Specific Yield Values Research Articles

Streamflow characteristics of Sangu-Matamuhuri watershed in the southeastern part of Bangladesh

Quantification of streamflow chatacteristics is considered crucial for designing effective management practices in a watershed. Sangu and Matamuhuri are two major rivers of Chittagong Hill Tracts (CHT's) and main sources of upland freshwater inflows to the south-eastern part of Bangladesh. This study was performed to evaluate the streamflow characteristics of Sangu-Matamuhuri watershed based on 25 years historical observed streamflow and rainfall records. Mean daily discharge data recorded by Bangladesh Water Development Board were collected and analyzed for the period of 1995–2019. Stream flow characteristics were determined in terms of different parameters including mean annual runoff discharge, specific water yield, run-off ratio, peak flow, seasonal flow and flow duration. Various statistical measures including mean, standard deviation, co-efficient of variation, lag-1 serial correlation, Mann Kendall test and Sen's slope estimator were applied to justify these parameters. The mean annual runoff discharges of 2167.77 and 1490.61 million cubic meters (mcm) were measured at the gaging stations at Sangu and Matamuhuri watershed, respectively. Matamuhuri basin showed higher value of specific water yield (1.52 mcm/sq. km) compared to the Sangu basin (1.02 mcm/sq. km). The average annual runoff coefficient value of Sangu watershed was found 0.36 while in case of Matamuhuri watershed it was about 0.49. The mean annual peak discharges of 25 years were found 607.63 m3s-1 and 628.42 m3 s-1 at Sangu and Matamuhuri watershed, respectively. Mann-Kendall Test (MK) and Sen's Slope Estimator method were applied for temporal trend analysis. An increasing trend in runoff observed during wet season which may cause flash floods and a decreasing trend observed during dry season that may cause water scarcity in Sangu-Matamuhuri watershed area. Flow duration curves based on 25 years' hydrological data were developed which showed progressive reduction in flows over time in both the watersheds for three periods 1995–2002, 2003–2010 and 2011–2019 with major changes occurred in Matamuhuri watershed during 2011–2020 which might be due to the impact of land use and land cover changes as well as changes in precipitation pattern. Implications of these findings indicate baseline information that can be used to evaluate the impacts of land use changes and climate change, and thereby may facilitate the planning and local management of water resources in the long term.

Mesophilic anaerobic co-digestion of two-phase olive-mill waste and cattle manure: Optimization of semi-continuous process

Anaerobic co-digestion of organic wastes is an effective technology for the management of two or more substrates with different characteristics. In this context, the main objective of this work was the optimization of biogas production for the treatment of a mixture of two-phase olive-mill waste (2POMW) and cattle manure (CM) (60:40 w/w) at mesophilic temperature range (35 °C). The effect of hydraulic retention time (HRT) on the performance and stability of the digestion process was studied. A decreasing series of HRTs in the range of 40–12 days was analyzed. The corresponding organic loading rates (OLR) were in the range 2.01–6.07 gVS/LR·d. Pseudo steady-state operation of the reactor was established for HRTs between 40 and 15 days. For 15-days HRT, the maximum values of methane productivity (0.94 LCH4/LR·d) and specific methane yield (0.52 LCH4/gVSremoved) were obtained while total acidity (measured as acetic acid) in the effluent were<150 mg/L, verifying process stability. In addition, the removal efficiencies of volatile solids (VS) and dissolved organic carbon (DOC) were 38 and 67 %, respectively. At 12-days HRT, decreases in methane production and organic matter removal efficiencies were observed, with values of 27 and 47 % for VS and DOC removal, respectively. Therefore, 12-days HRT was considered as inadequate for the anaerobic co-digestion of 2POMW and CM because a clear increase in volatile fatty acids was observed at the end of this period, leading to process destabilization and a decrease in biogas production.

