Session 5 | Quantifying regional hydrological change impacts

Session 5

Quantifying regional hydrological change impacts
Conveners: Salvatore Manfreda, Marc Voltz
Orals
| Wed, 14 Jun, 14:00–15:35|Saints Marcellino and Festo
Poster
| Attendance Thu, 15 Jun, 10:45–11:30|Poster area
Orals |
Wed, 14:00
Poster
Thu, 10:45
Water is the key factor for sustaining natural environments, agricultural and forest ecosystems as well as human activities. Our everyday activities rely on significant direct and indirect water use. For instance, food, feed, and biomass production for energy consumption (e.g. bio-based economy) are controlled by its availability. The water cycle is strongly influenced by climate and land-use change, but the extent and impact on water resources availability and ecosystem services and functioning are only roughly known. Global warming and economic growth are significantly impacting hydrological extremes, such as floods and droughts, and also on land cover. This may lead to severe economic, societal, and ecological impacts. This session solicits contributions outlining the impacts of climate and global change and exploring mitigation strategies for increasing hydrologic resilience in regions of high vulnerability.

Invited speaker: Florence Habets, France (florence.habets@ens.fr)

Orals: Wed, 14 Jun | Saints Marcellino and Festo

Chairpersons: Salvatore Manfreda, Marc Voltz
14:00–14:10
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GC8-Hydro-3
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Session 5
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ECS
Building reliable hydrological models for climate change studies
(withdrawn)
Marco Dal Molin and Fabrizio Fenicia
14:10–14:20
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GC8-Hydro-96
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Session 5
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ECS
Assessing the vulnerability and resilience of riparian vegetation to water stress 
Bryn Morgan and Kelly Caylor

Riparian corridors act as thermal and moisture refugia for a range of plant and animal species, particularly in water-limited environments. Declining water tables, increasing temperatures, and an increase in extreme hydrologic events due to climate change threaten the diversity of life these landscapes support. Successful adaptive conservation management strategies require an understanding of how species are responding to climate change and an ability to anticipate how changing patterns of water resource availability and demand will alter vegetation patterns and processes. 

Here, we investigate dryland riparian plant responses to fluctuating water availability and atmospheric demand using a novel drone-based approach for estimating transpiration. Integrating thermal imagery, structural data, and a suite of environmental sensors mounted on an unmanned aerial vehicle (UAV) platform, this approach was specifically designed to capture fine-scale functional data and variation in individual-level plant functional traits within riparian ecosystems and allows for efficient calculation of evapotranspiration for a site solely using data collected from the UAV. Using UAV-based measurements of transpiration across seasonal, diurnal, and spatial gradients of water stress, we quantify individual-scale hydraulic sensitivity to fluctuating water availability and atmospheric moisture demand. Finally, we highlight how these fine-scale estimates of plant water use facilitate understanding of how ecologically important plants respond to the increasingly variable hydrologic regimes that sustain them, yielding valuable insights into how such ecosystems will evolve in the face of global environmental change.

How to cite: Morgan, B. and Caylor, K.: Assessing the vulnerability and resilience of riparian vegetation to water stress, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-96, https://doi.org/10.5194/egusphere-gc8-hydro-96, 2023.

14:20–14:30
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GC8-Hydro-88
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Session 5
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Future drought and groundwater availability in the Netherlands: a growing concern 
Victor Bense, Adriaan Teuling, Syed Mustafa, and Martine van der Ploeg

Groundwater depletion from aquifers worldwide is of increasing intensity and this is reason for serious societal concern especially in areas of continuing population growth and where future dry periods are predicted to be more frequent in a changing climate. Groundwater depletion will occur, and groundwater development eventually unsustainable, where groundwater withdrawal rates exceed the groundwater recharge flux. However, the limited ability to assess groundwater recharge conditions gravely hampers effective groundwater resources management to avoid their overexploitation leading to groundwater depletion. Hence, mapping and quantifying groundwater flows is therefore increasingly recognized as one of human societies grand challenges. The Veluwe area is of the few topographically elevated areas in the Netherlands to enable appreciable groundwater recharge. Therefore, it hosts the largest fresh groundwater system of the Netherlands covering a surface area of approximately 1100 km2. The 2018 and subsequent 2021-2022 summer droughts led to a strongly increased demand for drinking water across the Netherlands which brought some groundwater abstraction licenses, set by regulatory government bodies, across the Veluwe area close to being exceeded. This cunningly demonstrated that, similar to many areas globally, in periods of water stress groundwater resources often are of crucial importance in maintaining a reliable supply of domestic water, and to meet agricultural and industrial demands. However, the relation between climate and groundwater drought is complex, in particular for areas with deep unsaturated zones such as the Veluwe, yet needs to be understood in the face of projected climate change. For this reason, already prior to 2018, the Veluwe area was listed as a nationally strategic water reserve, and as such should receive ample attention in considerations of National Security on the long term. However, since the mid-1990s the regional hydrogeological system of the Veluwe has not been subject of extensive experimental academic study as result of which it is highly questionable whether we can now reliably assess groundwater availability across the area in the decades to come. In this presentation, we outline ongoing and future efforts to monitor water fluxes in the Veluwe region. Past measurements have been focussing on water table fluctuations and soil-water modeling to estimate recharge. Current plans include establishing a drought observatory consisting of a precision lysimeter array complemented by eddy covariance observations of ET, that transects the from the high sandy grounds with deep groundwater tables to the seepage areas with shallow groundwater tables.

