A traversing system to measure bottom boundary layer hydraulic properties

This study describes a new convenient and robust system developed to measure benthic boundary layer properties, with emphasis placed on the determination of bed shear stress and roughness height distribution within estuarine systems by using velocity measurements. This system consisted of a remotely operated motorised traverser that allowed a single ADV to collect data between 0 and 1 m above the bed. As a case study, we applied the proposed traversing system to investigate bottom boundary layer (BBL) hydraulic properties within Coombabah Creek, Queensland, Australia. Four commonly-employed techniques: (1) Log-Profile (LP); (2) Reynolds stress (RS); (3) Turbulent Kinetic Energy (TKE); and (4) Inertial Dissipation (ID) used to estimate bed shear stresses from velocity measurements were compared. Bed shear stresses estimated with these four methods agreed reasonably well; of these, the LP method was found to be most useful and reliable. Additionally, the LP method permits the calculation of roughness height, which the other three methods do not. An average value of bed shear stress of 0.46 N/m², roughness height of 4.3 mm, and drag coefficient of 0.0054 were observed within Coombabah Creek. Results are consistent with that reported for several other silty bed estuaries.     

Potentially harmful metals,and health risk evaluation in groundwater of Mardan,Pakistan: Application of geostatistical approach and geographic information system

This study investigates the values of pH, total dissolved solids (TDS), elevation, oxidative reduction potential (ORP), temperature, and depth, while the concentrations of Br, and potentially harmful metals (PHMs) such as Cr, Ni, Cd, Mn, Cu, Pb, Co, Zn, and Fe in the groundwater samples. Moreover, geographic information system (GIS), XLSTAT, and IBM SPSS Statistics 20 software were used for spatial distribution modeling, principal component analysis (PCA), cluster analysis (CA), and Quantile-Quantile (Q-Q) plotting to determine groundwater pollution sources, similarity index, and normal distribution reference line for the selected parameters. The mean values of pH, TDS, elevation, ORP, temperature, depth, and Br were 7.2, 322 mg/L, 364 m, 188 mV, 29.6 °C, 70 m, 0.20 mg/L, and PHMs like Cr, Ni, Cd, Mn, Cu, Pb, Co, Zn, and Fe were 0.38, 0.26, 0.08, 0.27, 0.36, 0.22, 0.04, 0.43 and 0.86 mg/L, respectively. PHMs including Cr (89%), Cd (43%), Mn (23%), Pb (79%), Co (20%), and Fe (91%) exceeded the guideline values set by the world health organization (WHO). The significant R² values of PCA for selected parameters were also determined (0.62, 0.67, 0.78, 0.73, 0.60, 0.87, ?0.50, 0.69, 0.70, 0.74, ?0.50, 0.70, 0.67, 0.79, 0.59, and ?0.55, respectively). PCA revealed three geochemical processes such as geogenic, anthropogenic, and reducing conditions. The mineral phases of Cd(OH)_2, Fe(OH)_3, FeOOH, Mn₃O_4, Fe₂O_3, MnOOH, Pb(OH)_2, Mn(OH)_2, MnO_2, and Zn(OH)₂ (?3.7, 3.75, 9.7, ?5.8, 8.9, ?3.6, 2.2, ?4.6, ?7.7, ?0.9, and 0.003, respectively) showed super-saturation and under-saturation conditions. Health risk assessment (HRA) values for PHMs were also calculated and the values of hazard quotient (HQ), and hazard indices (HI) for the entire study area were increased in the following order: Cd>Ni>Cu>Pb>Mn>Zn>Cr. Relatively higher HQ and HI values of Ni, Cd, Pb, and Cu were greater than one showing unsuitability of groundwater for domestic, agriculture, and drinking purposes. The long-term ingestion of groundwater could also cause severe health concerns such as kidney, brain dysfunction, liver, stomach problems, and even cancer.     

