Irrigation Supply Research Articles

Incorporating long-term numerical weather forecasts to quantify dynamic vulnerability of irrigation supply system: A case study of Shihmen Reservoir in Taiwan

Incorporating long-term numerical weather forecasts to quantify dynamic vulnerability of irrigation supply system: A case study of Shihmen Reservoir in Taiwan

Hydrochemical Characteristics and Spatial Variability in Coastal Aquifers Southern IraqUtilizing a GIS Technique

The present study investigates water quality regarding drinking and irrigation supplies by gathering and analyzing twelve groundwater samples south of Basrah, south Iraq. Many wells in the area concerned are exploited mainly for various industrial and agricultural activities, impacting the ground water quality. The standard guidelines recommended by the Iraqi Quality Standard limits and the World Health Organization have been used to determine the suitability of drinking. The physicochemica analyses showed that all sampled waters are unsuitable for the drinking supply due to high total dissolved solids (TDS) levels reaching 12925 mg/L. Four valuable indices have been applied for estimating the irrigated water quality, namely, the sodium adsorption ratio (SAR), the soluble sodium percentage (SSP%), the magnesium hazard (MH%), and Kelly’s ratio (KR%). The results of water class as regards the percent of samples showed: SAR results, 25% excellent water, 41.7% good water, and 33.3% doubtful water; SSP% results, 16.7 % good water, 75% permissible water, and 8.3 % doubtful water; MH% results, 100% suitable irrigated water; and KR% results show 41.7% suitable water and 58.3 % unsuitable water. The USSL salinity diagram (Wilcox) result revealed 83.3 % of samples fall in very high salinity-very high sodium hazard class C4S4, and 16.7 % of samples fall in very high salinity-high sodium hazard class C4S3 and very high salinity-medium sodium hazard class C4S2, respectively. Increasing salinity of coastal aquifers has impacted sources such as seawater intrusion and intensive irrigation, and usages of excessive fertilizers and herbicides can largely pollute the groundwater quality.

Overall performance assessment of selected small-scale irrigation schemes using internal and external performance indicators in West Hararghe Zone, Eastern Ethiopia

This study was conducted to evaluate the overall performance of selected small-scale irrigation schemes using internal and external performance indicators. The performance of the irrigation schemes in relation to water balance was evaluated using three indicators. The results indicated that the relative water supply (RWS), relative irrigation supply (RIS), and field application ratio (FAR) of Midagdu irrigation scheme were 0.9, 1.3, and 0.75 respectively. This indicates that the water supply is not closely related to the water demand. However, for the Wadeti Irrigation scheme, the RWS, RIS, and FAR are 0.48, 0.35, and 2.83, respectively, indicating water stress. The Midagdu irrigation scheme shows 7496.75 birr/ha for both output per unit command area and output per unit cropped area. Output per unit irrigation water supply was 12.5 birr/m3, while output per unit water consumed was 4.4 birr/m3. For the Wadeti irrigation scheme, the values were 11,276.12 birr/ha, 11,276.12 birr/ha, 8.7 birr/m3, and 1.6 birr/m3, respectively. This study results showed that the Wadeti irrigation scheme is more land-efficient, while the Midagdu scheme is more water-efficient. The values of the hydraulic performance indicators Conveyance Efficiency (Ec), Water delivery capacity (WDC), and Delivery Performance Ratio (DPR), for the Midagdu irrigation scheme were 75 %, 0.45, and 0.8, respectively, while for the Wadeti irrigation scheme, the values were 42 %, 0.11, and 0.4, respectively. These results indicate that the water delivery performance of the two schemes was poor. Therefore, improving the hydraulic performance of the scheme requires minimizing water conveyance losses.

Different Quality Index of Irrigation Water From canal of Sone River

The purpose of this research was to examine the Different quality index of irrigation watercanal of Sone river. A canal is a man-made waterway dug to provide farms with irrigation supplies. Thewater is obtained from a lake, pond, river, or reservoir. In order to combat water erosion and seepage,canals may be constructed from concrete, brick, or a flexible stone. Irrigating land using a canal andassociated irrigation system is a time-tested and cost-effective strategy. The height of the water canalintake diagrams. Irrigation systems in fields rely on water drawn from reservoirs, such as ponds andreservoirs, or river wells, which are pumped to the fields.

