Comparative geomorphometric approach to understand the hydrological behaviour and identification of the Erosion prone areas of a coastal watershed using RS and GIS tools

Assessment of the geomorphometric parameters using Remote Sensing (RS) and Geographic Information System (GIS) tools forms an important part in routing the runoff and other hydrological processes. The current study uses a geospatial model based on geomorphometric parameters for the categorization of surface runoff and identification of the erosion-prone areas in the watershed of the Kuttiyadi River. The 4th order Kuttiyadi river is dominated by a dendritic to semi-dendritic drainage pattern in the subwatersheds. The linear aspect of the subwatersheds indicates towards the presence of permeable surface and subsurface materials with uniform lithology. The aerial and relief aspects of the subwatersheds shows fine drainage texture, gentle slopes, delayed peak flow, flatter hydrograph, and large concentration time which shows that subwatersheds are quite capable of managing flash floods during storm events. The estimated values of surface runoff (Q) and sediment production rate (SPR) are range from 2.13 to 32.88 km2-cm/km2 and 0.0004–0.017 Ha-m/100km2/year respectively and suggest that Subwatershed 1 (SW1) will generate more surface runoff and is prone to soil erosion followed by subwatershed 2 (SW2) in comparison to other subwatersheds. This paper aims to fill the knowledge gap regarding categorization of flow and erosion dynamics in a coastal river watershed. We believe that our work may work help in providing the crucial information for decision-makers and policymakers responsible for establishing suitable policies and sustainable land use practices for the watershed.

A survey of irrigation water and soil quality that likely impacts paddy rice yields in Kilimanjaro, Tanzania

In this study, the impacts of irrigation water quality and soil characteristics on paddy rice yields were investigated. Standard spectroscopy and spectrometry methods were used to analyze irrigation water and irrigated soil samples. The irrigation water had sodium adsorption ratio (SAR) values ranging from 0 to 3. The corresponding electrical conductivity (EC) values were between 0.2 and 0.7 dS/m and accounted for 14% of all samples—posing slight to moderate infiltration problem. Neither Na+ nor Cl− levels were high enough to cause toxicity problems in the irrigation water. For B, 54% of the samples were found to have moderate toxicity whereas ~ 14% of the samples indicated severe B toxicity in the irrigation water. For bicarbonate, about 86 and 14% of the irrigation water indicated slight-to-moderate and severe potential detrimental effect to plant growth, respectively. All trace elements in the irrigation water were too low to cause any harmful effect. Although soil EC, organic carbon (OC), and pH indicated favorable level, there were high standard deviation (SD) values in soil Fe and Zn. The mean value of Fe in soils was 19.8 mg/kg, indicating signs of Fe-deficiency. High SD values were also found in the total N (TN) content of the studied soils. Furthermore, a low soil K content was observed in the analyzed soil samples. Appropriate fertilizer application for improving nutrient deficiencies in the study area is highly recommended. Furthermore, on-farm management practices need to be guided by scientific findings from the present as well as other studies.

Spatiotemporal dynamics of glacial lakes (1990–2018) in the Kashmir Himalayas, India using Remote Sensing and GIS

This study is perhaps the first attempt to use satellite data (1990–2018) to analyze spatiotemporal changes in glacial lakes over the Kashmir Himalayas supplemented by field studies. Landsat images were used to delineate the spatial extent of glacial lakes at four-time points, i.e., 1990, 2000, 2010 and 2018. The total count of lakes as well as their spatial extent showed a discernible increase. The number increased from 253 in 1990 to 324 in 2018, with a growth rate of 21.4%. The area has increased from 18.84 ± 0.1 km2 in 1990 to 22.13 ± 0.12 km2 in 2018 with a growth rate of 14.7%. The newly formed glacial lakes, including supraglacial lakes, were greater in number than the lakes that disappeared over the study period. All glacial lakes are situated at elevations of 2700 m asl and 4500 m asl. More than 78% of lake expansion in the study region is largely due to the growth of existing glacial lakes. Through area change analysis, our findings reveal that certain lakes show rapid expansion needing immediate monitoring and observation. The analysis of the meteorological variables reveals that minimum and maximum temperatures in the Jhelum basin have shown an increasing trend. Tmax showed an increase of 1.25 °C, whereas Tmin increased to 0.7 °C from 1980 to 2020. On the other hand, precipitation has shown a decreasing trend, which can be attributed to one of the major causes of glacier recession and the expansion of glacial lakes in the Upper Jhelum basin. Consequently, this study could play a significant role in devising a comprehensive risk assessment plan for potential Glacial Lake Outburst Floods (GLOFs) and developing a mechanism for continuous monitoring and management of lakes in the study region.