3D numerical stability analysis of multi-lateral well junctions

The most important factors in multi-lateral well stability analysis are the magnitude of in situ stresses, the relation between the amount of in situ stresses and orientation of lateral wellbore. In this research, the stability analysis of multi-lateral junction is carried out using FLAC3D numerical code by considering seven varied stress regimes and different lateral wellbore orientations. The Normalized Yielded Zone Area (NYZA, ratio of surrounding yielded cross-sectional area to initial area of well) is determined for different junction mud pressures as well as diverse orientations of lateral wellbore. Then, the junction optimum mud pressure of each lateral wellbore orientation is calculated; hence, the optimum trajectory of lateral wellbore, in which the junction has got the lowest optimum mud pressure, is selected in each stress regime. The stability analysis of multi-lateral wells by means of finite difference method shows that in each stress regime the required mud pressure for the stability of junction is much more than that of the lateral branch and the main wellbore.     

Effect of geojute technique on density,diversity and carbon stock of plant species in landslide site of North West Himalaya

Mountainous regions of the globe experience landslides due to heavy rainfall and unplanned construction on slopes. Geojute is adopted globally as a landslide rehabilitation measure, but its impact on natural vegetation development is poorly understood. The present study was conducted to examine the impact of geojute application on vegetation restoration, ecology and carbon stock in a recently occurred landslide, during 2012. The results revealed that the geojute application improved the richness, diversity, density and basal area of plant species at the landslide site. Likewise, biomass production, carbon stock and carbon sequestration of plant species was observed significantly higher in geojute treatments compared to control (without geojute treatment). Moreover, significant improvement in soil moisture was recorded beneath the geojute treatments. Further, results showed that the geojute is highly effective in controlling soil erosion at the landslide site. The findings of this study revealed ecological and environmental benefits of geojute application in term of improvement in vegetation recovery processes, species diversity and carbon sequestration at the landslide site. The scientific outcome of this study can be helpful for planning the rehabilitation measures in landslide affected regions of the globe.     

Flood risk assessment of River Indus of Pakistan

Annual flood peak discharges is widely used in risk assessment. Major sources of flooding in Pakistan are River Jhelum, River Chenab, River Kabul, and upper and lower parts of River Indus. These rivers are major tributaries of the River Indus System which is one of the most important systems of the world and the greatest system of Pakistan. River Indus is the longest river of Pakistan containing seven gauge stations and several barrages, and it plays a vital role in the irrigation system and power generation for the country. This paper estimates the risk of flood in River Indus using historical data of maximum peak discharges. On the basis of our analysis, we find out which dam/barrage reservoir need to be updated in capacity, and whether there are more dams/barrages needed.     

Using beryllium-7 to evaluate soil erosion processes in agricultural lands in semiarid regions of Central Argentina

This work presents the results of a soil erosion study using the ⁷Be technique. This technique estimates the water erosion/deposition from the comparison between ⁷Be soil content of a reference site and an eroded or sedimented site. The soil samples were collected from an agricultural area of the semiarid region of Argentina near San Luis City, which has a marked rainfall season. The area has been used for crop cultivation, being subjected to plowing practices. The ⁷Be in the Reference Site was in the first centimeter of soil, showing the typical exponential decreasing of ⁷Be soil content with depth, with the ⁷Be inventories value being 340?±?50 Bq m^?2 for the dry season and 571?±?48 Bq m^?2 for the rainy season. The ⁷Be technique was applied to a potential eroded site subjected to traditional tillage practices (plowing). A net soil erosion value of 13.5 t ha^?1 (1.35 kg m^?2) was obtained. From the assumptions of the applied technique, we can draw the inference that this erosion was caused by rains produced in the month prior to the date of soil sampling.     