Unlocking Excellence: Khageri Irrigation System Benchmarking in Chitwan

The objective of the study was to assess the present service delivery, financial and productivity indicators. The performance of five branch canals i.e. Branch Canal 1, Branch Canal 4, Branch Canal 6, Branch Canal 7 and Branch Canal 8 of the Khageri Irrigation System was evaluated for 2023 AD using fifteen performance indicators under water supply, financial performance and agricultural productivity categories suggested by the International Programme for Technology and Research in Irrigation and Drainage (IPTRID). 331 farmers were interviewed in respective five branch canals from head, middle, and tail portions of the command area in order to get a representative sample. The data obtained from the interview was analysed and interpreted to calculate the values of the performance indicators. It was also found that the canal capacity and scheme infrastructure was not the limiting cause of this observation according to the calculation of water delivery capacity (1.08). The irrigation service fee charged was not sufficient to pay for the Operation and Maintenance (O&M) cost according to the calculation of revenue collection performance (0.5, 50%). Land productivity in this system was found to be unsatisfactory according to the calculations of output per unit command area (13084.76 Rs/ha), ouput per unit irrigated area (13216.93 Rs/ha) and output per unit irrigation supply (1.82 Rs/m3).

A quantitative analysis framework for analyzing impacts of climate change on water-food-energy-ecosystem nexus in irrigation areas based on WEAP-MODFLOW

Agricultural irrigation areas are vital for ensuring food security under climate change conditions with extensive water and energy consumption, which will inevitably exert pressures on ecosystem especially in arid and semi-arid areas normally with higher ecosystem degradation risk. The key to realize sustainable development lies in a quantitative analysis framework for analyzing impacts of climate change on water-food-energy-ecosystem nexus. Climate change exacerbates these challenges by impacting food production, water resources utilization, energy consumption for water supply and ecological conditions in irrigation areas. In this work, a quantitative analysis framework to analyze the trade-offs and synergies among various scenarios within the water-food-energy-ecosystem nexus in irrigation area was proposed. Two climate models (BCC and MIR1) were selected from the Coupled Model Intercomparison Project Phase 6 (CMIP6), and three Shared Socioeconomic Pathway (SSP) scenarios (SSP245, SSP370, and SSP585) were employed to quantitatively evaluate different sustainable development strategies among water, food, energy and ecosystem sectors from five key aspects: irrigation demand, food production, groundwater supply for irrigation, ecological base flow and irrigation water shortage. The results show that the sustainability index (SI) of combined management scenarios CC1-IM, CC5-IM, CC1-WSI and CC5-WSI could be 12% to 25% higher than that of the corresponding single management scenario. Among the four climate change and management scenarios, the SI of the integrated measures scenario (CC1-IM, CC5-IM) was the highest, with values of 1.39 and 1.12 respectively. This work highlights the pomising results of the integrated measures scenario in alleviating food production challenges, protecting ecological base flows, reducing groundwater extraction, alleviating irrigation water shortages and improving water supply efficiency when dealing with climate change challenges.

Determining Water Quality Status and Assimilation Capacity of Pollutant Loads in West Lombok Regency

Babak watershed is one of the essential watersheds in Lombok Island providing water supply for irrigation, fish pool, drinking water supply, and micro-hydro power plant. Excessive human activities degrade the water quality of Babak watershed, and more pollutants are present in the water column. Thus, this study aims to determine Babak watershed's water quality status and assimilating capacity to plan effective and holistic mitigation measures properly. The study calculates the pollution index (PI) using a formula based on the Minister of Environment No.115/2003 Decree and assimilating capacity (AC) based on the Minister of Environment No.110/2003 Decree. The results found that Babak watershed is lightly polluted, defined by exceeding chemical parameters such as DO, total phosphate, nitrite, and dissolved iron (Fe). Similarly, these parameters (total phosphate, nitrite, and Dissolved iron (Fe) also reached the maximum assimilation capacity of Babak watershed to contain and self-purify these pollutants from the water column. Thus, planning mitigation and adaptation measures are required to prevent further contaminations in this watershed.

Sustaining Irrigation Supplies through Immobilization of Groundwater Arsenic In Situ.

