Search Results (7)

Unsaturated zones are critical for water and material exchange between groundwater and surface ecosystems. Understanding the migration patterns of soil water and salts in these zones can offer theoretical support for maintaining the equilibrium between groundwater and surface ecosystems in Northwestern China’s salinized regions. This study explores the correlation between soil particle composition and soil water and salt distribution at a test site in the lower reaches of the Shiyang River basin. It analyzes the way in which water and salt patterns vary with different soil structures over various timescales. The results indicate that lithological profiles with similar structures but varying fine particle contents exhibit distinct water–salt variation patterns. Higher fine particle content leads to increased water and total dissolved solid content, but a decreased infiltration rate. When the middle layer has the highest fine content, soil evaporation is partially inhibited. The more complex the lithologic structure, the less effective irrigation is in leaching salt. However, when the lithologic structure remains constant, fine particle content has minimal impact on salt leaching. Full article

This study estimates the effect of climate change on water resource efficiency and crop/agronomic productivity at the Almyros basin in Greece. Groundwater resources are intensively used for irrigation, whereas their quantity and quality are highly downgraded. Climate change impacts have been assessed using Med-CORDEX bias-corrected climatic projections for RCP4.5 and RCP8.5 scenarios. Simulation of coastal water resources was carried out with an Integrated Modelling System (IMS) consisting of the modules of surface hydrology (UTHBAL), reservoir operation (UTHRL), groundwater hydrology (MODFLOW), nitrate leaching/crop growth (REPIC), nitrate pollution (MT3DMS), and salt wedge/salinization (SEAWAT). The indices of Standardized Chloride Hazard (SCHI), Crop Water (CWP) and Economic Water Productivity (EWP), Nitrogen Use Efficiency (NUE) have been employed to analyze water resource management and agronomic scenarios. The findings indicate the water resources’ capacity for adaptability and agronomic effectiveness under the influence of salinization and climate change. Full article

To solve the problem of soil salination and to desalinate saline–alkaline water in arid areas, this study involved the design and testing of a separation and desalination device for farmland saline–alkaline water that is suitable for arid areas. The results of this study indicate that after the pretreatment of farmland saline–alkaline water, the water yielded by the pretreatment device had a mean turbidity of <1 and a mean silt density index (SDI) of <3, which met the working conditions of nanofiltration (NF) and reverse osmosis (RO) membranes. When used to filter saline–alkaline water, the composite NF–RO membrane system achieved a desalination rate of 97.06%, a total hardness removal rate of 97.83%, and a Cl⁻ removal rate of 99.65%, which satisfied the standard for irrigation water quality. Some indicators of the yielded water reached the hygienic standard for drinking water, thus successfully reutilizing water resources. The circulating solar collector tube of the device was designed with a collection area of 6 m², which could basically satisfy the heat demand of the flash tank for distillation. The design of the flash tank and the shell-and-tube circulating condenser met the requirements for vapor condensation. The crystals in the solar salt box precipitated under solar action. X-ray diffraction was used to identify the primary compound of the crystals as NaCl, suggesting that the precipitates have potential value as industrial salts. This study offers new technical references and helpful engineering guidance for arid saline–alkaline enrichment areas facing the problem of saline farmland irrigation water. Full article

Salination poses serious hazards to farmland soil. For the purpose of solving soil salination, desalination of water sources, and other problems faced by arid areas, a separation and desalination process for farmland saline-alkaline water is proposed; a separation and desalination device based on this process is also presented and tested. Results indicate that water associated with the pretreatment device satisfied the working conditions of the composite nanofiltration (NF)-reverse osmosis (RO) membrane system. The composite NF-RO membrane system produced a better filtering effect than either the NF membrane or the RO membrane. When used for filtering saline-alkaline water, the composite NF-RO membrane system achieved a desalination rate of 96.06%, a total hardness removal rate of 98.93%, and a Cl- removal rate of 99.32%, adhering to the standard for irrigation water quality. The flashing-condensation process realized a fresh water recovery rate greater than 70%. During brine evaporation using solar salt making processes, the primary compound of crystals precipitated was NaCl (with a relative content of 93%), suggesting that the precipitates have the potential values of industrial salts. These findings offer new technical references for solving the problem of farmland irrigation water faced by saline-alkaline areas worldwide. Full article