Evaluating the contribution of satellite-derived evapotranspiration in the calibration of numerical groundwater models in remote zones using the EEFlux tool

Assessment of groundwater resources is crucial for developing water management practices for its sustainable exploitation, both for current and future needs. Numerical models are useful tools for such purpose. However, the lack of continuous monitoring networks, mainly due to difficult access to some remote locations, poses a challenge in developing and calibrating groundwater models. Remote sensing offers an alternative for acquiring information on hydrological and climatic variables at multiple spatiotemporal scales that has the potential to strengthen groundwater modeling. The aim of this study is to develop a methodology that uses remote sensing products to support model calibration. With this aim, we used the Parameter Estimation software (PEST) to calibrate a hydrogeological model of an unexploited basin located in the arid Chilean Altiplano using observed groundwater levels and evapotranspiration (ET) derived from the Earth Engine Evapotranspiration Flux (EEFlux) tool as observations. Our results show that the best model calibration is achieved using both EEFlux-ET and heads as observations to calibrate the hydraulic properties (normalized root mean square error = 4.1 %). We analyzed the effect of EEFlux-ET on the calibration of these properties and found a direct effect on specific yield parameters, which regulate the fluctuations of the water table over time. Incorporating EEFlux-ET estimates in the calibration resulted in lower values of specific yield across the aquifer. Therefore, incorporating remotely sensed ET as observations in the calibration of the groundwater model contributes to a better simulation of the spatiotemporal head variations in the basin.

Aquifer feature estimation in Basara basin using a groundwater modeling system for smart agriculture

We estimate aquifer characteristics in the Basara basin using Groundwater Modeling System (GMS) software in this article. The 960 hydraulic head measurements are taken from 16 observation wells across 60 stress periods in the proposed research. Calibration of aquifer parameters produced hydraulic conductivity values ranging from 1.96 to 117.8 m/d. The specific yield values varied from (=0.31) to (>=0.06). The daily recharge rates ranged from (3.33 *10-4) to (1 *10-3). We examined six pumping scenarios for 2020-2024. (S1–S6). Groundwater levels often dropped further as pumping rates rose and recharging rates decreased. The lower contour elevation for scenario 6 is 745.43 m, while it was 748.39, 753.56, 753.56, 753.56, and 753.86 m for scenarios 5, 4, 3, 2, and 1. The findings of this study help policymakers plan for potential shortages in semi-arid areas. The available options can be reproduced elsewhere to provide a more precise and reliable groundwater solution.

Locating optimal position of artificial recharge wells in aquifer using grey wolf optimization algorithm and isogeometric numerical method

The construction of injection wells is one of the direct methods of artificial recharge and determining their optimal location is one of the important issues that are discussed in the topics of projects related to the rehabilitation of aquifers. In this research, a simulation–optimization model was proposed to determine the optimal location of injection wells using the Isogeometric analysis (IGA) numerical model and the Grey wolf optimization algorithm (GWO). In this regard, first, a groundwater model based on Isogeometric analysis was created to simulate groundwater flow in a hypothetical aquifer. Finally, after ensuring the accuracy of the simulator model, the optimal location of 10 injection wells was evaluated under two scenarios based on different values of hydraulic conductivity and specific yield. The accuracy of the simulation model is computed based on three error criteria ME, MAE and RMSE were the evaluation criteria which equaled −0.96%, 1.11%, and 0.0146 m, respectively. The achieved results showed that the Isogeometric analysis model has high accuracy. The results of the IGA-GWO model indicated that after constructing injection wells in the optimal location, the groundwater table on average in 10 injection wells rises more than 50 cm in both scenarios. The results also showed that due to the change in aquifer hydraulic conductivity and specific yield in different regions and the defined boundary conditions in the problem, the optimal location of injection wells are in regions with more hydraulic conductivity and more specific yield. Also, injection in regions with more drops will increase the groundwater table.

