HS8.3.4

Irrigation with Treated Wastewater (TWW) is a well-known and long-established agricultural practice in Palestine. Being a source of water and nutrients, long term use of TWW can lead to imbalances that affect plant development, soil, and groundwater quality. Consequently, irrigation frequency and interval should be properly scheduled, especially when Salts and Fertilizers (FS-TWW) cannot be separated from water.

Physically based models may be relevant tools to support an adequate irrigation management with TWW for a simultaneous supply of water and fertilizers assessed pursuant to the effects of TWW on soil properties and water fluxes into and out of the root zone.

The present research was conducted in the framework of Non Conventional WAter Re-use in Agriculture in MEditerranean countries (MENAWARA) ENI CBC Med project, with the aim to propose an alternative TWW irrigation management based on both water requirements and allowable thresholds of soil solution electrical conductivity (ECe), to prevent soil salinity using physically-based Hydrus-1D model.

To this purpose, a case study in Beit Dajan cultivated with citrus and irrigated with TWW was selected to determine the long term effects of TWW on the soil and on root uptake, considering a two-year (2018-2019) simulations and generating two FS-TWW irrigation scenarios: 1) non-optimized salt supply (NONOPT-FS-TWW) where irrigation volumes fully satisfied crop evapotranspiration demand: 2) optimized salt supply (OPT-FS-TWW) accounting for crop evapotranspiration and respecting allowable thresholds of soil solution electrical conductivity (ECe) by assuming an average soil salinity tolerance in the root zone.

Soil water movement, ECe, nitrate and ammonium concentrations were simulated, inputting averaged ten-yearly climate data and soil and water quality data measured at the end of each of the two considered years. The results in terms of soil salinity and root uptake impact are considered to define a proper TWW irrigation management for citrus.

The outputs of the scenario OPT-FS-TWW clearly demonstrate the reduction of soil salinity in the root zone, and of water and nutrient fluxes below 60cm, and thus an improvement of water and nutrient uptake, as compared to NON-OPT-FS-TWW scenario.

The results suggest that aligning the classical irrigation practices to TWW reuse by considering ECe as an additional variable is appropriate, allows to curb soil salinity, and ensures root water uptake of citrus, although TWW has high salinity levels that may jeopardize plant response after a sequence of irrigation events.

How to cite: Dragonetti, G., Isleem, N., and Khadra, R.: Resizing irrigation management for TWW quality with a physically-based model to preserve soil quality: A case study in Beit Dajan-Palestine, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2067, https://doi.org/10.5194/egusphere-egu21-2067, 2021.

Agriculture is critical for human welfare and economic growth in Sub-Saharan Africa (SSA). However, especially rainfed agriculture remains vulnerable to the impacts of climate change in the region. This has generated increasing interest in practices such as Flood Based Farming Systems (FBFS) which enable turning flood water into an opportunity for crop production for smallholder farmers living in flood plains. Despite this interest, there is limited knowledge about farmers’ preference in terms of choices about a specific FBFS and therefore about which specific FBFS needs improvements for realizing its full benefits. The present study characterizes FBFS in Balaka District, Eastern Malawi, in order to develop a pilot approach for gaining knowledge and insights about farmers’ preferences. Data were collected from a sample of 398 questionnaires, direct observations, focus group discussions and key informant interviews, and they were analyzed through SPSS. Results show that Flood Recession Agriculture (FRA) was predominantly practiced (54%), together with other FBFS such as Depression Agriculture (DA), Spate Irrigation (SI) and Dug Outs (DO). Low capital investment and low level of awareness of farmers were referred to be critical for FRA adoption with (p<0.00003) and (p<0.004) respectively. Therefore, investing on FRA, which has already proven to be used in the area, could be a key to improve food security in the area. 

How to cite: Msume, A., Castelli, G., and Mwale, F.: Flood Based Farming Systems in South-Eastern Africa: Smallholder Farmers’ Choice, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-498, https://doi.org/10.5194/egusphere-egu21-498, 2021.

