Middle Catchment Research Articles

EVALUATION OF LAND COVER, LAND USE AND WATER QUALITY IN THE REGIONS WITH VARIOUS ANTHROPOGENIC ACTIVITY – A CASY STUDY OF OSAM RIVER BASIN, BULGARIA

Nowadays the world´s demand for natural resources is more pressing than ever before. The good quality of the water and it’s enough quantity, the provision of energy sources and food is a very important and difficult issue. This challenge could be done by ensuring a better management of the mentioned resources. Strengthening synergies and reducing trade-offs among the sectors is possible by applying a Nexus approach. This article aims to assets the land cover, land use and water quality in the upper and middle catchment of the Osam River (municipalities of Troyan and Lovech) for the period 2012-2019. Land use and land cover is a key factor in relation to water quality characteristics. The emphasis is on acquiring new knowledge through spatio-temporal analysis of the problem. To assess the river water quality this study considers the following parameters: pH, dissolved oxygen (DO), electric conductivity (EC), ammonia (N-NH4), nitrates (N-NO3), nitrites (N-NO2), phosphates (P-ortho-PO4), biological oxygen demand (BOD5). To identify the land use/cover in the region was based on GIS, digital topographic and thematic maps, Corine Land Cover data, high-resolution satellite imagery (Google Earth), digital elevation model, statistics and field studies. The obtained results are a good basis for popularizing the Nexus paradigm at different scales (i.e., local, regional, national, European and beyond) including planning and elaboration of the necessary policies for sustainable management of both land use and river waters in terms of their quality.

The Zambezi deep-sea fan: mineralogical, REE, Zr/Hf, Nd-isotope, and zircon-age variability in feldspar-rich passive-margin turbidites

ABSTRACT We here present the first comprehensive provenance study of the Zambezi deep-sea fan, based on integrated petrographic, heavy-mineral, elemental-geochemistry, isotope-geochemistry, and detrital-zircon-geochronology analyses of middle Pleistocene to Holocene turbidites. The Zambezi Valley and Fan represent the submarine part of an ∼ 5000-km-long sediment-routing system, extending from the heart of the South African Plateau to the abyssal depths of the Indian Ocean. Sediment is derived not only from the African side, but also from Madagascar Island mostly via the Tsiribihina Valley. Being shed by two dissected rifted margins, detritus supplied from opposite sides of the Mozambique Channel shares similar feldspar-rich feldspatho-quartzose composition, although with significant differences in heavy-mineral and geochemical signatures. The εNd values of Madagascar sand are markedly more negative and TNd model ages notably older. Zircon grains yield mostly Irumide (late Stenian) U-Pb ages in African-derived sand and mostly Pan-African (Ediacaran–Cryogenian) U-Pb ages in Madagascar-derived sand, which also yields a few grains as old as Paleoarchean and many discordant ages reflecting Pan-African reworking of Archean cratonic rocks. Lower Valley and Lower Fan deposits have intermediate fingerprints, indicating that sediment supply from Madagascar is not much less than from Africa despite a much smaller catchment area, which can be explained by deposition of a conspicuous part of Africa-derived sediment in the Intermediate Basin confined between the Zambezi Shelf, the Beira High, and the Îles Éparses. By assuming that compositional differences between Quaternary submarine deposits and modern Zambezi River sands primarily resulted from sediment impoundment by large dams, we could evaluate the anthropogenic impact on natural sediment fluxes. Quaternary turbidites are somewhat higher in quartz and poorer in heavy minerals with higher relative amounts of durable ZTR species, and yield more Ediacaran, Neoarchean, and Carboniferous detrital-zircon ages than modern river sands. The Orosirian peak characterizing the Intermediate Basin sample points to prominent supply from the middle and upper parts of the Zambezi catchment in the middle Pleistocene. Rough calculations suggest that pre-dam Zambezi sediments were generated ≤ 10% in the upper catchment, ∼ 60% in the middle catchment, and only ≥ 30% in the lower catchment that provides the totality of sediment reaching the Indian Ocean today.

