Inducing Water Productivity from Snow Cover for Sustainable Water Management in Ibrahim River Basin, Lebanon

International audienceThe aim of this paper is to explore the effects and linkages between snow cover areas, distribution, probability and measured water discharge along east Mediterranean coastal watershed using moderate-resolution satellite images (MODIS-Terra). The Nahr Ibrahim River is a typical Lebanese watershed with an area of 326 km2 stretching between the sea and mountainous terrain to the east. The largest snow cover often exists in January-February with snow-free conditions between June and November. Image analysis enabled to analyze the temporal variability of the mean and maximum monthly areas of snow cover between 2000 and 2013. Snow cover dynamics were compared with the discharge from main springs (Afqa and Rouaiss) feeding the river and the probability of snow cover was estimated. The mean monthly snow cover, snow melting rates and springs discharge were found to be in direct relationship. In addition, the measured water discharge at the river mouth was found to be higher than the discharge of the two main feeding springs. This indicates a contribution of groundwater to the stream flow, which is again in direct connection with snow melting at the upper bordering slopes and probably from neighboring watersheds. Considering the characteristics of the mountainous rocks (i.e. Sinkholes, fissured and karstified limestone), the pedo-climatic and land cover conditions affect the hydrological regime which is directly responding to the area and temporal distribution of snow cover, which appears after two months from snowing events. This is reflected on water productivity and related disciplines (Agricultural yield, floods). This study highlights the potential of satellite snow detection over the watershed to estimate snow cover duration curve, forecast the stream flow regime and volume for better water management and flood risk preparedness

Assessing Transmission Losses through Ephemeral Streams: A Methodological Approach Based on the Infiltration of Treated Effluents Released into Streams

Climate change and anthropogenic pressures are the main drivers of the quantitative and qualitative depletion of water bodies, worldwide. Nowadays, in many urban areas, discharging effluents from wastewater treatment plants (WWTPs) into surface water bodies is a management solution to face the problem of water scarcity and sustain environmental flows. Although this practice can cause some concerns in public opinion about possible ecological side-effects and impairment of quality on receiving streams, it is an important contribution to the environmental baseflow of ephemeral streams, but also to groundwater recharge, especially during dry seasons, and in semi-arid and arid regions. This latter occurs through losing reaches along the streambed, though many factors may affect the infiltration rate, such as spatial distribution of streambed sediments and bedrock or the presence of channel lining. Moving from such premises, this study focuses on the Canale Reale River, an effluent-fed stream located nearby the city of Brindisi on the south-eastern side of the Apulia Region, in Italy. The Canale Reale flows through the Torre Guaceto protected wetland, located along the Adriatic coast. It collects effluents from four WWTPs with wastewater contributing for about 16.5% of the annual volume of channel drainage (i.e., 3.82 Mm3 out of 23.02 Mm3 along its 50 km long course). Within the framework of a complex geological setting, the Canale Reale River crosses different lithologies, which implies different streambed infiltration conditions. Using the Reach Length Water Balance method (RLWB), the transmission losses between the watercourse and the underlying aquifers were investigated. Particularly, the method allowed for the estimation of a spatially-average value of the riverbed’s infiltration rate applicable to the whole river course as well as the minimum, average, and maximum potential transmission losses (TLP) from the river to the underlying groundwater systems. Combining the estimated TLP values and the Flow Duration Curve (FDC) allowed for the inferring of the Transmission Loss Duration Curves (TLDC). Finally, the water volume infiltrating during an average hydrological year was estimated to be 6.25 Mm3, 61% of which was due to treated wastewater discharge. The results obtained confirm that the practice of increasing the river flow rates with WWTP effluents reduces the dry riverbed periods, with potential improvements to the river’s ecological sustainability and relevant enhancement of groundwater recharge

Modelling crop pattern changes and water resources exploitation: A case study

Agriculture and farming worldwide are responsible for numerous environmental threats, including degradation of land and water resource depletion. Underlining the dynamic interaction between bio-physical and socio-economic drivers is the key towards a more sustainable land and water management. With regard to a highly-developed agricultural area in Southern Italy, multi-regression models were developed to provide an ex-post interpretation of the observed inter-annual variability of cropped land. The main drivers related to Common Agricultural Policy support, product market prices, crop yield, and irrigation water availability were investigated. The adopted models revealed the different weights of each driver. The findings reported the role that direct payments played in supporting the extension of irrigated crops, such as processing tomato. Likewise, the models pointed out the decoupled payment scheme as the most important driver of change in the crop pattern over the last years

Assessing Transmission Losses through Ephemeral Streams: A Methodological Approach Based on the Infiltration of Treated Effluents Released into Streams