Drought and climatic change are among the main environmental stressors for the water and soil qualities. Soil water potential is the major soil-related factor controlling water availability to plants and their evapotranspiration. It consists of two main components: matric and osmotic potential. Although the effect of matric potential on plant evapotranspiration has been extensively studied under various conditions, there is still a lack of quantitative studies on the effects of osmotic potential on evapotranspiration.

In our study, we investigated the influence of soil osmotic potential on the evapotranspiration rate and cumulative evapotranspiration of grass planted in small laboratory lysimeters. A sandy loam soil material was packed in four lysimeters with a volume of 6000 cm³ and equal bulk density. The soil material was air dried, freed from roots and passed through a 2 mm sieve. Each lysimeter was equipped with soil sensors at two different depths to monitor soil moisture, bulk electrical conductivity, temperature, and matric potential. To obtain continuous mass balance measurements, each lysimeter was placed on a balance connected to the computer. Grass seeds were planted in each lysimeter at the same density and irrigated with distilled water until plant height was 12 cm. Irrigation water of two different qualities (EC= 0 and 4.79 dS/m) was then applied to produce different levels (0 and -0.17 MPa) of osmotic potential. The volumetric water content was adjusted to a value between 15 and 20 % in each lysimeter during the grass growth period. When the volumetric water content reached 15 %, irrigation water was added to the lysimeters to increase it to 20 %. Data were collected to calculate changes in osmotic potential relative to changes in total soil water potential. In addition, the relationship between osmotic potential and evapotranspiration rate during the growing season was determined.

Our results indicate a controlling role of soil osmotic potential on total soil water potential. This role results a significant reductions in evapotranspiration in response to increases in osmotic potential, in addition to effects on plant health. Osmotic potential has a significant function on total soil water potential when the soil becomes dry and poor water qualities are used in irrigation.

How to cite: Salman, A., Durner, W., Joshi, D. C., and Naseri, M.: The response of Evapotranspiration to osmotic potential in small-scale lab lysimeters, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3033, https://doi.org/10.5194/egusphere-egu21-3033, 2021.

This reasearch discusses the necessary tasks to carry out the hydrogeological characterization of the sands, sandstones, and gravels of the Baixo Alentejo coast. Currently, this characterization has done in detail only in the areas where these formations constitute hydro-stratigraphic units of the aquifer systems of Sines and the Alvalade Basin. In addition to system hydrogeological characterization of the system, the volume of water used for irrigation in the study area was estimated, with the aim of characterizing its inter-annual evolution between 2000 and 2018 and intra-annual for the year 2018. To do so, remote sensing and satellite image processing methods were used (LANDSAT 5 and 8 and MODIS). A synthesis of the hydrogeological characterization is presented in an area of 195.8 km², divided into two aquifer sectors, one located north of the Mira River with 94.12 km² and the other south with 101.75 km². The first stage of the work consisted of the analysis of the studied aquifers recharge based on precipitation and the analysis of piezometry data in order to define the conceptual model of hydraulic functioning of the system. The available data were obtained from fieldwork and from the LIFE-Charcos Project (LIFE12NAT / PT / 997). In parallel, an analysis of land use and occupation performed, with emphasis on the identification of irrigation areas. Finally, the volume of water used in agriculture irrigation was determined using the method of estimating the consumptive use of water in irrigation at a local scale, based on the determination of evapotranspiration values, using the algorithm SEBAL, precipitation, and  irrigation efficiency. The results obtained were validated, with high precision, through the comparison with the irrigation volumes known during 2018, and the calibration of the monthly sequential water balance model at ground level.

Key words: aquifer system of sands, sandstones and gravels of the Baixo Alentejo coast; hydrogeology; Irrigation; Remote Sensing.

How to cite: Soares Lima, T. A., Geraldes Monteiro, J. P. P., and Dias da Costa, L. R.: Hydrogeological characterization and water use of a sector of sands, sandstones and gravel on the coast of Baixo Alentejo, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3505, https://doi.org/10.5194/egusphere-egu21-3505, 2021.

