HS2.1.4 | Hydrology, hydrometeorology and climate in drylands
EDI
Hydrology, hydrometeorology and climate in drylands
Convener: Nazaré Suziane SoaresECSECS | Co-conveners: Moshe ArmonECSECS, Rodolfo NóbregaECSECS, Andries Jan De VriesECSECS, Pedro AlencarECSECS, Kathryn Fitzsimmons, Yves Tramblay
Orals
| Mon, 24 Apr, 10:45–12:30 (CEST)
 
Room 2.31
Posters on site
| Attendance Mon, 24 Apr, 16:15–18:00 (CEST)
 
Hall A
Posters virtual
| Attendance Mon, 24 Apr, 16:15–18:00 (CEST)
 
vHall HS
Orals |
Mon, 10:45
Mon, 16:15
Mon, 16:15
Water is the main influencing factor for life in drylands. Dryland ecosystems and their inhabitants strongly rely on the scarce and often intermittent water availability in these regions. Drylands' characteristics make them more vulnerable to climate variability and more susceptible to the impact of extreme events. These events can reshape the landscape through the mobilisation of surface sediments and forming sedimentary deposits, which preserve and allow the reconstruction of past states of the Earth's system, including changes in the extent of deserts. Nevertheless, the study of hydroclimatic processes in drylands remains at the periphery of many geoscientific fields. A proper understanding of the hydrological, hydrometeorological and climatic processes in these regions is a cornerstone to achieve the proposed sustainable development goals we set for the end of this century.

This session brings together scientific disciplines addressing drylands' full range of environmental and water-related processes. The purpose is to foster interdisciplinary research and expand knowledge and methods established in individual subdisciplines.

Orals: Mon, 24 Apr | Room 2.31

Chairpersons: Nazaré Suziane Soares, Moshe Armon, Rodolfo Nóbrega
10:45–10:50
Hydrological processes from a watershed or restricted area perspective
10:50–11:10
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EGU23-9959
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HS2.1.4
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solicited
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Virtual presentation
Mohamed Sultan, Karem Abdelmohsen, Hassan Saleh, and Hadi Karimi

The Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) when combined with traditional data sources (geochronology, geochemistry, hydrology, modelling) can enhance our understanding and monitoring of elements of hydrologic systems including recharge of reservoirs, groundwater flow direction and rates, and the impacts of climate change on watersheds worldwide.  We cite a few examples. Large seasonal fluctuations (peak: Nov./Dec.; trough: July/Aug.) in Lake Nasser's surface water levels are accompanied by an increase in GRACETWS (average: 50 ± 13 mm/yr, up to 77 ± 18 mm/yr) over Lake Nasser in Upper Egypt and by a progression of a front of increasing GRACETWS values (> 50 ± 13 mm) away from the lake reaching distances of up to 700 km some 3 to 5 months following peak lake level periods. Those patterns are consistent with rapid turbulent groundwater flow from Lake Nasser along preferred flow directions (networks of faults and karst topography). The Tigris Euphrates watershed (30 dams) showed an impressive recovery following a prolonged drought (2007–2018; Average Annual Precipitation [AAP]: ~400 km3) by an extreme precipitation event in 2019 (726 km3) with no parallels in the past 100 years. This recovery (113±11 km3) compensated for 50% of the losses endured during drought by impounding a large portion of the runoff within the reservoirs (capacity: 250 km3). The Aswan High Dam, with its storage capacity of 150 km3 represents one of the best-engineered systems that enabled Egypt to ride out droughts and avoid extreme flooding events that affected neighboring Sudan. Additional engineering structures are recommended to take advantage of the excess Lake Nasser waters (35 km3), now residing in the Tushka lakes. In basins lacking artificial reservoirs, a different response to extreme precipitation events is observed from temporal GRACE solutions. Extreme precipitation events (2011-2022) over northern Arabia (PPT: Hail: 8.43 km3; Ad-Dahna: 2.22 km3 and Medina: 3.71 km3) and central Arabia (PPT: Riyadh: 4.66 km3 and Mecca: 0.21 km3) produced an increase in GRACETWS that lasted for a few months only. Cyclones over Oman (2011and 2015; PPT: 6 and 6.6 km3, respectively) had a similar effect. Findings demonstrate that highly engineered watersheds are better prepared to deal with the projected increase in the frequency and intensity of extreme rainfall and drought events in the 21st century.

How to cite: Sultan, M., Abdelmohsen, K., Saleh, H., and Karimi, H.: Recharge from Reservoirs, Groundwater Flow, and Response to Climate Variability in Arid Basins: Revelations from GRACE Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9959, https://doi.org/10.5194/egusphere-egu23-9959, 2023.

11:10–11:20
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EGU23-15835
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HS2.1.4
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Highlight
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On-site presentation
Marco Doveri, Matia Menichini, Luca Foresi, Andrea Berton, Letizia Costanza, Ilaria Baneschi, Simone Da Prato, Lorenzo Milaneschi, Brunella Raco, Alessandro Santilano, Sandra Trifirò, Roberto Giannecchini, and Maurizio Burlando

Understanding and quantifying hydrology processes represent a mandatory step in semi-arid and arid regions for defining the vulnerability of these environments to climate change and human pressure, as well as for providing useful data to steer mitigation and resilience strategies. This generally valid concept becomes even more stringent for highly sensitive ecosystems, such as small islands.

It is the case of Pianosa Island (Tuscan Archipelago) that extends a few more than 10 km2 within the Tyrrhenian Sea and it is characterised by a flat morphology (maximum altitude 29 m a.s.l.) and semi-arid climate conditions (550 mm and 17 °C as mean annual precipitation and temperature).

Because of the morphology and the medium-high permeability of superficial bio-calcarenite rocks, superficial water are absent. Nevertheless, the peculiar geological-hydrogeological setting guarantee a storage of groundwater in a phreatic aquifer and semi-confined/confined system, hitherto able to satisfy the local human water demand, mainly tied to seasonal tourism (thousands of visitors/year) and domestic exigencies (less than 30 permanent people). Evapotranspiration represents the most important voice of the water budget, given the windy and relative high temperature conditions.

In the precarious hydro-equilibrium for biosphere and human communities, and considering sea-level rise and climate regime trends that the Mediterranean is experiencing, HYDRO-ISLAND project (UNESCO’s program) intends to deploy a multi-disciplinary approach (geology, hydrogeology, geochemistry, geophysics, remote sensing-smart technology) for better understanding and quantifying the hydrological processes affecting the water availability and for sharing data and transfer knowledge to the community and younger generations, possibly suggesting best practices for water sustainability.