Assessment of Groundwater Flow Dynamics Using MODFLOW in Shallow Aquifer System of Mahanadi Delta (East Coast), India

Despite being a biodiversity hotspot, the Mahanadi delta is facing groundwater salinization as one of the main environmental threats in the recent past. Hence, this study attempts to understand the dynamics of groundwater and its sustainable management options through numerical simulation in the Jagatsinghpur deltaic region. The result shows that groundwater in the study area is extensively abstracted for agricultural activities, which also causes the depletion of groundwater levels. The hydraulic head value varies from 0.7 to 15 m above mean sea level (MSL) with an average head of 6 m in this low-lying coastal region. The horizontal hydraulic conductivity and the specific yield values in the area are found to vary from 40 to 45 m/day and 0.05 to 0.07, respectively. The study area has been calibrated for two years (2004–2005) by using these parameters, followed by the validation of four years (2006–2009). The calibrated numerical model is used to evaluate the net recharge and groundwater balance in this study area. The interaction between the river and coastal unconfined aquifer system responds differently in different seasons. The net groundwater recharge to the coastal aquifer has been estimated and varies from 247.89 to 262.63 million cubic meters (MCM) in the year 2006–2007. The model further indicates a net outflow of 8.92–9.64 MCM of groundwater into the Bay of Bengal. Further, the outflow to the sea is preventing the seawater ingress into the shallow coastal aquifer system.

Characterizing Recharge in Southern Mali Using a Combination of Modeling and Stable Isotopes

Groundwater recharge in southern Mali is investigated using interpretive recharge models and stable isotopes to identify the dominant recharge mechanism and explore how local variations in geological materials influence the recharge characteristics. At a regional scale, the groundwater level hydrographs from across southern Mali (1998–2002) are relatively consistent, showing seasonal variations, suggesting diffuse recharge is the dominant mechanism. Groundwater samples plot within the range of the weighted mean monthly δ18O and δ2H concentrations for July-August-September rainfall, and below the weighted mean annual δ18O and δ2H concentrations for rainfall, suggesting a dominantly rainy season source of recharge. Recharge is simulated for four representative unsaturated zone environments, each with varying soil, laterite and sedimentary bedrock layers, and three ranges of water table depths, for a total of 12 combinations. The simulated recharge response starts in July, 1 month after the arrival of the rainy season, and recharge is greatly accelerated through August to its peak in September. On an annual basis, ~72% of annual rainfall occurs between July and September, and nearly 60% of simulated recharge occurs between August and October. The simulated regional average annual recharge is 519 mm/year (479–560 mm/year range among models). By comparison, recharge estimated from the observed storage anomaly hydrographs using the water table fluctuation method is 384 mm/year (189–619 mm/year) using a specific yield of 0.05, although the range could be as high as 83–772 mm/year given the uncertainty in specific yield values (0.02–0.07). The simulated recharge also agrees with the timing of regional observed storage anomalies for all observation wells, but somewhat less so for the regional GRACE storage anomaly (2002–2008), which has a slower rate of rise in storage and a faster rate of recession compared to the observed storage anomalies and simulated recharge response.

Estimation of Dry-Season Fluctuation in Specific Yield using Water Budgeting Approach in Bonasuria Micro-watershed of Damodar River Basin, India

ABSTRACT Heterogeneity in lithological and structural characteristics results in variation of specific yield (Sy) value in spatial domain. It also depends upon degree of saturation of aquifer. This imparts temporal variation in Sy value in an aquifer. Bonasuria micro-watershed of Damodar river-basin in India is selected to undertake the study of estimation of temporal variation in Sy based upon monthly ground water budgeting for three non-monsoon months. Sy value gradually changes with progression of summer months. Average specific yield value has been estimated as 0.002593 in March and 0.001446 in April. Determined specific yield values indicate low water storage capacity of the shallow aquifer system. This highlights the need of efficient water management for sustainable development of the area. Present study indicates that this can be achieved through storing the effluent seepage going out of the micro- water shed system as base flow. By constructing appropriate water storage structure at the mouth of the water shed and diverting the same back to the aquifer through suitable means is expected to rejuvenate the aquifer system. Holistically this intervention will lead towards development of sustainable dry-season agricultural practices in the study area.