How to cite: Bense, V., Teuling, A., Mustafa, S., and van der Ploeg, M.: Future drought and groundwater availability in the Netherlands: a growing concern, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-88, https://doi.org/10.5194/egusphere-gc8-hydro-88, 2023.

14:30–14:40
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GC8-Hydro-43
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Session 5
Catchment-scale analysis of hydrological and agricultural impacts of small reservoirs 
Jérôme Molénat, Cecile Dagés, Nicolas Lebon, and Delphine Leenhardt

Small reservoirs are dams built to intercept and store runoff water. Small reservoirs can be a resource for farmers by providing water for crop irrigation. In agricultural areas, small reservoirs are seen as a way to sustain agriculture in times of drought. Changes in rainfall patterns due to climate change, with higher rainfall in some seasons and longer droughts in others, and the need to maintain or even increase agricultural productivity are also prompting some stakeholders to promote the development of small reservoirs. The proliferation of small reservoirs in a catchment can put pressure on the water cycle and have a cumulative impact on river flows and other hydrological components, which in turn can affect other water uses and the quality of downstream aquatic environments (Habets et al., 2018). There is a need to better understand and quantify both the cumulative hydrological impacts and the agricultural benefits of small reservoirs.

We present here an analysis of the cumulative impact of small reservoirs on hydrology and crop yield in an agricultural catchment. This analysis is based on the modeling of a 20 km² catchment in southwestern France. We used a new agro-hydrological model called Mhydas-Small-Reservoirs, a model coupling hydrological and crop processes with farmers' water management decisions (Lebon et al., 2022). Several catchment situations were considered. These situations combine different levels of reservoir use (current situation with 26 reservoirs of which only 13 are exploited for crop irrigation, a situation with no reservoirs at all, a situation where reservoirs currently not exploited are used for irrigation) and different climatic years (dry year, wet year, and year with average rainfall). The simulations were analyzed in terms of crop yields and different water balance terms (flow, ET, irrigation withdrawal). From the preliminary results, we show the interest and the need to take into account the interactions between hydrological and agricultural processes to quantify the impacts due to small reservoirs. We also identify the need for observations in agrohydrological modeling applied to catchments with small reservoirs.

References

Habets F., Molénat J., Carluer N., Douez O., Leenhardt D., 2018, The cumulative impacts of small reservoirs on hydrology: A review, Science of The Total Environment, 643, 850-867, https://doi.org/10.1016/j.scitotenv.2018.06.188

Lebon, N., Dagès, C., Burger-Leenhardt, D., Molénat, J. 2022, A new agro-hydrological catchment model to assess the cumulative impact of small reservoirs, Environmental Modelling & Software, Volume 153,2022, 105409, https://doi.org/10.1016/j.envsoft.2022.105409

How to cite: Molénat, J., Dagés, C., Lebon, N., and Leenhardt, D.: Catchment-scale analysis of hydrological and agricultural impacts of small reservoirs, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-43, https://doi.org/10.5194/egusphere-gc8-hydro-43, 2023.

14:40–14:50
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GC8-Hydro-12
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Session 5
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Quantifying global-warming-induced changes in spatial and temporal patterns of heavy precipitation events and the implications to flood properties in Mediterranean catchments 
Efrat Morin, Yair Rinat, and Moshe Armon

Flood properties are known to be sensitive to spatial and temporal patterns of precipitation, which in turn are affected by global warming. In this study, we investigated the effect of global warming on properties of heavy precipitation events (HPEs) in the eastern Mediterranean, focusing on hydrologically-important characteristics, including total precipitation amount, coverage area, precipitation duration and the distribution of rain rates for different durations. Then, we quantified how changes in precipitation due to global warming affect resulting flood properties for small-medium catchments in the study region.

We used the weather research and forecasting (WRF) model to simulate 41 HPEsin present and future (end of 21st century; RCP 8.5 scenario) climate conditions and output the precipitation fields at high resolution (1 km2, 10 min). The calibrated GB-HYDRA distributed hydrological model (<60 s, 100 m) was utilized to simulate floods from those HPEs in 4 small-medium-size basins (18–69 km2). To account for the rainfall spatial uncertainty in the simulations, spatial shifts were applied to the simulated HPEs in a range of 20 km north and south.

We found a major decrease in precipitation accumulation (−30% averaged across events) in future HPEs. This decrease results from a substantial reduction of the rain area of storms (−40%) and occurs despite an increase in the mean conditional rain rate (+15%). In addition, the duration of the HPEs decreases (−9%) in future simulations. The above changes were consistent across events.

These changes have opposite directions, suggesting that flood properties changes are not trivial. Our simulations indicate a future decrease in both flood volume (-27%) and peak discharge (-20%, non-significant) at the outlet of the catchments. On the other hand, peak discharge is increasing in the future for small sub-catchments (< 5 km2). We currently expand this research to account for expected changes in future antecedent soil moisture conditions and land-use.