First results pointed out as over the last decade the annual rainfall weakly tended to increase, but at the same time such increasing resulted concentrated in summer and autumn seasons, whereas during winter and spring a decreasing tendency is even observed. This precipitation regime has led to a major rate of evapotranspiration and minor effective infiltration that caused a decreasing of piezometric level over several years. Quantity and chemical-isotopic features of rainfall and effective infiltration water measured/collected by a raingauge and a high precision lysimeter describe the hydrological processes at soil level and characterize the rate and seasonality of groundwater recharge in an experimental site. Using multispectral data by drone, we are trying to extend the experimental site information to a wider area in order to understand the general behaviour at island scale. Measurements, water sampling and analyses for shallow and deep wells, together with the study of geological constraints, are highlighting the distribution and relationship among different groundwater components, including the seawater that intrudes the aquifer from the SE side of the island. Furthermore, the comparative analyses of continuative data monitoring in wells and weather station showed the presence of possible concentrated water infiltration processes during rainfall extreme events that induce a quick response of groundwater systems in terms of water level rise and decrease of electrical conductivity. Thus, elements of vulnerability of the aquifer to pollution are pointed out, as well as the possibility to provide technical solutions for enhancing water infiltration and groundwater availability.             

How to cite: Doveri, M., Menichini, M., Foresi, L., Berton, A., Costanza, L., Baneschi, I., Da Prato, S., Milaneschi, L., Raco, B., Santilano, A., Trifirò, S., Giannecchini, R., and Burlando, M.: Hydrological processes in the semi-arid small island of Pianosa: a multidisciplinary approach to increase knowledge, awareness and education on a highly climate-sensitive environment (HYDRO-ISLAND project UNESCO’s program), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15835, https://doi.org/10.5194/egusphere-egu23-15835, 2023.

11:20–11:30
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EGU23-12017
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HS2.1.4
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ECS
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On-site presentation
Anukritika Raj, Vikrant Jain, Vivek Kumar Bind, Virendra Padhya, and Rajendrakumar Dattatraya Deshpande

The Groundwater-Surface water (GW-SW) interaction governed by vertical connectivity, drainage pattern, subsurface lithology, vegetation cover, and land use determines the water availability in semi-arid dryland regions. It plays a crucial role in eco-hydrology, effective water resource management and overall socio-economic development in these marginal environments. Furthermore, the perennial dryland rivers flowing through these semi-arid dryland regions undergo substantial precipitation and flow variability, thus making sustainable water management challenging. Nevertheless, an understanding of the GW-SW dynamics, its spatial variability and the processes influencing the water supply in the semi-arid perennial dryland rivers are still lacking. For this purpose, the stable isotopes of oxygen and hydrogen, in terms of δ18O, δ2H and d-excess parameters of water samples, have been used to assess the GW-SW interaction in the semi-arid perennial Mahi River basin, India. The Mahi River has a length of ~560 km and a drainage basin area of ~34k km2. In total, 53 samples of groundwater and 14 samples of river water were collected during the dry season. In a given river transect, GW samples were collected from both river banks at a distance of around 1 km and 2km, respectively. The result shows changes in GW-SW connectivity at the reach scale. The SW in the downstream and middle reaches (36 to 208km from the river mouth) is characterised by a progressive decrease in δ18O from -1.3 ‰ to -2.6‰. The decrease in the δ18O value in the middle and downstream reaches indicates the mixing of depleted GW into the river. The trend changes in the upstream reaches (208 to 491km), where the SW becomes progressively enriched in δ18O from about -2.1‰ to 0.08‰, with reach scale variability. The upstream reaches also show a decrease in d-excess value from -3.2‰ to -7.2‰, along with the increasing δ18O values suggesting enhanced evaporation of SW during the low flow conditions. The average δ18O of SW in the middle and downstream reach is -1.9 ‰, whereas the average δ18O of the upstream reach is -0.5 ‰. The slope of the GW δ18O-δ2H regression line is lower than that of the Global Meteoric Water Line (GMWL), suggesting that the GW undergoes substantial evaporation. The variability of isotopic values and mixing of GW with SW demonstrates that the river channel shows enhanced vertical connectivity for middle and downstream reaches even during the dry season. However, there is vertical disconnectivity in the upstream reaches. This study highlights the need for different management strategies for various reaches of the spatially variable and dynamic perennial dryland rivers in a semi-arid region.

How to cite: Raj, A., Jain, V., Bind, V. K., Padhya, V., and Deshpande, R. D.: The GW-SW dynamics of a perennial dryland river in the semi-arid region, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12017, https://doi.org/10.5194/egusphere-egu23-12017, 2023.

Impact and pressure on water resources
11:30–11:40
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EGU23-780
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HS2.1.4
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ECS
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Highlight
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On-site presentation
Hiba Mohammad, Marco peli, and Stefano Barontini

Syria is now witnessing the dramatic effects of a multiyear drought that has been afflicting the country since 2006. The drought has impacted several regions, but the north-eastern Al Jazira region, corresponding to the Middle Euphrates River basin and considered the Syrian “breadbasket”, has been hammered particularly severely.

With this paper we aim at contributing to the knowledge on the consequences of multiyear meteorological drought on food security in the basin of the middle range of the Euphrates River in Syria.

Annual precipitation data were collected from 11 ground meteorological stations for the period 1983–2020 covering an area of 96800km2. Data were provided by the Syrian Ministry of Agriculture. In addition, the series of two satellite-based indices, namely Vegetation Condition Index (VCI) and Vegetation Health Index (VHI) were collected to analyse the vegetation responses to the meteorological drivers. These indices were downloaded at a resolution of 4-km for the time range 1983-2020, from the Centre for Satellite Applications and Research (STAR) of the National Oceanic and Atmospheric Administration (NOAA). The crop production data, including yields of cotton, wheat, and maize, were collected at provincial level over the period of 1983–2020 from Syria Statistical Yearbook.

Recent changes in meteorological drought features (e.g., frequency and intensity) throughout Syria for the years 1983–2020 were assessed by means of the Standard Precipitation Index (SPI), to characterize the meteorological draughtiness for the Al-Jazira region.

SPI was computed on a 12-month timeline to account for the delayed effect of rainfall deficiency on crop output. Commonly, agricultural droughts are evaluated using drought indices at these long timeframes (e.g., 18 and 24 months) because these longer timescales reflect the accumulated influence of meteorological drought that might alter soil water content and stream flow. The correlation matrices of the series of SPI, averaged at different time scales to focus on the effect of multiyear drought events, with the series of VCI and VHI, will be presented.

This work is preliminary to the GIS application of simplified Benfratello’s water balance method (Barontini et al., 2021) to assess the proneness to water scarcity and the irrigation deficit of different areas of the basin.

References

Barontini, S., Rapuzzi, C., Peli, M., and Ranzi, R.: A GIS based application of Benfratello's method to estimate the irrigation deficit in a semiarid climate, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12936, https://doi.org/10.5194/egusphere-egu21-12936, 2021.