Exploring the association between landslides and fluvial suspended sediment in a semi-arid basin in central Chile

The systematic monitoring of landslides is an essential input for their characterization and subsequent reduction of their risk. Along the western subtropical Andes, field monitoring is scarce, so alternative methods that can improve the monitoring are valuable. In this work, the capacity of fluvial suspended sediment to detect the occurrence of landslides in a basin was explored, emphasizing how the relationship varies depending on the hydro-sedimentological variable, the triggering causal factor and the landslide type. The values of suspended sediment concentration (SSC), water discharge (Q) and specific suspended sediment yield (SSY) associated with mass movements were collected from a fluviometric station, as well as maxima of these variables that were not associated with landslides. With these data, different General Linear Models were constructed considering possible non-linear effects of the covariates. Flow-type landslides triggered by rain (most of the events) are correctly predicted, especially using the linear effects of SSC and Q. For this mass movement type the prediction is suitable even for events triggered by isolated, short-lived rains, which are difficult to detect in mountainous areas with meteorological devices.

Sediment regimes in South Korea

AbstractA comprehensive review of the existing river flow and sediment measurement data of South Korea shows specific sediment yield values ranging from 5 to 1,500 tons/km2·year. The watershed characteristics decisively affect the shape of mass curves for water and sediment, as well as the flow duration and sediment rating curves. In terms of flow regime, small watersheds have flashy hydrographs and high sediment concentrations at a given flow discharge. The sediment rating curve coefficients decrease from 1 to 0.02 as the watershed area increases from 100 to 20,000 km2, while the exponents of these curves remain relatively constant between 1.5 and 2.0. The sediment transport in small watersheds depends on large floods, and the half‐yield discharge decreases with watershed area and typically ranges from 5 to 40 times the mean discharge. This study defines equations to calculate the mean annual flow discharge, flow duration curves, sediment yield, and cumulative water and sediment distribution curves validated with field measurements in South Korea. Additionally, the sediment regime is also presented in a continental perspective.

Infiltration coefficient, percolation rate and depth-dependent specific yields estimated from 1.5 years of absolute gravity observations near a recharge lake in Pingtung, Taiwan

An efficient underground reservoir management requires reliable hydrogeological parameters, such as infiltration coefficient, percolation rate and specific yield (Sy) values. The cross-well pumping test is a well-known method for determining Sy, but different unsaturated flow models can lead to various Sy results. Heterogeneity in unsaturated and saturated zones can restrict well-dependent methods in estimating these parameters on a regional scale, for which an alternative, gravity-based method is attempted in this study. We established an absolute gravity site at the Wanlong Primary school (WLPS) near a recharge lake (an artificial lake) in the Pingtung Plain and collected 1.5 years of gravity data in 2019–2020. Around a monsoonal rain event in late May 2020, gravity values underwent three stages of changes. The first stage experienced a rapid gravity rise of 18 μgal from infiltrated rain, followed by stable gravity values in the second stage when the infiltrated rain recharged the aquifer, and the third stage showed a persistent gravity increase with rising groundwater level. The gravity-based estimate of infiltration coefficient is 0.84 ± 0.14, and the percolation rate is about 15 m/day, suggesting that WLPS is over a high infiltration region. A depth-dependent Sy profile up to 30 m depth was constructed using gravity and groundwater data. In the dry season, it was found that Sy values are higher at the aquifer depths of 22–28 m than in the shallow part. However, some Sy values determined in the wet seasons are overestimated due to high soil water content (SWC) changes, which induced particularly large gravity changes in the 30-m unsaturated zone of WLPS when the wet season started. This study confirms the advantage of using high precise gravity measurements (at one μgal level) and hydrology records for regional hydrogeological parameter estimation.