Flow patterns and chemical loads in the middle Olifants River, Limpopo River System, South Africa

Historical data (July 1998 – June 2018) for the middle Olifants River, Limpopo River system, were compiled to evaluate the dynamics of selected water physico-chemical parameters with river discharge. The concentration of most water quality parameters increased over time. However, these concentrations are rapidly decreased, or reset, by the rapid filling, or spilling, of Loskop and/or Flag Boshielo Dams during a high-flow event. The flow-duration curves for stations below impoundments in the middle catchment on the Olifants River are typical of highly regulated rivers, although releases from Flag Boshielo Dam were more consistent through the 20 years. No outflow from Loskop Dam was recorded for 5.4% of the 20 years. The load-duration curves for gauging weirs on the Olifants and Elands rivers immediately upstream of Flag Boshielo Dam showed that the ‘tolerable’ concentrations were exceeded for total dissolved solids at the 60th and 20th percentiles of the flow, respectively. In addition, records for electrical conductivity, sodium, chloride, and alkalinity frequently exceeded the ‘tolerable’ concentrations at these sites. The results for Loskop and Flag Boshielo dams are generally lower than the tolerable concentrations for the parameters evaluated. Management of the flow regulation of the Olifants River should be aimed at meeting the water quality stipulations for all users in the agricultural, domestic, industrial, and recreational sectors.

Plant foods consumed at the Neolithic site of Qujialing (ca. 5800-4200 BP) in Jianghan Plain of the middle catchment of Yangtze River, China.

The site of Qujialing experienced a long, sustained process of the development of Neolithic culture in the Jianghan Plain, with a period of some1600 years. Our previous studies based on macrofossil remains and phytoliths revealed that rice (Oryza sativa) from Qujialing was already domesticated, and millet (Setaria italica and Panicum miliaceum) had also been spread into the site since the Youziling Culture period (5800-5100 BP). Nevertheless, no direct evidence has been provided regarding the daily consumed plant foods, especially plant foods obtained by gathering, throughout the site occupation. This paper thus examines pottery sherds (n=41) associated with culinary practices from Qujialing with starch grain analysis. Apart from starch grains from rice and millet, the results indicate that job's tears (Coix lacryma-jobi), lotus roots (Nelumbo nucifera), tubers possibly from Chinese yam (Dioscorea panthainca), acorns (Quercus sp.), and beans (Vigna sp. or/and Vicia sp.) were consumed by the ancient Qujialing people, within job's tears and lotus roots were not discovered before in the macrofossil remains and phytoliths. Combining the starch data and multiple lines of evidence from macrofossil remains and phytoliths, it is suggested that rice was among the most frequently consumed plant foods since the first occupation phase at Qujialing, while acorns could have been gradually replaced by other agricultural products (i.e., rice) and became less important food ingredients, especially when agriculture was more developed in the last occupation phase at Qujialing. These novel findings not only complement our previous research by providing the first line of evidence of paleodiet in the Jianghan Plain from the perspective of starch grain analysis but also delivers a better understanding of the characterized dietary trends and agricultural development in the research region.

Barriers to Adapting Water Supply Management to Climate Change in Nzoia River Basin, Kenya

