved through policies that create incentives for adopting smart cropping strategies, thus providing important guidelines for sustainable agriculture management and climate adaptation to improve future food security.

City water stress and industrial water-saving potential in stringent management of China

China’s industrial water withdrawal soared in the last decades and remained high. Stringent water management policies were set to save water through improving industrial withdrawal efficiency by 20% between 2015 and 2020. Although China has a nation-wide water scarcity, scarcity at city-level has not been fully explored. Thus, it is meaningful to use sectoral data to investigate industrial water saving potential and implication for alleviating scarcity. Here, we account for water withdrawal and scarcity in 272 prefectural cities, using a 2015 data benchmark. The top 10% of low-efficiency sectors occupied 46% water use. In scenario analysis of 41 sectors across 146 water scarce cities, we assume a convergence of below-average efficiencies to the national sector-average. Results reveal overall efficiency could be increased by 20%, with 18.9 km3 (±3.2%) water savings, equivalent to annual water demand of Australia or Hebei province in China. A minority of sectors (13%) could contribute to most (43%) water savings whilst minimizing economic perturbations. In contrast, implementing water efficiency measures in the majority of sectors would result in significant economic disruption to achieve identical savings. Water efficiency improvements should be targeted towards this minority of sectors: cloth(ing) supply-chain, chemical manufacturing, and electricity and heat supply.

Resource-saving Technologies and Some Proposals for the Creation of Automated Reclamation Systems

The results of experimental studies of the local subsurface irrigation method in comparison with drip irrigation carried out in the laboratory, which showed water savings due to a decrease in evaporation from the soil surface by 10–15 percent are presented. The method of irrigation in closed greenhouse farms using water with a high salt content is described. The paper proposes new patented schematic solutions for protecting plants from frost and pests, describes a multifunctional engineering and reclamation system capable of performing various operations depending on the emerging problems during the growing season.

Stormwater Harvested from Permeable Pavements as a Means to Save Potable Water in Buildings

The main objective of this work is to analyse the potential for potable water savings in university buildings by using stormwater collected from permeable pavements. Six buildings located on the campus of the Federal University of Santa Catarina (UFSC) were selected to obtain monthly water consumption patterns and parking lot areas. The same six buildings were then evaluated considering their location in eight different cities in Brazil, with different rainfall patterns. Simulations using the computer programme Netuno were run to obtain the potential for potable water savings in each building and city combined. The structural design of permeable pavements was also assessed using two methods available in the literature, that is, the American Association of State Highway and Transportation Officials (AASHTO) and Brazilian Portland Cement Association (ABCP). The hydrological-hydraulic design of the permeable pavement was also carried out. The designed thicknesses were compared with the thicknesses obtained using the computer programme Permeable Design Pro. The potential for potable water savings between 18.4% and 84.8% was obtained, depending on the city, building and non-potable water demand considered. For the structural design, the thicknesses obtained by using both methods were similar; however, it was observed that the AASHTO method better represents the pavement model. Regarding the hydrological-hydraulic design, the differences obtained show that the simplification performed for the pavement drainage was in favour of safety. In conclusion, the use of permeable pavements in stormwater harvesting systems is promising, aligning the drainage aid, structural capacity and potential for saving potable water.

Penghematan Air di Hotel X Kota Batam Provinsi Kepulauan Riau dengan Menerapkan Daur Ulang Air Limbah

Hotel X is a hotel located in the city of Batam, the province of the Riau Islands, which is expected to be visited by tourists on holiday in the city of Batam. As the main means of providing comfort and health to guests, Hotel X should plan a good clean water supply system in terms of quality, quantity, and continuity. Currently available clean water sources are limited, such that sufficient efforts must be made to recycle clean water. This research aims to plan water savings at Hotel X using the Green Building concept in the aspect of water conservation. The concept of this research is to recycling greywater into a second quality water source that can be used for rinsing and sprinkling water. Calculating of water requirements, generation of grey water wastewater refers to the Regulation of the 2017 Minister of Public Works and Public Housing Regulation, No. 4, Domestic Wastewater Management System. The greywater recycling process is conducted using biological and chemical processes. Based on the research use of recycled water research has the potential to conserve water use amounted to 200.32 m3/ day of total water use of 313 m3/ day or the percentage of water savings of 64%.