Environmental policies to address water quality impairments in the San Joaquin River of California have focused on the reduction of salinity and selenium-contaminated subsurface agricultural drainage loads from westside sources. On 31 December 2019, all of the agricultural drainage from a 44,000 ha subarea on the western side of the San Joaquin River basin was curtailed. This policy requires the on-site disposal of all of the agricultural drainage water in perpetuity, except during flooding events, when emergency drainage to the River is sanctioned. The reuse of this saline agricultural drainage water to irrigate forage crops, such as ‘Jose’ tall wheatgrass and alfalfa, in a 2428 ha reuse facility provides an economic return on this pollutant disposal option. Irrigation with brackish water requires careful management to prevent salt accumulation in the crop root zone, which can impact forage yields. The objective of this study was to optimize the sustainability of this reuse facility by maximizing the evaporation potential while achieving cost recovery. This was achieved by assessing the spatial and temporal distribution of the root zone salinity in selected fields of ‘Jose’ tall wheatgrass and alfalfa in the drainage reuse facility, some of which have been irrigated with brackish subsurface drainage water for over fifteen years. Electromagnetic soil surveys using an EM-38 instrument were used to measure the spatial variability of the salinity in the soil profile. The tall wheatgrass fields were irrigated with higher salinity water (1.2–9.3 dS m⁻¹) compared to the fields of alfalfa (0.5–6.5 dS m⁻¹). Correspondingly, the soil salinity in the tall wheatgrass fields was higher (12.5 dS m⁻¹–19.3 dS m⁻¹) compared to the alfalfa fields (8.97 dS m⁻¹–14.4 dS m⁻¹) for the years 2016 and 2017. Better leaching of salts was observed in the fields with a subsurface drainage system installed (13–1 and 13–2). The depth-averaged root zone salinity data sets are being used for the calibration of the transient hydro-salinity computer model CSUID-ID (a one-dimensional version of the Colorado State University Irrigation Drainage Model). This user-friendly decision support tool currently provides a useful framework for the data collection needed to make credible, field-scale salinity budgets. In time, it will provide guidance for appropriate leaching requirements and potential blending decisions for sustainable forage production. This paper shows the tie between environmental drainage policy and the role of local governance in the development of sustainable irrigation practices, and how well-directed collaborative field research can guide future resource management. Full article

The Mediterranean climate is marked by arid climate conditions in summer; therefore, crop irrigation is crucial to sustain plant growth and productivity in this season. If groundwater is utilized for irrigation, an impressive water pumping system is needed to satisfy crop water requirements at catchment scale. Consequently, irrigation water quality gets worse, specifically considering groundwater salinization near the coastal areas due to seawater intrusion, as well as triggering soil salinization. With reference to an agricultural coastal area in the Mediterranean basin (southern Italy), close to the Adriatic Sea, an assessment of soil salinization risk due to processing tomato cultivation was carried out. A simulation model was first arranged, then validated, and finally applied to perform a water and salt balance along a representative soil profile on a daily basis. In this regard, long-term weather data and physical soil characteristics of the considered area (both taken from international databases) were utilized in applying the model, as well as considering three salinity levels of irrigation water. Based on the climatic analysis performed and the model outputs, the probability of soil salinity came out very high, such as to seriously threaten tomato yield. Autumn–winter rainfall frequently proved to be insufficient to leach excess salts away from the soil profile and reach sustainable conditions of tomato cultivation. Therefore, alternative cropping strategies were investigated. Full article

In the Heihe River basin, China, increased salinity and water shortages present serious threats to the sustainability of arid wetlands. It is critical to understand the interactions between soil water and salts (from saline shallow groundwater and the river) and their effects on plant growth under the influence of shallow groundwater and irrigation. In this study, the Hydrus-1D model was used in an arid wetland of the Middle Heihe River to investigate the effects of the dynamics of soil water, soil salinization, and depth to water table (DWT) as well as groundwater salinity on Chinese tamarisk root water uptake. The modeled soil water and electrical conductivity of soil solution (EC_sw) are in good agreement with the observations, as indicated by RMSE values (0.031 and 0.046 cm³·cm⁻³ for soil water content, 0.037 and 0.035 dS·m⁻¹ for EC_sw, during the model calibration and validation periods, respectively). The calibrated model was used in scenario analyses considering different DWTs, salinity levels and the introduction of preseason irrigation. The results showed that (I) Chinese tamarisk root distribution was greatly affected by soil water and salt distribution in the soil profile, with about 73.8% of the roots being distributed in the 20–60 cm layer; (II) root water uptake accounted for 91.0% of the potential maximal value when water stress was considered, and for 41.6% when both water and salt stress were considered; (III) root water uptake was very sensitive to fluctuations of the water table, and was greatly reduced when the DWT was either dropped or raised 60% of the 2012 reference depth; (IV) arid wetland vegetation exhibited a high level of groundwater dependence even though shallow groundwater resulted in increased soil salinization and (V) preseason irrigation could effectively increase root water uptake by leaching salts from the root zone. We concluded that a suitable water table and groundwater salinity coupled with proper irrigation are key factors to sustainable development of arid wetlands. Full article