Water is projected to be the most affected by climate change. Many national and county governments are now developing adaptation policies and plans in response to climate change; however, many factors could stop, delay or divert these adaptation strategies if they are not adequately identified and addressed. Research on adaptation barriers is increasing as the need for climate change adaptation becomes evident, but studies regarding identification and classification of barriers into cartegories and establishing strategies for overcoming such barriers remain limited. This research identified barriers to adapting water supply management to climate change, classified them into cartegories and went ahead to establish strategies for overcoming such barriers in adapting water supply management to climate change in Nzoia River Basin. The study used a cross-sectional survey design and a qualitative technique since major sector players' perspectives are critical in deciding the path of climate change adaptation in the basin. Three counties were randomly selected from Nzoia River Basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. The study was carried out from May, 2017 to September, 2017. Stakeholders were carefully selected and consisted of water and climate change expert decision makers, practitioners, managers, scientists, academia, technology adopters, etc. Stakeholders were chosen based on their work portfolios or by other respondents' recommendations. Data collection involved questionnaires, in-depth expert-interviews, brainstorming sessions, focus group discussions, field observations and literature review. This study identified and ranked in order of priority the barrier clusters/cartegories for adapting water supply management to climate change in Nzoia River Basin as: Institutional and governance; Resources and funding; Leadership; Politics; Adaptation options/process; Science; Understanding; Technology/structural; Expertise; Attitudes, values and motivations of actors; Communication; and Personality issues. Individual barriers are seen to be highly interconnected and interdependent, allowing for the discovery of leverage areas for actions to maximize barrier elimination. This study provides valuable information for the national and county governments as they strive to develop climate change adaptation policies and plans in the basin.

Pottery Use and Starchy Foods During the Shuangdun Culture (ca.7.3–6.8 Ka BP) in the Middle Catchment of the Huai River, China

The use of rice and millet has been uncovered at a few archaeological sites associated with the Shuangdun Culture (ca. 7.3–6.8 ka BP) in the middle catchment of the Huai River, China. Nevertheless, the consumption of rice, millet, and other types of plant foods at other contemporaneous sites in the same region still needs supporting information from more case studies. This article examines pottery sherds (n = 21) excavated from another representative Shuangdun Culture site at Houjiazhai with starch grain analysis. Varied types of pottery vessels contain starch remains from rice (Oryza sativa), foxtail millet (Setaria italica), broomcorn millet (Panicum miliaceum), Job’s tears (Coix lacryma-jobi), Triticeae, roots of snake gourd (Trichosanthes kirilowii), lotus root (Nelumbo nucifera), Chinese yam (Dioscorea panthainca), lily bulbs (Lilium sp.), acorns (Quercus sp.), and beans (Vigna sp. or/and Vicia sp.). Further quantitative analysis of the starch data indicates that cereals, including rice and millet, were predominantly consumed in the pottery vessels. Changes and continuities of culinary practices are also present at Houjiazhai, which are reflected in the different pottery assemblages as well as the utilized plant species in different occupation phases at the site. Combining previous studies, this article also reveals the differences and similarities of the past population in choosing their plant food resources during the period of Shuangdun Culture in the middle catchment of the Huai River, China.

Antimicrobial resistance genes in microbiota associated with sediments and water from the Akaki river in Ethiopia.

The spread of antimicrobial-resistant pathogens is a global health concern. Most studies report high levels of antimicrobial resistance genes (ARGs) in the aquatic environment; however, levels associated with sediments are limited. This study aimed to investigate the distribution of ARGs in the sediments and water of the Akaki river in Addis Ababa, Ethiopia. The diversity and abundance of 84 ARGs and 116 clinically important bacteria were evaluated from the sediments and water collected from five sites in the Akaki river. Most of the ARGs were found in the city close to anthropogenic activities. Water samples collected in the middle catchment of the river contained 71–75% of targeted ARGs, with genes encoding aminoglycoside acetyltransferase (aac(6)-Ib-cr), aminoglycoside adenylyl transferase (aadA1), β-lactamase (blaOXA-10), quinolone resistance S (qnrS), macrolide efflux protein A (mefA), and tetracycline resistance (tetA), were detected at all sampling sites. Much fewer ARGs were detected in all sediments, and those near the hospitals had the highest diversity and level. Despite the lower levels and diversity, there were no unique ARGs detected in the sediments that were also not detected in the waters. A wide range of clinically relevant pathogens were also detected in the Akaki river. The findings suggest that the water phase, rather than the sediments in the Akaki river, is a potential conduit for the spread of ARGs and antibiotic-resistant bacteria.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-20684-2.