Co-culture of Indian white shrimp, Penaeus indicus and seaweed, Gracilaria tenuistipitata in amended biofloc and recirculating aquaculture system (RAS)

A 60 days nursery-based co-culture of Indian white shrimp, Penaeus indicus along with seaweed, Gracilaria tenuistipitata trial was carried out in Recirculatory Aquaculture System (RAS) of 6000 Liters capacity tank (FRP, reinforced fibre plastics) by using biofloc technology (BFT) to evaluate the growth, survival performance and immune potential. Accordingly a completely randomized experiment was designed with six treatments. These treatments were: T1- Static system (Control), T2 - RAS with BFT, T3 - RAS with Gracilaria, T4 - RAS and BFT customized with bacterial consortium, T5 - RAS with BFT + Gracilaria + bacterial consortium, T6 - Static + Gracilaria + BFT (without consortium and without RAS). Shrimp post larvae (0.08 ± 0.03 g) were stocked at a density of 3000 nos./ton. RAS with BFT along with the seaweed and bacterial consortium showed significantly higher growth and survival compared to control (T1) and treatments without BFT (T3). The control (T1) exhibited significantly lower growth, weight gain, specific growth rate, yield and higher FCR value than that of the RAS + BFT (T2), RAS+ seaweed (T3) and RAS + BFT or their combinations with bacterial consortium (T4 and T5). The treatment having seaweed without BFT (T3) showed higher survival than the static control (T1), but no significant difference in growth. The highest ABW of 4.23 ± 0.39 was obtained in T4 (BFT customized with consortium) followed by T5 (BFT + seaweed + bacterial consortium) and lowest was observed in T1 (2.14 ± 0.4). Similarly, the highest survival (92.33 ± 1.52) and production (10.39 ± 0.24 kg/ton) was observed in T5. Significantly higher NH4-N and NO2-N was accumulated in the control (T1) in comparison with other treatment like T4 and T5. Immune parameters viz., PPO activity, Total Serum Protein and Total Hemocyte Count (THC) showed significantly higher values in all the treatments compared to control. This study establishes the novel concept of incorporation of macroalgae in biofloc based RAS improving the production performance and immune response of shrimp during nursery as well as grow-out phase.

Cost-benefit analysis of the implementation of off-grid photovoltaic systems in the Northwest residential sector of San Pedro Sula, Honduras

This research analyzed the implementation, from a technical and financial point of view, of off-grid solar photovoltaic systems in the Northwest sector of San Pedro Sula, Honduras. The energy demand of the residential sector was studied, the monthly energy consumption data of 17 neighborhoods in the sector were processed and three main monthly energy consumption levels were determined. The sizing of the systems was carried out considering PV arrays connected to hybrid inverters. In addition, the nominal capacity of the battery banks of the three systems was defined based on 1 day of autonomy and a nominal voltage of the installation of 48V. PVsyst was used to approximate the energy that the photovoltaic array will potentially generate, and the specific yield value was used to project the energy to be generated throughout the life of the project. Homer Pro was used to determine the optimal configuration to find the lowest net present costs for each project. The financial analysis determined that the cost-benefit ratio is greater than 1 for systems with nominal DC capacity greater than 15.8kWp.

Hydraulic and Physical Properties of Managed and Intact Peatlands: Application of the Van Genuchten‐Mualem Models to Peat Soils

AbstractUndisturbed peatlands are effective carbon sinks and provide a variety of ecosystem services. However, anthropogenic disturbances, especially land drainage, strongly alter peat soil properties and jeopardize the benefits of peatlands. The effects of disturbances should therefore be assessed and predicted. To support accurate modeling, this study determined the physical and hydraulic properties of intact and disturbed peat samples collected from 59 sites (in total 3,073 samples) in Finland and Norway. The bulk density (BD), porosity, and specific yield (Sy) values obtained indicated that the top layer (0–30 cm depth) at agricultural and peat extraction sites was most affected by land use change. The BD in the top layer at agricultural, peat extraction, and forestry sites was 441%, 140%, and 92% higher, respectively, than that of intact peatlands. Porosity decreased with increased BD, but not linearly. Agricultural and peat extraction sites had the lowest saturated hydraulic conductivity, Sy, and porosity, and the highest BD of the land use options studied. The van Genuchten‐Mualem (vGM) soil water retention curve (SWRC) and hydraulic conductivity (K) models proved to be applicable for the peat soils tested, providing values of SWRC, K, and vGM‐parameters (α and n) for peat layers (top, middle and bottom) under different land uses. A decrease in peat soil water content of ≥10% reduced the unsaturated K values by two orders of magnitude. This unique data set can be used to improve hydrological modeling in peat‐dominated catchments and for fuller integration of peat soils into large‐scale hydrological models.

