Urban flood susceptibility evaluation and prediction during 2010–2030 in the southern watersheds of Mashhad city, Iran

Background Urban flood susceptibility evaluation (FSE) can utilize empirical and rational procedures to focus on the urban flood evaluation using physical coefficients and land-use change ratios. The main aim of the present paper was to evaluate a flood susceptibility model in the southern watersheds of Mashhad city, in Iran, for 2010, 2020, and 2030. The construction of the model depended on the utilization of some global datasets to estimate the runoff coefficients of the watersheds, peak flood discharges, and flood susceptibility evaluations. Results and conclusions Based on the climatic precipitation and urban sprawl variation, our results revealed the mean values of the runoff coefficient (Cr) from 0.50 (2010) to 0.65 (2030), where the highest values of Cr (> 0.70) belonged to the watersheds with real estate cover, soil unit of the Mollisols, and the slope ranges over 5–15%. The averagely cumulative flood discharges were estimated from 2.04 m3/s (2010) to 5.76 m3/s (2030), revealing an increase of the flood susceptibility equal 3.2 times with at least requirement of an outlet cross-section by > 46 m2 in 2030. The ROC curves for the model validity explained AUC values averagely over 0.8, exposing the very good performance of the model and excellent sensitivity.

Driving powers of the globalization on the urban ecology, a comparative study

Background The present study investigates the driving effects of globalization on the urban environment in two countries of Italy and Japan, which have the regular amplified economy among the advanced countries. For this purpose, a model with the collaboration of two main subjects of globalization coverage and urbanization and the methodological procedures of correlation test and structural analysis was constructed. A globalization index, namely the Maastricht globalization index (MGI), was assumed based on the integrated values of ten factors [HDI, ITA, GDP, FDI, TEI, GEE, GME, MCS, and IUI] besides three ecological indicators as the baseline of the urban environment, namely carbon dioxide emission (CDE), municipal solid wastes (MSW), and wastewater treatment plants (WTP). Results Results revealed the positive associations between globalization and wastewater treatment of urban areas in both countries, exposing the influential role of globalization in connecting the urban population to the sewage plants. The results confirmed the positive role of globalization in decreasing carbon dioxide emissions and overall its practical influences to mitigate urban air pollution. However, the overall globalization effect on urban waste production was estimated differently in both countries. Conclusions Based on the MICMAC analysis, only three factors, namely HDI, ITA, GDP, and FDI, can express driving powers and a significant share of globalization coverage. Consequently, enhancing such indicators that belong to globalization’s social and economic domains certainly can act as driver powers to mitigate the environmental issues of urbanization in the study areas.

A hierarchical analysis of ecosystem classification with implementing in two continental ecoregions

Background The ecosystem classification of land (ECL) has been studied for a couple of decades, from the beginning of the perfect organism system “top-down” approach to a reversed “bottom-up” approach by defining a micro-ecological unit. After comparing two cases of the ecosystem classification framework implemented in the different continental ecoregions, the processes were carefully examined and justified. Results Theoretically, Bailey’s upper levels of ECL (Description of the ecoregions of the United States, 2nd ed. Rev and expanded (1st ed. 1980). Misc. Publ. No. 1391 (Rev). Washington DC USDA Forest Service; 1995) were applied to the United States and world continents. For the first time, a complete ECL study was accomplished in Western Utah of the United States, with eight upper levels of ECOMAP (National hierarchical framework of ecological units. U.S. Department of Agriculture, Forest Service, Washington, DC. https://www.researchgate.net/publication/237419014_National_hierarchical_framework_of_ecological_units; 1993) plus additional ecological site and vegetation stand. China’s Eco-geographic classification was most likely fitted into Bailey’s Ecosystem Classification upper-level regime. With a binary decision tree analysis, it had been validated that the Domains have an empty entity for 500 Plateau Domain between the US and China ecoregion framework. Implementing lower levels of ECL to Qinghai Province of China, based on the biogeoclimatic condition, vegetation distribution, landform, and plant species feature, it had classified the Section HIIC1 into two Subsections (labeled as i, ii), and delineated iia of QiLian Mountain East Alpine Shrub and Alpine Tundra Ecozone into iia-1 and iia-2 Subzones. Coordinately, an Ecological Site was completed at the bottom level. Conclusions (1) It was more experimental processing by implementing a full ECL in the Western Utah of the United States based on the ECOMAP (1993). (2) The empty entity, named as Plateau Domain 500, should be added into the top-level Bailey’s ecoregion framework. Coordinately, it includes the Divisions of HI and HII and the Provinces of humid, sub-humid, semiarid, and arid for China's Eco-Geographic region. (3) Implementing a full ECL in a different continent and integrating the lower level's models was the process that could handle the execution management, interpreting the relationship of ecosystem, dataset conversion, and error correction.

