Agricultural Drainage Research Articles

Sustainable Development Goals for the Circular Economy and the Water-Food Nexus: Full Implementation of New Drip Irrigation Technologies in Upper Egypt

Saving fresh water is a big challenge for the next generation due to enhanced living standards and population growth. In addition, the expansion of agricultural and industrial activities is causing unmatched demands for fresh water supplies across Egypt. The Nile River is Egypt’s main water resource, representing 69.4% of the total water resources, while rainwater, torrential water and groundwater, as well as recycled agricultural and sanitary drainage water and desalinated seawater, are estimated at about 30.6%. Smart drip irrigation systems are in great demand, especially in Upper Egypt. SDG’s of the circular economy and the WEF nexus lead to full implementation of drip irrigation systems, achieving ~6.6 BM3/year of direct saving from fresh water and/or doubling the cultivated area. In addition to PV tubes and other utilities, renewable energy, e.g, photovoltaic panels, will posses an important role in low-energy driven drip irrigation systems, reducing fossil-uses, CO2 emissions and devolving more sustainable processes that are less dependent on conventional energy sources. The current research work is a case study of the substitution of flood with drip irrigation, and its positive advantages for the Egyptian agricultural economy and capital expenditures (capex), which depends on the country’s infrastructure and availability of utilities.

Study on the Hydraulic and Energy Loss Characteristics of the Agricultural Pumping Station Caused by Hydraulic Structures

The pumping station is an important part of the agricultural irrigation and drainage system. The sump is one of the common water inlet types of agricultural pumping stations. In the sump, to facilitate the installation and maintenance of equipment, some hydraulic structures, such as pump beams, maintenance platforms and chest walls, are added to the sump. At present, the impact of hydraulic structures in the sump on the hydraulic performance of the pump device is not clear, so this paper focused on the impact of hydraulic structures on the hydraulic characteristics and entropy generation characteristics of the pump device by using numerical simulation methods. The results showed that the installation of hydraulic structures in the sump has the greatest impact on the efficiency of the pump device. The efficiency coefficient increased after adding a pump beam in the sump and decreased by about 2% after adding a maintenance platform and a water retaining chest wall. Results also showed that the installation of hydraulic structures in the sump will lead to uneven distribution of entropy generation in the sump, especially in the vicinity of the hydraulic structures. The installation of the maintenance platform and chest wall will lead to the increase of the total entropy generation in the sump, which also means that the hydraulic loss in the sump will increase accordingly. Hence, in addition to the pump beam, other structures should be avoided in the sump.

ECONOMIC VALUATION OF IRRIGATING TOMATO PLANTS WITH AGRICULTURAL DRAINAGE WATER REMEDIATED WITH DHS TECHNOLOGY

An economic evaluation of the effect of irrigating tomato plants with agricultural drainage water remediated with DHS technology was conducted in a field experiment at Rahawy, Giza governorate. According to the findings, Egypt's reuse of agricultural drainage water meets around 15% of its irrigation needs, while the overall expenses of remediating one cubic metre of agricultural drainage water using DHS technology reached LE 1.03. The volume of irrigation water used to grow tomato plants decreased by 5% in non-remediated soil ecosystems, 14% in soil ecosystems remediated by microbial inoculation and fortified by bentonite clay mineral, and 22% in soil ecosystems receiving a mix of clay minerals, rock phosphate, and sulphur and inoculated by Thiobacillus sps and phosphate dissolving bacteria PDB. the productivity of one feddan of tomato crop irrigated with non-remediated agricultural drainage water reached 11.31 tons per feddan, irrigation with agricultural drainage water increased tomato crop by about 31%, all studied indicators of the economic efficiency of tomato production grown in remediated soil ecosystem and irrigated with remediated agricultural drainage water were higher than their counterparts grown in non-remediated soil ecosystem and irrigated with non-remediated agricultural drainage water, total tomato yield increased under irrigation with remediated agricultural drainage to LE 31.668, reaching 47% over its counterpart grown in non-remediated soil ecosystem irrigated with non-remediated agricultural drainage water, the net yield per feddan increased by 716% under irrigation with remediated agricultural drainage water over its counterpart irrigated with non-remediated agricultural drainage water. When irrigated with remediated agricultural drainage water, the cost of one tonne of tomato fruits harvested from non-remediated, remediated with bacteria, or remediated with clay minerals soil ecosystems decreased by 11%, 40%, and 44%, respectively, when compared to its counterparts irrigated with non-remediated agricultural drainage water. The profitability of one pound spent on tomato fruits harvested from non-remediated, remediated with bacteria, or remediated with clay minerals soil ecosystems decreased by 598 percent, 1010 percent, and 163 percent more than its counterpart irrigated with non-remediated agricultural drainage water, respectively, under irrigation with remediated agricultural drainage water. The net return of the water unit increased by 761 percent, 1367 percent, and 282 percent in tomato fruits harvested from non-remediated, remediated with certain microorganisms, or remediated with clay minerals soil ecosystems under irrigation with remediated agricultural drainage water, respectively, over its counterpart irrigated with non-remediated agricultural drainage water. The estimated profitability of each pound spent on agricultural drainage water remediation was LE 2.36 for tomato plants growing in an unremediated soil ecosystem, LE 10.07 for those remediated with specific microbes, and LE 33.43 for those remediated with clay minerals. The economic valuation of irrigating tomato plants with agricultural drainage water remediated with DHS technology was good, which will support farmers' social acceptance and sustainability of DHS use.

