Dry Drainage Research Articles

Water and Salinity Variation along the Soil Profile and Groundwater Dynamics of a Fallow Cropland System in the Hetao Irrigation District, China

Managing soil salinity has always been a difficult problem for agriculture. Balancing water and salt while maintaining crop quality and yield is a key issue for agricultural sustainability. The Hetao lrrigation District in China has a complex mix of cultivated and uncultivated land which plays a crucial role in soil salinization processes. To investigate the dynamic properties of soil moisture and salinity, soil ions and groundwater, cultivated and fallow soils in the Hetao lrrigation District were analyzed, side by side, using a combination of field and laboratory tests, with data processed using univariate and multivariate statistical approaches. The results showed that soil moisture increased with increasing soil depth in both cultivated and fallow soils. Salinity showed an increasing trend in 2022 and 2023 from April to September. The soil ions were mainly sulfate in the cultivated soils and chloride in the fallow soils. The characteristic factors affecting salt accumulation in cultivated soils are Na++K+, Cl−, SSC, SO42−, HCO3−, and pH, and the characteristic factors affecting salt accumulation in fallow soils are Na++K+, Cl−, SSC, HCO3−, and pH. Water table depth varied with irrigation and precipitation and was strongly influenced by external environmental factors. Groundwater salinity remained stable throughout the study period. This study provides a theoretical basis for the prevention and control of soil salinization in arid and semiarid areas through the “dry drainage salt” measure.

A Comparison of the Performance of Four Acoustic Modulation Techniques for Robot Communication in Pipes

Autonomous robotics is an emerging technology for the inspection of a vast network of underground pipes. Communication between autonomous robots is essential to optimise their efficiency and network coverage. However, sending a message acoustically is not a well-researched topic because most of the existing literature is devoted to the study of the acoustic properties of the pipe for the purpose of sensing rather than communication. In particular, the influence of multi-modal propagation and background noise on the quality of acoustic communication in pipes has not been well understood. This paper studies the performance of four standard acoustic communication techniques in a dry drainage pipe to fill this knowledge gap. The noise resistance, communication range and data rate of these techniques are estimated through numerical simulations and laboratory experiments. It has been found that the techniques based on shift keying requires at least 5--10 dB signal to noise ratio (SNR) to function properly while the chirp linear frequency modulation technique can operate reliably with SNR = 0 dB or event lower SNR. The results also suggest that the multi-modal propagation in the pipe has significant effects on the package error rate. The frequency dependent sound attenuation in the pipe also affects the communication range and data rate. In particular, for a 150 mm diameter dry pipe the maximum robot operation distance is likely to be limited to 50--100 m with the highest carrier frequency of around 10 kHz and data rates below 6300 bps. The results of this work pave the way to the development of acoustic communication modules to be deployed on tetheless robots designed to inspect a buried pipe network autonomously and collaboratively.

Evaluation of (Wet) and (Dry) Mediastinal Chest Drainage in Minimally Invasive and Conventional Cardiac Surgery.