To conclude: with global warming, HPEs in the eastern Mediterranean are becoming drier and more spatiotemporally concentrated. Consequently, small and larger catchments respond differently to this change, with the former reacting to the increase in rain rates and producing higher flood peak discharge, while the latter reacts more to the reduction in total rainfall, area and duration, and results in lower flood volumes and peaks.

How to cite: Morin, E., Rinat, Y., and Armon, M.: Quantifying global-warming-induced changes in spatial and temporal patterns of heavy precipitation events and the implications to flood properties in Mediterranean catchments, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-12, https://doi.org/10.5194/egusphere-gc8-hydro-12, 2023.

14:50–15:00
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GC8-Hydro-76
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Session 5
On the potential cross-mixing of Lake Bogoria and Baringo in the Rift Valley of Kenya 
Mathew Herrnegger, Pierre Kray, Gabriel Stecher, Nelly Cherono, and Luke Olang

The Rift Valley lakes of Kenya are biodiverse ecozones, classified not only as RAMSAR wetlands of international importance, but also as UNESCO World Heritage. In the last decade, starting in 2010, several Kenyan lakes have experienced significant rises in water levels. The consequences have been severe. Inundations of the riparian areas have not only flooded homes, schools and hospitals, but also the basis for the local livelihoods and economy such as agricultural fields, national parks or tourism infrastructure has been destroyed. Nearly eighty thousand households with 400,000 people are affected according to a governmental report published in 2021.

There is fear of an ecological catastrophe, should the water levels of the alkaline Lake Bogoria continue to rise. The result would be an overflow and mixing with the freshwater Lake Baringo, the basis of the local community supporting drinking water provision, agriculture, tourism and fisheries. Currently no analysis exists to understand the topographical conditions between the two lakes and the potential flow paths. It is unclear, what climatic rainfall conditions are necessary to lead to an overflow and sustained flows from Lake Bogoria towards Baringo. This analysis therefore assesses (i) the overflow or sill point location and potential flow paths towards Lake Baringo, (ii) the required lake water volume changes, until the sill point is reached and (iii) the mean rainfall conditions, which would be necessary to provide the required volume and a sustained flow towards Lake Baringo. The analysis relies on satellite altimetry-based lake levels and lake volume variations, remote sensing-based rainfall data and lake areas but also high-resolution space-borne and UAS-based DEMs. Field surveys and electrical conductivity measurements used as a proxy to understand flow paths in the flat and swampy Loboi plain between Bogoria and Baringo complement the data basis.

To reach the sill point elevation, the lake level of Bogoria would have to increase by around 0.6–0.8 m, compared to the maximum water levels of 2020. This translates to an additional water volume of around 0.033 km³. To put this into perspective: From 2009-2014, mean annual lake levels increased by 3 m (or 0.11 km³), and after a recession phase, from 2017-2020 by 2.3 m (0.10 km²). If the sill point would be reached, the rainfall conditions in the last decade would have allowed for a permanent flow towards Baringo, at least in single years. These preliminary results suggest that it is feasible that the sill point can be reached and that a permanent flow from Bogoria towards Baringo can be sustained, if wetter conditions – as we have observed in the last decade - persist for a longer period.

How to cite: Herrnegger, M., Kray, P., Stecher, G., Cherono, N., and Olang, L.: On the potential cross-mixing of Lake Bogoria and Baringo in the Rift Valley of Kenya, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-76, https://doi.org/10.5194/egusphere-gc8-hydro-76, 2023.

15:00–15:10
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GC8-Hydro-98
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Session 5
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Monitored Groundwater Storage Change:  An Overlooked, Essential Driver of Groundwater Management 
Graham Fogg and Carlos Flores

Groundwater overdraft is a global problem demonstrating a general inability of modern civilization to manage groundwater demand. Climate change only makes this problem more acute and challenging. A key reason for chronic overdraft is the relative invisibility of groundwater and pumpers’ effects on it. Here I assert (1) the need for real-time monitoring of an overlooked metric – change in groundwater storage (Δs), (2) its transformative potential for groundwater management and (3) a simple yet new approach to monitor Δs in real time. The hydrology community has failed to learn a key lesson from the impressive successes of measuring sub-continental scale Δs with GRACE satellite technology. The lesson: monitoring Δs (rather than simply changes in groundwater levels, Δh) increases dramatically peoples’ awareness of groundwater overdraft and their motivation to better manage groundwater. Unfortunately, the sub-continental resolution (~400 km) of GRACE makes it ineffective as a tool for monitoring and managing groundwater at a functional basin scale, which is typically on the order of 10’s of km and rarely as large as ~400 km. Although monitoring of Δs in shallow, unconfined aquifers is relatively simple, it is much more challenging in most sedimentary basins that contain most of the world’s major aquifer systems, and where myriad, interbedded aquifer and aquitard layers create depth-variable degrees of semi-confinement that complicate the relationships between Δs and Δh. Here I demonstrate a simple approach in which a calibrated groundwater flow model is used to translate data on Δh into real-time estimates of Δs, despite massive (104) spatial variations in the effective storage coefficients (Δs/Δh). This meta-modeling approach means that it is feasible today to monitor Δs with conventional hydrogeologic data and tools, highlighting missed opportunities for more effective, science-based groundwater management. I will also articulate the need for much greater research emphasis on new methods for monitoring Δs, including combined use of machine learning methods leveraging diverse datasets along with conventional data and models.

