Marianne Milano

Impact of climate change and anthropogenic pressure on the groundwater resources in arid environment

Climate and anthropogenic changes are expected to reduce renewable groundwater resources and to increase the risks of water scarcity, particularly in arid regions. Understanding current and future risks of water scarcity is vital to make the right water management decision at the right time. This study aims to analyze the impact of both human and climate pressures on groundwater availability in an arid environment: the Regueb basin in Central Tunisia. An integrated approach was used and applied at a monthly time step over a reference period (1976–2005) and a future period (2036–2065). Groundwater resources were assessed using hydrogeological modeling. Irrigation water withdrawals were evaluated based on remote sensing and the CropWat model. Urban water use was estimated from population growth and specific monthly water consumption data. The resulting values were used to compute two indicators (water stress index, groundwater balance) to evaluate water scarcity risks at the 2050 horizon. To assess current and future climate forcing on water resources, three climate scenarios were generated based on simulations from Coupled Model Intercomparison Project Phase 5 (CMIP5) data. A business-as-usual and an adaptation scenario (optimal cropping scenario) were performed by varying the surface areas and the crops grown in the irrigated area. Results show that the average annual water use will increase by 3.8 to 16.4% under climate change only, whereas it will increase by 100% under the business-as-usual scenario. Under the optimal cropping scenario, total water demand will increase by 50%. Water stress index indicates that under the climate change only scenario, water demand should be satisfied by the 2050 horizon, while under the other two scenarios, severe water stress will occur by 2050. The developed framework in this paper aims to fit in arid and semiarid regions in order to evaluate groundwater stress and to assess the efficiency of adaptation strategies. It results in two major recommendations regarding changes in land use and the improvement of groundwater monitoring.

Assessing watercourse quality: challenges in implementing European and Swiss legal frameworks

Hydro-climatic changes and the increasing release of pollutants into rivers by human activities tend to affect the quality of watercourses, to alter aquatic ecosystems and to reduce the amount of useable water. The ecological and chemical states of rivers and their evolution is thus of growing concern. In Europe and Switzerland, water policies are progressively shifting towards a holistic approach of river systems. The European Commission notably established a framework to highlight rivers’ ecological deficits and to enhance regional or local water management plans. In Switzerland, a similar framework is currently under development. In this paper, both procedures are compared and implemented in a Swiss catchment dominated by agricultural activities. The aim is to define the challenges that still need to be addressed to assess and sustain river health. The hydromorphological, ecological, and ecotoxicological quality of the river was evaluated. Both frameworks highlighted the fact that no section of the river can currently be classified as being in a good environmental state and that the state deteriorates as tributaries and wastewater discharge flow into the main riverbed. Chemical issues and water quality changes due to hydro-climatic variations and management strategies were also pinpointed. Both frameworks are thus useful tools to survey changes in rivers quality in space and over time. However, challenges remain regarding the appropriate strategies to monitor and analyze chemicals, the definition of target values and conditions, the evaluation and integration of human-induced pressures, and the overall evaluation of the state of a river. The development of integrated indicators or of ecosystem services approaches is considered as a potential solution to explore river health and to define efficient restoration measures by water managers.

Monitoring Water Use Regimes and Density in a Tourist Mountain Territory

Lack of water use data at the user scale is frequently noted in integrated water management and water demand modelling studies. This situation affects particularly mountain tourist areas, where high seasonal water demand related to the variation of temporary population are rarely documented. Irrigation is also a major water use in moutain territories but is not commonly measured. This paper proposes a framework for local-scale monitoring of seasonal water use behaviours and their territorial inprint. A monitoring strategy was developed to collect water demand data at thin spatio-temporal scales which were analysed using two concepts: (i) the water use regime, describing the dynamics of water uses throughout the year using normalised values, and (ii) the water use density, expressing the territorial footprint of a water use, in terms of unit area. This strategy was applied in the alpine tourist municipality of Montana (Switzerland). A two-year monitoring campaign of irrigation and drinking water uses was carried out combining in-field measurement (water metres) with interviews of water users. The temporal resolution of the collected water use dataset (bi-weekly, daily) was sufficient to assess the specific water demand patterns and the short-term water use peaks responsible for water stress in Alpine tourist regions. It provided the first irrigation monitoring in the area and a classification of drinking water data according to their spatial distribution, the type of building and the permanency of residents. The water use density method gives a new prespective on the spatial intensity of water uses, highlighting the importance of garden irrigation in Montana. Also, the water use regime method identified July as the period of water demand peaking. The monitoring of water uses at such thin temporal scale constitutes the necessary dataset for the creation of water balance models that accurately reproduce the effective water use behaviours.