Climate change and anthropogenic pressures are the main drivers of the quantitative and qualitative depletion of water bodies, worldwide. Nowadays, in many urban areas, discharging effluents from wastewater treatment plants (WWTPs) into surface water bodies is a management solution to face the problem of water scarcity and sustain environmental flows. Although this practice can cause some concerns in public opinion about possible ecological side-effects and impairment of quality on receiving streams, it is an important contribution to the environmental baseflow of ephemeral streams, but also to groundwater recharge, especially during dry seasons, and in semi-arid and arid regions. This latter occurs through losing reaches along the streambed, though many factors may affect the infiltration rate, such as spatial distribution of streambed sediments and bedrock or the presence of channel lining. Moving from such premises, this study focuses on the Canale Reale River, an effluent-fed stream located nearby the city of Brindisi on the south-eastern side of the Apulia Region, in Italy. The Canale Reale flows through the Torre Guaceto protected wetland, located along the Adriatic coast. It collects effluents from four WWTPs with wastewater contributing for about 16.5% of the annual volume of channel drainage (i.e., 3.82 Mm3 out of 23.02 Mm3 along its 50 km long course). Within the framework of a complex geological setting, the Canale Reale River crosses different lithologies, which implies different streambed infiltration conditions. Using the Reach Length Water Balance method (RLWB), the transmission losses between the watercourse and the underlying aquifers were investigated. Particularly, the method allowed for the estimation of a spatially-average value of the riverbed’s infiltration rate applicable to the whole river course as well as the minimum, average, and maximum potential transmission losses (TLP) from the river to the underlying groundwater systems. Combining the estimated TLP values and the Flow Duration Curve (FDC) allowed for the inferring of the Transmission Loss Duration Curves (TLDC). Finally, the water volume infiltrating during an average hydrological year was estimated to be 6.25 Mm3, 61% of which was due to treated wastewater discharge. The results obtained confirm that the practice of increasing the river flow rates with WWTP effluents reduces the dry riverbed periods, with potential improvements to the river’s ecological sustainability and relevant enhancement of groundwater recharge

Climate Change Adaptation in a Mediterranean Semi-Arid Catchment: Testing Managed Aquifer Recharge and Increased Surface Reservoir Capacity

Among different uses of freshwater, irrigation is the most impacting groundwater resource, leading to water table depletion and possible seawater intrusion. The unbalance between the availability of water resources and demand is currently exacerbated and could become worse in the near future in accordance with climate change observations and scenarios provided by Intergovernmental Panel on Climate Change (IPCC). In this context, Increasing Maximum Capacity of the surface reservoir (IMC) and Managed Aquifer Recharge (MAR) are adaptation measures that have the potential to enhance water supply systems resiliency. In this paper, a multiple-users and multiple-resources-Water Supply System (WSS) model is implemented to evaluate the effectiveness of these two adaptation strategies in a context of overexploited groundwater under the RCP 4.5 and the RCP 8.5 IPCC scenarios. The presented a case study that is located in the Puglia, a semi-arid region of South Italy characterized by a conspicuous water demand for irrigation. We observed that, although no significant long-term trend affects the proposed precipitation scenarios, the expected temperature increase highly impacts the WSS resources due to the associated increase of water demand for irrigation purposes. Under the RCP 4.5 the MAR scenario results are more effective than the IMC during long term wet periods (typically 5 years) and successfully compensates the impact on the groundwater resources. Differently, under RCP 8.5, due to more persistent dry periods, both adaptation scenarios fail and groundwater resource become exposed to massive sea water intrusion during the second half of the century. We conclude that the MAR scenario is a suitable adaptation strategy to face the expected future changes in climate, although mitigation actions to reduce green-house gases are strongly required

Modeling the impacts of volumetric water pricing in irrigation districts with conjunctive use of surface and groundwater resources

Water pricing has been identified as a generally valid water supply policy to help solve problems of water scarcity and competition. As for the non-agricultural sectors, in the last three decades water pricing has been widely discussed in and promoted with regard to the irrigation management, though in the actual practice its effectiveness is quite controversial. This is particularly true in semi-arid regions, where conjunctive use of collective facilities and on-farm groundwater pumps may cause conflicts and mismanagement of water resources. Under such circumstances, irrigation water pricing policies are not easy to deploy and implement effectively, due to potential occurrence of side and unintended effects. In this framework, the present work aims at investigating the impact at the district scale of water pricing policies, on both surface water (SW) and groundwater (GW) resources. In this regard, a model which deals with the analysis of farmers' decision concerning water source selection is proposed. The analysis is carried out keeping capital asset as given, also with the aim to elicit the relevance of on-farm irrigation water cost on resources use during the irrigation season. Reference is made to an intensive agricultural district in Southern Italy, conjunctively supplied by collective schemes managed by the local irrigation board and on-farm individual groundwater pumping systems. The proposed model was built along with local stakeholders, in order to (i) underline the relationship between the water tariff applied for collective supply service and the irrigation source selection during the irrigation season; and (ii) the relevance of the conjunctive use of GW based on pumping cost convenience and service standards needed to fulfill the irrigation requirements. The results have been then integrated into a quantitative water balance model, and a scenario analysis used to show the potential side impacts that a restrictive SW tariff policy applied during drought periods may have on the GW state, in different hydrological conditions

