Sustainability of Water Quality and Ecology最新文献

The impact of continuing rainforest transformation on hydrological functioning and other ecosystem functions in South East Asia remains uncertain. The vast majority of the local residents in our study area believe that the expansion of oil palm reduced the flow regulation function of a watershed causing more frequent flooding in the rainy season and water scarcity problems during the dry season. The research aimed to characterize surface runoff as an indicator of water flow regulation and simulate effectiveness of different mitigation options for surface runoff management in a watershed with rapid expansion of oil palm plantations. Our study started with plot experiments to characterize surface runoff used to adapt curve number (CN) values of the different land-use types required for SWAT modeling. Further, we carried out small watershed experiments to adapt the CN values of different mitigation options. The SWAT model performance was in satisfactory agreement with the Nash–Sutcliff efficiency values of 0.88 and 0.82 for calibration and validation, respectively. After successful model calibration and validation, we simulated the effectiveness of the following mitigation options: (a) frond pile management, and (b) frond pile management and silt pit treatment with a density of 20 units per ha. Both options were chosen for their simple construction enhancing their adoption and sustainable application. Frond pile management and the combination of frond pile and silt pit treatment reduced total surface runoff in a watershed scale from 151 mm to 141 mm (10%) and from 151 mm to 109 mm (31%), respectively. The mitigation options which were evaluated in this study were ecologically effective in regulating water flow through reduction of surface runoff. They were also economically viable, because the mitigation options increased the availability of water which can increase oil palm production while the implementation costs are low due to the simple design using frond leaves residues abundantly available onsite. Due to the fulfillment of at least two sustainability pillars, these mitigation options should be adopted as one evaluation criterion in the certification process carried out by Indonesian certification body for sustainable palm oil (ISPO). Further research is still needed to study optimal design criteria for mitigation options including their dimension, density and spatial distribution in a watershed.

Understanding the relationship between land use and freshwater quality is necessary for effective water management. This study sought to evaluate the impacts of future land use change on water quality in an agriculture dominated watershed in South Dakota. Taking into account three cases (A1B, A2 and B1) of the FOREcasting SCEnarios (FORE-SCE) of Land use Change modeling framework, possible changes in surface runoff, sediment, nitrate and total phosphorus by the end of the 21st century were assessed relative to the baseline (National Land Cover Database 2011) comprising a multi-year period from the recent past (2006–2014). The Soil and Water Assessment Tool (SWAT) was used for simulating hydrology and water quality, where particular attention was given to land transformation from “high-input” to “low-input” agriculture. The analysis revealed that urban areas and low-input hay/pasture production would expand from conversion of forest, grassland and high-input cultivated cropland. While afforestation might also occur under certain future scenario assumptions such as B1, all the three scenarios are suggestive of complete grassland depletion by the first quarter of this century. Simulation results suggested that water quality would improve with expansion of hay/pasture production (as low-input agriculture), reducing surface runoff volume, sediment, nitrate and total phosphorus loads by 3–14% across all three future scenarios of land use change. This study provides an example on how physically-based land use projections can be ingested in SWAT modeling to identify possible environmental implications of future land use changes. Similar studies adopted on large scales would be useful to support holistic water resources management strategies and associated policy interventions.

Today’s water sector is governed by some hot topics, and this is no different in Belgium. As for the International Water Association (IWA), the goal of its Belgian division (B-IWA) is to gather different stakeholders, i.e. academics, policy makers and people from industry active in the (Belgian) water sector and trigger the debate. In May 2015, a first Nocturnal was organised to accomplish just this. Seven hot water topics, proposed by participants at the time of their online registration, were addressed in rotating round table discussions. These topics included resource recovery, micropollutants, water scarcity, hydroinformatics, integrated water management and modeling, technology vs. legislation and Computational Fluid Dynamics in water applications. The lively discussions led to the idea of this short contribution describing the outcomes of these round table discussions, along with some additional research on the topics. Main conclusions include the need for education (both of scholars and young professionals), inter-domain communication and the growing importance of IT in the water sector.