Adapting Strategies for Water Supply Management to Climate Change in Nzoia River Basin, Kenya

Climate change is influencing the hydrological cycle on a global scale, and enhancing communities' ability to adapt to these changes is critical for long-term growth and survival. Climate change is expected to have a negative influence on water resources and supply. Other water stresses, such as population expansion, land-use change, growing per capita water demand, and regulatory changes, frequently exacerbate the consequences of climate change. Mitigation will not be enough to minimise the significant repercussions on the water industry, especially in poor nations. The study adopted a cross-sectional survey design. Three counties were randomly selected from Nzoia River Basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. The study was carried out from May, 2017 to September, 2017.A carefully selected team of water and climate change experts consisting of decision makers, practitioners, managers, scientists, technology adopters and other stakeholders were used to identify the five main climate change challenges affecting water supply management in Nzoia River Basin (water scarcity and drought, flooding, water quality effects, unknown climate change risks and disaster preparedness) and the accompanying strategies and technologies for adapting water supply management to climate change through questionnaires, in-depth expert-interviews, brainstorming sessions, field observations and literature review. The adaptation strategies and technologies identification exercise drew from multiple sources of information including the national context where national development plans were used; adaptation technologies proposed in previous documents; technologies currently in use and supported by national water policy; initiatives in the pipeline under the larger water sector; appropriateness of technologies in the local context and the social acceptability among other sources. Stakeholder engagement helps to foster local ownership and buy-in, which is often necessary for long-term project viability. The study has also assessed the level of implementation for the adaptation strategies and the agencies involved. The adaptation strategies were identified and ranked using the total weighted scores as follows: Water storage, Water efficiency and demand management, Water augmentation, Alternative water sources, Water allocation, Urban storm water management, Riverine flood protection, Hazard and risk assessment, Vulnerability assessment, Disaster response, and Early warning. The Total weighted scores under ranking are very close to each other, implying that all the strategies/technologies listed for adapting water supply management to climate change are good. The results of this study provide valuable information that can be used by national and county governments in adapting water supplies to climate change.

Effect of Rainfall Variability on Groundwater Levels in Nzoia River Basin, Kenya

Groundwater is a critical supply of freshwater in Africa, providing safe drinking water near to where it is needed for homes, agricultural, and industrial uses. Due to the high vulnerability of surface water resources to anthropogenic activities and climate change, groundwater consumption has increased dramatically over the last 50 years and is likely to continue rising in future. This study examines the effect of rainfall variability on groundwater levels using rainfall and groundwater level fluctuation data from Nzoia River Basin, Kenya. A cross-sectional survey design was used. Three counties were randomly selected from the basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. Groundwater is the main drinking water resource in the basin supplying 78.8% of the population. Knowledge of long-term rainfall variability and the associated response of the basin’s groundwater resources are essential for efficient and sustainable groundwater management. Despite the relatively short period for which water level records are available, these records contain valuable information that can be used beneficially in the development of strategies to assist in the responsible management of our limited groundwater resources. Rainfall and groundwater levels were analysed using the parametric test of linear regression and the non-parametric Mann–Kendall statistical test. Rainfal data for this study was obtained from the Kenya Meteorological Department (KMD) and the Groundwater levels from Kenya Water Resources Management Agency (WRMA). Pearson moment correlation was used to check the relationship between monthly rainfall and monthly groundwater levels. Correlations between groundwater levels and rainfall will help assess aquifer vulnerability to climate change in the basin. Our results indicate that rainfall variability induced by climate change has greatly impacted groundwater levels in the basin. Annual groundwater levels have been steadly falling at the rate between 0.03 ft/year (Kakamega Tande School) and 0.49 ft/year (Kitale Golf Club) in the basin. Annual rainfall over the basin has shown stations recording both decreasing and increasing trends. The falling groundwater level trends indicate a cause for concern and provide a scientific basis for the national and county governments in the basin to strategize on ground water development and management for sustainable water use.

