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130 million residents use the Niger River water for agriculture, fishing, transport and domestic activities. Suspended particulate matter (SPM) and other waste, washed into the river during rainy events,  constitute a favorable environment for bacteria proliferation since it provides protection from ultraviolet radiation, offers nutrients and ideal living environment. The objectives of this work are to: characterize the concentration and nature of SPM in the middle Niger River and analyze their spatio-temporal variability; study the link between SPM and indicator of fecal bacteria contamination (E. coli); quantify the part of fecal pollution that the Niamey city brings into the Niger River.

Two regular monitoring sites were set up on the Niger River and two periurban lakes east of Niamey. Measurements of SPM were made by filtering water samples acquired during two full years. Water color was monitored by above-surface radiometer operating in red and infrared bands and Sentinel-2 satellite. E. coli content and physico-chemical water parameters were also monitored and SPM were analyzed using electronic microscopy and laser granulometry.

The analysis of SPM revealed extremely fine (0.2 µm) particles of mineral origin (kaolinite) with some iron oxide/hydroxide during the red flood. Radiometric measurements by both the in-situ radiometer and Sentinel-2 were found to be well suited to monitor SPM dynamics in this area. SPM and discharge showed a complex relationship : SPM increases before the discharge increase at the beginning of the red flood but they are at their lowest during the black flood. SPM concentration and E. coli somewhat co-vary at the beginning of the rainy season but E. coli values remain relatively high during the black flood, despite low SPM at that time. E. coli concentration at the downstream station reveals an important fecal pollution from the Niamey city with E. coli values on average 10 times higher than the upstream station. Maintaining and developing monitoring tools in this area is particularly important in the context of  global environmental changes, as for example the increase in the red flood discharge observed  in Niamey since the 90’s, that may deeply modify the transfer of contaminants in surface waters.

How to cite: Boubacar Moussa, M., Abdourhamane Touré, A., Lartiges, B., Rochelle Newall, E., Kergoat, L., Robert, E., Gosset, M., Alkali Tanimoun, B., and Grippa, M.: Suspended particulate matter and water fecal pollution in the Niger River at Niamey, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-184, https://doi.org/10.5194/iahs2022-184, 2022.

Coastal areas are areas where a very large number of laguno-marine species reproduce, grow or transit, which are most often the subject of fishing exploitation. The purpose of this study is to analyse the risk of contamination of fisheries ecosystems and its consequences on the evolution of aquatic resources in the coastal zone and more specifically from south-west Benin to south-east Togo.

The methodology adopted is based on the collection and processing of raw data such as: hydrometric data, particle size data, climatological data, data from fauna and flora inventories, supplemented by those from in situ measurements and those from laboratory analyses made from sediment samples and some species caught during fisheries during the different hydrological seasons.

Analysis of the results revealed that pollution of the lagoon channel in Cd, As, Pb and some major ions such as Cl -, NO3- and PO43- are responsible for its eutrophication. In addition, organic matter and MES in high concentrations lead to the covering of aquatic habitats, particularly spawning grounds and suffocation of eggs by reducing essential metabolic exchanges (supply of oxygen and nutrients, evacuation of metabolic waste) through the decrease in the concentration of dissolved oxygen within the substrate. Analysis of trace elements in the flesh of samples of Captain fish (Polydactylus quadrifilis), white grouper (Epinephelus aeneus), Tilapia zillii, and white catfish revealed their rate of contamination with metallic trace elements. Behavioural effects (abandonment of shelter areas and avoidance reaction) are thus recorded; subletal effects (short-term reduction in feeding rate; minor physiological stress; increased cough frequency; increased breathing rate; moderate physiological stress; major; delayed outbreak; reduction of population density; mortality). According to 89% of fishermen, the decline in fish species caught is recorded during dry periods, when the channel has a high rate of contamination with heavy metals and major ions.