Влияние коэффициента рециркуляции эффлюента метантенка на выход биоводорода в двухстадийном процессе анаэробной биоконверсии жидких органических отходов

This paper considers the production of biohydrogen in a two-stage process of anaerobic bioconversion of organic matter (OM) of liquid waste with recirculation of digester effluent into an anaerobic bioreactor for dark fermentation (ARDF). The values of the average biohydrogen specific yield (BSY) and the average volumetric biohydrogen production rate (VBPR) were obtained at 4 recirculation ratios (RR) of the digester effluent (1, 1.1, 1.18, 1.25) and 2 hydraulic retention times (HRT) ( 1 and 2.5) in ARDF. Organic loading rate (olr) varied from 7.96 to 21.6 g OM / (l ∙ day). The pH value in ARDF practically did not depend on RR and HRT, and ranged from 3.8 to 4.16. The maximum BSY was 0.108 l / (day ∙ g OMin) with a RR of 1.11 and a HRT of 2.5 days. The maximum VBPR was observed at RR 1 and HRT 1 day and amounted to 1.67 l / (l ∙ day). The methane content in biohydrogen-containing biogas at modes providing maximum BSY and VBPR was no more than 0.01%, but it increased sharply at higher values of RR and HRT. The hydrogen content in biogas averaged 50-52% for all combinations of RR and HRT, but it sharply decreased to 46.7% with HRT 2.5 and RR 1.25. In general, with RR 1.11 and HRT 1 day, an increase in BSY by 9.05% was observed, while the VBPR decreased by 1.04% (compared with RR 1.0 and HRT 1 day). In general, the experi- mental data obtained allow us to speak of a RR equal to 1.11 as the most effective for both HRTs in the studied range of RR.

Meteorological Controls on Water Table Dynamics in Fen Peatlands Depend on Management Regimes

Fens belong to the most threatened ecosystems in Europe. Maintaining a high water table through rewetting is an effective measure to rehabilitate many of their ecosystem functions. However, the impact of meteorological conditions such as vapor pressure deficit (VPD) and precipitation on water tables is still unclear for rewetted fens. Here, we compare the impact of meteorological factors on water table dynamics in a drained and a rewetted fen, using multiple regression with data from continuous high-resolution (temporal) water level monitoring and weather stations. We find that an increase in the daily mean VPD causes a higher drop in the water table at the drained and degraded fen compared to the rewetted fen. Precipitation contributes to recharge, causing the water table to rise higher at the drained site than at the rewetted site. We attribute the differential influence of meteorological conditions on water table dynamics to different soil specific yield values (i.e., water storage capacity) largely driven by lower water table position at the drained site. Our study underlines the importance of understanding how and why water tables in peatlands vary in response to meteorological factors for management decisions (e.g., rewetting). Continuous monitoring of water table and vegetation development in rewetted fen peatlands is advisable to ensure long-term success especially under climate change conditions and associated drought events.