How to cite: Fogg, G. and Flores, C.: Monitored Groundwater Storage Change:  An Overlooked, Essential Driver of Groundwater Management, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-98, https://doi.org/10.5194/egusphere-gc8-hydro-98, 2023.

15:10–15:20
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GC8-Hydro-66
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Session 5
The role of agriculture irrigation on the Po river basin hydrological balance 
Giovanni Ravazzani, Marco Mancini, Mouna Feki, and Alessandro Ceppi

Changes in climate can have profound effects on river systems and cause important variation in availability of water, with significant impacts on uses highly dependent on the hydrological regime, such as hydropower production and agricultural irrigation. Under this circumstances, current amount of water used for irrigation could not be sustainable in the future. This work presents insight into the Po river basin hydrological balance, investigating the impact of irrigation on water resources availability.

The extreme complexity and heterogeneity of processes involved in river basin hydrology requires the use of integrated modelling approaches for water resources planning and management. In this work the FEST-WB model was employed, that is an integrated spatially distributed physically based hydrological model capable to keep into account anthropogenic structures and management practices that interact with natural hydrological cycle such as artificial regulated reservoirs and agricultural irrigation, and interaction of stream and groundwater.

The study is performed in two steps: first, the hydrological model FEST-WB is calibrated and validated against discharge observations; second, the impact of irrigation is assessed through the simulation of different scenario of irrigation strategies.

How to cite: Ravazzani, G., Mancini, M., Feki, M., and Ceppi, A.: The role of agriculture irrigation on the Po river basin hydrological balance, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-66, https://doi.org/10.5194/egusphere-gc8-hydro-66, 2023.

15:20–15:35
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GC8-Hydro-118
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Session 5
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keynote
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How to quantify regional hydrological change impact: some examples from France 
Florence Habets

Regional hydrology vibrates to the rhythm of the weather intercepted by the soil-vegetation continuum and controlled by human abstraction and managements.
How can we interpret the observations? Does an observed trend is a signal of climate change? or natural variability ? Is the absence of trend associated to compensating trends?

To do so, long-term observations are indeed a key issue. I’ll show a study on the Seine basin, for which we wanted to assess the impact of the Atlantic Multidecadal Variability on the river & groundwater flows. To do so, 60-years is barely enough, and it was necessary to cover all the XXth century. There are few research networks on such long period, and the required observations come mostly from the public survey. Several issues were to face: data rescue, re-interpretation of the data (from river level to river discharge) and  the combined study of modeling and observations. It remains hard to interpret all the observed variations, especially due to the strong artificialization of the basin. However, it helps interpret the impact of natural variability, and how it could impact the basin in the next decades.

Long term lysimetric observations can help interpret the impact of land cover change and agricultural practices change on the regional hydrology. By using a 60-year lysimeter data set with several crop rotations and a bare soil, we were able to assess the impact of climate change and the impact of catch crop on the groundwater recharge. Unfortunately, such data set are not that common, and it is one of the objectives of the OneWater French research program to help building a lysimeter long term network in France.

Another challenge is to estimate the effect of human management on the water resource.  For groundwater and river abstraction, most of the time, the observations are partial and most often at an annual time scale. Among the human impact, those associated to large reservoirs are difficult to hide. If in Spain, there is free access to the associated data, it is more difficult in France if they are devoted to hydroelectricity or irrigation.  Small dams are far more numerous, but their direct and cumulative effects are not easy to quantify, especially, since there are few information on how the reservoir fill and spill, and how the water is used. I’ll show some elements on how the combination of biotic and abiotic data can be used to assess the impact of small reservoirs and how their impact can change with climate change.

The results were achieved in collaboration with Remy Bonnet & Julien Boé, Antoine Sobaga, Bertrand Decharme & Nicolas Beaudoin, Jérôme Molénat, Nadia Carluer, Elodie Philippe, Patrick LeMoigne & Claire Magand

How to cite: Habets, F.: How to quantify regional hydrological change impact: some examples from France, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-118, https://doi.org/10.5194/egusphere-gc8-hydro-118, 2023.

Poster: Thu, 15 Jun, 10:45–11:30 | Poster area

Chairpersons: Salvatore Manfreda, Marc Voltz
P1
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GC8-Hydro-9
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Session 5
Constraining Climate Model Projections of Regional Precipitation Change 
brian soden and Bo Zhang

As communities prepare for the impacts of climate change, policy makers and stakeholders increasingly require locally-resolved projections of future climate. Statistical downscaling uses low-resolution outputs from climate models and historical observations to both enhance the spatial resolution and correct for systematic biases. By examining the downscaled rainfall over land, we show that although bias corrections are effective in reducing biases in the current climate, they do not reduce the intermodel spread in future rainfall projections. This failure stems from the strong dependence of future rainfall change upon the current climatological rainfall patterns. Even after bias corrections are applied, the downscaled projections of precipitation change retain this dependence upon their native climatology. However, we show that this dependence can be exploited; even very simple methods to sub-set models according to their ability to resolve the observed rainfall climatology can substantially reduce the intermodel spread in rainfall projections.

How to cite: soden, B. and Zhang, B.: Constraining Climate Model Projections of Regional Precipitation Change, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-9, https://doi.org/10.5194/egusphere-gc8-hydro-9, 2023.