Melanoides tuberculata is now been monitored worldwide because of its fast growing distribution and its economic importance. M. tuberculata, a freshwater mollusc that is an invasive species of freshwater snail, serves as vector transmitting several diseases causing parasites, was found inhabiting Eleyele dam in Ibadan, Nigeria. The prevailing environmental conditions of Eleyele dam were studied between May and October, 2013. Standard methods were used to collect and analyze water samples for physico-chemical variables at four different points on the dam. Conductivity, total solid, water temperature, water depth, dissolved oxygen, biological oxygen demand, nitrate, calcium, alkalinity, total hardness, total suspended solids ranged between 123.95 ± 100.66 mg/L, 143.34 ± 73.21 mg/L 28.42 ± 1.05 °C, 25.73 ± 6.70 cm, 2.71 ± 1.33 mg/L, 0.85 ± 0.90 mg/L, 1.44 ± 1.86 mg/L, 30.70 ± 27.56 mg/L, 43.12 ± 45.04 mg/L, 25.33 ± 23.71 mg/L, 63.15 ± 50.71 mg/L respectively. Calcium significantly correlated with alkalinity (r = 0.864, P < 0.05), total hardness correlated with calcium concentration (r = 0.86, P < 0.05) and alkalinity (r = 0.984, P < 0.05), conductivity with total dissolved solids (r = 0.97, P < 0.05). The observed environmental conditions that favor colonization of M. tuberculata in the Eleyele dam suggest its possible spread in several water bodies in Nigeria. Great precaution must be taking when introducing new aquatic plants into water bodies because this provides a likely route for introduction of nonnative snails as small snails can easily be overlooked on leaves and also during the introduction of M. tuberculata as biocontrol of snails, particularly hydrobes that may carry Schistosoma.

The number of states that have adopted numeric nutrient water-quality standards has increased to 23, up from ten in 1998. One state with both stream and reservoir phosphorus (P) numeric water-quality standards is Oklahoma. There were two primary objectives of this research: (1) determine if Oklahoma was meeting the stream and reservoir numeric water-quality standards in the Illinois River and Eucha–Spavinaw watersheds, respectively and (2) identify various combinations of management practices required to meet the water-quality standards. A Soil and Water Assessment Tool (SWAT) model was developed for each watershed. After runoff and P calibration and validation, each model was used to determine if the numeric water-quality standards were exceeded. Due to recent land management changes in the Eucha–Spavinaw watershed, Oklahoma was meeting the established water quality standard, 0.0168 mg L⁻¹ total P in Lake Eucha. Although extensive efforts to reduce P loads have been conducted in the last decade in the Illinois River watershed, a large quantity of P is still reaching the streams and Tenkiller Ferry Lake in the Illinois River watershed. The model was used to identify a combination of potential land management practices in Oklahoma to meet to meet the water-quality standard, 0.037 mg L⁻¹ total P, in three of Oklahoma’s designated Scenic Rivers: the Illinois River, Barren Fork Creek and Flint Creek. With recent reductions in poultry litter application and improvements in municipal waste water treatment plants, future conservation practices need to focus on cattle production and elevated soil test P. This research illustrated how a watershed model can provide critical information for watershed-based plans to address numeric water-quality standards.

Saltwater intrusion and upconing phenomena affect coastal aquifers worldwide. These phenomena can be partially mitigated by an adequate management of the aquifer. In this work, the optimal pumping schedule for one coastal well has been defined by a decision model that minimizes desalination and pumping costs, while taking into account the aquifer salinity levels near the well. The dynamics of the aquifer is described in terms of two state equations related to salinity concentration in the pumped water and cumulative pumped water up to a specific instant. A case study is presented with application to a well in Hawaii islands.

In water-scarce environments, surface water bodies serve both as water sources and waste disposal channels. The Molopo River that drains through Mafikeng, South Africa, has been dammed for agricultural and municipal water supply, resulting in four reservoirs near Mafikeng. It receives municipal waste water discharges from point pollution source sewage processing plants. In this study the spatial variation in the manifestation of eutrophication in the reservoir water was examined. Surface water samples were collected from the four reservoirs in July (dry season), and analysed for nutrient (NO₃⁻, PO₄³⁻) concentrations. The dry season low river flow period was perceived as the period when the eutrophication problem is more acute. Near infrared (NIR) reflectance from the reservoirs, due to algae and macrophytes like the water lettuce (Pistia stratiotes), was used as manifestation of eutrophication on satellite imagery. The presence of these plant NIR reflectors in the water bodies was assessed using near-concurrent multispectral SPOT 5 images. The image digital number (DN) values were converted to reflectance values. Geostatistical analysis indicated autocorrelation of algal abundance as indicated by the near infrared (NIR, 0.78–0.89 μm) reflectance. Ordinary kriging interpolation indicated change in algal abundance away from the point nutrient sources. Reservoirs with direct effluent point sources had higher nutrient concentrations and NIR reflectance than those without direct point sources. The results indicate the reservoirs to range between eutrophic and hypertrophic, and show the suitability of SPOT 5 imagery for use in the assessment of eutrophication in support of environmental quality assessments for inland water bodies.