Study the optical properties of drinking water supply by KUKL and KVWSIP in Kathmandu Valley

The optical properties of two water supply samples Kathmandu Upatyaka Khanepani Limited (KUKL) and Kathmandu Valley Water Supply Improvement Project (KVWSIP) in the Kupondole Area, Lalitpur, Nepal show that the transmittance of light is higher for KVWSIP sample water than for KUKL. A large amount of work has been done to test the purities of KUKL and KVWSIP water supplies (chemically), but even their optical properties have not been studied. This method has no hazardous side effects or requires chemical method testing. In comparing the optical properties, the authors recommended that the public take KVWSIP water for good health and wealth rather than KUKL if they have an option.This is because KUKL is more contaminated and has more total dissolved solids (TDS) particles, while KVWSIP has fewer TDS particles. Therefore, if people take KVWSIP water in their daily life, they obtain relief from different types of water-related diseases.

Application of multivariate statistical analysis and water quality index for quality characterization of Parbati River, Northwestern Himalaya, India

The present study is an attempt to accomplish the understanding of the factors impacting Parbati river water quality in Kullu district of Himachal Pradesh. The main objective is to assess the overall water quality, to explore its hydrogeochemical characteristics including major ion contents and other chemical parameters using Water Quality Index (WQI), statistical techniques (principal component analysis) and conventional graphical representation such as Piper trilinear diagram, Durov. Eighteen surface water samples were collected from different altitudinal sites to analyze physico-chemical parameters for June 2019 and September 2019. Analytical outcomes of thirty-six surface water samples collected in Pre-monsoon and Post-monsoon seasons are well within the permissible limits as per BIS, 2012 and WHO 2011 for drinking and domestic purposes. Water quality characterization for the assigned use shows that maximum surface water samples fall under excellent to good water quality index and are suitable for drinking without conventional treatment. The Piper trilinear diagram classified 100% of surface water samples for both seasons’ falls in the fields of Ca2+-Mg2+-HCO3− water type indicating temporary hardness. Abundance of ions in the water samples is in the order: anions HCO3−>Cl−>SO42−>NO3− and cations Mg2+>Ca2+>Na+>K+. PCA identifies that the surface water chemistry is influenced by natural factors as well as minor anthropogenic activities in both the seasons. The correlation matrix has been prepared to analyse and observe the significance of the factors on the assessment of river water quality. Periodic assessment of surface water samples of the Parbati river and adjoining areas should be carried out. This approach will help in finding out any contamination of water occurring due to rapid socio-economic development as well as explosion of tourism industry in the region. Present study will work as baseline database for any future work in the region.

Structural diversity of organic contaminants in sewage sludge: a comparison of sewage fingerprints from Germany and China

Sewage sludge is formed during wastewater treatment and in recent years, the amount of sewage sludge increased rapidly all over the world. This sewage sludge is attractive for usage in agriculture as an inexpensive nitrogen and phosphorus fertilizer. However, there is only very limited knowledge about the spectrum of organic pollutants that might occur in sewage sludge and is probably posing a threat to the environment. We therefore conducted GC–MS based non-target screening analyses in order to identify a wide spectrum of organic contaminants in sludge samples from several wastewater treatment plants and to figure out corresponding finger-prints of pollution. The plants are located in Germany and China and have various capacities ranging from 35,000 to 1.1 million population equivalents. The special focus was to reveal information on the structural variety of individual organic compounds in sludge samples from the two countries. Several emerging pollutants including some fragrances, pharmaceutical educts, vitaminoids, technical additives were identified accompanied by compounds of biogenic origin. Some of these compounds have rarely been reported as constituents of sewage sludge to date and, consequently, are relevant candidates for more specific assessments including the ecotoxicological long-term effects. Based on the results of this study, it seems mandatory to establish non-target screening analyses on a regularly base as a tool for a comprehensive identification of the variety of anthropogenic organic constituents. Following, such contaminant spectrum can act as basis for further environmental risk assessments as well as to provide individual fingerprints for evaluation of impacts on ecosystems.