Monitoring the Drainage Efficiency of Infiltration Trenches in Fractured and Karstified Limestone via Time-Lapse Hydrogeophysical Approach

In the test site of Castellana Grotte (Southern Italy), since 2016, around 2300 m3d−1 of tertiary treated wastewater has been alternatively spread in nine infiltration trenches, dug into fractured and karstified limestone. In one of these trenches, located upstream, seasonal variations in the infiltration rate were observed, with a lower infiltration rate during summer than in winter. This effect could be due to the occurrence of a bioclogging phenomenon in the warm season. In addition, time-lapse electrical resistivity tomography (ERT) was carried out in two different periods, corresponding to the wet and dry seasons, in order to investigate the infiltration process dynamics below the bottom of the trench. Remarkable variability was observed between the south and north sides of the trench—clearly related to the local-scale heterogeneity of the rock formation of the trenches. The results suggest that such an integrated approach should be considered of great interest in case of using infiltration trenches as managed aquifer recharge (MAR) plants. This methodology could provide useful information about the heterogeneities of the rock formation, supporting an alert system for the identification of clogging effects during the life cycle of the plant

Combined Discharge and Thermo-Salinity Measurements for the Characterization of a Karst Spring System in Southern Italy

The hydrological monitoring of springs is an auxiliary and indispensable tool that goes alongside investigations in wells to reconstruct a conceptual phenomenological model of an aquifer–groundwater system and its interactions with surface waters. There are manifold ways to carry out this monitoring, but the choice of which way is significant for a correct qualitative and quantitative knowledge of spring systems. The present work focuses on the characterization of the thermo-saline and flow regimes of the Tara spring system along the northern coast of Taranto (southern Italy), where a karst groundwater basin is the major source of the Tara River and the surrounding coastal wetland. A series of measurements was carried out on the spring system to support a technical feasibility study on the possible use of the brackish water of this river to feed a future desalination plant. To estimate the flow rate, a comparison was made between different flow measurement methods in a derivation channel. Through an analysis of the available dataset, the response of the aquifer to the autumn–winter recharge, for which updated hydrologic measurements were not available, is highlighted

Appraising water and nutrient recovery for perennial crops irrigated with reclaimed water in Mediterranean areas through an index-based approach

The use of reclaimed water for agricultural irrigation is among the agronomic practices being increasingly valued by policy-makers, water planners, and regulators to pursue more sustainable resource management in many arid and semi-arid agricultural production areas worldwide. This practice can make additional supply available in water-scarce areas, provide crop nutrients, and reduce the disposal of wastewater to the environment, thus providing considerable agronomic and environmental benefits. However, the process for treated wastewater reuse is complex because of multiple interactions among technical, economic, environmental, and public health related aspects. In this context, the application of quantitative indices capturing agronomic, engineering, and environmental factors and their possible inter-relations enable to appraise the potential benefits and risks of treated wastewater reuse at individual project¿s scale and for regional policies. The present article describes a quantitative approach that utilizes a set of proposed indices to characterize various aspects affecting water and nutrient recovery for specific combinations between the characteristics of the treatment facility and the attributes of the irrigation district supplied with reclaimed water. The proposed index-based approach was tested on datasets collected for 11 pilot reuse schemes located in the Apulia region of southern Italy with the aim to evaluate the potential for water and nutrient recovery resulting from irrigation with reclaimed water. Results from the data analysis and interpretation showed that the proposed indices enabled to quantify the environmental benefits of irrigation with RW that leads to divert less freshwater from conventional sources and dispose less reclaimed water into natural water receptors, as well as the agronomic advantages of using RW, which can partially fulfill the irrigation and nutrient requirements for the supplied districts' service areas. Overall, the proposed set of indices can provide valuable information for the successful implementation of water reuse policies for irrigated agriculture.This research was co-funded by the Regione Puglia as the project “Sistema innovativo di monitoraggio e trattamento delle acque reflue per il miglioramento della compatibilità ambientale ai fini di un'agricoltura sostenibile” - SMART WATER (No. 5ABY6P0) through the INNONETWORK CALL 201