Drainage of fluid and evacuation of air from the pericardial and pleural spaces after cardiothoracic surgery is necessary to prevent effusion, tamponade, and pneumothorax, and also to detect hemorrhage. For this purpose, negative-pressure drains are placed in the mediastinum and pleural cavities. We compared the efficacy and safety of two systems wet and dry drainage for the management and monitoring of negative pressure and anti-reflux valve safety systems, to promote healing of the pleural and pericardial cavities. Two devices for mediastinal chest drainage [Venice PAS (Wet) and Rome PAS (Dry); both Eurosets SRL, Medolla, Italy] were evaluated in terms of safety, efficacy and clinical outcomes in a cohort of 60 patients who underwent elective cardiac surgery procedures. The patients were divided into a minimally invasive cardiac surgery (MICS) group [n=30; mitral valve surgery (MVS) by right anterolateral mini-thoracotomy] and a conventional cardiac surgery (CCS) group [n=30; coronary arterial bypass grafting (CABG) in full sternotomy] at a single institution (Anthea Hospital GVM Care & Research, Bari, Italy). Negative pressure was managed with a target value of -20 cmH2O measured in the chest tube and was related to the device: deviation of ± 1 cmH2O for the Venice PAS (Wet) and 0 cmH2O for the Rome PAS (Dry) in the MICS group; deviation of 1 ± 0.8 cmH2O for the Venice PAS (Wet) and 0.8±0.2 cmH2O for the Rome PAS (Dry) in the CCS group. A constant volumetric air leak meter (VALM) value and the absence of air-leak bubbling were correlated with the absence of air in the pleural cavity and complete pulmonary re-expansion to restore normal respiratory dynamics in the MICS group for both models of chest drainage. The maximum total pericardial blood drained was 1104 ± 302 ml with Venice PAS (Wet) and 1530 ± 230 with Rome PAS (Dry) in the CCS group. There were no reports of cardiac tamponade in either group. The two mediastinal chest drainage devices [Venice PAS (Wet) and Rome PAS (Dry)] in this study were effective, accurate for measuring the applied negative pressure, and safe in their application after cardiac surgery procedures via minimally invasive and conventional approaches for blood and liquid drainage, prevention of cardiac tamponade, and restoration of normal respiratory dynamics after surgical pneumothorax. Both systems are equipped with anti-reflux valves to prevent air and blood from entering the drainage, and no adverse events were reported.

A monthly distributed water and salt balance model in irrigated and non-irrigated lands of arid irrigation district with shallow groundwater table

Water scarcity and soil salinization are two major problems threatening the sustainability of irrigation districts in arid regions with shallow groundwater table. To study water and salt balances in arid irrigation districts, we developed a monthly distributed water and salt balance model for arid irrigation district (DAHMID-S) with shallow groundwater table by integrating models of major hydrological processes and the associated salt transport processes, including irrigation, evapotranspiration, soil water and groundwater and salt balances, drainage of water and salt through ditches, and interior drainage of water and associated dry drainage of salt between irrigated and non-irrigated lands. The model was successfully applied to the Hetao Irrigation District (HID), the largest irrigation district in the arid region of China. Results indicate that evapotranspiration is the dominant water consumption component in the HID and accounts for about 95% of the total irrigation and precipitation, while drainage through ditches accounts for 10.5% of the total irrigation. Only 49.4% of the introduced salt is discharged from the HID through drainage ditches. Consequently, most parts of the HID are in the state of salt accumulation except the northern Wulate sub-irrigation district, and the problem of salt accumulation is more serious in the western and southern HID under more favorable conditions of water use. Dry drainage plays a crucial role in salt balance of both irrigated and non-irrigated lands, which results in desalinization in most irrigated lands while salt accumulation in non-irrigated lands. Appropriate measures should be taken to solve water and salt-related problems to improve the sustainability of the HID. In the western HID, irrigation water diversion should be decreased, and the drainage system should be further improved to decrease the salt accumulation to a lower level. Meanwhile, the irrigation water diversion can be increased in the southeastern HID by planting more corn and wheat. Besides, irrigation management should be improved to reduce the surface water return flow to increase the groundwater drainage capacity, especially in the southwestern HID.

Growing season water and salt migration between abandoned lands and adjacent croplands in arid and semi-arid irrigation areas in shallow water table environments

In arid and semi-arid irrigation areas with shallow water tables and fragmented arrangement of croplands and abandoned lands, dry drainage could be an optional management practice mitigating soil salinization. A dry drainage system lets non-irrigated abandoned lands serve as evaporative salt sinks receiving water and salt fluxes from adjacent irrigated croplands. Therefore, this research takes a typical dry drainage unit in the Hetao Irrigation District—one abandoned land and its adjacent croplands—as an example to directly reveal the field scale water and salt migration between abandoned lands and adjacent croplands. It was found that during the growing season, the water input, i.e. field irrigation and precipitation, raised the water table of the croplands and drove water and salt migration from croplands to the abandoned lands. However, the evapotranspiration in the croplands was also larger than that in the abandoned lands. Thus, during the intervals of irrigation (the “phreatic evaporation periods”), in some circumstances, evapotranspiration could drive water and salt flux from the abandoned lands to the croplands, which would influence the groundwater salinity of the croplands. Therefore, it is recommended to plant halophytes on the abandoned lands to enhance its evapotranspiration and hinder the water and salt flux from the abandoned lands to the croplands during intervals of irrigation. This management practice could help form more effective dry drainage systems between abandoned lands and adjacent croplands, and help better control the root zone salinity of the croplands.