Effect of Climate Change on Drinking Water Utilities in Nzoia River Basin, Kenya

Climate change is already having noticeable effects on water utilities in Nzoia River Basin. Extreme weather and climate-related occurrences are becoming more common and intense, as predicted by the Intergovernmental Panel on Climate Change (IPCC), Third Assessment Report. Because most water utilities are unprepared, the repercussions might be severe. The water supply infrastructure is built for resiliency and sustainability of operations during weather events or other circumstances that could potentially interrupt services; but when events that were historically considered to be “100-year” events happen more and more frequently, utilities must prepare for a new normal. These extreme events are occurring or being exceeded more regularly, and as a result, the past may no longer be a reliable predictor of the future. In Nzoia River Basin, the water supply infrastructure currently designed for historical climate conditions is more vulnerable to future weather extremes and climate change. This study assessed the effect of climate change on drinking water utilities in Nzoia River Basin. A cross-sectional survey design was used. Three counties were randomly selected from the basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. The study was carried out from May, 2017 to September, 2017. In-depth expert interviews and brainstorming sessions were used to identify the climate change impacts affecting drinking water utilities experienced in the last ten years in the basin. A carefully selected team of water and climate change experts consisting of decision makers, practitioners, managers, scientists and technology adopters were used to rank the severity of the climate change impacts. Climate change occurring in Nzoia River Basin is expected to have a wide range of consequences for drinking water utilities. By assessing its potential impacts on water utilities, we become better positioned to make improvements today to decrease the future risks. The results of this study provide valuable insights for the national and county governments in preparing to effectively anticipate and respond to the relevant issues that they can expect to face in the coming century.

Sponge City Program (SCP) and Urban Flood Management (UFM)—The Case of Guiyang, SW China

Flood management is a complex issue in Chinese cities that exhibit high populations and have undergone rapid urbanization. Urban flood management (UFM) approaches can be used to mitigate urban flood risk. To address urban issues of poor water quality and urban surface flooding, the Sponge City Program (SCP) was initiated in 2013 in China. The SCP aims to provide an opportunity for Chinese cities to improve their current UFM practices. This study looks at Guiyang (a pilot sponge city located in SW China) as a case study to identify the challenges and opportunities of UFM in China. Guiyang is a valley city surrounded by a hilly landscape. Using interview records and flood data, we illustrate that the primary type of flood in Guiyang is fluvial rather than surface water flooding. In Guiyang, the current function and targets of the SCP have yet to engage with the catchment level flood management, instead mainly focusing on the site-specific context (i.e., community level). Catchment flood management planning (CFMP) and natural flood management (NFM) both address this problem and may be a more suitable approach to manage flood discharge from the upper and middle catchments in Guiyang. In addition, it is suggested that a mixed option combining “hard” infrastructure (e.g., reservoirs and floodwalls) with “soft” flood management measures (e.g., improving people awareness and participation) may improve urban flood resilience in Chinese cities.

Lowering water level of Dongting lake of the Mid-Yangtze River in response to large-scale dam construction: A 60-year analysis