Water quality assessment of Mansbal Lake in Kashmir

ABSTRACT Manasbal Lake is one of the hotspots of Kashmir tourism. Due to the negligence of concerned authorities and the greediness of humans residing proximate, the ecosystem of the lake is highly disturbed and compromised. The current study emphasizes and attempts to analyze the various significant physico-chemical parameters of the lake. For studying overall pollution load on water of the lake, water samples were collected from five different sites of lake. These samples were collected on monthly basis for seven consecutive months by following the methods given in. Fourteen important physico-chemical parameters were analyzed and results were recorded. The study was made to spectacle the involvement of humans in the degradation of natural resources and the impact of pollution on the population residing in the nearby areas. The population of catchment area is directly or indirectly dependent on this lake for livelihood. So, it is necessary to conserve this natural resource for the present and future generations to survive and fulfill their daily needs. Some of the studied parameters revealed that the sites where human settlements are existing are contaminated showing worse water quality. Almost 80% of the lake seems covered under the substantial amount of weeds, because of the presence of a high concentration of nutrients and other favorable elements and heavy eutrophication. Some toxic elements in excess quantity were found in the water of the lake, which makes it unsuitable for domestic uses. Sewage outlets, agricultural drainage, waste disposal, shrinking up of land, and practice of stone quarrying and functioning of limestone kilns in catchments are recognized as the main sources of pollution in the Manasbal lake. The present study impulses the requirement of curative procedures for purification and protection of this lake.

ECONOMIC VALUATION OF IRRIGATING GREEN BEANS PLANTS WITH AGRICULTURAL DRAINAGE WATER REMEDIATED WITH DHS TECHNOLOGY

A field experiments were conducted at Belbeis, Sharkia governorate, to evaluate the economic impact of irrigating green bean plants with agricultural drainage water remedied with DHS technology. The obtained results showed that agricultural drainage water is reused in Egypt, where it provides about 15% of the country's irrigation needs. The costs of remediating one cubic metre of agricultural drainage water with the DHS technology totaled LE 1.03, and the amounts of remediated agricultural drainage water used to irrigate green beans grown in a soil ecosystem remediated with either microorganisms or clay minerals was reduced by 50% and 28.6% of their treasury, respectively. The net return per feddan under irrigation with remediated agricultural drainage water reached 261 percent over its counterpart irrigated with non-remediated agricultural drainage water, and the cost of each ton produced decreased under irrigation with remediated agricultural drainage water to LE 35,720. This represents 83 % more for plants grown in non-remediated soil ecosystem and irrigated with non-remediated agricultural drainage water. In comparison to its counterpart irrigated with non-remediated agricultural drainage water and grown in non-remediated soil ecosystem or in soil ecosystems remediated with either microorganisms or clay minerals respectively, the profitability of each pound spent on the production of green beans increased in soil ecosystems irrigated with remediated agricultural drainage water by 201, 99, and 126 %. For a non-remediated soil ecosystem, the return on investment per pound spent on remediating agricultural drainage water was LE 5.17; for a non-remediated soil ecosystem treated with microorganisms, LE 9.8; and for a non-remediated soil ecosystem treated with clay minerals, LE 15.58.