Geogenic arsenic (As) in groundwater is widespread, affecting drinking water and irrigation supplies globally, with food security and safety concerns on the rise. Here, we present push-pull tests that demonstrate field-scale As immobilization through the injection of small amounts of ferrous iron (Fe) and nitrate, two readily available agricultural fertilizers. Such injections into an aquifer with As-rich (200 ± 52 μg/L) reducing groundwater led to the formation of a regenerable As reactive filter in situ, producing 15 m3 of groundwater meeting the irrigation water quality standard of 50 μg/L. Concurrently, sediment magnetic properties were markedly enhanced around the well screen, pointing to neo-formed magnetite-like minerals. A reactive transport modeling approach was used to quantitatively evaluate the experimental observations and assess potential strategies for larger-scale implementation. The modeling results demonstrate that As removal was primarily achieved by adsorption onto neo-formed minerals and that an increased adsorption site density coincides with the finer-grained textures of the target aquifer. Up-scaled model simulations with 80-fold more Fe-nitrate reactants suggest that enough As-safe water can be produced to irrigate 1000 m2 of arid land for one season of water-intense rice cultivation at a low cost without causing undue contamination in surface soils that threatens agricultural sustainability.

Analysis of Erosion and Sedimentation Rates on the Service Life of Telaga Lebur Dam

Dam is a civil construction structure in hydrology. The concept of a dam essentially provides a solution by serving as a water reserve, meaning that during the rainy season, water is collected in the dam reservoir, and during the dry season, the stored water can be used as needed. Dams are highly effective in addressing water scarcity issues, both for raw water supply and irrigation purposes. The purpose of building dams is to create a water supply system to supply water for village residents and for irrigation needs. Water availability in dry climate regions is generally limited. Climate change phenomena exacerbate water scarcity issues. As a precaution and mitigation measure against water scarcity, the Indonesian government is actively constructing dams across various provinces. Particularly in West Nusa Tenggara (NTB), a dry climate province facing challenges in water supply for households and irrigation, dam construction is essential. The level of total erosion hazard rate in the Telaga Lebur Dam Catchment Area is 5463.94 Ton/Ha/Year. 67.78% of the area of the Telaga Lebur Dam Catchment Area (11.23 km²) experiences erosion at a rate of 3703.5 Ton/Ha/Year, classified as very light erosion. 11.58% of the area of the Telaga Lebur Dam Catchment Area (25.90 km²) experiences erosion at a rate of 632.7 Ton/Ha/Year, classified as light erosion. 9.20% of the area of the Telaga Lebur Dam Catchment Area (20.58 km²) experiences erosion at a rate of 502.7 Ton/Ha/Year, classified as moderate erosion. 3.66% of the area of the Telaga Lebur Dam Catchment Area (8.19 km²) experiences erosion at a rate of 200 Ton/Ha/Year, classified as heavy erosion. 7.78% of the area of the Telaga Lebur Dam Catchment Area (17.41 km²) experiences erosion at a rate of 425.1 Ton/Ha/Year, classified as very heavy erosion. The total sediment yield in Telaga Lebur Dam is 16.619 m³/year. The reservoir's useful lifespan based on the analysis results is 11.44 years.

Factors Affecting the Farmer’s Use of Modern Irrigation Systems in Northern Aleppo

This study investigates the adoption of modern irrigation methods, specifically sprinkler and drip irrigation, among farmers in northern Aleppo, Syria. Through a sample of 210 farmers selected via random sampling, we analyze how socio-demographic, geographic, and socio-economic factors impacting the adoption of modern irrigation methods. Using the chi-square test of independence, we compared users and non-users of modern irrigation systems to discern significant disparities across various characteristics. Our findings indicate the use of modern irrigation methods is influenced by various factors in northern Aleppo. These include the educational level of the farmers, the number of years of experience in agriculture, the size of the family, the slope of the land, the distance of the land from surface water sources, the size of the farm, the source of labor, ownership of an agricultural tractor, and the prices of agricultural inputs. In light of these insights, we propose targeted interventions by local authorities and agricultural extension organizations to promote modern irrigation methods in collaboration with educated and experienced farmers. Additionally, raising awareness among farmers about the water crisis and the importance of modern irrigation for enhancing production should be prioritized. Moreover, ensuring the accessibility of quality irrigation supplies at affordable prices, potentially through the facilitation of soft loans, stands imperative to incentivize adoption among interested stakeholders.