How to cite: Ahéhéhinnou Yêdo, M. F., Amoussou, E., Ahouansou, M. M., Kodja, J. D., and Totin Vodounon, S. H.: Inland Fisheries and Risk of Contamination of Fisheries Ecosystems in the Gbaga Lagoon Channel (Benin-Togo Coastal Zone), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-404, https://doi.org/10.5194/iahs2022-404, 2022.

Coastal Mediterranean hydrosystems, especially Mediterranean lagoons provide a wide range of ecosystem goods and services that human societies take advantage from. Those socio-hydro-eco-systems are most of the time groundwater dependent ecosystems, however their hydrogeological functioning, essential for their management is still little-known.

Catchment anthropization is one of the highest pressure for the lagoons and can increase their ecological vulnerability, especially by the pollutants flowing to the lagoons via groundwater and surface water. The consideration of the groundwater as an inertial system with the ability to store pollutants is not yet taken into account by the water resource managers. South of Corsica is an interesting study area due to the presence of numerous small lagoons and a high rate of urbanization. The catchments of the Balistra, Santa Ghjulia and Arasu lagoons were investigated to explore the types and concentrations of contaminants of emerging concerns. These specific pollutants being considered here as relevant tracers of the coastal Mediterranean anthropization phenomenon with high population increase due to strong seasonal touristic activity.

An original multi-tracer approach, combining physico-chemical parameters, major ions and trace elements as well as, stable isotopes of the water molecule was carried out on 48 points divided in surface water (16 points), groundwater (18 points) and lagoon water (14 points) on the 3 watersheds. On selected relevant points, the analysis of emerging compounds was also realized to identify potential sources of pollutions.

Emerging compounds analysis shows that the three sites are concerned by contamination, nevertheless at very low content. DEET- diethyltoluamid have been found on 78% of the sampling points with concentrations between 16.2 ng/l to 198 ng/l. It is the most commonly found compounds in groundwater with caffeine and benzotriazoles.

The presence of emerging compounds in groundwaters of the 3 catchments with different level of anthropization reveals a high human footprint due to sewage system leakage which is a vector of pollution to the lagoons. In a context of global change, the hydrological balance of such systems is fragile and the degradation of the quality of groundwaters highlighted by the emerging compounds is increasing the vulnerability of the Mediterranean lagoons.

How to cite: Crayol, E., Huneau, F., Garel, E., Mattei, A., Santoni, S., and Pasqualini, V.: Contaminants of emerging concerns in groundwater as tracers of antropization to small Mediterranean lagoons hydrosystems, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-444, https://doi.org/10.5194/iahs2022-444, 2022.

Micro-estuaries are very common in the Mediterranean. Their ecological role is also of uppermost importance for the preservation of biodiversity as well as for the nutrient input towards the coastal marine environment. Strong seasonal contrasts are characteristic of the Mediterranean regions, for the hydrological behaviour of rivers but also for activities in relation with the tourism industry. Therefore, in coastal regions water bodies can be exposed to very strong impacts due to the very focused touristic activity especially along the most appreciated zones like beaches, sand dunes and sand bands where micro-estuaries are very frequently also located. Due to the very short duration of the highest touristic season and to the very frequently under-calibrated capacities of sanitation infrastructures, it is frequent to observe wastewaters releases towards the surface waters which can contaminate groundwaters and in the end micro-estuaries. It is then of major interest to evaluate what type of emerging contaminants can be found in these regions, and if a clear seasonality in the contaminant release can be observed.

The strategy is to investigate the emerging contaminant content in waters of micro-estuaries and other types of connected waters (river waters, groundwaters) from a coastal areas of North-Western Corsica characterized by a very dynamic seasonal touristic activity. Sampling were organized before the touristic period and after in order to appreciate the impact of the high season peak on the water quality. 102 molecules were analyses on 20 water samples from 4 different coastal watersheds.