COMPARATIVE ANALYSIS OF NITROGEN COMPOUNDS POLLUTION IN CONTROLLED AND FREE DRAINAGE WATER

Agricultural drainage and associated water management systems are designed to eliminate to an acceptable level the factors associated with excess water that limit crop growth. In order to eliminate excess water in cultivated areas, it is important to reduce the leaching of nitrogen compounds flowing together with drainage water, as well as to ensure the safe and sustainable use of plant protection products and fertilizers. One possible solution is to transform free drainage structures into controlled drainage systems. In such systems, it is possible to regulate the groundwater level according to the needs of the plants and reduce the leaching of nutrients with drainage water. This paper presents a comparative analysis of controlled and free drainage water pollution by nitrogen compounds. The research was carried out in Pasvalys district, where both types of drainage systems operate next to each other.

Seeping, maintaining, flooding and repairing

This paper outlines the experiences of a short artist in residency called Follow the water at the Vancouver Arts Centre in Albany, Western Australia that began in November-December 2018. Investigating the local network of urban and peri-urban drainage, the project was an attempt to reframe drains from what they are normally seen as—of a way of transferring ‘problems’ to elsewhere—into a space of reparative engagement. Intimate, makeshift walks were taken with drain allies along road culverts and agricultural drains and through snaky, polluted and weedy country. Walks were recorded with cyanotypes and a further cyanotype workshop was conducted with the public on the subject of local watercourses. Whilst being attentive to the local stories of water, settler history and regeneration, the project nevertheless attempted to problematise the current quasi-legal and commonplace notions which see the flow of water leaving a property downstream (and downslope) as being ‘not my problem’. In a small way, this art project works through the “impurity of caring” (that acts of caring contain the wish that it were not so (Shotwell), at the same time that they are entangled) with a tactical move that I have termed “porous repair.” It therefore provides a short example of the complications of thinking through water stories using artistic means.

The Investigation of Artificial Wetland Systems for the Improvement of Agricultural Drainage Water

Harmful substances in the wastewater negatively affect the ecological balance by reducing the dissolved oxygen concentration. High phosphorus and nitrogen compounds discharged into surface water resources may cause to eutrophication, due to increased algal growth. In this study, Elodea densa (Egeria), Lemna minor (Duckweed), Micranthemum micranthemoides (Micra), Pistia (Water Lettuce), Ceratophyllum demersum (Foxtail) plants were investigated for the removal of nitrate and ammonium from rice field drainage water. Synthetic drainage water was prepared to rely on the literature and real rice field drainage water composition from the Samsun Bafra region. Artificial wetland studies were carried out as individual systems in order to understand the treatment ability of each plant and as a combined system in batch and continuous flow mode. pH, electrical conductivity, dissolved oxygen, nitrate, and ammonium values were measured periodically. Results of the individual plant wetland system represented that the wetland plant Elodea densa revealed the highest nitrate removal efficiency (77%) at the end of 1 day, followed by Pistia (76%). It was observed that the treatment efficiency increased with increasing hydraulic retention time. In the combined system, the nitrate removal efficiency was 40%, while the ammonium removal efficiency was 51% at the end of the first day. It was concluded that the wetland plants successfully reduced the ammonium and nitrate content of the drainage water and showed resistance to the drainage water with high salinity. In the wetland experiments carried out under continuous flow mode, ammonium was reduced from 0.80 mg/L to 0.10 mg/L, while nitrate was reduced from 1.90 mg/L to 1.40 mg/L, yielding approximately 90% and 30% at the end of the 16th day. Studies have in general revealed the importance of plant type as well as residence time.

Novel electro-oxidation unit for electro-disinfection of E. coli and some waterborne pathogens during wastewater treatment: batch and continuous experiments