Calibration, testing and application of the AquaCrop model for bean crop under irrigation regimes.

Crop growth simulation models relate the soil-water-plant-atmosphere components to estimate the development and yield of plants in different scenarios, enabling the identification of efficient irrigation strategies. The aim of this study was to calibrate crop coefficients for a common bean cultivar (IAPAR 57) and assess the AquaCrop model's efficacy in simulating crop growth under different irrigation regimes (T0 - non-irrigated, T1-fully irrigated, and T2-deficit irrigated) and sowing dates (S1-March 21, S2-April 24, and S3-August 23). Successful calibration was achieved for crop seasons with suitable temperatures to crop growth (S1 and S3). However, during periods with suboptimal temperatures (April 24 season), coupled with reduced irrigation supply (T0 and T2), the AquaCrop model did not appropriately account for the combined effects of thermal and water stresses. Despite adjustments to stress coefficients, this led to an overestimation of crop growth and yield. In long-term simulations, the model successfully replicated the variability of crop water availability over cropping seasons, reflecting the impact of precipitation variations. It recommended irrigation strategies for the study region (irrigate at depletion of 120 and 170% of readily available water for sowing on March 21 and August 24, respectively) to achieve high crop yield (> 2,769kgha-1) and water productivity (1,050 to 1,445kgm-3) with minimal application depths (< 150mm). While acknowledging the need for improvements in thermal stress calculations, the AquaCrop model demonstrates promising utility in studies and applications where water availability significantly influences crop production.

Precision Phenotyping of Wild Rocket (Diplotaxis tenuifolia) to Determine Morpho-Physiological Responses under Increasing Drought Stress Levels Using the PlantEye Multispectral 3D System

The PlantEye multispectral scanner is an optoelectrical sensor automatically applied to a mechatronic platform that allows the non-destructive, accurate, and high-throughput detection of morphological and physiological plant parameters. In this study, we describe how the advanced phenotyping platform precisely assesses changes in plant architecture and growth parameters of wild rocket salad (Diplotaxis tenuifolia L. [DC.]) under drought stress conditions. Four different irrigation supply levels from moderate to severe, required to keep 100, 70, 50, and 30% of the water-holding capacity, were adopted. Growth rate and plant architecture were recorded through the digital measure of biomass, leaf area, Canopy Light Penetration Depth, five convex hull traits, plant height, Surface Angle Average, and Voxel Volume Total. Vegetation color assessments included hue, lightness, and saturation. Vegetation and senescence indices were calculated from canopy reflectance in the red (620–645 nm), green (530–540 nm), blue (peak wavelength 460–485 nm), near-infrared (820–850 nm), and 3D laser (940 nm) ranges. The temperature, relative humidity, and solar radiation of the environment were also recorded. Overall, morphological parameters, color, multispectral data, and vegetation indices provided over 7200 data points through daily scans over three weeks of cultivation. Although a general decrease in growth parameters with increasing stress severity was observed, plants were able to maintain the same morpho-physiological performances as the control during the early growth stages, keeping both 70% and 50% of the total water-holding capacity. Among indices, the Normalized Differential Vegetation Index (NDVI) contributed the most to the differentiation between different stress levels during the cultivation cycle. Across the 3 weeks of growth, statistically significant differences were observed for all traits except for the Saturation Average. Comparisons with respect to the control highlighted the strong impact of drought stress on morphological plant traits. This study provided meaningful insights into the health status of wild rocket salad under increasing drought stress.

Groundwater geochemistry and hydro-geochemical processes in coastal area South Phan Thiet, Binh Thuan Province, Vietnam