Electrical imaging of the groundwater aquifer at Banting,Selangor, Malaysia

A geophysical study was carried out in the Banting area of Malaysia to delineate groundwater aquifer and marine clay layer of the alluvial Quaternary deposits of Beruas and Gula Formations. The Beruas Formation is formed by peat and clayey materials as well as silt and sands, whereas the Gula Formation consists of clay, silt, sand and gravels. Both Formations were deposited on top of the Carboniferous shale of the Kenny Hill Formation. A 2-D geoelectrical resistivity technique was used. Resistivity measurement was carried out using an ABEM SAS 4000 Terrameter. The 2-D resistivity data of subsurface material for each survey line was calculated through inverse modelling and then compared with borehole data. The resistivity images of all the subsurface material below the survey lines show similar pattern of continuous structure of layering or layers with some lenses with resistivity ranging from 0.1 to 50 Ωm. The upper layer shows resistivity values ranging from 0.1 to 10 Ωm, representing a clay horizon with a thickness up to 45 m. The second layer with depth varies from 45 to 70 m below surface and has resistivity values ranging from 10 to 30 Ωm. Borehole data indicate coarse sand with some gravels for this layer, which is also the groundwater aquifer in the study area. The lowermost layer at a depth of 70 m below ground level shows resistivity values ranging from 30–50 Ωm and can be correlated with metasedimentary rocks consisting of shale and metaquartzite.     

Promoting the Nexus Approach of Climate,Ecosystems and Livelihoods in Africa through China-Africa Cooperation

Africa is facing both challenges and opportunities in pursuing sustainability. The nexus approach of Climate, Ecosystems and Livelihoods (CEL) is a promising way to seize the “power of integration” for achieving sustainability of the African continent. Based on taking stock of the work of various organizations especially the United Nations Environment Programme International Ecosystem Management Partnership (UNEP-IEMP) in the Africa, this article explores the demands and opportunities for delivering the CEL approach in Africa and provides perspectives on how to promote it in the framework of China-Africa cooperation in future. It concludes that Africa is one of the focal regions in the delivery of the CEL nexus approach; UNEP-IEMP has launched several major initiatives that lay the foundation for delivering the nexus approach of CEL in Africa; however, more ambitious cooperation should be taken through a broad China-Africa partnership, based on existing institutions, networks and ongoing programmes in both Africa and China, to support future China-Africa cooperation on the nexus approach of CEL.     

Numerical Modeling of the Stability of Horizontal Multidrain Oil Wells

The stability of the horizontal multidrain wells is a crucial issue and several factors are involved in this matter, including in-situ stresses, magnitude and distribution as well as the mainbore trajectories. In this paper, this issue is evaluated by assuming different circumstances for the above mentioned factors, based on finite difference three-dimensional modeling by using the finite difference numerical software, FLAC3D. The stability of the mainbore and lateral branches is analyzed based on the Normalized Yielded Zone Area (NYZA) criterion, i.e. the ratio of the surrounding yielded cross-sectional area to the initial area of the well. Optimum mud pressures are obtained in the mainbore and lateral branches in different mainbore trajectories under three in-situ stress regimes. In addition, the stability of the junction where the lateral branches are bifurcated from the mainbore is assessed in those situations. The optimum trajectory of the mainbore, in which the junction has obtained the most stable condition, is selected in each stress regime. It was concluded that in the Normal Faulting (NF) stress regime, the mainbore and junction stability varies in relation to the mainbore trajectories, inversely. However, in the other two stress regimes, i.e. Strike Slip (SS) and Reverse Faulting (RF), the variations of the mainbore and junction stability are in the same trend with respect to the mainbore trajectory deviations.     

Snowmelt runoff assessment and prediction under variable climate and glacier cover scenarios in Astore River Basin,Western Himalayas

Climate change is expected to have a significant impact on the Himalayan region, which may ultimately affect the water security and agriculture productivity in the region. Investigations of hydrologic regimes and their linkage to climatic trends are therefore gaining importance to reduce vulnerability of growing implications in the region. In the present study, the eWater source software implementation of GR4JSG snow melt model was used for snow melt runoff modeling of the Astore river basin, western Himalayas. The model calibration and validation indicated a close agreement between the simulated and observed discharge data. The scenario of 0.9 °C increase in temperature indicated 33% rise in the river discharge, while an increase of 10% in precipitation may exaggerate the river flows by 15%. The scenario of 100% increase in glaciated area showed 41% increase in the Astore river discharge. On the other hand, reduction of 50% glacier cover may result in 34% decline in the river discharge, while 0% glacier coverage may reduce the river discharges by 49% from that of the base year 2014. It is essential to develop a long-term water resource monitoring process and adapt water management systems taking into account the socio-economic and ecological complexities of the region.