P2
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GC8-Hydro-29
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Session 5
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ECS
Drought Monitoring using the Enhanced Complementary Relationship of Evapotranspiration and Remote Sensing 
Homin Kim and Jagath Kaluarachchi

Many operational drought indices use precipitation and temperature data together with vegetation conditions obtained with advanced remote sensing technologies. However, there are only a few indices that use actual evapotranspiration (ET) but still do not address the effect of precipitation. In this work, we brought actual ET using enhanced complementary relationship method to include precipitation and vegetation conditions when depicting drought conditions.  We compared the proposed drought index with the U.S. Drought Monitor (USDM) which is widely used within the United States. The results of this study showed that the drought patterns from the proposed drought index are consistent with USDM, and the use of an accurate ET method improved its performance as a drought index. The key strengths of this study are that the proposed index can serve as an indicator of rapid droughts developing over a few weeks, and uniquely describes the drought conditions with vegetation conditions which have large impacts on predictions compared to other drought indices.

How to cite: Kim, H. and Kaluarachchi, J.: Drought Monitoring using the Enhanced Complementary Relationship of Evapotranspiration and Remote Sensing, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-29, https://doi.org/10.5194/egusphere-gc8-hydro-29, 2023.

P3
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GC8-Hydro-35
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Session 5
A Climate Based-Projection of Future Drought in Aegean Region of Turkey 
Mir Jafar Sadegh Safari, Mustafa Nuri Balov, and Babak Vaheddoost

The frequency, intensity and duration of drought events are expected to increase during the coming years. Hence, the resilience against climate changes and water deficit would be of concerns to ensure agro-food and energy safety. To address this issue, the outputs of general circulation models (GCM) under various emission scenarios are used to generate two meteorological and hydrological drought indices for a number of meteorological stations scattered in three major basins namely Buyuk Menderes, Kucuk Menderes, and Gediz located in the western Turkey (the Aegean Region). The biases in the outputs of GCMs were corrected using linear scaling method with respect to the reference period (1990-2020). The results were assessed in two 30-years period as mid-time future (2041-2070) and late future (2071-2100). Afterward, the well-known standard precipitation index (SPI) together with the streamflow drought index (SDI) are determined based on the outputs of the climate scenarios for the allocated time periods. The results of the study showed a significant increase in the number and severity of the drought events by the end of the century under all emission scenarios.  

How to cite: Safari, M. J. S., Nuri Balov, M., and Vaheddoost, B.: A Climate Based-Projection of Future Drought in Aegean Region of Turkey, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-35, https://doi.org/10.5194/egusphere-gc8-hydro-35, 2023.

P4
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GC8-Hydro-41
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Session 5
OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments 
Jérôme Molénat, Damien Raclot, Rim Zitouna, Jean Albergel, and Marc Voltz and the OMERE Team

This communication is dedicated to the Mediterranean agro-hydrological observatory OMERE (Mediterranean Observatory of Rural Environment and Water). It aims to explain the observation strategy and to highlight how this strategy and the associated research have contributed to a better understanding of the impact of agricultural and land management on water and soil resources in Mediterranean catchments.

OMERE is a Franco-Tunisian observatory based on two agricultural catchments, one in northern Tunisia and the other in southern France, representing the diversity of agricultural and ecosystem situations in hilly Mediterranean regions. The observatory was created more than twenty years ago to answer key scientific questions concerning the impact of global changes on soil and water resources (Voltz and Albergel, 2002). More specifically, the motivation has been to study how hydrological processes involved in water cycles and in the mass transport, such as contaminants and sediments, are affected by changes in farming practices and landscape management . The processes underlying these changes may be slow, such as in land use or contaminant dynamics, or infrequent over time, such as erosion. Understanding these processes and their relationship requires long-term observations to capture slow dynamics or infrequent events, which motivated the OMERE observatory.

The OMERE observatory belongs to the French national network OZCAR, dedicated to the observation of the critical zone. The observation strategy is motivated by monitoring the flow of water, sediments and contaminants and hydrological and climatic variables at different spatial scales from cultivated plots and landscape elements to the catchment scale (Molénat et al., 2018). These measurements were made with fine temporal resolution on a long-term scale and examining land use, agricultural practices and soil surface characteristics. The long-term observation strategy aims to support multidisciplinary integrative research to elucidate the conditions that improve soil and water management and the provision of ecosystem services in the Mediterranean context of rain-fed agriculture. The observatory helped to address three scientific questions: (i) better understand water flows, erosion and contaminants, in particular pesticides, and their natural and anthropogenic factors in the short and long term; (ii) analyze the overall effects of agriculture and land management on mass flows at different scales, from the plot to the watershed or the landscape; and (iii) develop new scenarios for sustainable agricultural management and better delivery of ecosystem services. Some of the main scientific advances of research conducted using the observatory obtained through OMERE are presented. The main perspectives in matter of the observation strategy are also drawn.