How to cite: Mohammad, H., peli, M., and Barontini, S.: The Impact of Meteorological Drought on Vegetation Health in the Middle Euphrates River Basin (Syria), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-780, https://doi.org/10.5194/egusphere-egu23-780, 2023.

11:40–11:50
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EGU23-17048
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HS2.1.4
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ECS
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Highlight
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On-site presentation
Yiben Cheng, Xuying Bai, Xiaoxu Ma, Zhiming Xin, Wei Feng, Wenbin Yang, and Jinxin Zhou

Rainfall in arid and semi-arid areas converts faster in the local SPAC system. Deluge in drylands may be an important source of groundwater recharge. We have been conducting a thirty-year observational in the Mu Us sandy land at the northwest China, we use remote sensing imagery to observe changes in the water body area and in situ observations to monitor rainfall infiltration. A total of 30 periods of Landsat remote sensing images were processed using the Google Earth platform to obtain the characteristics of surface water body changes. The results show that there are strong seasonal characteristics in the changes of water bodies area in the Mu Us sandy land, with two peaks in April and August, and the inter-monthly area increases of 44.867 km2 (28.60%) and 47.832 km2 (28.31%) respectively. 379.770 km2 to 275.492 km2, a total reduction of 104.278 km2 (27.46%). Deep soil as a percentage of annual precipitation of woodland, shrubland, grassland, farmland and bare land were 2.88%, 17.36%, 3.64%, 1.21% and 44.30%, respectively. The change in the water body area in the Mu Us sandy land is mainly influenced by three factors, rainfall, vegetation coverage, and human activities, with a correlation coefficient of 0.57 (α=0.05) between rainfall and water body area. The correlation coefficients were 0.79, 0.79 and 0.86 (α=0.05) for the years 1991-1997, 1998-2005 and 2006-2017, respectively; vegetation coverage and water body area were negatively correlated overall in 30 years. The correlation coefficient was 0.57 (α=0.05), indicating that human activities in the Mu Us sandy land have a greater impact and human activities in the sands should be reduced in order to manage the sands.

How to cite: Cheng, Y., Bai, X., Ma, X., Xin, Z., Feng, W., Yang, W., and Zhou, J.: Response of ecological restoration to rainfall in arid zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17048, https://doi.org/10.5194/egusphere-egu23-17048, 2023.

11:50–12:00
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EGU23-583
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HS2.1.4
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ECS
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Highlight
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On-site presentation
Ajay Ajay and Prasanta Sanyal

Despite the riparian state of river Yamuna and local groundwater reserves, Delhi depends on other rivers to fulfil the rising demand for drinking water.  In the last ten years, the water demand has increased by 39% (2006-2016). In this study, we have tried to understand the domestic water supply system by studying the spatiotemporal variation in the stable isotopic composition of tap water. The stable water isotopes are powerful tracers of hydrological processes in natural and human-managed systems. There are three primary sources with distinct stable water isotopic composition River Yamuna, Upper Ganga canal, Munak canal and local groundwater reserves; the glacial-fed Himalayan rivers and canals fulfil around 90% of the water demand. Numerous government-operated treatment plants in Delhi purify the water from one of the above sources and supply it to consumers. We collected the water sample at every stage of the water supply, from the primary source to the sink, such as samples of canal or river water, raw water before treatment, filtered water after treatment, storage reservoirs, groundwater samples and finally, the household tap waters. 

Contrary to the river, canal water’s isotopic composition shows no spatial variation. Also, the isotopic composition of raw water is similar to the filtered water, indicating no significant loss due to evaporation or any other hydrological process. However, the isotopic composition of tap water shows considerable variation and deviation from its source value. In most regions, tap water’s isotopic composition is higher than that of source water. In Delhi, among all the other sources, the isotopic composition of surface water is lower than that of groundwater. Thus, only the mixing of groundwater with surface water before supplying it to households can explain the observed large variation in the isotopic composition of tap water. Furthermore, our observation suggests groundwater extraction for domestic purposes has increased from 2019 to 2021. The demand for domestic water per capita is rising with the increase in the population. However, the production of treated water is almost constant and depends upon the raw water availability. The excess extraction of groundwater fulfils the gap between supply and demand. Our study suggests that the surface water (river and canal water), or the number of treatment plants, is insufficient to meet the rising water demand in Delhi, which has led to the overexploitation of limited groundwater reserves in the past few years. Therefore, besides irrigation, the excessive groundwater extraction for domestic purposes results in a drop in the North-west India groundwater table. 



How to cite: Ajay, A. and Sanyal, P.: An increase in domestic tap water consumption led to a decline in the groundwater reserves of Delhi, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-583, https://doi.org/10.5194/egusphere-egu23-583, 2023.

12:00–12:10
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EGU23-3315
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HS2.1.4
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Highlight
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On-site presentation
Weihong Li, Zhi Li, Yaning Chen, and Gonghuan Fang

The arid Tarim River Basin, situated in the Eurasia hinterland, serves as the heart of China’s Silk Road Economic Belt. It covers an area of 1.02 million km2 and is surrounded by the Tienshan Mountains to the north, the Kunlun Mountains to the south and the Pamir to the west. During the past few decades, the contradiction between economic growth and environmental protection is particularly evident. For example, the desert riparian forest vegetation has declined along the lower reaches of the Tarim River.

Under global warming, the climate has experienced significant warming and moistening trend during 1961–2018, and the most dramatic increase has occurred since the mid-1980s. The increased precipitation and temperature and the resulted hydrological and ecological changes lead to a hot debate about the “warm–wet” trend. This study systematically investigated the climate change and their impact on hydrological and ecological processes. The temperature increased at a rate of 0.224 ℃ per decade and an evident jump was detected in 1998. For precipitation, about 72.3% meteorological stations experienced significant increase, with an average increasing rate of 7.47 mm per decade. The changes in climatic factors contribute to the changes in the accumulation and ablation of snow and glaciers, which resulted in changes in hydrological processes. The total lake area in the Tarim River has expanded at a rate of 23.79 km2 per year during 2012–2021. More specially, the lake area of Ayakum Lake (located near the northern boundary of the Tibetan Plateau) has increased by 50% since 1990, with an increment of 111.61 km2 during 1990–2000 and 401.4 km2 during2000–2020. The runoffs of the headwaters (i.e., Kaidu River, Aksu River, Yarkant River and Hotan River) of the Tarim River have also increased by a rate of 2.06×108m3, 2.11×108m3, 1.12×108m3 and 2.56×108m3 per decade, respectively.