Traditional irrigation systems, apart from being an important cultural heritage element, are considered vital for sustainable water resource management and climate change adaptation measures. However, these traditional forms of irrigation and agriculture, with direct implications in food security at a local scale, have been suffering from abandonment or degradation worldwide. In light of this, the need to fully comprehend the complex linkage of their abandonment with different driving forces is essential. The identification of these dynamics enables the adoption of appropriate interventions with local initiatives and policies on a larger scale.

The present scientific contribution aims at presenting a valid methodology to consistently address the multidisciplinarity and the multifacetedness that emerge in studies relating to traditional irrigation systems.

The methodological approach introduced regards that of system dynamics and is geared to outline a combined framework at the service of stakeholders and policy makers. This approach has been already adopted previously, in different studies to tackle down the complexity stemming from the heterogeneity of drivers in complex water-related and ecosystem modeling problems. Among its advantages there are its ease of implementation in any given scenario and its ability to integrate qualitative and quantitative assessments of multidisciplinary nature that can even be interconnected. Moreover, its applicability in cases affected by data scarcity allows to address issues in those areas of the world which often are more vulnerable, poorer and marginalized and which consequently suffer from a lack of interest in monitoring environmental and social variables, properly.

The abstract is based on Boselli, V., Ouallali, A., Briak, H., Houssni, M., Kassout, J., El Ouahrani, A., & Michailidi, E. M. (2020). System Dynamics Applied to Terraced Agroecosystems: The Case Study of Assaragh (Anti-Atlas Mountains, Morocco). Water, 12(6), 1693. doi.org/10.3390/w12061693

How to cite: Boselli, V., Michailidi, E. M., Kassout, J., Houssni, M., El Ouahrani, A., Sesana, M., Borroni, M., and Cristoforetti, S.: Assessing traditional irrigation systems in data scarcity conditions, a proposal for a methodological approach., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9887, https://doi.org/10.5194/egusphere-egu21-9887, 2021.

Water resources in arid regions around the world are under a lot of strain due to extremely low precipitation rates and very high evaporation. In addition to water scarcity, irrigation methods can be quite inefficient. For example, over-irrigation beyond soil saturation can cause many problems, such as increase in soil salinity and decrease in productive soil capacity.

This research aims to investigate evaporation losses in a vineyard in San Juan province, Argentina. Trucks are used to deliver irrigation water to the raisin-producing vineyard, which ends up being over-flooded due to poor irrigation schedules, making the process highly costly.
For the estimation of evaporation losses, we use a coupled water, vapor, and heat flow model implemented in DRUtES software, Kuraz and Blöcher (2020). The model’s top boundary condition solves the surface energy balance. For that we need the solar radiation as input, which we compute based on equations suggested in the FAO Irrigation and Drainage guideline No. 56 and by Saito et al. (2006).

Due to the lack of measurement data  on the study site, soil hydraulic and thermal properties are estimated. We neglect the effect of soil organic matter in the water retention model  and assume a homogenous type of soil for the thermodynamic model. While climatic data is available from a nearby meteorological station, access to backdated files is not possible. This limits our choice of simulation period. To solve this issue, we create Python codes that produce automated daily procedures to access the weather servers. This transcribed data record is then used as input for DRUtES configuration files. We also establish communication with sensors installed in the soil using Python-script automation, in order to rectify missing measurements and use them as the model’s initial conditions.

The result is output records that simulate pressure heads and water content distribution across the flow field over the simulated period. We present a system that describes the flow field allowing us to calculate evaporation rate changes with time, thereby optimizing the irrigation process according to soil and plant needs. This can be a helpful decision-making tool for farmers.

How to cite: Chmeis, A., Blöcher, J., and Kuráž, M.: Input data automation to model evaporation loss in an Argentinian vineyard using a coupled water, vapor and heat flow model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9972, https://doi.org/10.5194/egusphere-egu21-9972, 2021.

In the Mediterranean basin, rice is cultivated over an area of 1,300,000 hectares. The most important rice-producing countries are Italy and Spain in Europe (72% of the EU production; 345,000 ha), and Egypt and Turkey among the extra-EU countries (almost totality of the production; 789,000 ha). Traditionally, rice is grown under continuous flooding; thus, it requires more water than non-ponded crops. On the other hand, rice is strategic for food security in some countries such as Egypt, and human consumption in the whole Mediterranean is steadily increasing.