Heavy metals risk assessment of water and sediments collected from selected river tributaries of the Mara River in Tanzania

This study investigated the levels of Pb, Hg, Cr, Cd, and As in water and sediments from the tributaries of the Mara River, Tanzania. Pollution risk of water and sediments was investigated using seven indices and five metals. During the dry period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 17.45 ± 1.22, 0.01, 1.56 ± 0.5, 1.3 ± 0.09, and 30.81 ± 0.02 mg/kg, respectively. During the wet period, the highest concentration of Pb, Hg, Cr, Cd, and As in sediments was 4.37 ± 0.28, 0.012, 2.58 ± 0.57, 2.25 ± 0.35, and 53 ± 0.02 mg/kg, respectively. For surface water, the respective highest concentrations of Pb, Hg, Cr, Cd, and As were 0.76 ± 0.09, 0.04, 0.68 ± 0.09, 0.74 ± 0.1, and 0.47 ± 0.06 mg/L for the dry period. The wet period max concentrations for Pb, Hg, Cr, Cd, and As in surface water were 0.56, 0.03, 0.55 ± 0.03, 0.48 ± 0.03, and 0.4 ± 0.03 mg/L, respectively. Principal component analysis results indicated dominant loadings for Pb and As in sediments during the dry period. Comparison of sediment concentrations with sediment quality guidelines revealed that As and Cd were enriched. Correlation coefficient results indicated that As had a strong negative correlation with the rest of the elements in sediments during the dry period. In the wet period, As had a significant correlation with Cd (r = 0.92, p < 0.01) in sediments. The analysis of environmental risks indicated significant enrichment of sediments with As and Cd. It is important to put in place relevant control mechanisms targeting metals in the studied tributaries, with a focus on As and Cd.

Borehole inventory, groundwater potential and water quality studies in Ayede Ekiti, Southwestern Nigeria

This study aims at determining the state of government provided boreholes, evaluating groundwater potential and quality assessment within the Ayede Ekiti community. 12 Vertical Electrical Soundings (VES) were conducted using Schlumberger array in order to determine geoelectric layers and fracture attributes. Also, 12 water samples were collected from the study area to evaluate physicochemical characteristics of the groundwater. The study revealed average values of total depth of boreholes, static water levels and water column in the boreholes to be 18.77 m, 6.77 m and 11.99 m respectively. 70% of the boreholes are either abandoned, damaged or with evidence of corrosion and encrustation. Geophysical investigation revealed weathered layer thickness ranging from 1.3 to 34.7 m with two regimes of fracture at 40–50 and 75–80 m. The frequency of curve types obtained shows 16.67%, 33.33%, 25%, 8.33%, 8.33% and 8.33% for AK, HA, KH, AA, QH and HK respectively while weathered and fractured basement are identified as the two types of aquifer unit. Results of water analysis unveiled that dominance cations are in order Ca2+ > Na+ > K+ > Mg2+while anions are in the order of HCO3− > Cl− > SO42−. Three types of hydrochemical facies present are CaHCO3 > NaHCO3 > CaCl in 66.67%, 25% and 8.33% respectively. The Wilcox plot suggests the suitability of the groundwater samples for irrigation purposes when compared with the World Health Organization standards. Despite potential for groundwater and good quality of analyzed samples, the problem of water in this community is traceable to inadequacy in exploration, shallow boreholes with consequent seasonal water availability.