Results show a clear impact of the increase in the population due to the touristic activity, but a baseline contamination is also observed for the winter season. 11 molecules are present for each sampling and mostly composed of pharmaceuticals, nicotine and caffeine metabolites as well as artificial sweeteners. A tendency towards the reduction of concentrations is observed in rivers along the flow due to dilution processes and degradation of contaminants. Groundwater contamination appear as really more stable and mostly in relation with the immediate vicinity of boreholes and wells. Micro-estuaries, which are the final collector all the watershed pollution sources, are the most contaminated water bodies of the survey.

How to cite: Huneau, F., Garel, E., Santoni, S., Mattei, A., Tafani, C., and Pasqualini, V.: Impact of seasonal touristic activity on emerging contaminants of micro-estuaries and hydraulically connected water bodies in North-Western Corsica, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-497, https://doi.org/10.5194/iahs2022-497, 2022.

Algeria has established a growing urban pole, therefore urbanization and urban dynamics are increasing from year to another, and it occurs a flow of excessive urban wastewater discharges from these agglomerations.

In this research, we are interested in the evaluation of the current state of wastewater, which comes from 1114 residences by household activities and human metabolism, or the mixing of domestic wastewater with water runoff.

In the extreme North east of Algeria, the predominantly domestic waters of Drâa-Errich city, evacuated through collectors and without treatment they are rejected in nature, and the quality of the water at the level of the Gueridjima wadi has deteriorated and these waters currently constitute a polluted effluent which joins the waters of the El Aneb wadi to the west. 

A set of analyzes was carried out (period of April to May 2021) on domestic wastewater to assess their quality.

Sampling and analysis carried out of surface water (02 samples from Gueridjima wadi and 02 samples from El Aneb wadi) and groundwater (01 well), covering an area of 15 km.

The physic-chemical parameters measured with the WTW multiparameter are pH, temperature, electrical conductivity EC, biological demand in oxygen BOD₅. In addition, the undesirable substances are Nitrates (NO₃^-), Nitrites (NO₂^-), Phosphates (PO₄^-), and orthophosphate.

In front of this situation, the measures proposed are the systems for treating domestic wastewater sewage, seen the advantages represented by the topography of the land in the region; remains the better solution for possible reuse recovery of wastewater, in agriculture sector. This measure will certainly improve the quality in terms of production of an acceptable quality of (purified) wastewater, and reduce environmental problems

Keywords: current state - domestic wastewater - sewage - admissible quality.

How to cite: Bougherira, N., Hani, A., Chaffai, H., Vanclooster, M., Djabri, L., Nechem, D., Saadali, B., Boubelli, S., and Nahal, A.: Identification of some water quality parameters of the liquid effluents discharged from recent urbanization, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-578, https://doi.org/10.5194/iahs2022-578, 2022.

The Beale’s ratio estimator (Beale, 1962) had been proven to be an unbiased pollutant loading calculator. However, Dolan et al (1981) cited that the estimator may have poor performance due to inadequate stratification. This study evaluated the error in phosphorus annual load calculation using an automated stratified sampling Beale’s ratio estimator of weekly, bi-weekly, and baseflow + storm event sampling schedules. The uniform random sampling and genetic algorithm approaches to search the optimal stratification and the number of strata were implemented in R programming language. The data from the National Center for Water Quality Research’s (NCWQR) tributary loading program in Ohio, USA and the Norwegian Institute for Bioeconomy’s (NIBIO) JOVA monitoring program in Norway were used in this study. The minimum number of strata required in uniform random sampling and the number of sample size and iterations for the genetic algorithm were identified to obtain the stratification that has the lowest load mean square error calculation. The results of this study can be used to find the optimal pollution sampling strategy with minimal loading calculation error depending on monitoring infrastructure and constraints.

How to cite: Confesor, R., Bechmann, M., Deelstra, J., and Stolte, J.: R-Beale: an automated stratified Beale’s ratio estimator to calculate pollutant loading from measurements with missing observations., IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-628, https://doi.org/10.5194/iahs2022-628, 2022.