Estimation of hydrogeological parameters using physically based hydrological modelling and lithology data in ungauged creek catchments of southern Taiwan

ABSTRACT Streamflow recession analysis is widely used for estimating catchment-scale hydrogeological parameters in gauged catchments because of its low cost, ease of use, and efficiency in terms of results. In this work, however, the same methodology was applied to ungauged creek catchments, where low recession flows were simulated using physically based, semi-distributed, continuous hydrological modelling. Moreover, a combination approach was used to reasonably estimate the effective aquifer depth (D) with borehole lithology and digital elevation model data. The estimated hydraulic conductivity (k) values ranged between 10–5 and 10–3 m s–1, and they were comparable with the results of a field test. By contrast, the specific yield (Sy ) values obtained through streamflow recession analysis (10–7 to 10–5) were lower than the results of the field tests at different aquifer depths. However, the Sy values obtained for alluvial catchments (on the order of 10–5) were comparable. Thus, the results of the comparison support the application of the streamflow recession analysis scheme for estimating hydrogeological parameters in ungauged creek catchments.

A Comprehensive Review of Specific Yield in Land Surface and Groundwater Studies

AbstractSpecific yield is a key parameter for estimating water table depth in land surface models, which can strongly modulate the interaction between soil moisture and groundwater and further affect the water budget between the land surface and the atmosphere. The error in water table simulation comes mainly from the uncertainty in determining the specific yield. The determination of specific yield in land surface models is simplified, and a uniform empirical constant value of specific yield is generally used in global simulations, especially for deep aquifers, for its convenience. However, a uniform fixed value is insufficient for worldwide aquifers with diverse environments. Before estimating specific yields for global aquifers in Earth system simulations, a comprehensive understanding of the specific yield and comparison of current determination methods are required. This study provides a comprehensive review of the literature focusing on different concepts of the specific yield, complex variabilities, and various determination methods. Specifically, we detail the distinction and interconversion of different subconcepts that are used to reflect the influence of different factors on the specific yield and are likely to confuse scholars; present the representative comparisons of previous estimated specific yields using different methods, and summarize the applicabilities and limitations of these methods, indicating directions for their future improvement.

Parametric uncertainty analysis on hydrodynamic coefficients in groundwater numerical models using Monte Carlo method and RPEM

Groundwater resources are the only source of water in many arid and semi-arid regions. It is important to manage these resources to have a sustainable development. However, there are many factors influencing the accuracy of the results in groundwater modeling. In this research, the uncertainty of two important groundwater model parameters (hydraulic conductivity and specific yield) were considered as the main sources of uncertainty in estimating water level in an unconfined aquifer, in Iran. For this purpose, a simple method called Rosenblueth Point Estimate Method (RPEM) was used to assess groundwater modeling parametric uncertainty, and its performance was compared with Monte Carlo method as a very complicated and time-consuming method. According to calibrated values of hydraulic conductivity and specific yield, several uncertainty intervals were considered to analyze uncertainty. The results showed that the optimum interval for hydraulic conductivity was 40% increase–30% decrease of the calibrated values in both Monte Carlo and RPEM methods. This interval for specific yield was 200% increase–90% decrease of the calibrated values. RPEM showed better performance using the evaluating indices in comparison with Monte Carlo method for both hydraulic conductivity and specific yield with 43% and 17% higher index values, respectively. These results can be used in groundwater management and future prediction of groundwater level.

Environmental competitiveness evaluation by life cycle assessment for solid fuels generated from Sida hermaphrodita biomass

As part of a comprehensive evaluation of the use of Sida hermaphrodita (hereafter referred to as Sida) biomass as a solid biofuel, a life cycle assessment (LCA) according to ISO 14040/14044 was carried out by means of a suitable cradle-to-gate system design. The supply and use of chips, pellets and briquettes was studied by internal and external comparisons to show competitiveness and improvement options. The results show fewer differences within the Sida process chain designs but larger distinctions to compared alternative biofuels such as wood or Miscanthus pellets. A major finding is that Sida process chains cause lower environmental impacts in comparison with alternative biofuels. The study identified hot spots within the Sida process chains and starting points for further improvement. A sensitivity analysis of important parameters, such as specific yield or heating values was performed. Because there are no similar investigations on the environmental impact of Sida used as a biogenic solid fuel to date this manuscript presents first results. So far, the results indicate that Sida provides a more sustainable option for the use of biomass in combustion processes in relation to environmental impacts.