The MEDWATERICE project (PRIMA-Section 2-2018; https://www.medwaterice.org/), which started in April 2019, aims to explore the sustainability of innovative rice irrigation methods and technologies in the Mediterranean basin, in order to reduce rice water use and environmental impacts, and to extend rice cultivation outside of traditional paddy areas to meet the growing demand. The MEDWATERICE consortium includes universities, research centres and private companies operating in the Mediterranean area (IT, ES, PT, EG, TR, IL). Case studies (CSs) are implemented in pilot farms of the countries involved in the project. Tested alternative irrigation methods and technologies adopted in each CS are being tailored to local conditions using a participatory action research approach through the establishment of Stake-Holder Panels in each country, which include regional authorities, water managers, farmers’ associations and consultants, and private companies of the rice production chain. Irrigation strategies experimented in the pilot farms and compared to the continuous flooding (considered as the ‘reference’ irrigation method in all CSs), are: dry seeding and delayed flooding, alternate wetting and drying, lengthening of drying periods, reduction in irrigation inflow/outflow, hybrid irrigation, multi-nozzle sprinkler irrigation, surface and sub-surface drip irrigation, and waste-water reuse through sub-surface drip irrigation. For each irrigation solution, innovative technologies and the most appropriate rice varieties and agronomic practices are tested to minimize impacts of irrigation water reduction on yield quantity and quality. Data collected at the farm level are extrapolated to the irrigation district level to support water management decisions and policies. Indicators for quantitative assessment of environmental, economic and social sustainability of the irrigation options are also being defined. Outcomes produced by MEDWATERICE are expected to generate knowledge on how to improve sustainability of rice production in the countries of the Mediterranean area, with particular attention to the adoption of water-saving techniques.

During the conference, approaches and methodologies adopted and developed within the project, and results obtained so far will be presented, with particular attention to the experimentation conducted in the pilot farms, to the methods for the upscaling the achievements to the irrigation district scale, and to the set of indicators for quantifying economic, environmental and social sustainability of irrigation methods and technologies currently under definition.

How to cite: Facchi, A. and the MEDWATERICE Team: The MEDWATERICE project: Towards a sustainable water use in Mediterranean rice-based agro-ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10369, https://doi.org/10.5194/egusphere-egu21-10369, 2021.

Irrigation with treated wastewater (TWW) has become a common practice in Israel and is accepted as an environmentally responsible way of managing water resources. Although negative effects of high sodium (Na⁺) and dissolved organic carbon (DOC) concentrations have been reported, many fields have been irrigated with TWW for more than three decades. It is therefore assumed that chemical equilibrium has been reached. In recent years, however, desalination has become the main water source for urban and industrial use. Thus, the salinity of TWW is expected to decrease and the relative concentration of Na⁺ to calcium (Ca⁺²) and magnesium (Mg⁺²), quantified by the Sodium Adsorption Ratio (SAR), may increase. The effects of this new TWW quality need to be understood in order to mitigate potential damage to irrigated soils structure and hydraulic characteristics. The main objective of this study was to quantify the effects of desalinized water derived TWW with different levels of salinity, SAR and DOC on soil structural and hydraulic properties. The results demonstrated that irrigation with TWW derived from desalination is more detrimental for the soil hydraulic and structural properties when compared to TWW derived from freshwater sources. Particularly, the combination of lower salinity and higher SAR in desalination derived TWW results in a depth dependent increase of exchangeable sodium. Consequently, clay dispersion and pore clogging occurred, thus reducing the saturated hydraulic conductivity of the examined soils. Further results will be presented and the implications for long-term sustainable irrigation will be discussed. 

How to cite: Neufeld, R. and Arye, G.: Effect of desalinized water derived treated wastewater on soil structure stability and hydraulic properties, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10692, https://doi.org/10.5194/egusphere-egu21-10692, 2021.