The ZanjanRud Basin, in north-western Iran, Zanjan Province, has recently experienced the worst drought conditions in over 50 years of records. Watershed management decisions and climatic shifts resulted in hydrological drought in the middle reaches of the ZanjanRud River from 1999 to 2018. Average River discharge (0/49 m³/s at Sarcham Hydrometric station) in the drought period (2008-2018) were approximately 0.65 m³/s lower than the long-term average (1.2 m³/s) and represented a 54.16% reduction in water discharge. The purpose of this study was to increase understanding of the water quality and ecology of the river, provide additional information for investigation of watershed management options which are compatible with climate change.

Water quality was investigated at the middle part of the river (2 sites) which were regularly (fifteen–monthly) monitored from October 2016 to March 2018. This reach has experienced municipal effluent discharge and are at risk of acidification. The water quality parameters considered in this report were general water quality parameters (EC, temperature, pH, TDS, TSS, turbidity), nutrients (total nitrogen, TN; total phosphorus, TP), dissolved oxygen, chemical oxygen demands, color, and particle metals. Hydrological parameters were also assessed as potential drivers of water quality change. The concentration of dissolved and particulate material in the study sites increased during hot and dry months driven by evaporation and the associated large reduction in water volume. The lack of runoff also resulted in the observation of a high concentration of nutrients and green-algae during the low flow period. Turbidity also increased during the drought period. The results revealed that the middle part of the river is highly influenced by effluents from the municipal area (Zanjan City). Further assessment of water quality during future low flow events is recommended in our study area.

How to cite: Abdollahi, Z., Kavian, A., and Sadeghi, S. H. R.: The Effect of Hydrological Drought on Water Quality in Zanjanrud River, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-741, https://doi.org/10.5194/iahs2022-741, 2022.

How to cite: de Lavenne, A., Tournebize, J., Henine, H., Chelil, S., and Andréassian, V.: Modeling Nitrate export with GR4J and StorAge Selection functions, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-65, https://doi.org/10.5194/iahs2022-65, 2022.

Veterinary pharmaceuticals, widely used in intensive livestock production, may contaminate surface waters. Identifying their sources and pathways in watersheds is difficult because i) most veterinary pharmaceuticals are used in human medicine as well and ii) septic or sewer wastewater treatment plants (WWTP) can release pharmaceuticals into surface water, even in agricultural headwater watersheds. This study aimed to analyze the spatiotemporal variability of animal-specific, mixed-use, and human-specific pharmaceuticals, from agricultural headwaters with intensive livestock production and a WWTP to a watershed used for Water Framework Directive monitoring. Grab sampling was performed during three hydrological year in seven nested watersheds in intensive husbandry area upstream and downstream from a WWTP with areas of 1.9-84.1 km². Twenty pharmaceuticals were analyzed. Microbial fecal indicator E. coli and fecal stanols were determined. Fecal stanols are microbial source tracking tool allowing to identify the origin of the fecal contamination (porcine, bovine or human). Animal-specific pharmaceuticals were detected at all sampling dates upstream and downstream from the WWTP and at concentrations higher than those of human-specific pharmaceuticals. Animal-specific pharmaceuticals were detected mainly during runoff events associated with bovine or porcine fecal contamination. A large percentage of mixed-use pharmaceuticals was assigned to animal sources. Mixed-use and human-specific pharmaceuticals predominated in the largest watersheds when runoff decreased. In areas of intensive livestock production, mitigation actions should focus on agricultural headwater watersheds to decrease the number of pathways and the transfer volume of veterinary pharmaceuticals, which can be the main contaminants.

How to cite: Jaffrezic, A., Charuaud, L., Liotaud, M., Mercier, F., Le Bot, B., and Jardé, E.: Veterinary pharmaceutical and fecal contamination in mixed-land use watersheds: from agricultural headwater watersheds to water-monitoring watersheds., IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-534, https://doi.org/10.5194/iahs2022-534, 2022.