The prime objective of the current investigation is to evaluate a promising alternative method for disinfection wastewater using a novel electro-oxidation unit. The study focused on determining the best-operating conditions from a techno-economic point of view to be applied to continuous flow simulating actual disinfection modules. The treatment unit consisted of a Plexiglas container with a 3 L volume containing nine cylindrical shape electrodes (6 graphite as anode and 3 stainless steel as a cathode) connected to a variable DC power supply. Determination of the best operating parameters was investigated in batch mode on synthetic wastewater by studying the effect of contact time, current density (CD), total dissolved solids concentration (TDS), and bacterial density. Moreover, the continuous mode experiment was considered on real wastewater from an agricultural drain and the secondary wastewater treatment plant effluent before chlorination. The batch mode results revealed that the best applicable operational conditions that achieved the complete removal of E. coli were at a contact time of less than 5 min, TDS of 2000 mg/L, and CD of 4 mA/cm2. Application of these conditions on the continuous mode experiment indicated the complete removal of all bacterial indicators after 5 min in the drainage wastewater and after 3 min in the secondary treated wastewater. Physico-chemical characterization also suggested that no chlorine by-products displaying the hydroxide ion formed due to water electrolysis is the main reason for prohibiting the growth of pathogenic microbes. The electrical consumption was calculated in the continuous mode and found to be 0.5 kWh/m3 with an operational cost of about 0.06 $/m3, including the cost of adding chemicals to increase the TDS. The results proved that this novel electro-oxidation unit is a robust and affordable disinfection method for complete bacterial removal from wastewater and is more environmentally benign than other conventional disinfection methods.

THE NATIONAL AND INTERNATIONAL WATER POLICIES WITH FOCUS ON THE DRAINAGE WATER REUSE PRACTICES AND THE MEGA WATER PROJECTS

The overgrowing water scarcity in Egypt should be the motive to develop alternative water resources. The article focuses on a technical review of the state-of-the-art water policies for the reuse of agricultural drainage water in irrigation worldwide and in Egypt, due to the increasing pace of implementing mega water projects. Satisfying future water demands in Egypt depends on better utilization and efficient use of the available water resources. Optimal water management, particularly the nonconventional water resources, is an essential prerequisite for the sustainable development of Egypt. The hypotheses examined are that the available quantities of agricultural drainage water in Egypt shall decrease and the quality of that drainage water shall improve. In the meantime, it is expected that soil and water salinity rates shall rise as a result of the multiple reuses of the drainage water and also due to the expansion of modern irrigation practice not only in the newly reclaimed desert lands but also in some old heavy soil lands. In addition, a technical review of the impacts of those changes above on the phenomenon of seawater intrusion in the northern parts of the Nile Delta is presented. It is concluded that the impact of the national water-saving, irrigation improvement projects, and expansion in land reclamation in the desert are inversely proportional to the resulting amount of agricultural drainage water in Egypt. That reduction is interpreted as about 20%, which needs further extensive applied research to verify. That amount might be compensated with the safe reuse of treated wastewater, with the due health safeguards. Accordingly, as stated in the NWRP2037, caution should be taken while projecting the future available agricultural drainage water for reuse in each geographic zone in Egypt.

Distribution Characteristics and Source Analysis of Nitrogen and Phosphorus in Different Rivers in Two Water Period: A Case Study of Pi River and Shiting River in the Upper Reaches of Tuo River in China.

In this paper, the distribution characteristics of total nitrogen (TN), total phosphorus (TP) and fractions of nitrogen and phosphorus in water and surface sediments of the Pi and Shiting rivers in the dry and wet seasons were studied by molybdenum blue/ascorbic acid spectrophotometry and Standard Measurements and Testing (SMT). Correlation analysis, cluster analysis and principal component analysis were used to identified nitrogen and phosphorus pollution sources. The results showed that: (1) nitrogen and phosphorus in water and surface sediments in the study area were at different levels. (2) In the Pi river, the decomposition of animal and plant residues, the leachate from the accumulation of aquaculture wastewater and urban domestic sewage were the main sources of nitrogen and phosphorus pollution, while in the Shiting river, the unreasonable application of pesticides and fertilizers, the degradation of animal and plant residues, agricultural wastewater from agricultural drainage channels, industrial production wastewater and the weathering of agricultural wastes had a great impact on the nitrogen and phosphorus pollution. The results in this study provide reliable experimental data and a reference to local relevant departments for the implementation of effective control measures for the reduction of the nitrogen and phosphorus pollution load in the river basin.

Integrated river water quality and quantity management based on undesirability and cost‐effectiveness

AbstractIntegrated water resources management aims to simultaneously solve water shortage and contamination problems by considering economic, social, and environmental criteria. To that view, this study has developed a two‐objective optimization model regarding water allocation (WA) and wasteload allocation (WLA) in the Zayandehrood river basin, the central part of Iran. The model aimed to supply the users' water demand considering the downstream environmental flow to fulfill the social‐environmental requirements. Besides, satisfying the river water quality standards was regarded as the environmental‐economic criteria. The WA objective function minimizes the undesirability caused by reduced allocated water and downstream environmental flow. The QUAL2K model was used to simulate the wasteload discharge impacts on the river water quality. The water quality parameters included biochemical oxygen demand (BOD), TP, and TN for the urban and industrial wasteload and nitrate for the agricultural drainage. The results showed that a joint WA ‐ WLA optimization reduced the total average WA by 15% and increased the downstream flow by three times the base level. Also, the water quality violations of the standard limits were reduced by 18, 4, and 15 times for BOD, NO3, and TP, respectively.