River-lake systems, crucial to both the ecological environment and societal development, have been affected by increasing anthropogenic activities in addition to climate and environmental changes. Here, annual water discharge and sediment load data (1956–2017) and rainfall data (1960–2016) from Dongting Lake in the middle catchment of the Yangtze River were analysed at four major inlets and one outlet, and their connections with lake level variations were evaluated using multiple analytical methods. The results show that minor fluctuations were found in rainfall and discharge during the study period, but the sediment load entering Dongting Lake decreased significantly from 231 mt/year (before 1969) to 123 mt/year (1970–2002) and then 17 mt/year (after 2003, post TGD). The variation in the sediment was mainly induced by increasing anthropogenic activities in the lake system. During period 1 (before 1969), human impact was weak compared to the dominant natural forces. However, anthropogenic force showed an increasing contribution to the loss of sediment load since then, as it increased from 43.0% (1970–1987, post cut-off engineering) to 64.8% (1988–2002, post Gezhou Dam) and extended to 90.2% during 2003–2017 (post TGD). Nevertheless, continuous sediment accumulation over the past decades in the lake has caused a rising water level. During period 1, high sediment input contributed to an average annual increase of 13.96 cm in the lake level, but it decreased significantly to 1.94 cm year−1 during 1970–2002 due to intensive anthropogenic regulations. Since 2003, the completion of the TGD intercepted abundant sediment, eventually leading to a shift from net deposition to net loss of the sediment budget in Dongting Lake, and consequently, the lake level fell. In the future, if the net sediment supply was kept below ~18 mt/year, the lake level would continue to fall, causing severe problems to the lake ecosystem, especially during drought years.

Community Knowledge and Perception on Climate Change and Drinking Water Supply in Nzoia River Basin, Kenya

Nzoia River Basin is one of the regions in Kenya that is highly vulnerable to climate change. An understanding of community knowledge and perception on climate change and drinking water supply will provide strategic directions for national and county government policy, adaptation strategies and development of community-based guidelines on climate change. This study assessed community knowledge and perception on climate change and drinking water supply in Nzoia River Basin. A cross-sectional survey design was used. Three counties were randomly selected from the basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. The study was carried out from May, 2017 to September, 2017. Multistage random sampling technique was used to select the 403 households administered with questionnaires. An observation checklist was used by the interviewers to collect household- and community-related information. The study results revealed that the community largely comes from low socio-economic background: only 24 % had post secondary education or higher, the majority were small scale farmers, housewives, casual workers and househelps (58 %), and only 25 % earned a monthly income above Ksh. 20,000 (equivalent to US $200). The majority of the participants 81 % had some knowledge about climate change but 19 % did not. On level of knowledge about climate change, 70% know a little/something about climate change, 21% know nothing about climate change and 9% know a lot about climate change. Majority of respondents, 76% receive climate change news from mass media (radio, newspaper and magazines, television); and 81 % point out that climate change will have public health risks in the community. The knowledge level about climate change in the basin was average. National and county governments should work with the sector stakeholders in the basin to improve community knowledge and perception regarding climate change, drinking water supply and health needs with proper content. The results of this study will go a long way in bridging the gap between policy formulation and building adaptive capacity to climate change in the basin.

Stalagmite flooding frequency record since the middle Little Ice Age from Central China

Comparison of the climate, especially extreme climate changes between the Little Ice Age (LIA) and the present, could provide important information for the predication of extreme climate change in the future. Based on a laminated stalagmite from the middle reaches of the Yangtze River, Central China, an annually resolved stalagmite record of growth rate has been produced dating from 1640 AD. An 11-year running variance sequence of the growth rate shows a positive correlation with a local historical flooding frequency record from 1640 to 1920 AD, suggesting that the stalagmite growth rate variance could be used as a local flooding frequency indicator. In the middle Yangtze catchment, the flooding frequency during the late LIA (1750–1900 AD) is much higher than during the middle LIA (1640–1750 AD) and the early twentieth century (1900–1920 AD). The discrepancy between the stalagmite growth rate variance and the flooding frequency after 1920s AD suggests that the scale of modern flooding is possibly larger than during the earlier periods. Spectral power analysis on growth rate variance of the stalagmite suggests that the flooding cycles around the middle Yangtze River catchment may relate to El Nino/Southern Oscillation (ENSO). The comparison between the stalagmite growth rate variance and reconstructed ENSO records further suggests a link between strong ENSO and high flooding frequency in the middle Yangtze catchment.