References

Molénat, J., Raclot, D., Zitouna R., ...., Albergel, J., and Voltz M., 2018, OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments, Vadose Zone J., 17:180086. doi:10.2136/vzj2018.04.0086

Voltz, M., and A. Albergel. 2002. OMERE: Observatoire Méditerranéen de l’Environnement Rural et de l’Eau- Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d’Observatoire de Recherche en Environnement. Minist. Français Rech., Paris

more information at : www.obs-omere.org

How to cite: Molénat, J., Raclot, D., Zitouna, R., Albergel, J., and Voltz, M. and the OMERE Team: OMERE: A Long-Term Observatory of Soil and Water Resources, in Interaction with Agricultural and Land Management in Mediterranean Hilly Catchments, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-41, https://doi.org/10.5194/egusphere-gc8-hydro-41, 2023.

P5
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GC8-Hydro-50
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Session 5
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ECS
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GIS—based application of Benfratello's method to estimate the irrigation deficit and its variability in the Capitanata plain under climate change 
Marco Peli, Muhammad Faisal Hanif, Stefano Barontini, Emanuele Romano, and Roberto Ranzi

Benfratello's Contribution to the study of the water balance of an agricultural soil (Contributo allo studio del bilancio idrologico del terreno agrario) was firstly published in 1961. The paper provides a practical conceptual and lumped method, based on climatic forcings and on the field capacity, to determine the irrigation deficit in agricultural districts. It generalizes the previous Thornthwaite (1948) and Thornthwaite and Mather (1955) water balances thanks to the application of a dimensionless approach introduced by De Varennes e Mendonça (1958), and of a power—law desiccation function. Since then, it has been used in many semi—arid areas in Southern Italy.

Due to its simplicity and to the small number of required parameters, Benfratello's method could be regarded to as an effective tool to assess the effects of climatic, landuse and anthropogenic changes on the soil water balance and on the irrigation deficit, both at the climatic scale and in real time.

In previous EGU—GA contributions (Barontini et al., 2021, 2022) we presented a GIS—based implementation of Benfratello's method to assess the irrigation deficit in the Capitanata plain (4550 km2), and a theoretical development of the method to estimate in closed form the interannual variability of the calculated irrigation deficit, once known the variability of temperature and precipitation.

In this contribution we present the results obtained by applying the GIS—based Benfratello framework to assess the irrigation deficit and its variability in the Capitanata plain under different climate change scenarios.

The scenarios were generated with the following procedure: (i) evaluation of different GCMs (CNRM-CM5, CMCC-CM and IPSL-CM5A-MR) in comparison with the historical data, (ii) correction of systematic biases, (iii) application of the same biases to the corresponding IPCC RCP4.5 and RCP8.5 scenarios, (iv) statistical downscaling of the obtained models to estimate future time series for the meteorological stations of interest in the considered case study and (v) spatial interpolation with ordinary Kriging.

How to cite: Peli, M., Hanif, M. F., Barontini, S., Romano, E., and Ranzi, R.: GIS—based application of Benfratello's method to estimate the irrigation deficit and its variability in the Capitanata plain under climate change, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-50, https://doi.org/10.5194/egusphere-gc8-hydro-50, 2023.

P6
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GC8-Hydro-74
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Session 5
Historical and future changes on water resources in the Flumendosa basin, Sardinia. 
Roberto Corona, serena Sirigu, and Nicola Montaldo

In Mediterranean climates during the winter months much of the precipitation recharges sub-surface and surface reservoirs. However, in the late winter and early spring, when vegetation growth conditions are favorable, much of the precipitation can be depleted by transpiration and, furthermore, runoff reduced directly by the increased vegetation cover. In the Mediterranean regions there is the evident effect of climate changes that it is causing several problems on the water resources availability. Several scientists have shown a strong decreasing trend in winter precipitation amounts and an evident shift in how the precipitation is distributed across the winter and spring months. Considering that most of the runoff to surface reservoirs occurs in the winter months and that spring hydrologic response is likely to be influenced strongly by vegetation, these precipitation changes can be considered hydrologically important. Case study is the Flumendosa basin (Sardinia), which is one of the case studies of the ALTOS European project, characterized by a reservoir system that supplies water to the main city of Sardinia, Cagliari. Data are from 42 rain gauges stations (1922-2021 period) over the entire basin and data of runoff are available for the same period. In the Flumendosa reservoir system the average annual input from stream discharge in the latter part of the 20th century was less than half the historic average rate, while the precipitation over the Flumendosa basin has decreased, but not at such a drastic rate as the discharge, suggesting a marked non-linear response of discharge to precipitation changes. We developed and calibrated a distributed hydrological model at basin scale which predicts runoff, soil water storage, evapotranspiration and grass and tree leaf area index (LAI). Hydrometeorological variables provided by the future climate scenarios predicted by Global Climate Model (CMPI-6 MPI-ESM1-2-LR downscaled) have been used as input in the model to predict soil water balance and vegetation dynamics under the future hydrometeorological landcover scenarios. The historical observations highlighted strong negative trends in precipitation series and in the number of wet days (examined using the Mann-Kendall trend test). The results from model application showed that tree dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with tree density changing according to seasonal rainfall. At the same time the tree dynamics affected the soil water balance. We demonstrated that future warmer scenarios would impact the forest, which could be not able to adapt to the increasing droughts. In addition,  future scenarios predict a reduction of the runoff, which is crucial for the dam reservoir recharge. The water resources system planning needs to carefully takes into account the effect of future climate change on water resources and vegetation dynamics.