However, the changes in ecological systems don’t reflect the wetter trend in the Tarim Basin. The negative effects of climate change on the region’s vulnerable ecology have intensified. The snowfall fraction experienced an overall declining trend, increasing at a rate of 0.6% per decade prior to the mid-1990s, followed by a downward trend at a rate of 0.5% per decade. Potential evaporation decreased at a rate of 41.66mm/10a per decade prior to the mid-1990s, and inversed to increase at a rate of 56.68 mm per decade. Prior to 1998, the normalized difference vegetation index (NDVI) of natural vegetation exhibited an increasing trend at a rate of 0.012 per decade, but from 1999 onwards, the NDVI started decreasing at a rate of 0.005 per decade. The bare soil areas of the Taklamakan Desert boundaries expanded by 7.8 % since 1990. Excessive water use, including unrestrained overpumping of groundwater, causes the loss of groundwater.

This study sheds light on the debate of changes in climate and ecological security under global warming in the endoreic Tarim River Basin. However, more efforts should be made on the continuity of these changes, which is crucial for local development and water and ecological security along the Silk Road.

How to cite: Li, W., Li, Z., Chen, Y., and Fang, G.: Is there a turning-point towards improved water and ecological security at the arid Tarim River Basin?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3315, https://doi.org/10.5194/egusphere-egu23-3315, 2023.

Atmospheric water: use and measurement
12:10–12:20
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EGU23-6074
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HS2.1.4
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On-site presentation
Dilia Kool and Nurit Agam

Atmospheric water, or non-rainfall water inputs (NRWIs) are a critical, albeit largely overlooked, component of the global hydrological cycle. Water vapor adsorption specifically, is not only the least studied form of NRWI but likely the most common one in arid areas.

Lysimeter measurements in the Negev desert during the summers of 2019-2022 indicate that water vapor adsorption in loess soil amounts to at least 33 mm when looked at cumulatively over the summer (0.3-0.5 mm night-1): about ~30% of annual rainfall (116 mm). Given the challenges using lysimeter measurements, attempts to quantify NRWI amounts and duration have generally been limited to short time periods at point or local scales. Determining the true importance of NRWIs in arid and extremely arid environments, which comprise 20% of the terrestrial surface, requires new approaches to measure water content in the 0.5-5% range.

Using weighing lysimeters as a reference, we tested of-the-shelf temperature and relative humidity sensors to assess changes in water content with high temporal resolution over longer periods of time for sand and loess soils. Relative humidity was converted to water potential (Kelvin equation). The water content was then determined using a water retention curve measured with a vapor sorption analyzer. Results showed diurnal patterns in water content consistent with lysimeter measurements. Maximum increase in water content correlated well with lysimeter measured NRWIs. While not all issues are yet resolved, this direction opens possibilities to expand our measurement capacity over longer periods of time and increase the number of measurement locations at relatively low cost. This provides one step forward in trying to understand the magnitude of NRWIs in arid environments across the globe.

How to cite: Kool, D. and Agam, N.: Atmospheric water capture by desert soils: can we measure it?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6074, https://doi.org/10.5194/egusphere-egu23-6074, 2023.

12:20–12:30
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EGU23-9376
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HS2.1.4
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ECS
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On-site presentation
Felipe Lobos Roco, Francisco Suarez, Rodrigo Escobar, Pablo Osses, Carla Ramirez, Klaus Keim, Ignacio Aguirre, Francisca Aguirre, Constanza Vargas, Francisco Abarca, and Camilo del Rio

The Atacama desert is one of the most promising places on Earth for developing solar power energy due to its aridity, irradiation, and market conditions. However, the high levels of dust attenuate solar power production. This problem is solved by frequent cleaning of the solar panels, which requires a significant amount of water in one of the driest places in the world. Despite the drought condition, the fog and dew formed at the coastal zone of the desert arise as a complementary water source that can potentially be tapped. In this study, we assess the potential of atmospheric water for usage in four solar power plants. We conduct this assessment by combining a satellite-spatial analysis of fog and low cloud frequency, a thermodynamic vertical characterization of the marine boundary layer, and an observational analysis of fog and dew collection using different instruments. Our results reveal that fog and dew are a regular phenomenon in the solar power plants analyzed, being present between 3% and 20% of the year. Oceanic conditions control such phenomena through the inland advection of the marine boundary layer. This layer interacts with a complex topography characterized by natural corridors that allow fog and low clouds to penetrate farther inland. Our observations show that fog and dew are collected mainly during the night, with average rates between 0.1 and 0.2 L m-2 day-1. Our research confirms that atmospheric water potential vastly exceeds the solar power plant water demand, demonstrating that atmospheric water is a reliable source for the industry.

How to cite: Lobos Roco, F., Suarez, F., Escobar, R., Osses, P., Ramirez, C., Keim, K., Aguirre, I., Aguirre, F., Vargas, C., Abarca, F., and del Rio, C.: The usage of fog and dew in solar power plants of the Atacama Desert, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9376, https://doi.org/10.5194/egusphere-egu23-9376, 2023.

Posters on site: Mon, 24 Apr, 16:15–18:00 | Hall A

Chairpersons: Kathryn Fitzsimmons, Yves Tramblay
A.26
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EGU23-975
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HS2.1.4
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ECS
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Shixuan Lyu and Junlong Zhang

Yellow River is the mother river of the Chinese nation. It has provided available water resources for more than 5000 years and makes the Yellow River Basin (YRB) a significant grain-producing in China. Recently, promoting the high-quality development of the YRB has been proposed as a Chinese national strategy, highlighting the high status of the YRB in China. However, covering a large area of the arid and semi-arid region, hydrometeorological extremes such as droughts have often occurred in historical periods in the YRB, with prolonged effects on agricultural production. In addition, water conflicts (i.e., water shortage) between human beings’ needs and water resource availability have been much more severe due to population growth and global warming, affecting the ecological health of basins and challenging the lives of riparian residents. Baseflow is a stable flow during the drought season to discharge total streamflow from the groundwater and other delayed sources, which is significant for maintaining the ecological health of river basins and promoting sustainable economic development in arid and semi-arid catchments. Therefore, it is urgent to investigate baseflow characteristics and their determinants for understanding the hydrological processes better and provide scientific foundations for mitigating water shortage problems in the YRB.

Based on that, we collected the daily streamflow records from the main catchments in the YRB. The daily ensembled mean baseflow records derived from Lyne-Hollick, Chapman-Maxwell, Eckhardt and United Kingdom of Institute Hydrology (UKIH) separation algorithms were obtained after the 21st century to reduce simulation uncertainties. Dynamics hydrological signatures were extracted to investigate baseflow spatiotemporal variations and their determinants. Catchments’ physical properties, including topography, vegetation, soil and human activities, were selected. The stepwise model was conducted to see how these catchments’ properties influence the hydrological signatures variability and the ranking of their importance. Our findings showed significant spatial distribution patterns of hydrological signatures in the YRB. Most of them had higher values in upstream and downstream reaches, while low values were in the middle reaches. The magnitude of temporal variation of hydrological signatures was strongly correlated with the catchment topography, vegetation conditions and cropland coverage. It is challenging to discover one single controlling property influencing hydrological signatures for all catchments across the YRB. For most of the hydrological signatures, soil textures, precipitation and vegetation conditions are the most significant influencing factors, indicating the baseflow processes are influenced by a synergistic effect in the YRB.