Noise vulnerability of stone mining and crushing in Dwarka river basin of Eastern India

The present paper has intended to explore the noise level and vulnerability to noise produced in the stone mining and crushing area and the surroundings in the heavily stressed stone mining and crushing area of Middle catchment of Dwarka river basin of Eastern India. Field-based noise recording has been done at different times in every recorded days. Fuzzy logic-based weighting and integration of eight parameters have been done in four selected cluster for noise susceptibility mapping. For exploring noise annoyance odd and risk ratio have been computed for different communities. From the recorded noise level in stone crushing clusters, it is found that the noise level is > 85 dBA from 6 a.m. to 4 p.m. when the stone crushers are running on and it is above the ambient noise threshold defined by Central Pollution Control Board in 2000. Maximum noise level is recorded as 112.41 dBA which may cause deafness. Noise intensity gradually decreases from crushing centre towards outside and it prevails up to 500–650 m away from the crushing unit. Noise vulnerable areas constructed based on eight noise level addressing and noise effect indicating parameters using fuzzy logic revealed that about 10.46–27.98% areas fall under very high to high noise vulnerable zones. Therefore, the labourers and the peoples who are living at close proximity of crusher units are highly prone to noise pollution along with stone dust pollution. The effect of noise is highly age and sex sensitive due to their differences in physical strength. These findings could effectively be used for saving the exposed communities from noise vulnerability.

Analysis of River Tributaries’ Streamflow Contribution Using WEAP Model: A Case of the Ngwerere and Kanakatampa Tributaries to the Chongwe River in Zambia

Ngwerere and Kanakatampa Streams are the main tributaries of the Chongwe River. The Ngwerere stream originates from the city of Lusaka and meanders through Lusaka City and Chongwe Town for an approximate distance of 41 km before joining into the upper part of Chongwe River. The Kanakatampa Stream is a tributary of the Chongwe River. It meanders from the Kanakatampa Area for approximately 52 km before discharging into the middle of the upper part of the Chongwe River. The Chongwe River Catchment which is a sub-catchment of the Zambezi Basin drew the attention of researchers and policymakers when the Chongwe River started drying up in the dry seasons causing a water crisis particularly in the downstream regions of the middle catchment. Therefore, it is important from the water resources management perspective, to assess the contribution of tributaries into the flows of the Chongwe River. Ngwerere and Kanakatampa streams are socially, economically, and environmentally important streams for the city of Lusaka and surrounding area. This study, therefore, concentrated on evaluating the flow contribution of the two streams to the Chongwe River using the Water Evaluation And Planning (WEAP) tool. The streamflow data (1970-2010) recorded at the Chongwe Great East Road Bridge gauging station were used in the WEAP embedded Parameter ESTimation (PEST) auto-calibration tool to calibrate (1970-1999) and validate (2000-2010) the model. The monthly streamflow model calibration and validation results were assessed using the correlation coefficient (CC), Coefficient of determination (R2), Nash-Sutcliffe Coefficient of Efficiency (NSE), and Percent bias (PBIAS). The model performance results achieved were PBIAS of 1.24%, CC = 0.81, R2 = 0.66 and NSE = 0.62 during the calibration period and a positive PBIAS of 2.94%, CC = 0.81, R2 = 0.67 and NSE = 0.62 during the validation period. The median of the flows (Q50) was obtained from the historical flow duration curves (FDCs) generated in averaged intervals of 10-year from 1970 to 2019. The results showed that on average, the Ngwerere and Kanakatampa Streams contribute 52.8% and 29.6% respectively, to the flow of the Chongwe River in the upper and middle Catchment. The results also showed that the contribution of the Ngwerere and Kanakatampa Streams to the Chongwe River discharge has been reducing historically at a rate of 0.65% per decade and 1.35% per decade respectively over a period of 50 years (1970-2019). Suggestions for sustainable management of the tributaries such as the Ngwerere and Kanakatampa Streams were provided in this study.