As one of the largest dragon fruit areas and many tourism projects, the southern coastal area of Phan Thiet (including three communes: Tien Thanh, Thuan Quy, and Tan Thanh) has been a bright spot in the economy of Binh Thuan. Economic development puts pressure on water resources, especially groundwater resources, the main supply for irrigation and domestic water in the region. In this research, 19 groundwater samples from the Holocene and Pleistocene aquifers were collected in February 2023 and analyzed for the concentration of Ca2+, Mg2+, Na+, K+, NH4 +, NO3 −, PO4 3-, Cl−, HCO3 –, and SO4 2-, thereby evaluating groundwater geochemistry, hydro-geochemical processes, and the suitability for irrigation purposes. The rank of cations in the aquifers of the region is Na+ > Ca2+ ∼ Mg2+, and Ca2+ ∼ Mg2+ > Na+ respectively. The concentrations of major anions in the study area are in order Cl− > HCO3 − > SO4 2- respectively. The predominant processes in the aquifer involve the interplay between rock and water as well as anthropogenic activity. The saturation indices of dolomite, gypsum, and halite are under-saturated in all collecting sample sites. According to the quality evaluation for irrigation, 14 of the 19 samples with % sodium levels less than 60 are suitable, while the others should be treated before use. The study area also indicated nitrate pollution (4/19 groundwater samples exceeding 15 mgN L−1 of the Nitrate limited for groundwater, National technical regulation on underground water quality). It is recommended that local authorities have strategies to supply water for different purposes, control pollution sources, and treat water waste to protect these aquifers.

Effect of variable irrigation supply based diversification of Bt cotton (Gossypium hirsutum)–wheat (Triticum aestivum) system on productivity, profitability, soil fertility and water expense efficiency

A field experiment was conducted during 2011–12 and 2012–13 at Morena, Madhya Pradesh, to study the ef fect of nutrition management, and methods and scheduling of irrigation on soybean [Glycine max (L.) Merr.] chickpea (Cicer arietinum L.) cropping sequence. An irrigation at 0.6 irrigation water:cumulative pan evaporation (IW:CPE) ratio resulted in significantly higher growth, yield attributes, seed yield, economic benefits and water pro ductivity of soybean compared with 0.4 and 0.8 IW:CPE. Similarly, an irrigation at 0.4 IW:CPE ratio significantly in fluenced the yield-attributing characters, seed and straw yields, economic benefits and water productivity of chickpea compared with 0.6 and 0.8 IW:CPE ratios, whereas height and number of branches increased with in creasing IW:CPE ratio. Sprinkler irrigation resulted in significantly higher growth and yield attributes, seed and straw yields, economic benefits and water productivity of both the crops. The irrigation at 0.6 IW:CPE ratio showed 51.3% and 39.0% higher seed of soybean over 0.4 and 0.8 IW:CPE ratio, whereas 0.4 IW:CPE of irrigation yielded 14.5% and 32.5% higher seed of chickpea compared with 0.6 and 0.8 IW:CPE. Mean response of sprinkler irriga tion was recorded 8.3% in soybean and 11.7% in chickpea higher seed yield over check basin irrigation. Likewise, increases in growth and yield attributes, seed yield, water productivity and protein production of soybean and chickpea were noticed with application of 75% recommended dose of fertilizer (RDF) + 2.5 t FYM/ha compared with other nutrition treatments. Addition of 75% RDF + 2.5 t FYM/ha also achieved higher system productivity, net profit and production and economic efficacy. After harvesting of the second crop of chickpea, maximum availability of N, P, K and S was recorded under 0.4 IW:CPE ratio, sprinkler irrigation and application of 75% RDF + 2.5 t FYM/ha compared to other treatments.

Coping with salinity stress: segmental group 7 chromosome introgressions from halophytic Thinopyrum species greatly enhance tolerance of recipient durum wheat.