How to cite: Corona, R., Sirigu, S., and Montaldo, N.: Historical and future changes on water resources in the Flumendosa basin, Sardinia., A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-74, https://doi.org/10.5194/egusphere-gc8-hydro-74, 2023.

P7
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GC8-Hydro-80
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Session 5
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ECS
TVET SUDS MAR opportunities for water sustainability 
Raushan Amanzholova, Dr.Catalin Stefan, Dr. Jana Sallwey, M.Sc. Nurlan Ongdas, Dastan Sarbassov, Akgulim Sailaubek, and Dr.Jay Sagin

Floods and droughts are widespread emergency event (EE) issues in Central Asian (CA) countries. Water sustainability and efficient use of water resources are connected to complicated problems in CA. SustDrain (https://www.susdrain.org/ )  will be reasonable to expand in an application for the proper water management, collection, and efficient use of flood water. We are working on the potential expansion in applications of the TERESA project for CA, https://teresa.inowas.com/about/. TERESA is a nature-based solution for urban catchments by combining the advantages of sustainable urban drainage (SUDS) and MAR systems. The vulnerability to flooding and the growing demand for drinkable water are complicated issues for CA regions. Integrated water management, which integrates surface water management (stormwater catchment, flood protection) and groundwater management, is required to address both issues simultaneously (recharge measures, recovery for different uses). The development of multifunctional solutions should reduce stormwater runoff and increase groundwater recharge for the mitigation of flooding and protection of groundwater-dependent ecosystems. Some of the complexities to expanding the TERESA project applications are related to the acceptance of this approach with the expansion of the connected TVET (technical and vocational education and training) programs among the CA communities. The current customs, community attitude, and legislation system will be reasonable to update in combination with water efficiency technologies, modeling, and prediction analysis. For example, snow in urban Kazakhstan areas is categorized as “ waste”, and municipalities usually collect snow and damp snow by moving out by the big tracks in the garbage collection sites, without proper localized SusDrain MAR approach, as the TERESA project implementation program suggests. The current status of the TVET SUDS MAR activities for CA communities will be presented during the conference

How to cite: Amanzholova, R., Stefan, Dr. C., Sallwey, Dr. J., Ongdas, M. Sc. N., Sarbassov, D., Sailaubek, A., and Sagin, Dr. J.: TVET SUDS MAR opportunities for water sustainability , A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-80, https://doi.org/10.5194/egusphere-gc8-hydro-80, 2023.

P8
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GC8-Hydro-110
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Session 5
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ECS
Reconstruction of annual flood series in Southern Italy 
Manuele Messina, Salvatore Manfreda, Angelo Avino, Teresa Pizzolla, and Awais Naeem Sarwar

In the last few years, several studies have detected changes in the rainfall regime which may have an impact on hydrological extremes and water resources availability. In addition, the lack of continuous observations as well as the significant transformations of river basins limits our ability to fully characterize hydrological response. Therefore, it is urgent to update current methods and tools in order to shed light on the expected hydrological changes.

In the present study, we try to construct a detailed description of extreme flow patterns in Southern Italy in the period 1920-2020. For this reason, the dataset of annual maximum discharges was constructed using all available records and extended using indirect measurements (e.g., daily discharge and water levels). The data before 1980 were collected in the SIMN Special Publication No. 17 and in the SIMN Hydrological Yearbooks, which provide the annual maximum flow rates and the annual rating curves. Hydrological observatory have been transferred to the regional Department of Civil Protection, but only water level observations are available for the most recent period.

Dataset from different sources requires a significant effort to reconstruct reliable timeseries. In order to extend the historical series of floods annual maxima, we tried to transform mean daily maxima into peak flow values by means of a conversion factor proposed by Taguas et al. (2008). Additionally, the database was also integrated with the most recent data converting water level measurements in annual floods by using the annual maxima flow rating curve. Such rating curve turned out to be quite stable over time as demonstrated by Claps et al. (2010) and it was verified using also hydraulic numerical models.

The present study results complement the outcomes of the recent study by Blöschl et al. (2017), who investigated flood trends over the last five decades in Europe. This study provided a clear overview on the recent tendencies in Europe except for southern Italy because of the limited and discontinuous data availability. Therefore, the study allowed to reconstruct a relevant number of timeseries representative of the entire southern Italy. The homogeneity of the reconstructed data have been verified using the Kolmogorov-Smirnov test. Then, the obtained series were analysed in order to detect possible trends by using the Mann-Kendall non-parametric test. Results highlights the dynamics of flood production over the entire southern Italy.

 

References

Blöschl G., Hall J., Parajka J., Perdigão R.A.P., Merz B, Arheimer B., Aronica G.T., Bilibashi A., Bonacci O., [...], Živković N. (2017). Changing climate shifts timing of European floods. Science, 357, pp. 588-59.

Claps P., Ganora D., Laio F., and Radice R. (2010) Riesame ed integrazione di serie di portate al colmo mediante scale di deflusso di piena, Atti del XXXII Convegno Nazionale di Idraulica e Costruzioni Idrauliche, Idraulica e Costruzioni Idrauliche, Palermo, 14-17 settembre 2010.