Flood Change Detection and Attribution Using Simulation Approach in Data-Scarce Watersheds: A Case of Wabi Shebele River Basin, Ethiopia

Flood events vary with sub-regions, sites and time and show complex characteristics. This study investigated temporal variabilities in flood discharges and relationships with principal driving factors in data scarce Wabi Shebele River Basin. The preliminary analysis using exploratory data analysis (EDA) on annual and seasonal maximum discharge reveals that there are cycles of extreme flows at five- and ten-year intervals respectively throughout the basin. The statistical verification using the Mann-Kendall test and Quantile perturbation method indicates a significant trend in flood magnitude and frequency entire the basin in the early 21st century. For longest period (1980-2010) annual maximum stream flow shows significant positive trend (p-value < 0.05) in middle catchments and negative trend (p-value < 0.05) in eastern catchments. The years: 1986-1995, 2006-2010 are the years in which positive significant anomalies occurred in all seasons, while the years: 1980-1985, 1996-2005 are the occurrence years of significant negative anomalies. Rainfall from climate drivers; DA, BE, VS and fraction of sand from environmental background drivers; fraction of forest and population density from external factors were identified as the powerful driving factors of flood variabilities in the Wabi Shebele River Basin.

Tsallis Entropy for Assessing Spatial Uncertainty Associated with Mean Annual Runoff of Quaternary Catchments of the Middle Vaal Basin in South Africa.

This study assesses mainly the uncertainty of the mean annual runoff (MAR) for quaternary catchments (QCs) considered as metastable nonextensive systems (from Tsalllis entropy) in the Middle Vaal catchment. The study is applied to the surface water resources (WR) of the South Africa 1990 (WR90), 2005 (WR2005) and 2012 (WR2012) data sets. The q-information index (from the Tsalllis entropy) is used here as a deviation indicator for the spatial evolution of uncertainty for the different QCs, using the Shannon entropy as a baseline. It enables the determination of a (virtual) convergence point, zone of positive and negative uncertainty deviation, zone of null deviation and chaotic zone for each data set. Such a determination is not possible on the basis of the Shannon entropy alone as a measure for the MAR uncertainty of QCs, i.e., when they are viewed as extensive systems. Finally, the spatial distributions for the zones of the q-uncertainty deviation (gain or loss in information) of the MAR are derived and lead to iso q-uncertainty deviation maps.

Luminescence dating of eolian and fluvial archives in the middle and lower Danube catchment and the paleoenvironmental implications

Luminescence dating of eolian and fluvial archives in the middle and lower Danube catchment and the paleoenvironmental implications

Modelling human health vulnerability using different machine learning algorithms in stone quarrying and crushing areas of Dwarka river Basin, Eastern India

Stone dust induced risk and vulnerability in the developing nations is very thought-provoking and therefore is necessary to address scientifically to manage it. Identifying vulnerable areas using the robust method is preliminary and essential steps. The present study has intended to delineate Human health vulnerability models (HHVMs) using machine learning algorithms and justify whether ensemble prediction can provide improved results in stone quarry and crushing dominated Middle catchment of Dwarka river basin. Support Vector Machine (SVM), Artificial Neural Network (ANN), Random Forest (RF), Reduced Error Pruning (REP) Tree, Gaussian Process algorithms and ensemble prediction have been applied for HHV modelling. Total 6.9 to 7.37% in cluster 1, 9.11 to 9.6% in cluster 2, 19.63 to 26.79% and 5.34 to 12.85% areas in cluster 3 and 4 is found into very high human health vulnerable class as per the five applied models. REPTree model is found consistent for predicting vulnerability in case of all the clusters followed by GP model. As per the result of RMSE, the RF model is appeared as the most consistent model followed by REPTree. Some of the ensemble prediction models are potential for yielding improved result than individual algorithm.