Factors Driving the Spatiotemporal Variation of Dissolved Organic Carbon Flux from Croplands in the Midwestern USA

Improving understanding of dissolved organic carbon (DOC) cycling from farmlands to rivers is a challenge due to the complex influence of farming practices, the hydrology of predominantly flat lowlands, and seasonal snowpack effects. Monthly field DOC concentrations were measured throughout the year at sub-basin scale across the Chippewa River Watershed, which falls within the Corn Belt of the Midwestern United States. The observations from croplands were benchmarked against the data sampled from hilly forested areas in the Connecticut River Watershed. The Soil Water Assessment Tool (SWAT) was used to simulate daily soil water properties. This method tests for a framework for using the combination of new field data, hydrological modelling, and knowledge-based reclassification of Land Use/Land Cover (LULC) to analyze the predictors of both the spatial and temporal changes of DOC over farmlands. Our results show: 1) DOC concentrations from cropland baseflow were substantially high throughout the year, especially for spring runoff/snowmelt scenarios, 2) gradient analysis with spatial factors only was able to explain ~82% of observed annual mean DOC concentrations, and 3) with both spatial and temporal factors: [Evapotranspiration, Soil Water, and Ground Water], the analysis explained ~81% of seasonal and ~54% of daily variations in observed DOC concentrations.

Emerging Contaminants in Streams of Doce River Watershed, Minas Gerais, Brazil

This study investigated the occurrence and risk assessment of ten pharmaceutical products and two herbicides in the water of rivers from the Doce river watershed (Brazil). Of the 12 chemicals studied, ten (acyclovir, amoxicillin, azithromycin, ciprofloxacin, enrofloxacin, fluoxetine, erythromycin, sulfadiazine, sulfamethoxazole, glyphosate and aminomethylphosphonic acid) had a 100% detection rate. In general, total concentrations of all target drugs ranged from 4.6 to 14.5 μg L−1, with fluoroquinolones and sulfonamides being the most representative classes of pharmaceutical products. Herbicides were found at concentrations at least ten times higher than those of the individual pharmaceutical products and represented the major class of contaminants in the samples. Most of the contaminants studied were above concentrations that pose an ecotoxicological risk to aquatic biota. Urban wastewater must be the main source of contaminants in waterbodies. Our results show that, in addition to the study of metal in water (currently being conducted after the Fundão dam breach), there is an urgent need to monitor emerging contaminant in waters from Doce river watershed rivers, as some chemicals pose environmental risks to aquatic life and humans due to the use of surface water for drinking and domestic purposes by the local population. Special attention should be given to glyphosate, aminomethylphosaphonic acid, and to ciprofloxacin and enrofloxacin (whose concentrations are above predicted levels that induce resistance selection).

Evaluation and Re-estimation of Instream Flow Considering the Water Quality and Aquatic Ecosystem of the Seomjingang River Watershed

In this study, the appropriateness of the current publicly announced and managed instream flow in the Seomjingang River watershed was evaluated based on the water quantity, water quality, and state of the aquatic ecosystem. The stream flow was evaluated based on the observed water flow rate at the Gurye-gun (Songjeong-ri) station that is the main point of the Seomjingang River flow management and located at the lowest downstream of the main stream of the Seomjingang River. Another important reason for choosing this station was that observational data from before the construction of the major dam to the present day were available. The water quality and aquatic ecosystem conditions were reviewed based on the data measured over the past 20 years, and the achievement ratio of instream flow was compared with that of stations in the other major river systems. Based on the evaluation result, the instream flow was re-estimated for the 11 important stations of the Seomjingang River and its two branches. Based on the currently permitted water use of the Seomjingang River, the amount of water required to supply for the instream flow deficit during dry seasons was predicted and presented as a reference for water management work.

Impact of Climate Change on Runoff Prediction in Ogbese River Watershed

Increased rainfall amounts are projected in the humid southern parts of Nigeria due to climate change. The consequence of higher rainfall in future years would result to higher peak runoffs and flood stages in streams in these parts. The focus of this study is to simulate peak runoff at the outlet of Ogbese river watershed for future years of 2030, 2040, 2050 and 2060. Local twenty years (2000-2019) historical rainfall depths were used to statically downscale General Circulation Model outputs in the future for RCP 4.5 climate scenario. Downscaled rainfall depths were inputted in HEC-HMS model version 4.2 for rainfall-runoff simulation. The watershed was delineated with DEM in ArcGIS while four land use and land cover classifications were extracted with QGIS. Maximum rainfall depths projected in years 2030, 2040, 2050 and 2060 were 38.5mm/hr, 39mm/hr, 42mm/hr and 46mm/hr respectively. Peak runoff discharge simulated for RCP 4.5 climate scenario in years 2030, 2040, 2050 and 2060 are 1771m3/s, 1826 m3/s, 1897 m3/s and 2200 m3/s respectively. This represents 24.2% increase peak discharge between 2030 and 2060. Land area delineated for the catchment is 1946.2 km2. The LULC classification areas for urban area, forest, rock outcrop and bare land are 81.59 km2, 1721.84 km2, 146.27 km2 and 4.11 km2 respectively. The soil types are sandy clay loam (92.51 %), sandy loam (6.84 %), and clay (0.65 %). Curve Number and Initial abstraction parameter values are 70.27 and 2.89 respectively. Keywords- Climate change, GCM, HEC-HMS , Ogbese river, Peak runoff

THE ASSESSMENT OF POTENTIAL ELECTRICITY PRODUCTION FROM SURPLUS CROP RESIDUES IN THE SON RIVER WATERSHED

The article explores potential energy production quantity from surplus crop resides in the son river watershed. A special focus on the agricultural regions of the Son watershed through an analysis of the real potential of surplus crop residues resource. The emphasis on residues energy greatly significant in current practices and future expectation. The United Nations Development Programme, for example, refers to sustainable development as a fundamental question of our generation's development, which challenges the aspiration to enlighten humanity's collective journey towards a better future. National and international development agencies whose actions are commonly combined in the context of the development of clean renewable energy under the sustainable and clean development mechanism goals. These concerns are based on consensus among scientific and development approaches that global climate change triggers profound shifts in power/energy resources associated with ecological systems that will significant transformation in local and global environment. The most serious impacts of fossil fuel are generally seen to be concentrated among the world's poor and especially those living in the global south. The article also attempts to emphasize the importance of regional perspective and production of crop residue quantities. Crop -based residues resource has several distinct advantages such as wide periodically availability that puts it ahead among the renewable energy options.