18/03/2019 - Louvain4Water Seminar - The language of Water

Ce projet est axé sur la gestion durable des ressources en eau dans les bas-fonds en vue d’assurer la sécurité alimentaire et améliorer les moyens d’existence des ménages agricoles. Le projet s’intègre directement dans les priorités du Programme d’Action du Gouvernement béninois (PAG), du Plan Stratégique de Développement du Secteur Agricole (PSDSA) 2025 et du Plan National d’Investissements Agricoles et de Sécurité Alimentaire et Nutritionnelle (PNIASAN) 2017 – 2021. En particulier, l’aménagement des bas-fonds adresse simultanément les trois projets phares du PAG: (i) Filières à haute valeur ajoutée (produits maraîchers) ; (ii) Filières conventionnelles (riz) ; et (iii) Mise en valeur de la basse et moyenne vallée de l’Ouémé.

Film, en Français, 15 minutes

Les quartiers informels des 'bas-fonds' de Yaoundé, Cameroun concentrent  les populations socialement les plus précaires dans des conditions d'insalubrité et d'exposition aux risques naturels graves. La situation est empirée par la prolifération de déchets bouchant les systèmes d'irrigations formels et informels. En saison de pluie, cette situation provoque des inondations importantes. En saison sèche, la stagnation d'eaux usées provoque des dangers sanitaires importants.  Face à cette situation, ni les autorités publiques et ni les populations locales ne disposent des moyens et méthodes adéquats.

Le film retrace les résultats d'un premier workshop ayant eu lieu en novembre 2018 à l'Ecole Spéciale Supérieure d'Architecture du Cameroun. Il a comme objectif évident d'être un moyen de sensibilisation au problème. Mais plus fondamentalement, le média "film" est lui-même expérimenté comme un outil de recherche permettant de construire progressivement un dialogue prospectif et collaboratif entre les différents acteurs concernés.

The hydrological behavior of karstic systems is difficult to theorize holistically because of their specific heterogeneities leading to distinctive nonlinear processes. Karstified systems present great opportunities for field exploration and hydrogeological monitoring of the vadose zone through its network of caves and conduits. These unique but explorable environments are predisposed to an inductive scientific approach where transfer processes associated with hydrological connections are directly inferred from the data.
This is done conventionally using dye tracing from which connections and transfer times are undeniably revealed. However, single tests do not allow appreciating the dynamic character of the hydrological connections. Nowadays, several methods in data analysis aim at the detection of causal relationships between time series allowing the investigation of long-term dynamics and interactions. Some are designed for linear systems as the simple cross-correlation method or the Granger causality, while others are suitable for nonlinear interactions, such as the Convergent Cross Mapping method.
Here, these methods are applied in order to draw up and compare short-term causal interactions in the Lhomme Karst System in Belgium. The Lhomme Karst System has been monitored since 2013 and many time series are available: meteorological data, soil moisture, drip discharges in the caves, piezometric levels, and local gravimetric time series. The PICO seminar introduces briefly the causal inference methods that are used in this research with some causal mapping examples applied to hydrological data sampled at the Lhomme Karst System.

L'étude montre qu’il existe des liens entre la terre arable, les mines et les cours d’eau sur les territoires dont les ressources sont exploités par des entreprises. Cela suppose que l’exploitation de ces deux premières ressources peut avoir des effets négatifs sur l’accès à l’eau pour les populations locales. A partir des cas d'étude en RDC, ce travail essaie de montrer ces effets négatifs et de tirer des leçons en termes de politiques publiques

The presence of anti-cancer drugs in European surface waters indicates that currently applied wastewater treatments are not effective for the removal of persistent compounds. In this work, three advanced oxidation processes (UV, UV/TiO2 and UV/H2O2) were applied first on laboratory grade water and then on real secondary effluent spiked with four anti-cancer drugs at 500 µg/L. Direct photolysis in laboratory water led to degradation rates of 0.191 ± 0.007 1/min for 5-fluorouracil, 0.078 ± 0.005 1/min for capecitabine, 0.047 ± 0.008 1/min for cyclophosphamide and 0.039 ± 0.004 1/min for ifosfamide. Improved removal performances were observed when catalyst was brought in suspension: capecitabine (+37%), cyclophosphamide

(+35%) and ifosfamide (+32%). Regarding chemical oxygen demand abatement, electrical energy per order, operating and environmental costs, the UV/H2O2 process scored best. This technology appears thus to be an efficient barrier against anti-cancer drugs discharge in surface waters.

Citizen Science (CS) has been emerging in the last decade as a new field of environmental monitoring involving a direct collaboration between everyday citizens and scientists. The concept is now also introduced in hydrology.

In Tunisia, several recent governmental efforts aimed at reinforcing the existing official water-related information through the renovation of the Tunisian monitoring systems. However, the lack of reliable hydrological data still an issue. This major point of concern can be partially addressed through a CS approach.

In this study, we present results of the test phase of the Together4Water initiative, a water resources CS project that was launched in Tunisia in 2018. We monitored river flow, rainfall and water quality in a test area of the Medjerda catchment using cost-effective and/or public available sensors. For river flow we used the ‘Discharge app’, for rain simple manual pluviometers and for water quality simplified water quality strips. We used a stepby- step approach to target, to engage and to train citizens on using the monitoring tools and transmitting the data to a centralized online platform. The collected CS data are compared with data from the governmental reference stations. Preliminary results yield a good agreement between CS river flow data collected at two sites (Slouguia and Medjez) and the reference stations (correlation coefficient R ranges between 0.8 and 0.97 for all citizens).

For rainfall, measurements collected by citizens in eight locations correlate well with reference data (R ranges between 0.95 and 0.98). Finally, CS water quality data (PH, NO3, NO2, KH, GH and Cl2) are also consistent with the laboratory measurements (R ranges between 0.75 and 0.8). In addition, uncertainty of the CS data are compared with the uncertainty associated with the official governmental data. We conclude that the Together4Water CS test phase delivered a consistent hydrometrological data set. The variability between the citizens’ measurements can be explained by many factors such as the location of pluviometers for rainfall observation, the wind and light reflection for river flow measurement using Discharge app, and colors identification for the water quality strips. The CS approach is considered promising to complement existing Tunisian monitoring systems, and also to enhance innovation, adaptation, and local capacity building in the Tunisian water sector.

The Mediterranean area is considered to be a hotspot for climate change. This will have a considerable impact on hydrologic and ecosystem services of Mediterranean catchments.

Due to complicated interconnections in the hydro-meteorological system, quantifying the influence of individual factors on streamflow alteration remains challenging. In this study, we explore the causes of hydrological alteration within the Tunisian-Algerian transboundary basin of the Medjerda and we extract factors that dominate streamflow alteration. This basin covers

23 700 km2 of which 7 870 km2 are in Algeria, or 32% of the total area.

Reference hydrometrological data in the basin are collected and provided by the local authorities. The data base is enriched with generic time series on evapotranspiration, temperature and NDVI, inferred from the Google Earth Engine cloud-based platform.

Nonlinear time series analysis tools (convergent cross mapping, CCM) are implemented to quantify the causality of individual factors on streamflow.

The results proved that the CCM method is able to detect quantitative influences of individual factors on streamflow, and to discriminate the role of climate factors (rainfall, evapotranspiration, temperature) from other environmental factors (e.g. land use related NDVI) on hydrological alterations. Understanding the individual role of factors on hydrological alteration is essential for designing appropriate water management adaptation programs in this water stressed basin.