Caves as geoheritage resource in remote desert areas: a preliminary evaluation of Djara Cave in the Western Desert of Egypt

AbstractCaves are rare in northeast Africa and, thus, deserve attention as potential geoheritage objects (geosites). Assessment of Djara Cave and its vicinity (Western Desert, Egypt) has permitted to document unique features, such as the cave itself as a peculiar subsurface landform, speleothems providing data for palaeoenvironmental reconstructions, rock art demonstrating elements of past landscapes, siliceous nodules weathered from Eocene limestones and a network of dry drainage channels indicative of wetter palaeoenvironments. These features are assigned to geomorphological, sedimentological and palaeogeographical types of geoheritage. Djara Cave and its vicinity are proposed as a geosite of national rank; it is vulnerable to anthropogenic stress and needs geoconservation measures and instalment of interpretative signs. This geosite is already popular among tourists, and can be used for further tourism development. More generally, the presence of caves in Egyptian desert areas makes possible the recognition of national speleological heritage that requires special country-level strategies of management.

Modeling the behavior of shallow groundwater system in sustaining arid agroecosystems with fragmented land use

Shallow groundwater often presents multiple behaviors in supporting the sustainability of arid agroecosystems. The behaviors are especially important and complicated for the arid irrigated areas with fragmented land-use types. In the view of understanding the role of shallow groundwater in such areas, the MODFLOW and MT3DMS (with the assistance of HYDRUS-1D) were used to simulate groundwater flow and salt transport in a typical observation site of the arid upper Yellow River basin (YRB). The original MODFLOW was modified with introducing a variable expression of specific yield, aiming to improve the modeling accuracy in shallow groundwater environments. The model was calibrated and validated using the observation data of groundwater depth and drainage in 2013 and 2012, respectively. Groundwater evapotranspiration and lateral water-salt exchange among different land-use types were simulated and analyzed; meanwhile, the dry drainage effect of non-cultivated natural land was quantitatively interpreted. Results indicated that the fragmented land-use/planting pattern (with different irrigation scheduling) resulted in significant lateral groundwater flow and water/salt redistribution among different land-use fields during irrigation. The groundwater evapotranspiration ranged at about 160–220 mm for different land-use types, reaching to 0.30–0.45 of plant evapotranspiration (ETpt) during the growing seasons. This effectively supplemented the plant water use in arid climate, especially for the unirrigated cultivated land (during some stages) and the non-irrigated natural land. Meanwhile, the lateral groundwater flow drove salt migrating from the cultivated land to the natural land. The natural land accumulated 27–40% of salts introduced by irrigation, playing a significant role in accommodating salts (i.e. the dry drainage effect). Moreover, our modeling work further implied that the reliable groundwater modeling in arid and shallow groundwater areas required a more detailed model conceptualization and more accurate information of land-use distribution, irrigation scheduling, and local microrelief than the general understanding in the past.