Increased soil salinization, tightly related to global warming and drought and exacerbated by intensified irrigation supply, implies highly detrimental effects on staple food crops such as wheat. The situation is particularly alarming for durum wheat (DW), better adapted to arid/semi-arid environments yet more sensitive to salt stress than bread wheat (BW). To enhance DW salinity tolerance, we resorted to chromosomally engineered materials with introgressions from allied halophytic Thinopyrum species. "Primary" recombinant lines (RLs), having portions of their 7AL arms distally replaced by 7el1L Th. ponticum segments, and "secondary" RLs, harboring Th. elongatum 7EL insertions "nested" into 7el1L segments, in addition to near-isogenic lines lacking any alien segment (CLs), cv. Om Rabia (OR) as salt tolerant control, and BW introgression lines with either most of 7el1 or the complete 7E chromosome substitution as additional CLs, were subjected to moderate (100 mM) and intense (200 mM) salt (NaCl) stress at early growth stages. The applied stress altered cell cycle progression, determining a general increase of cells in G1 and a reduction in S phase. Assessment of morpho-physiological and biochemical traits overall showed that the presence of Thinopyrum spp. segments was associated with considerably increased salinity tolerance versus its absence. For relative water content, Na+ accumulation and K+ retention in roots and leaves, oxidative stress indicators (malondialdehyde and hydrogen peroxide) and antioxidant enzyme activities, the observed differences between stressed and unstressed RLs versus CLs was of similar magnitude in "primary" and "secondary" types, suggesting that tolerance factors might reside in defined 7el1L shared portion(s). Nonetheless, the incremental contribution of 7EL segments emerged in various instances, greatly mitigating the effects of salt stress on root and leaf growth and on the quantity of photosynthetic pigments, boosting accumulation of compatible solutes and minimizing the decrease of a powerful antioxidant like ascorbate. The seemingly synergistic effect of 7el1L + 7EL segments/genes made "secondary" RLs able to often exceed cv. OR and equal or better perform than BW lines. Thus, transfer of a suite of genes from halophytic germplasm by use of fine chromosome engineering strategies may well be the way forward to enhance salinity tolerance of glycophytes, even the sensitive DW.

Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA

Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled by complex interactions between mixed land uses, oil-field infrastructure, and natural processes. In 2020–2021, samples of groundwater and surface water were collected and analyzed for a large suite of inorganic and organic chemicals and isotope and gas tracers to test this hypothesis. Those data are supplemented with ancillary data on historical geochemistry, hydrology, geology, and oil-field infrastructure. Hydrocarbons in groundwater (e.g., methane through pentane gases and benzene) are associated with natural processes (e.g., fault offsets or transition in sediment depositional environment) and oil-field infrastructure (e.g., fluid-migration pathways associated with uncemented annulus in oil wells or unlined pits). Arsenic concentrations >10 μg per liter (μg/L; maximum concentration 12.9 μg/L) are associated with natural processes in old, high-pH groundwater, and more recent recharge of water from natural and/or engineered recharge processes. Along the southwest margin of the oil field, pumping for drinking-water and irrigation supplies in combination with engineered groundwater recharge produce a depression in groundwater elevations where groundwater with elevated sulfate concentrations from agricultural areas and groundwater with hydrocarbons from the oil field mix to produce a zone of sulfate reduction that removes hydrocarbons and arsenic from groundwater but produces elevated sulfide (S2-) concentrations (maximum concentration 29 mg per liter, mg/L). In this study, multiple approaches were required to resolve the overlapping effects of land uses, oil-field infrastructure, and natural processes on the distributions of hydrocarbons and arsenic in groundwater. The combined use of geographic, historical, physical, chemical, isotopic, and other information to constrain processes could be a useful approach for studies in other hydrocarbon-production areas. This is particularly important where land uses affect aquifer hydrology to an extent that causes mixing of groundwaters with different chemical compositions.

On‐farm performance evaluation of small‐scale irrigation schemes in the Ethiopian Rift Valley: Internal and external performance process approach

AbstractThis study evaluated the on‐farm performance of two small‐scale irrigation schemes, Furfuro and Bedene Alemtena (hereafter referred to as Bedene), in the Ethiopian Rift Valley. Two sets of performance indicator parameters were used. The first group was internal performance indicators, which included conveyance, water application and application uniformity. The water flow velocity through canals was monitored using the floating method. The amount of irrigation water applied to the fields was measured using a cutthroat flume. The second group was external performance indicators, including agricultural performance, water use performance and physical sustainability indicators. The results indicated that Furfuro had average conveyance, application and uniformity efficiencies of 84%, 59% and 50%, respectively, while that of Bedene were 79%, 63% and 55%, respectively. The overall efficiencies for both schemes were about 49%, which is lower than the minimum permissible values. The outputs per irrigation supply and consumed water for Furfuro were 0.14 and 0.16 US$/m3, respectively, and they were 0.11 US$/m3 for Bedene. The relative irrigation and total water supply of Furfuro were 1.21 and 1.20, respectively, indicating the presence of excess water in the command area during the study season. The relative irrigation and water supply of Bedene was 0.81, which indicated that the scheme was water deficient. Irrigation water management practices need improvement in the two schemes.