This study comprehensively investigated the baseflow characteristics in the whole YRB. It can not only provide scientific foundations for water resources management in the YRB but also take an example of how to quantitively evaluate the baseflow characteristics in large semi-arid and arid catchments.

How to cite: Lyu, S. and Zhang, J.: Evaluation of baseflow processes in the Yellow River Basin, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-975, https://doi.org/10.5194/egusphere-egu23-975, 2023.

A.27
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EGU23-1745
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HS2.1.4
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Highlight
Ambroise Dufour, Suleiman Mostamandi, Kasper Johansen, Oliver Lopez Valencia, and Georgiy Stenchikov

Growing forests is an effective way of removing CO2 from the atmosphere. Forestation projects were started in China, Germany, and the Middle East. Saudi Arabia announced its ambitious “Saudi Green Initiative,” intending to plant ten billion trees. Given the insufficient rainfall to support the initiative, vegetated areas will require irrigation, effectively increasing evaporation. In addition, those areas have a lower albedo than bare land, absorbing more solar radiation. Enhancing precipitation due to the recycling of evaporated water is important as it reduces the amount of freshwater required for irrigation.

In this study, we focus on the regional climate impact of irrigated forested or vegetated areas on temperature and precipitation over the Arabian Peninsula to quantify their effect on livability and evaluate the water recycling potential. First, we studied the climate effect of irrigated farming developing over vast areas in Saudi Arabia since the 1980s. The agricultural areas were mapped using available satellite-based observations from the Landsat platforms, which capture optical and thermal data every 16 days at a resolution of 30 m to 100 m. Second, we projected the climate impact of widespread forestation over the Arabian Peninsula.

The analysis of the long-term precipitation changes caused by irrigated farming is hindered by the lack of in situ observations and the limitations of global-scale observation data sets. Most reanalysis products have contradictory evaporation trends and indicate an overall reduction in rainfall since the 1980s. The recycled precipitation cannot be estimated reliably because of reanalysis increments and background rainfall variability. Presumably, the local increase in rains occurs downstream of the irrigated areas rather than over them. Along with the analysis of observations, we conducted numerical experiments mimicking the effect of irrigated agricultural fields using a non-hydrostatic regional meteorological model (WRF), covering the whole Arabian Peninsula by a 9x9 km2 grid, with 3x3 km2 nesting over the irrigated areas. Irrigation water is accounted for by tagging moisture evaporated from agricultural regions. The amount of tagged water vapor falling as rain represents recycled precipitation. The simulated evaporation and local temperature response strongly depends on the level of irrigation. Large-scale subsidence suppresses the local deep convection over most parts of the Arabian Peninsula. Strong turbulence quickly mixes evaporated water vapor within a six km thick atmospheric boundary layer, preventing precipitation in shallow convection so that the fraction of recycled rainfall appears to be low.

How to cite: Dufour, A., Mostamandi, S., Johansen, K., Lopez Valencia, O., and Stenchikov, G.: Impact of Forestation and Land-use Changes on Desert Climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1745, https://doi.org/10.5194/egusphere-egu23-1745, 2023.

A.28
|
EGU23-4167
|
HS2.1.4
|
ECS
|
Moshe Armon, Andries Jan de Vries, Francesco Marra, Nadav Peleg, and Heini Wernli

The Sahara is the largest and perhaps the driest desert in the world. This desert however, has not always been this dry. In fact, it is presumed that a few thousand years ago it was much wetter. Moreover, it is projected that, by the end of the 21st century, the Sahara will exhibit the strongest relative increase in precipitation outside the polar regions. To better grasp this information, however, we need to answer some questions: wetter than what? What is the present-day rainfall climatology of the Sahara and what are the synoptic conditions during rainstorms in the desert?

Currently, rainstorms in the Sahara are considered a rare phenomenon. However, rain-bearing cyclones intruding from wetter neighboring regions are possible, and can lead to heavy precipitation events (HPEs) which cause hazardous desert floods. When rainfall occurs, the chances for it to be observed and measured at the ground are close to zero due to the scarcity of rain gauges and the small scale of the precipitation systems. Consequently, the characteristics of rainfall during Saharan rainstorms were seldom analyzed, especially at the scale of the whole desert. In this study, we use high-resolution satellite precipitation estimates (IMERG) and meteorological reanalysis (ERA5) to (a) identify thousands of HPEs that occurred over the Sahara in the past 21 years, (b) characterize rainfall properties during these events, and (c) identify the governing atmospheric conditions on HPE-days, with a focus on surface cyclones.

Our results show that HPEs may occur throughout the entire Sahara. Summer events happen mainly in the southern Sahara. They tend to be short-lived (on average ~12 h) and small in size (~8000 km2), with high-intensity convective rainfall. Conversely, winter HPEs occur primarily in the northern and western parts of the desert, they are longer (~16 h) and larger (15,000 km2) and produce higher rainfall volumes with lower rainfall intensities. When associated with cyclones (29% of events), HPEs exhibit 15% lower rainfall intensities, and 46% higher volumes. This is likely due to a much greater (+64%) areal extent. Our analysis compensates the small number of events at each location with the huge area of the desert, so that a HPE is observed on average every second day. The high-resolution datasets we use enable us to characterize small-size events, with substantial implications for the local scales. Hopefully, such an analysis can serve as a starting point to cope with natural hazards and better understand the future of HPEs in the Sahara.

How to cite: Armon, M., de Vries, A. J., Marra, F., Peleg, N., and Wernli, H.: Heavy precipitation events where there’s no rain: Saharan rainfall climatology and its relationship with cyclones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4167, https://doi.org/10.5194/egusphere-egu23-4167, 2023.

A.29
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EGU23-5987
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HS2.1.4
|
ECS
Vilmos Steinmann and Ákos Kereszturi

There are many hydrological models for normal terrestrial environments based on precipitation related erosion, but few of them work well in arid and hyper-arid conditions. These extreme arid regions can be good Mars analogue sites to test and model the conditions and laws of precipitation fed runoff and produced erosion on the Red Planet and infer to past periods. The hydrological model we have developed is primarily designed for Martian conditions and has been tested and validated in the Zafit subbasin of the Zin basin of the Negev desert, the eastern part of Israel. The calculated model data were also compared with data from hydrological models and field measurements in the area. Our applied hydrological model without precipitation data is able to estimate the main hydrographic characteristics of the sample area, such as flow discharge, flow velocity, flow depth, and the model is also able to estimate the Formation Timescale (FTS) of some surface features, as well as vertical erosion rates. The model was developed in the open source QGIS software using SAGA and GRASS GIS modules. It uses input variables that can be measured not only under terrestrial conditions but also measured or estimated under Martian conditions, and there are good quality datasets of them. Examples of such variables are the aridity index, which plays an important role in determining the flow discharge, or the density of the rock that makes up the grains, water density, gravity, and grain size classes. The model can be run on any DTM (Digital Terrain Model), the most important constraint being that the linear unit of projection used is defined in SI metres. The hydrological part of the model is complete however under continuous development, and the final model will be complemented by a further developed erosion model to simulate long term surface evolution and change, thus facilitating the understanding of not only terrestrial but also fluvial erosion produced Martian surface changes.