Water Engineering at Precolumbian AD 600–1100 Tiwanaku’s Urban Center (Bolivia)

The pre-Columbian World Heritage site of Tiwanaku (AD 600–1100) located in highland altiplano Bolivia is shown to have a unique urban water supply system with many advanced hydraulic and hydrological features. By use of Computational Fluid Dynamics (CFD) modeling of the city water system, new revelations as to the complexity of the water system are brought forward. The water system consists of a perimeter drainage channel surrounding the ceremonial center of the city. A network of surface canals and subterranean channels connected to the perimeter drainage channel are supplied by multiple canals from a rainfall collection reservoir. The perimeter drainage channel provides rapid draining of rainy season rainfall runoff together with aquifer drainage of intercepted rainfall; water collected in the perimeter drainage channel is then directed to the Tiwanaku River then on to Lake Titicaca. During the dry season aquifer drainage continues into the perimeter drainage channel; additional water is directed into the drainage channel from a recently discovered, reservoir connected M channel. Two subterranean channels beneath the ceremonial center were supplied by M channel water delivered into the perimeter drainage channel that served to remove waste from the ceremonial center structures conveyed to the nearby Tiwanaku River. From control of the water supply to/from the perimeter drainage channel during wet and dry seasonal changes, stabilization of the deep groundwater level was achieved—this resulted in the stabilization of monumental ceremonial structure’s foundations, a continuous water supply to inner city agricultural zones, water pools for urban use and health benefits for the city population through moisture level reduction in city ceremonial and secular urban housing structures.

Experimental study and numerical simulation of soil water and salt transport under dry drainage conditions

In this research, the effect of dry drainage on the distribution of soil water content and salinity were experimentally and numerically investigated for 84 days. In the experimental study, soil water content and salinity were measured at different soil depths and four times after planting. Numerical simulation was carried out with HYDRUS-2D which was calibrated and validated using measured data from the experimental study based on different assumptions. Results showed that dry drainage could not only control the soil water content of the irrigated area but also transfers large amounts of salts from this area to the fallow area. So that at the end of the experiment, soil surface salinity of the irrigated and fallow area increased up to 145% and 270% more than initial values, respectively. Based on statistical indices, the accuracy of HYDRUS-2D simulation was improved by considering differences between parameters of the irrigated and the fallow areas including soil hydraulic and solute transport parameters. Furthermore, this accuracy was increased due to the application of the multiplicativity approach for combining water and salinity stresses. In addition, two indices of variations, soil surface salinity percent and soil salinity ratio, are recommended as suitable criteria for determining salt scratching time from soil surface of the fallow area and ensuring the sustainability of the dry drainage system.

Experimental and Mathematical Modeling of Monotonic Behavior of Calcareous Sand

The prominent performance of wave elimination and energy absorption makes calcareous sand important and useful in infrastructure construction and protection engineering. Due to the high compressibility induced by remarkable intragranular void and irregular shape, calcareous sand presents different mechanical behaviors from common terrestrial sands. Considerable efforts have been made to explore the static and dynamic mechanical properties of calcareous sand. In this paper, a series of monotonous experiments have been performed on calcareous sand utilizing the electrohydraulic servo‐controlled test apparatus designed by the Global Digital Systems Ltd (GDS). The effects of confining pressure and relative density on the mechanical properties of dry, drained, and undrained saturated sand were studied, and the underlying micromechanism of deformation and failure was discussed. It can be found that the residual stress of dry calcareous sand is independent of the relative density, while the peak stress and residual stress of drainage saturated sand have a positive correlation with the relative density. The increase of confining pressure makes the strain softening more remarkable and heightens the peak stress and residual stress. The stress‐strain curve of calcareous sand can be divided into two portions: prepeak portion and postpeak softening portion. For the dry sand and drainage saturated sand, the softened part can be partitioned into three phases, i.e., accelerated phase, steady phase, and degradation phase, while the undrained saturated sand tends to hyperbolic softening. A mathematical model composed of a hyperbolic function and an inverted S‐shaped function was formulated to describe the multiphase characteristic, in which the setting of parameter p expands its applicability. The experimental result validated the model, showing that the model can better describe the monotonic stress‐strain relationship of calcareous sand. Besides, the physical meanings of model parameters were discussed.