Taguas E.V., Ayuso J.L., Pena A., Yuan Y., Sanchez M.C., Giraldez J.V., and Pérez R. (2008) Testing the relationship between instantaneous peak flow and mean daily flow in a Mediterranean Area Southeast Spain, Catena, 75, pp. 129-137. https://doi.org/10.1016/j.catena.2008.04.015

How to cite: Messina, M., Manfreda, S., Avino, A., Pizzolla, T., and Naeem Sarwar, A.: Reconstruction of annual flood series in Southern Italy, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-110, https://doi.org/10.5194/egusphere-gc8-hydro-110, 2023.

P9
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GC8-Hydro-111
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Session 5
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Phenomena of Intense Climatic Changes over the Territory of Ukraine and a Vision for the Extension of the Climatic Monitoring System 
Boris Faybishenko, Mikhail Romashchenko, Roman Saydak, and Sebastien Biraud

The purpose of the presentation is to present evidence and analyze the temporal-spatial changes in the climatic zonation of the territory of Ukraine based on the evaluation of the following metrics of meteorological and water balance parameters for the period from 1945 to 2021: temperature, precipitation, relative humidity, evapotranspiration (ET), Standard Precipitation Index (SPI), and Standard Precipitation Evapotranspiration Index (SPEI). We then performed multivariate and univariate (ET and SPEI) hierarchical clustering and Principal Component Analysis (PCA) for periods before and after the temporal structural breaks/breakthroughs, which were used for zonation and 2D mapping of the territory of Ukraine. These data indicate a remarkable pattern of the spatial and temporal variability of climatic changes within the territory of Ukraine, which apparently exceeded the averaged trend of global warming. The most significant increase in temperature occurred in January–March and July–August periods. Almost in all regions of Ukraine, with the exception of central and northern parts, annual precipitation slightly increased, with the most significant increase in precipitation during the September–October period. Despite of a slight increase in precipitation, the level of moisture supply within the territory of Ukraine, resulting from the increased evaporation, has significantly worsened. However, the obtained 2D spatio-temporal data are insufficient to explain the impact of climatic processes on land-atmosphere processes in Ukraine. We hypothesize that an extension of the FLUXNET global network of micrometeorological tower sites (based on the application of eddy covariance methods) over the territory of Ukraine is needed to measure and calculate vertical turbulent fluxes within atmospheric boundary layers. This will help construct reliable 3D climatic models, which will help explain the impact of observed climatic changes on water cycle in Ukraine and surrounding European regions.

How to cite: Faybishenko, B., Romashchenko, M., Saydak, R., and Biraud, S.: Phenomena of Intense Climatic Changes over the Territory of Ukraine and a Vision for the Extension of the Climatic Monitoring System, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-111, https://doi.org/10.5194/egusphere-gc8-hydro-111, 2023.

P10
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GC8-Hydro-116
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Session 5
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Ecological flow assessment in a non-perennial river under climate variability: the case study ofthe Lake Ancipa 
Brunella Bonaccorso and Claudia Iannello

In 2012 the European Commission launched a Blueprint to Safeguard Europe's Water Resources to foster the sustainable use of water resources in agreement with the Water Framework Directive (WFD2000/60/EC). The document introduced the concept of Ecological Flow defined as the amount of
water to be maintained in a river to ensure good (or optimum) conditions for the existing ecosystems. By definition, the Ecological Flow is associated with the quality status, the hydrological regime and the morphological dynamics of the river.

In the present study a methodology for Ecological Flow assessment in a non-perennial river, established by Decree n. 30/STA 2017 of the Ministry of the Environment and Soil and Sea Conservation, is implemented. The proposed methodology is based on the monthly flow duration curve from which threshold flows are defined by the so-called Aquatic States, i.e., the set of habitats occurring on a given stream reach at a given time, depending on the hydrological conditions.

The methodology was applied to evaluate the Ecological Flow downstream of the Ancipa reservoir along the Troina river, a tributary of the Salso-Simeto river basin system in Eastern Sicily.

Monthly streamflow data used for the flow duration curve, were estimated using both a non-linear regressive model and an artificial neuronal network, calibrated and validated on monthly rainfall data and average temperature data retrieved by the BIGBANG database developed by the Italian Institute for Environmental Protection and Research (ISPRA), as well as on inflow data estimated through the reservoir water balance between 1956 and 2002. The best-performing model was therefore used to extend monthly inflow data up to 2019, using contemporary values of rainfall and temperature. Then, the monthly flow duration curve was constructed and threshold values of Ecological Flows were derived, after fitting a gamma probability distribution.

Finally, the effect of climate variability on the threshold flow values corresponding to a duration of 10 days, Q10, was analysed by means of a 30-year moving window. The results show a clear decreasing trend of Q10 values, which can be largely explained by the increase in average temperature
and, in turn, in the lake evaporation.

Further research is ongoing to assess future changes in the Ecological Flow values by forcing the proposed model with projected meteorological inputs provided by Regional Climate Models.

How to cite: Bonaccorso, B. and Iannello, C.: Ecological flow assessment in a non-perennial river under climate variability: the case study ofthe Lake Ancipa, A European vision for hydrological observations and experimentation, Naples, Italy, 12–15 Jun 2023, GC8-Hydro-116, https://doi.org/10.5194/egusphere-gc8-hydro-116, 2023.