How to cite: Steinmann, V. and Kereszturi, Á.: Testing hydrological model for Mars using Negev desert based field observations on the Earth., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5987, https://doi.org/10.5194/egusphere-egu23-5987, 2023.

A.30
|
EGU23-778
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HS2.1.4
|
ECS
Marco Centanni, Giovanni Francesco Ricci, Anna Maria De Girolamo, and Francesco Gentile

In the Mediterranean Region basins are characterized by a specific hydrological regime that generally includes periods of absence of flow and flash flood events. Lithological and geological features are factors that greatly affect the flow regime. In this work, the Soil and Water Assessment Tool (SWAT) model was applied to simulate the Canale d'Aiedda (Apulia, Italy) flow regime, a Mediterranean temporary karst river basin with limited data availability. Different basin delineations and model parameterizations were adopted that include: (i) cut-off of karst areas in GIS (Configuration A); (ii) setting up the basin including the karst areas (Configuration B) and (iii) parameterizing, in the calibration process, the Crack Flow function in the karst sub-basins (Configuration C). The model performed satisfactorily for daily streamflow for configurations B and C and good for A. A better simulated large floods. C was the best solution for monthly flow from May to July. Regarding the water balance, C showed higher surface runoff values and lower total water yield values than A and B. The Crack flow function proved to be a valid option to improve the simulation of hydrological processes in karst areas. Several factors, such as the final aim of the study, data availability, and basin characteristics should be considered in selecting the best model configuration.

How to cite: Centanni, M., Ricci, G. F., De Girolamo, A. M., and Gentile, F.: Different approaches to model temporary hydrological regimes in a Mediterranean karst basin using the SWAT model., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-778, https://doi.org/10.5194/egusphere-egu23-778, 2023.

A.31
|
EGU23-7066
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HS2.1.4
|
ECS
|
Nazaré Suziane Soares, Carlos Alexandre Gomes Costa, Till Francke, Pedro Henrique Augusto Medeiros, Christian Mohr, Wolfgang Schwanghart, and José Carlos De Araújo

Intermittent and ephemeral rivers are characterized by periods of drying and rewetting which occur along different reaches of the channel. Where the channel dries or develops into ponds related to factors such as discharge, topography, geology and riparian vegetation. The aim of this work is to evaluate the spatial patterns and dynamics of intermittency in reaches of a Brazilian semiarid river. Using repeated surveys with unmanned aerial vehicles (UAVs), we characterize its connectivity by identifying locations with different water condition. The Umbuzeiro River (approximately 80 km long; 6.65°S, 40.41°W) is the main river in the Benguê catchment (~1000 km²) that is controlled by the Benguê reservoir, with a storage capacity of 18 hm³. Umbuzeiro is an intermittent/ephemeral river and spatially coherent streamflow occurs mainly in the wettest months of the rain season. We conducted UAV surveys each month from March to June 2022, allowing us to produce detailed hydrological characterizations along different sections of the river. The imagery sets from different UAVs, i.e. DJI Phantom 4 pro and eBee SQ, provided relatable characteristics for a same reach. Visually analysing the reaches, their water condition was determined for smaller subsets, i.e. ponds or dry spots. Observing the temporal and spatial patterns of the presence of water on the riverbed in the different reaches for each survey, we conclude that the patterns are not only dependent on the contributing area of each section, but also on the river’s natural sinuosity, riffle-pool sequences and riparian vegetation. Our results highlight and provide an explanation for the hydrological diversity of semiarid rivers which is important to understand their ecological role and habitat.

How to cite: Soares, N. S., Costa, C. A. G., Francke, T., Medeiros, P. H. A., Mohr, C., Schwanghart, W., and De Araújo, J. C.: Spatial distribution of intermittency in a Brazilian Semiarid river, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7066, https://doi.org/10.5194/egusphere-egu23-7066, 2023.

A.32
|
EGU23-13957
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HS2.1.4
|
Roberto Corona, Serena Sirigu, Nicola Montaldo, and Gabriel G. Katul

Sardinia island is a reference for ecohydrological studies on past and future climate change effects, representing typical conditions of the western Mediterranean Sea basin. Ecosystems are heterogenous, and trees optimize the use of water through the root systems, uptaking water from the deep layers.

Two micrometeorological towers have been installed in two different sites under different precipitation conditions. The first is installed in Orroli (annual precipitation of about 600 mm), in a patchy mixture of wild olive trees and C3 herbaceous that grow in a shallow under a rocky layer of basalt, partially fractured (soil depth 15 40 cm), with a tree cover percentage of 33% in the footprint. Instead, the second is in a mountainous forest site of Quercus ilex characterized by steeper slopes and rocky outcrops (mean annual precipitation of about 800 mm), and tree cover percentage of 68% in the footprint. In both sites land surface fluxes and CO2 fluxes are estimated using the eddy correlation technique while soil moisture was estimated with water content reflectometers, and periodically leaf area index (LAI) were estimated.

The following objectives are addressed:1) pointing out the dynamics of land surface fluxes, soil moisture and CO2 for two contrasting sites; 2) assess the impact of vegetation dynamics and type on the CO2 and water balance dynamics; 3) evaluate the soil effect on water and energy budgets.

The Orroli site is more controlled by rainfall seasonality, and vegetation species use the source of water stored in the deep rocky layer to sustain their physiological activity. In the Orroli site we found seasonal dynamics in the CO2 flux and in the evapotranspiration (ET) terms, which are higher when grass and woody vegetation species are present and lower when the grass component dies. Instead, we found a constant flux of ET in the Marganai highlighting the high efficiency of tree species in extract the deep sources of water. ET is higher in the Orroli site if the grass species are present in live form, and then LE is higher in the Marganai forest. The ET of Quercus ilex in the Marganai forest seems being not controlled by surface soil moisture, because the annual precipitation is enough for sustain the transpiration needs of that fraction of tree cover. The results confirm a threshold of 700 mm/year of rain, below which rain can restrict tree cover growth.