ASSESSMENT OF SOLUTE TRANSPORT AND DISTRIBUTION UNDER DRY DRAINAGE CONDITIONS USING A PHYSICAL MODEL

AbstractResearchers have recently investigated dry drainage in respect of decreasing environmental effects and investment cost reduction of traditional drainage systems in arid and semi‐arid regions. This study investigated the effect of dry drainage on solute transport in a loamy soil using a physical model. The experiment lasted 84 days and results showed that the dry drainage system transferred a significant amount of dissolved salts from the irrigated area into the fallow area. Moreover, sodium, potassium, calcium, nitrate and chloride ions accumulated in the upper layers of soil of the fallow area but magnesium accumulated in the deeper layers. The ratios of sodium, potassium, calcium, magnesium, nitrate and chloride concentrations at the soil surface of the fallow area to the corresponding values in the irrigated area were 1.67, 1.20, 1.81, 0.90, 2.58 and 1.20, respectively. In addition, variation of SAR in the soil profile of the irrigated area was low and its value approached 1.58, but it increased with decreasing soil depths of the fallow area reaching 2.17 at the soil surface of this area. Although the results demonstrated the capability of dry drainage to transfer ions from the irrigated to the fallow area, further investigation regarding different aspects of this method is recommended. © 2019 John Wiley & Sons, Ltd.

Five-Year Experimental Study on Effectiveness and Sustainability of a Dry Drainage System for Controlling Soil Salinity

The dry drainage system (DDS) is an alternative technique for controlling salinization. To quantify its role in soil salinity control, a five-year field observation from 2007 to 2011 was completed in a 2900 ha experimental plot in Yonglian Experimental Station, Hetao Irrigation District, China. Results showed that the groundwater table depth in the fallow areas quickly responded to the lateral recharge from the surrounding croplands during irrigation events. The groundwater electrical conductivity (GEC) of fallow areas increased from 5 mS·cm−1 to 15 mS·cm−1, whereas the GEC below croplands produced small fluctuations. The analysis of water and salt balance showed that the excess water that moved to fallow was roughly four times that moved by an artificial drainage system and with 7.7 times the corresponding salt. The fallow areas act as a drainage repository to receive excess water and salt from surrounding irrigated croplands. Slight salt accumulation occurred in irrigated croplands and salts accumulated, with an accelerating trend over the final two years. The evaporation capability weakened, partly due to the salt crust in the topsoil, and the decrease in soil permeability in the soil column, which was almost impermeable to water. Using halophytes may be an effective method to remove salts that have accumulated in fallow areas, having great economic and ecological value. A DDS may be effective and sustainable in situations where the fallow areas can sustain an upward capillary flux from planted halophytes.

Extraction of dry drainage system based on independent component analysis and morphological characteristics

Extraction of dry drainage system based on independent component analysis and morphological characteristics

Numerical Evaluation of the Effects of Increasing Ratio of Cropped to Uncropped Width on Dry Drainage Efficiency in Salty Soils

AbstractSustainable agriculture can contribute to food security in arid and semi‐arid regions if soil salinity in the root zone is kept under control. Recently, experts have been concentrating their research towrds alternative and environmentally friendly solutions. In this study, dry drainage was evaluated as a sustainable and cost‐effective alternative technique, by means of both field experiments and a numeric approach based on the HYDRUS‐2D modelling environment. Results showed that soil salinity in the cropped area increased from the soil surface to the bottom, and soil salinity movement (transport direction) was from the cropped to uncropped area. Increasing the ratio of cropped to uncropped width led to an increase in soil salinity of the cropped root zone and lack of stabilization of salinity concentration. Results of modelling showed that there are no significant differences between observed and modelled data, even though HYDRUS‐2D simulated soil water content better than soil salinity. Averages of performance indices for simulated soil water content (SE = 0.08, NRMSE = 0.133) were better in comparison with simulated soil salinity (SE = 0.28, NRMSE = 0.262). Soil surface salinity in the cropped area increased 2.7 times (from 2.1 to 5.7 dS m−1) during the experiment for equal cropped to uncropped width (1 (cropped): 1 (uncropped)), and by increasing cropped width (2 (cropped): 1 (uncropped)) it increased 7.5 times (from 2.3 to 17.3 dS m−1). Copyright © 2017 John Wiley & Sons, Ltd.