Reverse Osmosis Membrane Zero Liquid Discharge for Agriculture Drainage Water Desalination: Technical, Economic, and Environmental Assessment.

Agricultural drainage water (ADW) represents a potential source for fresh water after receiving appropriate treatments to satisfy the water quality requirements. Desalination of ADW with medium salinity and moderate contamination with organic and inorganic chemical pollutants could provide a techno-economically feasible approach for facing water scarcity in arid areas. The current work presents a conceptual zero liquid discharge ADW desalination system proposed to treat 300,000 m3/d. The system is based on pretreatment to remove impurities harmful to desalination by staged reverse osmosis (RO) membrane. The brine from the last RO stage is treated via thermal vapor compression followed by evaporation in solar ponds to recover more fresh water and salts of economic value. The essential technical features of the proposed system components are formulated. The proposed system components and its technical and economic indicators are deduced using available software for water pretreatment, RO membrane, desalination, thermal desalination, and solar evaporation ponds. The system provides total distilled water recovery of about 98% viz. 294,000 m3/d in addition to recovered salts of 245,000 t/y. The net cost of water production amounts to USD 0.46 /m3. The environmental considerations of the system are addressed and advantages of applying zero liquid discharge system are elucidated.

Ecosystem-atmosphere CO2 exchange from semiarid mangroves in the Gulf of California

Mangrove wetlands play an essential role as blue carbon ecosystems. However, worldwide they also face imminent threats caused by anthropogenic activities and climate change. Mangroves in the semiarid region of the Gulf of California are highly vulnerable to both threats. In this study, we present eddy covariance measurements of net ecosystem exchange of CO2 (NEE), gross primary productivity (GPP), and ecosystem respiration (Reco) at a preserved mangrove (Estero El Sargento) and a site influenced by anthropogenic activities (Bahia del Tobari) located in northwest Mexico. Both sites were net annual carbon sinks but had different dynamics. The net annual carbon gain for Estero El Sargento was −717 g C m−2 y−1 while for Bahia deTobari was −247 g C m−2 y−1. Over the studied year, Estero El Sargento had lower Reco(329 g C m−2) during the winter-spring months and an overall lower annual Reco/GPP (0.42) than Bahia de Tobari. The Reco was notably high during the winter-spring period at Bahia de Tobari when agriculture drainage from the intensive food production activities at the Yaqui Valley reaches the bay. The contrasting NEE patterns and magnitude between both mangrove sites suggest that anthropogenic activities influencing coastal ecosystems exert an important control on the CO2 sink potential.

Development and validation of analytical method for acidic pesticide residues determination in water using LC-MS/MS: a one year surveillance program for two Egyptian governorates

ABSTRACT An applicable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is developed to enable the efficient residue detection of fifteen acidic pesticides in water (drinking, ground, irrigating, and agricultural drainage water). The extraction and sample concentration were accomplished using the solid-phase extraction (SPE) technique. The developed method was fully validated according to the EU validation guidelines. The accuracy and precision calculations were evaluated by sample fortifications at concentrations of 0.1–1.0 µg/L. Acceptable recoveries and precisions were obtained of 70–120% and below 20%, respectively. The method showed good linearity ≥0.995. The developed method’s quantitation limit was 0.1 µg/L for most studied pesticides. The uncertainty measurement, expressed as expanded uncertainty, in terms of relative standard deviation (at 95% confidence level) is within the range of ±44%. A survey study was successfully conducted by collecting 108 water samples from different water sources in Egypt during the period between June 2020 and May 2021. The obtained results showed the absence of residue for most of the acidic pesticides in the collected samples, except for bentazone which was present in 33% of the collected samples with a concentration range of 0.1 to 0.29 µg/L.