How to cite: Corona, R., Sirigu, S., Montaldo, N., and Katul, G. G.: On the Evapotranspiration estimates of two contrasting and Heterogenous Ecosystems in Sardinia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13957, https://doi.org/10.5194/egusphere-egu23-13957, 2023.

A.33
|
EGU23-775
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HS2.1.4
|
ECS
Marianna Leone, Francesco Gentile, Antonio Lo Porto, Giovanni Francesco Ricci, and Anna Maria De Girolamo

The general aim of this work was to define a methodology for setting the environmental flows (E-Flows) in a temporary river with limited data availability through a case study. In the literature, there are many methods to set up an E-Flow, however, the issue is still an emerging discipline in non-perennial rivers due to the lack of specific guidelines at the European and national level and the limited availability of data (i.e., hydrological/biological).

The study area is the Locone river basin (219 km2) located in southern Italy. The climate is typically Mediterranean. The flow regime shows a pattern of low flow and zero flow in summer. The Locone is classified by the River Basin Authority as a temporary river. Upstream of the dam, streamflow was measured from 1971 to 1983. The main land use is winter wheat (64% of the total area), followed by broad-leaved woods (6.6%) and broad beans (5.4%). The main hydrological pressure in the basin is represented by the Locone dam. It was built in 1986 for agricultural purposes (approximately 5,000 hectares are irrigated) and for a hydroelectric power station (1,693,000 kWh / year).

To compensate for the lack of hydrological and ecological data, which characterizes these types of rivers, the open-source Soil and Water Assessment Tool Plus (SWAT +) model was applied. SWAT + is a completely revised version of the SWAT model, which is a physical scale and watershed model, which operates on a daily time step (Arnold et al., 1998). The model was calibrated (NSE = 0.720; Pbias = -11.514 and R2 = 0.84) and validated (NSE = 0.42; R2 = 0.45; Pbias = -12.5). The flow regime has been characterized under un-impacted conditions over a long period (1971-2020) using hydrological alteration indicators (IHAs) based on modeled daily flows. The E-Flow was set by fixing the variability range of each IHA within the interquartile (25th-75th percentile) by applying the Range of Variability Approach. For the Locone reservoir, the mean monthly flow of water releases, the magnitude, and duration of high and low flows, as well as the timing and frequency of floods and drought conditions were defined.

This work made it possible to test the SWAT+ model in a Mediterranean environment, confirming its potential. The applied method represents a first useful evaluation analysis that should be revised following ecological data monitoring actions to corroborate the eco-hydrological relationships.

How to cite: Leone, M., Gentile, F., Lo Porto, A., Ricci, G. F., and De Girolamo, A. M.: Predicting un-impacted flow regime in a Mediterranean catchment with SWAT+ for setting an Environmental Flow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-775, https://doi.org/10.5194/egusphere-egu23-775, 2023.

A.34
|
EGU23-14719
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HS2.1.4
|
ECS
Yash Duggad, Vikrant Jain, Virendra Padhya, and Rajendra Deshpande

Understanding the groundwater-surface water (GW-SW) interaction is critical for river management, especially in water-stressed regions such as semi-arid and arid areas. The pattern of GW-SW interaction may vary across variable valley settings, floodplain width and river planform.

This study aims to analyse the pattern of GW-SW interaction in different River Styles reaches. The study is carried out in the Sabarmati River basin in using stable isotopes. Sabarmati River is an intermittent River of 419 km in length that drains a 21,085 km2 area in the semi-arid region of Western India. Representative sites of each River Styles were selected for water level measurement and stable isotope samples. The study was conducted in the post-monsoon period of 2021-22, which represents groundwater contribution to river system after major runoff seasons. Samples at each River Styles reach were collected along a cross-section. 1 river water and up to 4 groundwater samples (2 from each bank) were collected along the transect. A total of 48 samples were collected along 11 such transects. The depth of groundwater and stage of river water at each sample site was also measured.

 

The GW depth and river stage data indicate GW-SW connection for 9 sites (all except 1 are from the upstream region), while was inconclusive for 2 (all in the middle and lower reaches). Stable isotope-based analysis suggests a similar scenario. The upper reaches, which are gaining, have enriched δO18 composition and lower d-excess than the groundwater. The depleted isotopic composition of groundwater indicates faster groundwater recharge from the meteoric water. Such reaches are characterized by boulders and gravel beds. The reach-scale variability of the river from the losing-gaining stream also collaborates with the reach-scale variation of δO18 isotopic values. The losing reach has a depleted δO18 isotopic composition than the groundwater, thus indicating recharge of groundwater from the river water and the impact of evaporation. The integration of the River Styles map and GW interaction study suggests the following – (a) Generally, River Styles that were showing connected and gaining reaches were found to have low sinuosity  (b) River Styles with occasional and discontinuous flood-plains showed an inconclusive result about river aquifer connectivity by both methods (c) For all confined or partly unconfined reaches with bedrock margin-controlled settings, a connected river aquifer system was noted. The study highlights geomorphic control on the important process of GW-SW interaction in a semi-arid river channel.  

Keywords: River style, stable isotope, river-aquifer interaction

How to cite: Duggad, Y., Jain, V., Padhya, V., and Deshpande, R.: Water level and stable Isotope based river aquifer interaction in different river styles of a semi-arid river, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14719, https://doi.org/10.5194/egusphere-egu23-14719, 2023.

A.35
|
EGU23-16423
|
HS2.1.4
Paolo Perona, Emmanuel Dubois, Montana Marshall, Fatimetou Boukhreiss, Saleck Moulaye Ahmed Cherif, Jerôme Chenal, and Charlotte Grossiord

Despite a warm and dry climate, the city of Nouakchott has been facing constant flooding for almost a decade, making part of the city inhabitable and posing long-term health threats. Groundwater levels are relatively constant over the year, except for October, when the groundwater table rises at the end of the rainy season, resulting in an almost doubled flooded area in the city compared to drier periods. Saltwater intrusion maintains a constant level in the water table beneath the city. However, the infiltration of most of Nouakchott’s used water acts as systematic artificial aquifer recharge, thus increasing the risk of groundwater saturation excess and flooding. Hence, in comparison to the driest decade (1971-1980), flooding in the city today cannot only be attributed to the slight increase in precipitation over the last decade. This project hypothesizes that increasing the resilience to urban flooding in the city of Nouakchott can be achieved by using salt-tolerant plants to lower the water table level. This work presents a joined interdisciplinary ecohydrology and plant physiology approach for monitoring and modeling the transpiration and dewatering capacity of different local tree species. The project aims to provide scenarios for an integrated and sustainable afforestation strategy for Nouakchott. In addition to increasing the city’s resilience to flooding, the role that afforestation could play to enhance the provision of sustainable services for the people and the economy (e.g., shade in the streets, potential fruit harvesting and wood market, etc.) will also be discussed. The first field campaign of the project allowed to monitor five observation wells with automatic water depth measurements and 12 sap flow sensors on three tree species. Eventually, to reinforce the relatively scarce groundwater data, a spatiotemporal time series of the city's flooded areas was also reconstructed using remote sensing data, and its reliability to calibrate an eco-hydrogeological model will be discussed.