Effects of supplemental irrigation on yield, water use efficiency and nitrogen use efficiency of potato grown in mollic Andosols

Background Low soil fertility and reduced seasonal rainfall contribute to low potato (Solanum tuberosum L.) yield in Kenya. Nitrogen (N) deficiency is the major problem facing by the smallholder farmers of Kenya due to lack of fallow. Hence an introduction of supplemental irrigation with an adequate application of this nutrient could increase potato yield. The objective of this study was to determine the effects of supplemental irrigation and N-fertilisation on potato tuber yield, water use efficiency (WUE) and nitrogen use efficiency (NUE). The experiment was conducted in Nakuru County, Kenya for two seasons. The experimental soils are classified as mollic Andosols. The treatments comprised two irrigation treatments of full supplemental irrigation (FI) and rainfed production (RF) and four N levels of four N levels of 0 (N0), 60 (N1), 90 (N2) and 130 kg N/ha (N3). Results The results showed that total tuber yield, marketable tuber yield and NUE were significantly (P < 0.001) affected by irrigation × N-fertilisation while WUE was only affected (P < 0.001) by N-fertilisation. The highest total tuber yield, 58.28 tonnes/hectare (t/ha), was recorded under FI combined with N3. Treatment FI significantly increased marketable tuber yield by approximately 125.58% in all N treatments compared to RF. The highest NUE of potato (236.44 kg/kg of N) was obtained under FI combined with N3 but not significantly different from the NUE of potato obtained under FI with N2. N-fertilisation N3 produced the highest WUE of 14.24 kg/m3. Significant correlation was obtained between tuber yield and number of tubers/plant (r = 0.75, P < 0.001), NUE (r = 0.95, P < 0.001) and WUE (r = 0.72, P < 0.001). Conclusion High potato yield and marketable tuber yield can be achieved in mollic Andosols when water deficits of the growing season are eliminated with supplemental irrigation and an application of 130 kg N/ha.

Dispersants as marine oil spill treating agents: a review on mesoscale tests and field trials

The increasing oil demand and busy waterways highlight the importance of oil spill preparedness and responses. Dispersants attract attention as an effective response tool to manage the impacts of major spill incidents. Despite in-depth laboratory evaluations on the effectiveness of chemical dispersants and their impacts on the transportation and fate of spilled oils, how dispersant works at sea remains a question and calls for the tests with greater realism to validate laboratory results, bring in energy impacts, and evaluate dispersant application equipment. Mesoscale studies and field trials have thus been widely conducted to assist better spill response operations. Such research attempts, however, lack a systematic summary. This study tried to fill the knowledge gaps by introducing the mesoscale facilities developed to advance the understanding of dispersant effectiveness on various sea conditions. An up-to-date overview of mesoscale studies and field trial assessments of dispersant effectiveness has also been conducted. We ended this review by highlighting the importance of public perception and future research needs to promote the approval and application of dispersants in spill incidents.

Geotechnical evaluation of gully erosion and landslides materials and their impact in Iguosa and its environs, southern Nigeria