The Effect of Irrigation with Treated Municipal Wastewater and Agricultural Drainage Water on Soil Chemical Properties

ABSTRACT This study was carried out to investigate the effect of irrigation with treated municipal wastewater and agricultural drainage water on Ahvaz (southwest Iran) soil chemical properties in 24 plots with 1 × 1 (m) area in farm No. 1 of Shahid Chamran University of Ahvaz in 2018–2019. The experiment was carried out as a factorial experiment in a completely randomized block design with three replications. The experiment factors included eight irrigation treatments (A: Irrigation with Karun River water as control), (F: Irrigation with treated municipal wastewater). (Z: Irrigation with agricultural drainage water), (Z1F1: 30% Agricultural drainage water +70% Treated municipal wastewater), (Z2F2: 70% Agricultural drainage water +30% Treated municipal wastewater), (Z3F3: 50% Agricultural drainage water +50% Treated municipal wastewater), (Z4A4:50% Agricultural drainage water +50% Karun River water), (F5A5: 50% Treated municipal wastewater +50% Karun River water), at five time levels (including pre-treatment, first month, second month, fourth month, sixth month were performed at three depths (0–20), (20–40), (40–60) cm. The traits examined in this experiment were pH (Acidity), EC (Electrical Conductivity), Ca2+ (Calcium), Mg2+(Magnesium), Na+(Sodium), K+(Potassium), HCO3-(Bicarbonate), CO3 −2(Carbonate), SAR (Sodium Adsorption Ratio). Experimental factors had different effect on studied traits. Results showed that with increasing soil depth, all treatments except carbonate and acidity decreased. Calcium, magnesium, sodium and bicarbonate showed significant differences over time (P < 0.01). Non-significant difference in potassium was observed during this time (P > 0.01). There was significant increase in salinity over time (P < 0.01). In T1 period Karun River water showed the highest salinity amount irrigation treatment. Also, F5A5 treatment had the lowest concentration of Ca2+, Mg2+, K+ and the highest concentration of SAR. The Z4F4 treatment showed the lowest concentration of SAR and the highest concentration of Mg2+.The Z treatment had the lowest concentration for Mg2+. The A treatment showed the lowest concentration for HCO3-. The F treatment had the highest concentration for Ca2+; the Z3F3 treatment had the highest concentration for K+, the Z1F1 and Z2F2 treatments showed the highest concentration in terms of SAR.

Novel ecological ditch system for nutrient removal from farmland drainage in plain area: Performance and mechanism.

The loading of nitrogen (N) and phosphorus (P) from agricultural drainage as the non-point sources is a worldwide environmental issue for aquatic ecosystem. However, how to remove these nutrients effectively from agricultural drainage remains a big challenge with increasing cemented ditches for better management. Here, we designed a novel ecological ditch system which integrated an earth ditch and a cemented ditch with iron-loaded biochar in the Chengdu Plain to reduce the loss of N and P from farmland. After a two-year monitoring, the removal efficiency of total N and total P reached 24.9% and 36.1% by the earth ditch and 30.7% and 57.8% by the integrated ditch system, respectively. The water quality was evidently improved after passing through the ditch system with the marked decrease in the concentrations of N and P. Dissolved organic N, nitrate, and particulate P became the dominant fractions of N and P loss. Rainfall soon after fertilization increased the concentrations of N and P in the ditch system and markedly affected their removal efficiency. The iron-loaded biochar effectively removed N and P from the drainage, especially at the high concentrations, which was mainly attributed to its high adsorption of the dissolved N and P fractions and the interception of the particulate nutrients. Our results indicate that the designed ecological ditch system has a high potential for alleviating agricultural non-point source pollution in the plain area and can be extended to other lowland agricultural ecosystems.

Improvement of the DRAINMOD model's performance under time-variable surface storage capacities using neural network models

DRINAMOD is a superior model being used globally to assess the impacts of different agricultural drainage layouts and practices on farmlands' water balance. But the model considers a fixed value of surface storage capacity (SSC) for the whole simulation period, which causes the model to predict improper water distribution patterns in farmlands where SSC varies with time due to agricultural practices. The present study presents a novel artificial neural network model (ANNM) that mimics the DRAINMOD model and overcomes such a shortage of considering a fixed SSC value when predicting farmlands' water balance. After training the ANNM by sets of data, which were generated by the DRAINMOD model after being calibrated and validated in rice-wheat rotation farmland at the lower reaches of the Yangtze River basin, China, groundwater tables in the study area were predicted by both models under different scenarios of drainage layouts and management practices. Results show that there were excellent agreements between these predictions, which validates the applicability of the developed ANNM in predicting the water balance in artificial-drained farmlands. The developed ANNM enhances water fate predictions in artificial-drained farmlands characterized by time-variable surface storage capacities, thus resulting in a better assessment of the available water resources alongside high agricultural productivity. Findings from the present study point also to the potential role of neural network models as a tool to enhance the performance of hydrologic models without modifying their source code.