Modeling and assessing the function and sustainability of natural patches in salt-affected agro-ecosystems: Application to tamarisk (Tamarix chinensis Lour.) in Hetao, upper Yellow River basin

Relatively low-lying zones of natural vegetation within irrigated areas are not only carriers of biodiversity but also dry drainage areas of excess water and salts applied to nearby croplands. It is thus useful to have a correct understanding of the soil water-salt dynamics and plant water use for keeping the sustainability of those natural areas. The HYDRUS-dualKc model that couples the HYDRUS-1D model with the FAO-56 dualKc approach was extended to simulate the eco-hydrological processes in natural patches of Hetao Irrigation District (Hetao), upper Yellow River basin. Field experiments were conducted in a tamarisk (Tamarix chinensis Lour.) dominated area during the growing seasons of 2012 and 2013. The model was calibrated and validated using the two-year experimental data, and applied to analyze the water and salt dynamics and the tamarisk water consumption for the present situation. Then, various groundwater depth (i.e. the depth from groundwater surface to water table, GWD) scenarios were simulated while considering the fluctuating and constant regimes of GWD changes, as well as variations of the rooting depth. Results indicated that this natural land functioned efficiently as a drainage area for subsurface flow and excess salt from surrounding croplands. However, the present GWDs were too shallow leading to high soil evaporation and severe salt stress. The soil evaporation accounted for 50% of the total evapotranspiration (ETa) while root zone salt storage increased about 50% during growing seasons. On the basis of scenario analysis, an optimum groundwater depth of 140–200 cm with smaller fluctuation was suggested for the growing seasons of natural patches. In addition, tamarisk growth could be largely improved if the roots can grow deeper with water table decline in the future. We demonstrated that monitoring and modeling could be used to support the development of water management strategies in Hetao aimed at conserving water while sustaining local ecosystems.

Health effects following subacute exposure to geogenic dust collected from active drainage surfaces (Nellis Dunes Recreation Area, Las Vegas, NV).

The specific health effects of direct inhalation of fine minerogenic dusts generated by natural soil surfaces remain poorly known and relatively little researched. To learn more about this exposure and its contribution to human health effects, we surveyed surface sediment and characterized dust from the Nellis Dunes Recreation Area (NDRA) in Clark County, Nevada, a popular off-road vehicle (ORV) recreational site. Dry drainage systems at NDRA are commonly used as natural trail systems for ORV recreation; these surfaces also are characterized by high concentrations of heavy metals. Geogenic dust with a median diameter of 4.05μm, collected from drainage surfaces at NDRA contained a total elemental concentration of aluminum (79,651μg/g), vanadium (100μg/g), chromium (54μg/g), manganese (753μg/g), iron (33,266μg/g), cobalt (14μg/g), copper (37μg/g) zinc (135μg/g), arsenic (71μg/g), strontium (666μg/g), cesium (15μg/g), lead (34μg/g), and uranium (54.9μg/g). Adult female B6C3F1 mice exposed via oropharyngeal aspiration to 0.01-100mgdust/kg body weight, four times, a week apart, for 28-days, were evaluated for immuno- and neurotoxicological outcomes 24h after the last exposure. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100mg/kg. Splenic lymphocytic subpopulations, hematological and clinical chemistry parameters were affected. In brain tissue, antibodies against NF-68, and GFAP were not affected, whereas IgM antibodies against MBP were reduced by 26.6% only in the highest dose group. A lowest observed adverse effect level (LOAEL) of 0.1mg/kg/day and a no observed adverse effect level (NOAEL) of 0.01mg/kg/day were derived based on the antigen primary IgM responses after subacute exposure to this geogenic dust.