Background Detailed field surveys and geotechnical evaluation of soils in Iguosa and its environs, Southern Nigeria, were undertaken to determine the root causes, mechanisms, and impacts of landslides and gully erosion. This was done to suggest appropriate mitigation measures to reclaim the affected land and prevent future occurrences in the study area. Results Field study revealed high elevations, a steep slope, high rainfall and inadequate drainage systems. Also, human activities and socio-cultural activities have contributed to the large lateral extents in depths and widths of the landslides and gullies in the study area. The geotechnical analyses reveal that soil samples from SB1, SB2, SB6 and SB7 lithological units are mainly sandy clay with a coefficient of permeability ranging from 3.5 × 10−4 to 4.2 × 10−4 cm/s, the cohesion ranges from 27 to 28 kƿa and angle of internal resistance ranges from 27° to 30° respectively. The plastic limit ranges from 2 to 4, and liquid limit ranges from 33 to 38, and the plasticity index ranges from 30 to 36. Ajali sand units SB3, SB4, SB8 and SB9, consist of coarse-grained sand with no plasticity. The coefficient of permeability ranges from 2.8 × 10−4 to 3.2 × 10−4 cm/s, the cohesion range from 10 to 18 kƿa, angle of internal resistance 24° to 26°, respectively. The soil samples from SB5 and SB10 lithological units are silty-clay with a coefficient of permeability of 4.6 × 10−4 to 4.8 × 10−4 cm/s. The cohesion of 45 to 46 kƿa, and angle of internal resistance of 37° to 40°, respectively. The plastic limits ranges from 35 to 36, and liquid limit is 76, and the plasticity index ranges from 40 to 41. Conclusion Field survey and geotechnical evaluations of the soils revealed that high elevation, a steep slope and the geotechnical properties of the soils were the initial conditions that initiated landslides and gully developments in the study area. This has also been influenced by rainfall, poor vegetation, inadequate drainage systems, and human activities as well as socio-cultural activities. Over four hundred and thirty-two houses and farmlands and other properties have been damaged and abandoned in the study area. Covering the landslide areas with impermeable layers/materials, diverting surface water away from the landslide areas, enacting laws to prevent the erection of structures on landslide prone-areas, sound drainage systems, the use of biotechnical slope and bioengineering methods, afforestation and re-vegetation were the proposed mitigation measures to tackle this menace in the study area.

Residual effects of corncob biochar on tropical degraded soil in central Uganda

Background The residual effects of biochar are yet to receive adequate research attention in Sub-Saharan Africa despite the assumption that the positive effect of biochar may last longer on degraded tropical soil. Hence a field experiment was conducted to assess the residual effects of biochar, farmyard compost and NPK fertilizer applications on a Ferralsol in central Uganda. The field used for the study was previously used to conduct experiments for two seasons to assess the contribution of corncob biochar to the chemical properties of this highly degraded tropical soil. Result The co-applied biochar with compost and NPK fertilizer significantly (p < 0.05) increased some soil chemical properties such as soil pH, available phosphorus, soil organic carbon, and potassium than the control. The co-applied biochar with compost also significantly (p < 0.05) increased the soil pH and effective cation exchange capacity compared to the solely applied compost and NPK fertilizer. Collard plant height, canopy, stem girth, number of leaves, leaf length, and total biomass were significantly (p < 0.05) higher in the biochar amended soil than the unamended soil. Conclusion It was concluded that the addition of biochar with compost and NPK fertilizer had a significant residual effect on degraded tropical soils than solely applied NPK and compost.

Early transplanting of rainfed rice minimizes irrigation demand by utilizing rainfall

Background Rainfall is the key contributor to provide soil moisture for wet season rice (T. Aman) cultivation. Erratic rainfall often causes water shortage resulting negative impact on plant growth and grain yield. The study aimed to determine suitable transplanting window that utilize maximum rainfall for T. Aman rice. Firstly, three years field experiment were conducted in Kushtia, Bangladesh from T. Aman, 2013 to 2015, and then the findings were implemented for another two adjacent locations, Panba and Rajshahi. The field experiment considered six transplanting dates of popular cultivar BR11 (growth duration 145 days) at 7 days interval starting from 10 July to 14 August. The CROPWAT 8.0 model was used to calculate crop water requirement (CWR), effective rainfall and irrigation demand (ID) from collected weather data in each growth phase of rice. Results In all locations T. Aman rice received enormous rainfall up to vegetative phase resulting no irrigation demand in all three tested years. The early transplanting received more rainfall in reproductive phase than late planting. Thus, Irrigation demand increased at reproductive phase with delay transplanting in moderate drought prone Kushtia, Pabna and Rajshahi. A significant relationship (R2 = 0.71) observed between reproductive phase ID and grain yield, while grain yield responded weakly with the ID at ripening phase. Based on yield performance 10–24 July found suitable transplanting window for BR11 in Kushtia. Considering the relationship between ID and grain yield, 10–17 July and 10–24 July considered the best transplanting window in Pabna and Rajshahi, respectively. Conclusions Location specific suitable transplanting windows were selected considering minimum ID at reproductive phase and the maximum grain yield. Delay in transplanting demanded more irrigation and reduced grain yield. Whereas, early transplanting utilized maximum rainfall, reduced ID in reproductive stage and ensured desired grain yield.