Performance evaluation of the Bilate and Furfuro irrigation schemes in Silti Zone, southern Ethiopia

Many irrigation schemes are performing poorly for a number of reasons, and this should be improved to increase the efficiency and productivity of the schemes. This study attempted to determine the performance of the Bilate and Furfuro irrigation schemes in Silti Zone, southern Ethiopia. For field data measurements, three farmers’ fields were selected at the head, middle, and tail end of each scheme. Average conveyance efficiencies were 53% and 56.1%, average field application efficiencies were 55.9% and 58.0%, average water storage efficiencies were 53% and 46.5%, irrigation uniformity was 91.03% and 92.9%, and overall irrigation efficiency was 28% and 32% for Bilate and Furfuro schemes respectively. This implied that the two schemes were performing inefficiently and inadequately, but water was distributed uniformly. The reason might be most canal sections had unreasonable losses of water in two schemes. Additionally, relative water supply was 0.68 and 0.79, relative irrigation supply was 0.61 and 0.77, output per unit irrigated area was 4140.4 and 1781.5 ($/ha), output per unit command area was 4510.3 and 1968.5 ($/ha), output per unit irrigation supply was 0.94 and 0.28 ($/m3), output per unit water consumed was 0.99 and 0.39 ($/m3), sustainability of irrigation area was 1.05 and 1.02, and irritation ratio was 1.11 and 1.09 for Bilate and Furfuro schemes respectively. This revealed that the applied water was not satisfied the crop water demand, but their irrigated lands were expanded for two irrigation schemes. Furfuro scheme was better than Bilate in terms of relative water supply and relative irrigation supply, but their results obtained were below acceptable values. However, Bilate scheme had significantly better land and water productivity than Furfuro scheme. This may be use high value crops, better agricultural inputs, and removal of grass cover and sedimentation from canal systems. Hence, Bilate irrigation scheme was better performing than Furfuro scheme. Therefore, adopt the best practices learned from Bilate irrigation scheme for the Furfuro scheme.

Hydro-economic basin impacts of extensive adoption of deficit irrigation by farmers: Are we overestimating water resources?

Deficit irrigation (DI) is an agronomic practice in which the volume of irrigation water applied is below maximum yield requirements, usually during drought-sensitive growth stages. DI is often used when water is scarce, and farmers need to either reduce the irrigated area or reduce the water supply to the existing irrigated area. This research presents an agroeconomic model of field efficiencies and related losses to study the relationship between DI adoption and return flows (RF). Results show that RF are significantly overestimated when DI is widely adopted as there are no losses when relative irrigation supply (ν) is low. The hydrological impact at basin level has been illustrated for the Guadalquivir River Basin, showing that RF and water resources are substantially overestimated when constant efficiency values (an assumption common to many hydrological models) are used without including the impact of DI on RF.

Sodium accumulation vs. nitrate leaching under different fertigation regimes in greenhouse soils in South Uruguay

In greenhouse conditions, soil salinity and N leaching depend on the provision of irrigation, the irrigation water quality and the application of fertilizers and organic amendments. The objective of this study was to quantify and analyze the accumulation and/or leaching process of NO3- and Na+ in greenhouse tomato production in the south region of Uruguay in fine-textured soil under different fertigation regimes. The study was conducted in four tomato crops during 2019/20/21 seasons. Three fertigation regimes were applied. Irrigation volume was the same for all treatments. Drainage was determined by using free drainage lysimeters. Concentration in soil solution and leaching of NO3- and Na+ was measured by monitoring soil solution and drainage solution. Yield, N uptake and N utilization efficiency were determined for each treatment. Soil total drainage was the main factor explaining N and Na+ leaching. The leaching of N ranges from 0 to 23.4 kg N ha-1 per tomato crop with total drainage between 0 and 46.2 % of total irrigation. Drainage necessary to avoid Na+ accumulation was 13 % of total irrigation. This drainage produced 8.4 kg of N leaching per ha-1 during tomato cropping period. Optimizing irrigation is the key factor to the salinity-nitrogen leaching paradox. Irrigation amount and timing should attempt: (1) to avoid excessive irrigation when NO3- concentration in soil solution is high, and (2) to apply leaching irrigation when Na+ concentration in soil solution is high. Soil solution monitoring with suction probes and rapid chemical analysis systems could be a useful tool to identify periods of high risk of N leaching and the right time for leaching irrigation.