How to cite: Perona, P., Dubois, E., Marshall, M., Boukhreiss, F., Ahmed Cherif, S. M., Chenal, J., and Grossiord, C.: Enhancing Urban Resilience to flooding using Afforestation: the case of Nouakchott city, Mauritania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16423, https://doi.org/10.5194/egusphere-egu23-16423, 2023.

Posters virtual: Mon, 24 Apr, 16:15–18:00 | vHall HS

Chairpersons: Pedro Alencar, Andries Jan De Vries
vHS.10
|
EGU23-1808
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HS2.1.4
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ECS
|
Mariame Rachdane, El Mahdi El Khalki, Mohamed Elmehdi Saidi, Mohamed Nehmadou, Abdellatif Ahbari, and Yves Tramblay

Precipitation is the main component of the hydrological cycle; it is a crucial source of data in hydroclimate applications for water resources management. However, several regions, especially mountainous and arid regions, suffer from limited data from a ground measurement network. Remotely sensed data may provide a viable alternative for these regions. This study aims to evaluate six high spatio-temporal resolution satellite products (GPM-F, GPM-L, GPM-E, CHIRPS, PERSIANN-CCS-CDR and PDIR-Now) in the sub-Saharan regions of Morocco during the period September 2000-August 2020. The record data from 33 rain-gauge stations was used to evaluate these products on two spatial scales (pixel and basin scales) and three temporal scales (daily, monthly and annually), adopting a quantitative and qualitative evaluation. For all examined timescales, the results showed that the GPM-F product performed the best quantitatively, while at the detection capability tested for different threshold and at daily time scale, the GPM near real-time products (GPM-E and GPM-L) were better at detecting more intense rainfall events higher than 40 mm/day. At the daily time scale, GPM-E and GPM-L and, on monthly and annual scales, CHIRPS and PERSIANN-CCS-CDR, provided satisfactory precipitation estimates. Moreover, the evaluation based on the altitudes of rain gauges revealed a bias increasing from low to high altitudes. The findings also highlight that the continental and mountainous basins showed the lowest performance compared to the other locations closer to the Atlantic Ocean. The latitude-based analysis showed a decrease of bias and increase of correlation towards the most arid zones. These results provide valuable information for a scarcely gauged and arid regions, showing that GPM-F could be a valuable alternative to rain gauges.

How to cite: Rachdane, M., El Khalki, E. M., Saidi, M. E., Nehmadou, M., Ahbari, A., and Tramblay, Y.: Assessment of six satellite precipitation products in a Moroccan arid area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1808, https://doi.org/10.5194/egusphere-egu23-1808, 2023.

vHS.11
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EGU23-2519
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HS2.1.4
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Efrat Morin, Tamar Ryb, Ittai Gavriely, and Yehouda Enzel

A novel quantitative assessment of late Holocene precipitation in the Levant is presented, including mean and variance of annual precipitation and their trends. A stochastic framework was utilized and allowed, possibly for the first time, linking high-quality, reconstructed rises/declines in Dead Sea levels with precipitation trends in its watershed. We determined the change in mean annual precipitation for 12 specific intervals over the past 4500 yr, concluding that: (1) the twentieth century was substantially wetter than most of the late Holocene; (2) a representative reference value of mean annual precipitation is 75% of the present-day parameter; (3) during the late Holocene, mean annual precipitation ranged between −17 and +66% of the reference value (−37 to +25% of present-day conditions); (4) the driest intervals were 1500–1200 BC and AD 755–890, and the wettest intervals were 2500–2460 BC, 130–40 BC, AD 350–490, and AD 1770–1940; (5) lake-level rises and declines probably occurred in response to trends in precipitation means and are less likely to occur when precipitation mean is constant; (6) average trends in mean annual precipitation during intervals of ≥200 yr did not exceed 15mm per decade. The precipitation trends probably reflect shifts in eastern Mediterranean cyclone tracks.

How to cite: Morin, E., Ryb, T., Gavriely, I., and Enzel, Y.: Mean, variance, and trends of Levant precipitation over the past 4500 years from reconstructed Dead Sea levels and stochastic modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2519, https://doi.org/10.5194/egusphere-egu23-2519, 2023.

vHS.12
|
EGU23-10173
|
HS2.1.4
|
Tadanobu Nakayama

In Mongolia, overuse and degradation of groundwater is a serious issue. The authors have recently applied a process-based eco-hydrology model, NICE (National Integrated Catchment-based Eco-hydrology) to urban and mining hubs to explicitly quantify spatio-temporal variations in water availability (Nakayama et al., 2021a, 2021b). In this study, NICE was scaled up to the total of 29 river basins in the entire country (Ministry of Nature, Environment and Tourism, 2013). The model simulated the effect of past climatic change and human activity on water resources during 1980-2018 there. The model reasonably reproduced observed river discharge with a maximal value during summer rainfall seasons. The simulation also revealed heterogeneous distributions of hydrologic budget and its response to climatic and anthropogenic disturbances. In addition, the authors detected hot spots of groundwater degradation by anthropogenic activity in the national scale. Analysis of relative contribution of environmental factors further clarified the characteristics in these areas and quantified spatio-temporal trends in groundwater level due to the effects of changes in precipitation and various water uses. Generally, the result showed changes in precipitation had a large effect on changes in groundwater levels until 2000. In contrast, the model clarified human activities have recently had a large impact on groundwater level changes (Banerjee et al., 2014). This trend was particularly conspicuous in river basins with urbanization and mining development such as Orkhon, Kharaa, Tuul, Galba, Ongi, Altain Uvur Govi, and Taats River Basins. This methodology is powerful to resolve future competition for water resources in areas with fewer inventory data that could potentially trigger conflicts between urban, mining, industry, herders and local communities.

 

References;

Banerjee, R., et al. 2014. 2030 Mongolia: Targeted Analysis on Water Resources Management Issues, https://www.2030wrg.org/mongolia-targeted-analysis-wrm-issues/.

Ministry of Nature, Environment and Tourism. 2013. Basin Boundary Data in Mongolia, Ulaanbaatar.

Nakayama, T., et al. 2021a. Ecological Modelling, doi:10.1016/j.ecolmodel.2020.109404.

Nakayama, T., et al. 2021b. Ecohydrology & Hydrobiology, doi:10.1016/j.ecohyd.2021.07.006.

How to cite: Nakayama, T.: Impacts of anthropogenic activity and climate change on water resources for the whole of Mongolia by using process-based eco-hydrology model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10173, https://doi.org/10.5194/egusphere-egu23-10173, 2023.