The use of low-quality irrigation water in arid regions ensures the reconstruction of diverse physical and chemical dynamics in the soil profile. The objective of this study was to examine the efficacy of two water flow velocities of tap and sodic water for characterizing ion exchange of colloidal particles. Undisturbed samples were taken into the plexiglas columns with 40 cm in height and 6.9 cm in diameter from the dry area of Konya, Turkey. Two different water sources with varying qualities, tap water and poor quality sodic water (ESP≈20, obtained by preparing solution from analytically pure NaHCO₃), were applied to the top of the columns as leaching water in two water flow velocities; close to saturated hydraulic conductivity (Ks) (fast, saturated condition) and unsaturated condition (slow). The number of the columns with duplicated experiments was 8. In each leaching, a quarter pore volume (350 ml) of water was regularly applied and leachates were collected from the outlet of columns. The water flux in the soil column decreased faster in the fast leaching application than in slow leaching as the sodic irrigation water was applied. This shows to destructive effect of Na+ on inner surface of water flow channels in the soil. Gradual increases for the pH of the leachates in both water quality and velocity experiments were detected. The EC of the leachates dropped very fast at the beginning of leaching in both water quality applications, and then, became steady. No effect of tap water treatment on Ca⁺² contents of the leachates was observed. However, sharp decreases in Ca⁺² concentration were detected at the beginning of sodic water application, and then remained constant. All sodic water applications caused an increase in Na+ concentration of leachates till the end of treatments. In slow leaching applications, the increase in Na concentration in the leachates was slower compared to those of the fast leaching. While Ca⁺² concentrations in the leachates remained constant with tap water applications, although the soils are calcareous. Ca⁺² was transported remarkable high at the beginning of the sodic water application. As the leaching progressed, transport of Ca⁺² from the soil continued constantly due to the Na-Ca exchange processes. The effects of different leaching treatments were clearly observed from the pH-EC, Ca⁺² and Na⁺transports. Consequently, sodic water application caused significant changes in the pH values of the soils with the effect of time, and this effect was expressively marked from the changes in the salt and sodium contents of the soils.

Keywords: flux, ion exchange, leaching, saturated and unsaturated leaching, solute transport, water flow velocity

Acknowledgement: This work was supported by the Scientific and Technological Research Council of Turkey [Project number: TUBİTAK-118Y343].

How to cite: Deviren Saygin, S., Ozturk, H. S., Izci, E., Menon, M., Maghami Nick, S., Erpul, G., Mawodza, T., and Copty, N.: Solute movement through undisturbed calcareous and dry region soils under differing water flow velocities, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15203, https://doi.org/10.5194/egusphere-egu21-15203, 2021.

The use of saline groundwater for irrigation can lead to significant salt accumulation in agricultural soils. This in turn can lead to a decrease in crop yields threatening food security. This study examines the impact of irrigation pattern and soil compaction on the salt dynamics in soils. Laboratory-scale column experiments were conducted for different irrigation patterns, water quality and soil compaction conditions. Two water qualities were applied: fresh (DI water) and saline (~3.4 mS/cm). The soil columns (having 60 cm height and 16 cm diameter) were packed with agricultural soil samples from a 10-year non-tilled profile of an apple farm located in the plain of Konya, Turkey. The experiments were numerically modelled with the Hydrus-1D computer program which can simulate water and solute movement in unsaturated soils. Results show that the fate and transport of salts in the topsoil is governed by capillary action, evaporation, sub-surface soil compaction and soil moisture retention characteristics. Overall, it is demonstrated that properly managed irrigation schemes and tillage practices can help alleviate the problem of soil salinization. Farmer strategies to minimize the significance of salinity of agricultural soils are discussed.

Acknowledgement: This work was supported by the Scientific and Technological Research Council of Turkey [Project number: TUBİTAK-118Y343].

How to cite: Maghami Nick, S., Emadian, S., Deviren Saygın, S., Akça, M. O., Demirel, B., Sabri Öztürk, H., Sedighi, M., Babaei, M., and K. Copty, N.: Impact of irrigation and soil compaction on salinization of soils in semiarid agricultural lands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15370, https://doi.org/10.5194/egusphere-egu21-15370, 2021.