Titus Phase Ceramics from the Pine Tree Farm Site (41WD51) in the Lake Fork Creek Basin, Wood County, Texas

The Pine Tree Farm site, an ancestral Caddo site occupied during the Titus phase (ca. A.D. 1430- 1680), was recorded by Bob D. Skiles in June 1977, on the basis of investigations conducted there by Skiles and James E. Bruseth, then a graduate student at Southern Methodist University, as well as work done by Skiles in 1970. The site is on a flat upland landform (400 ft. amsl) ca. 300 m northeast of Myrtle Springs Branch, a tributary to Dry Creek in the Lake Fork Creek drainage in the East Texas Pineywoods. The Goldsmith site (41WD208) is ca. 0.4 km to the east on Dry Creek, and several kilometers below the dam at Lake Quitman. The Dry Creek drainage basin, as well as the Caney Creek arm of Lake Fork Reservoir, have clusters of Late Caddo period Titus phase sites. The main known feature at the site was a large trash midden or midden mound that was ca. 20 x 22 m in size and approximately 35 cm in thickness. The midden deposits contained many Caddo ceramic vessel sherds, animal bones, mussel shell, charcoal and other charred plant remains (hickory nut shells), and ash deposits. Most of the trash midden was excavated in 1970, but there were intact midden deposits along the western and southern part of the trash midden, and in June 1977, several small units were excavated by Skiles and Bruseth in those areas. The ancestral Caddo ceramics discussed herein come from Units 2-4 in the southern part of the trash midden, but are not all of the sherds that were recovered in that work.

On the effectiveness of dry drainage in soil salinity control

Dry drainage is thought to be a potential approach to control soil salinity. This study took the Hetao Irrigation District as an example and evaluated the effectiveness of dry drainage by using remote sensing, a conceptual model and a field experiment. Archived remote sensing images from 1973–2006 were used to delineate the temporal and spatial change of soil salinity. The conceptual water and salt balance model was used to evaluate the role of dry drainage in removing excess salt from the irrigated land. The field experiment was performed to get field validation and give more accurate estimation. The results show that dry drainage did contribute to remove excess salt from the irrigated land and succeed in controlling soil salinity in the Hetao Irrigation District. It can be taken as an alternative approach in (semi-)arid area where artificial drainage is not applicable.

Heat and Mass Transport in the Unsaturated Porous Media: Application to the Soil Dry Drainage Method

Salinity currently has the highest priority of all environmental issues nowadays. The only means of preventing the development of soil salinity was combining leaching and artificial drainage. Recently a new method of capturing and removing salt from the soil surface called a dry drainage method [1-4] has been studied (fig.1) to help arid soils prevention against such threat. This work is a numerical simulation of the simultaneous water, solute and heat transfer in an unsaturated porous media during the simultaneous evaporation and drainage of saline dry land soils. A detailed mathematical model was formulated to describe the non-isothermal transport of water in the unsaturated porous media [5]. The model consists of the coupled conservative equations of mass for liquid phase, gas phase, water vapour, species and the energy. The boundary conditions at the soil–atmosphere interface include dynamical mass flux and energy flux. Comparison of numerical simulations with analytical results demonstrated that the present model is able to describe water and energy transport dynamics.

Prediction of future drawdown of water levels of the Pleistocene aquifer system of Wadi El-Assiuti Area, Eastern Desert, Egypt, as a criterion for management and conservation

Wadi El-Assiuti designates a remarkable dry drainage basin in Middle Egypt. The Pleistocene groundwater aquifer of this area represents the main water source used for reclamation and domestic purposes. The increasing number of groundwater wells drilled at the entrance of Wadi El-Assiuti in recent years, with its consequent over consumption of the groundwater reservoir, seems to be the clear-cut cause for groundwater levels drawdown and quantity deterioration. The constructed flow net map for the Pleistocene aquifer system sketched a pattern of piezometric pressures and flow directions. The regional water flow is from east–northeast towards west–southwest directions, with some adverse minor directions at the north-central part of the study area. This map declared the areas suffering from over pumping (piezometric lows). However, using empirical formulae and assumptions, the expected drop of piezometric levels of groundwater in the Pleistocene aquifer, as future scenarios, was predicted for 5, 10 and 20 years. These future scenarios reflected the urgent need for a policy or management scheme to decrease the severe drawdown of water level in this important developmental area.