An overview of flood mitigation strategy and research support in South Asia: implications for sustainable flood risk management

South Asia faces increasing flooding risks due to climatic and socio-economic changes. Various measures have been adopted by the governments of the countries in this region. However, these measures are not adequate to protect the vulnerable communities from ever-increasing flood losses. This study assesses the policy and planning processes and flood-related scientific research in India, Pakistan and Bangladesh. Based on a systematic review, a comparison of the existing flood management systems of the three countries is undertaken, and a framework for sustainable flood management in the region is suggested. Insights from the literature show that Bangladesh has been able to develop an effective governance structure to address flood hazards, while Pakistan’s approach to flood management planning is found to be largely inadequate. This inadequacy is mainly attributed to missing links in policy formulation and planning processes, along with a lack of institutional coordination. The results of the literature analysis reveal poor support from scientific research focusing on flooding issues in the case of Pakistan, while Bangladesh and India seem to have benefited from research support in formulating their flood management strategies. Based on these findings, an alternative framework is suggested, emphasizing the need to enhance institutional linkages, community participation and evidence-based research.     

Methods to convert lignocellulosic waste into biohydrogen,biogas, bioethanol,biodiesel and value-added chemicals: a review

Environmental Chemistry Letters - In the context of climate change and the circular economy, there is an urgent need to develop biofuels and value-added chemicals from lignocellulosic waste such as...     

Air pollution and hospitalization in megacities: empirical evidence from Pakistan

Environmental Science and Pollution Research - Air pollution has become a threat to human health in urban settlements, ultimately leading to negative impacts on overall economic system as well....     

Renewable-nonrenewable energy: institutional quality and environment nexus in South Asian countries

Environmental Science and Pollution Research - Today energy has become a fundamental need; without energy consumption, no country can survive economically. Along with developed economies,...     

Enhanced effect of HAH on citric acid-chelated Fe(II)-catalyzed percarbonate for trichloroethene degradation

This work demonstrates the impact of hydroxylamine hydrochloride (HAH) addition on enhancing the degradation of trichloroethene (TCE) by the citric acid (CA)-chelated Fe(II)-catalyzed percarbonate (SPC) system. The results of a series of batch-reactor experiments show that TCE removal with HAH addition was increased from approximately 57 to 79% for a CA concentration of 0.1 mM and from 89 to 99.6% for a 0.5 mM concentration. Free-radical probe tests elucidated the existence of hydroxyl radical (HO^•) and superoxide anion radical (O₂ ^•-) in both CA/Fe(II)/SPC and HAH/CA/Fe(II)/SPC systems. However, higher removal rates of radical probe compounds were observed in the HAH/CA/Fe(II)/SPC system, indicating that HAH addition enhanced the generation of both free radicals. In addition, increased contribution of O₂ ^•- in the HAH/CA/Fe(II)/SPC system compared to the CA/Fe(II)/SPC system was verified by free-radical scavengers tests. Complete TCE dechlorination was confirmed based on the total mass balance of the released Cl⁻ species. Lower concentrations of formic acid were produced in the later stages of the reaction for the HAH/CA/Fe(II)/SPC system, suggesting that HAH addition favors complete TCE mineralization. Studies of the impact of selected groundwater matrix constituents indicate that TCE removal in the HAH/CA/Fe(II)/SPC system is slightly affected by initial solution pH, with higher removal rates under acidic and near neutral conditions. Although HCO₃ ⁻ was observed to have an adverse impact on TCE removal for the HAH/CA/Fe(II)/SPC system, the addition of HAH reduced its inhibitory effect compared to the CA/Fe(II)/SPC system. Finally, TCE removal in actual groundwater was much significant with the addition of HAH to the CA/Fe(II)/SPC system. The study results indicate that HAH amendment has potential to enhance effective remediation of TCE-contaminated groundwater.

     

Arsenic concentration variability, health risk assessment, and source identification using multivariate analysis in selected villages of public water system, Lahore, Pakistan

This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87 % of samples exceeded the WHO standard of 10 μg/L for As while 77 % of samples have As concentration >50 μg/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r?=?0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB>KLW>MM, with 87 % of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3–48.6) which was 83 % (ranging from 0.3–41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.     

Performance evaluation of 1-D numerical model HEC-RAS towards modeling sediment depositions and sediment flushing operations for the reservoirs

Sediment inflow to the reservoir is a key factor to calculate life of the reservoir. Flushing is a very useful technique in order to enhance the life of reservoir. From the literature review, 14 reservoirs were considered where flushing has already been practiced and only 6 reservoirs were found successful in flushing. The others were found partially flushed. In this research, data of three successfully flushed reservoirs namely Baira reservoir (India), Gebidem reservoir (Switzerland), and Gmund reservoir (Austria) were used to run 1-D numerical model HEC-RAS. In the first phase, the longitudinal profiles of delta were modeled and calibrated with observed sediment depositions. In the presence of available data of discharges and respective reservoir levels, the modeled deltas were used for flushing the deltas. With the help of modeled delta and corresponding flushing discharges, sediment deposition and flushing durations were computed. The simulated flushed durations were 31, 102, and 180 h for Baira, Gebidem, and Gmund reservoirs, respectively. The simulated flushed durations were found close to observed durations. Hence, the use of 1-D numerical model HEC-RAS is encouraged for modeling of sediment deposits and flushing operations.     

Environmental sustainability through renewable energy and banking sector development: policy implications for N-11 countries

Environmental Science and Pollution Research - Climate change has become an alarming condition for developed and developing countries. The main reason for this is the use of non-renewable energy...     

Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil

Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer + rapeseed residue (N70 + R), 30% mineral N fertilizer + rapeseed residue (N30 + R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70 + R and N30 + R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability.     

Environmental contamination using accumulation of metals in marine sponge,Sigmadocia fibulata inhabiting the coastal waters of Gulf of Mannar,India

Coastal marine ecosystems in many parts of the world are under unrelenting stress caused by urban development, pollutants and other ecological impacts such as building of infrastructure, land reclamation for port and industrial development, habitat modification, tourism and recreational activities. The present work is a first extensive field study using the marine sponge, Sigmadocia fibulata as a bioindicator to detect metal pollution between inshore and offshore environment of the ‘Gulf of Mannar’, India. Samples of S. fibulata were collected from different places of inshore (0.1–0.5?km) and offshore (3–5?kms) locations. Metal concentrations in water and bioaccumulation in sponges were determined by ICP-MS (Inductively coupled plasma-mass spectrometry). Enrichment of metal contamination was more in the inshore, when compared to offshore environment. Higher concentrations of metals Fe, Al, Ni, Mn, Cu, Cr, Co, Ba, Zn, V, Pb and Cd in inshore waters (3–6.4 times than offshore) may be due to the discharge of monsoonal rains, carrying a discharge of industrial and agricultural wastes and sewage directly into the coast. This is substantiated by a highly significant positive correlation between concentrations of metals in the water and accumulation in sponges. The bioaccumulation of metals in sponge tissue were in order of Fe?>?Al?>?Ni?>?Mn?>?Cu?> Cr?>?Co?>?Ba?>?Zn?>?V?>?Cd?>?Pb in both the inshore and offshore regions. Apparently, the macromolecule composition (sugars, proteins and lipids) was significantly reduced by the accumulation of metals in inshore sponges. The current findings indicated that the frequent monitoring is necessary to assess the eco-health of the marine environment by choosing bio-indicator species like S. fibulata, which provide accurate, reliable measurements of environmental quality.