Investigation of several heavy metals in Al-Saddah agricultural drainage in Hilla city /Iraq

This study was done to determine the concentration of several heavy metals in the water of Al-Saddah agricultural drainage in Al-Saddah District in Babylon Province/Iraq. The concentrations of six heavy metals were measured (Pb, Cd, Cu, Hg, Fe, Zn). It was found that Pb concentration ranged from 0.06 mg/L at St.2 in autumn to 0.13 mg/L at St.2 in winter. Fe concentrations ranged from 0.04 mg/L at St.2 in autumn and winter to 0.41 at St.2 in Summer. Cd concentrations ranged from 0.008 mg/L at St.2 in summer to 0.05 mg/L at St.2 in winter. Cu concentrations ranged from 0.01 mg/L at St.1 in both autumn and winter to 0.63 mg/L at St.2 in winter. Hg concentrations was ranged from 0.002 mg/L at St.2 in summer to 0.009mg/L at St.2 in spring. Zn concentrations ranged from 0.02 mg/L at St.2 in summer to 0.14 mg/L at St.2 in winter. physiochemical parameters of water such as temperature, pH, E.C. D.O., and B.O.D.5 was also measured.

Simulation and evaluation of soil water and salt transport under controlled subsurface drainage using HYDRUS-2D model

Controlled drainage is an important measure to improve salinized soil in arid and semi-arid areas. However, free drainage during the growth period leads to excessive water loss, and crops lack water in the later growth period, resulting in crop yield reduction. Therefore, in arid and semi-arid areas, soil salts should be leached during the non-growing period, and drainage should be controlled during the growing period to ensure that crops have adequate water absorption and utilization, improve soil water availability for optimal water supply and salinity control. In this study, through field trials in 2020 and 2021, 3 treatments were set up. The depth of free drainage (FD) is common subsurface pipe drainage and the controlled drainage in the growth period were 40 cm (CWT1) and 70 cm (CWT2), respectively, and the drainage depth in the non-growing period was 100 cm. Using the HYDRUS-2D model to simulate the dynamic changes of soil water and salts in the 0–100 cm range, the calibration and validation of the HYDRUS-2D model were performed using the measured soil water and salt content values of 2020 and 2021. The results showed that the simulated soil water and salt contents agreed well with the measured contents. Controlled Drainage (CD) is a new agricultural drainage management practice that involves periodically increasing the outlet elevation of subsurface drainage pipes, CD significantly increased the water content of the 0–100 cm soil layer—especially at 0–40 cm depth—after growth stage irrigation. Under FD, CWT1, and CWT2, the 2-year mean soil water content of the 0–40 cm soil layer after growth stage irrigation in 2020 and 2021 was respectively 0.263, 0.278, and 0.267 cm3 cm−3, with the latter two values being higher by 5.70 % and 1.52 % than the former value, respectively. Soil water uptake by sunflower after irrigation mainly occurred in the 0–40 cm soil layer, which contributed 55.88–78.51 % of the total soil water uptake. Soil re-salinization occurred in the late growth stage (the flowering stage) under different treatments, with a mean re-salinization rate (relative to the period before spring irrigation) of 29.29 %, 33.48 %, and 30.34 % under FD, CWT1, and CWT2, respectively. Although the re-salinization rate was relatively high under CWT1 and CWT2, it had a low effect on crop growth as well as crop yield. HYDRUS-2D simulation was performed to compare different drain depths in the growth stage in order to determine the optimal drain depth for sunflower in moderately saline soils. To this end, the following metrics were considered for the main root zone (0–40 cm): soil water content, soil salt content, soil de-salination rate during spring irrigation, and soil re-salination rate in the late growth stage. Reduce soil salt content during spring irrigation, increase soil water content after irrigation during growth period, and minimize soil salt return rate in late growth stage, that is, to provide suitable water conditions for crop growth and minimize salt stress. The optimal drain depth during the growth stage was ultimately determined to be 50 cm.