Developing horizontal subsurface flow constructed wetland using pumice and Chrysopogon zizanioides for tannery wastewater treatment

Background High-strength wastewater defined by elevated levels of hazardous pollutants measured in BOD, heavy metals, nutrients and other toxic substances. This kind of wastewater discharged to water body without treatment from different industrial sectors that adversely affects aquatic environment and downstream water consumers. The general objective of this study is to investigate efficient substrate with selected plant type for constructed wetland to remove hazardous pollutants from tannery wastewater. This study was conducted at Modjo town, Modjo tannery PLC. Plug flow experimental study design was carried out. The substrate (Pumice) was collected around the study area and chemical characteristics were determined. Chrysopogon zizanioides was planted and grown for 5 months before running tannery wastewater for the treatment. The composite wastewater was introduced to the constructed wetland from Modjo leather industry, Ethiopia. The physicochemical analysis of the sample wastewater was done before and after treatment at four different hydraulic retention time. Results Characterization of the untreated tannery wastewater revealed that the mean concentration of BOD5, COD, TSS, PO4-P, TP, NO3-N, TN and total chromium were 1641 ± 373.6, 6953.33 ± 339.4, 1868 ± 863.1, 88.06 ± 40.8, 144.53 ± 20.8, 116.66 ± 26.6, 650.33 ± 93.6 and 18.33 ± 6.7 mg/l respectively beyond the permissible limits. The maximum removal efficiency of the constructed wetland in pumice bed revealed that BOD5 at HRT 7and 9 days (96.42%, 96.30%), COD at HRT 5 and 7 days (96.76%, 96.91%), NO3-N at HRT 5 and 7 days (99.99%, 99.68%), TN (98.67%, 99.00%), PO4-P HRT 7and 9 days (96.97%,100%), TP at HRT 5 and 7 days (94.79%, 96.17%) and total Chromium at HRT 5 and 7 days (98.36%, 98.91%) respectively. Whereas, the removal efficiency of constructed wetland bed with gravel substrate used as a control subject with similar condition to pumice showed lower performance. The result between pumice and gravel bed was tested for their significance difference using two sample t-test statistics. Based on the test statistics, the pumice substrate perform better than the gravel significantly at 95% confidence interval, p-value = 0.01. Conclusion Pumice substrate and Chrysopogon zizanioides have a potential ability to remove hazardous pollutants from tannery wastewater in horizontal subsurface constructed wetlands.

Impact of landscape dynamics and intensities on the ecological land of major cities in Ethiopia

Background Understanding the dependence of ecological land and dynamics of the human-nature-coupled landscape is crucial for urban ecosystem resilience. In this study, we characterized and compared the Spatio-temporal responses of ecological land to urban landscape dynamics in Bahir Dar, Addis Ababa, Adama, and Hawassa cities in Ethiopia for the last three decades (1990–2020). Three sets of Landsat satellite images, field observations, and urban land indexes were used to produce landscape maps and geo-spatial data analysis. Results The results showed that in all cities ecological land has had changed intensely during 1990–2020 regarding its quantity, and spatial pattern. Besides, the substantial expansion of built-up ecosystems was manifested at the cost of ecological land. The built-up ecosystem was augmented by 17,341.0 ha (32.16%), 2151.27 ha (19.64%), 2715.21 ha (12.21%), and 2599.65 ha (15.71%) for Addis Ababa, Adama, Bahir Dar, and Hawassa cities respectively from 1990 to 2020 periods. A total of 40.97% of the prolonged built-up area was obtained from urban agricultural land alone. Moreover, urban sprawl is likely to continue, which will be outweighed by the loss of the open space ecosystem. The finding also confirmed the value of land-use intensity (LUI) of Addis Ababa (3.31), Bahir Dar (3.56), Hawassa (4.82), Adama (5.04) was augmented parallel with accelerated growth in the built-up ecosystems. Besides, the Integrated land-use dynamics degree (ILUDD) analysis confirmed that the spatial pattern of ecological land loss significantly consistent with LUI in all cities. Conclusion Land-use intensity (LUI) dynamics pattern was followed by urban ecological land to the multi-complex human-dominance ecosystem with a substantial influence on urban greenery and ecosystem services provides. Thus, in all cities, the implementation of effective ecological land management and urban planning policies are required to ensure economic development and ecosystem resilience.